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BASIC ELECTRONICS ENGINEERING 1 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. Department of Electronics & Telecommunication. Experiment No. : 01 Date of Performance: ----------------- Name of the student: --------------------------------------------------------------------------------------------- Division: --------------- Roll No. :--------------- Passive Components AIM: Study of Passive components Resistors, Capacitors, Inductors, Relays, Switches, Transformers, Connectors. PREREQUISITE: Knowledge of active components. Knowledge of passive components. Difference between active and passive components. OBJECTIVE: Types and subtypes of passive components. Applications of passive components. COMPONENTS: 1) Resistors, 2) Capacitors, 3) Inductors, 4) Relays, 5) Switches, 6) Transformers, 7) Connectors THEORY: Resistor A resistor is a two terminal electronic component that produces a voltage across its terminals that is proportional to the electric current through it in accordance with Ohm‘s law. V = I .R Where, V = Voltage across resistor I = Current flowing through resistor R = Resistance of the resistor Resistor having the physical material which resists the flow of electric current to some extent is called as resistor. Resistors are circuit element having function of offering electrical resistance in circuit. The resistance of a material with length ‗l‘ and area ‗A‘ is given by, R= ( * l) / A Where is the resistivity Classification of Resistor: A) Fixed Resistor: Fixed resistor are classified into 4 types based on various factors like manufacturing style, resistance range, power rating etc.
Transcript
Page 1: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 1

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 01 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Passive Components

AIM Study of Passive components ndash Resistors Capacitors Inductors Relays Switches

Transformers Connectors

PREREQUISITE

Knowledge of active components

Knowledge of passive components

Difference between active and passive components

OBJECTIVE

Types and subtypes of passive components

Applications of passive components

COMPONENTS

1) Resistors 2) Capacitors 3) Inductors 4) Relays 5) Switches 6) Transformers

7) Connectors

THEORY

Resistor

A resistor is a two terminal electronic component that produces a voltage across its terminals that is

proportional to the electric current through it in accordance with Ohmlsquos law

V = I R

Where V = Voltage across resistor

I = Current flowing through resistor

R = Resistance of the resistor

Resistor having the physical material which resists the flow of electric current to some extent is

called as resistor Resistors are circuit element having function of offering electrical resistance in

circuit The resistance of a material with length llsquo and area Alsquo is given by

R= ( l) A

Where is the resistivity

Classification of Resistor

A) Fixed Resistor Fixed resistor are classified into 4 types based on various factors like

manufacturing style resistance range power rating etc

BASIC ELECTRONICS ENGINEERING 2

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1) Carbon composition

2) Carbon film

3) Metal film (Thick and Thin film type)

4) Wire-wound (Power and Precision style type)

Symbol of Fixed Resistor

B) Variable Resistor Variable type resistor are used in electronic circuits to adjust the value

of voltages and currents For example it used in Television as volume control brightness

control etc There are three types of variable resistor

1) Potentiometer

2) Rheostat

3) Trimmer

Symbol of Variable resistor

Types of Fixed resistor

1) Carbon composition resistors

It is the most common type as they are cheap general purpose resistor Their resistive element is

manufactured from a mixture of finely ground carbon dust or graphite (similar to pencil lead) and

non-conducting ceramic (clay) powder to bind it all together

Carbon composition resistors are low to medium power resistors with low inductance which makes

them ideal for high frequency application but they can also suffer form noise and stability when

heat is dissipated in temperature

2) Carbon film and Metal film resistors

They are generally made by depositing pure metals such as nickel or an oxide film tin-oxide onto

an insulating ceramic rod or substrate

BASIC ELECTRONICS ENGINEERING 3

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The resistive value of the resistor is controlled by increasing the desired thickness of the film and

then by laser cutting a spiral helix groove type pattern into this film It has much better temperature

stability low noise and is generally better for high frequency or radio frequency applications

3) Wire wound resistors-

Wire wound resistor is made by winding a thin metal alloy wire (Nichrome) or similar wire onto on

insulating ceramic former in the form of a spiral helix similar to the film resistors These types of

resistors are generally only available in very low ohmic high precision values (from 001 to

100Kohm) due to gauge of the wire and number of turns possible on the former making them ideal

for use in measuring circuits and Wheatstone bridge type applications

Types of Variable resistor

1) Potentiometer

A potentiometer (colloquially known as ―pot) is a three terminal resistor with sliding contact that

forms an adjustable voltage divider

Where A and B fixed terminals

W is the variable terminal

2) Rheostat

The most common way to vary the resistance in a circuit is to use a variable resistor or a rheostat

A rheostat is two terminal variable resistors

Symbol of Rheostat Actual picture of Rheostat

They are designed to handle much higher voltage and current Typically these are constructed as a

resistive wire wrapped to form a toroid coil with the moving over the upper surface of toroid

sliding from one turn of the wire to next

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3) Trimmer

A trimmer is a miniature adjustable electrical component It is called trimmer potentiometer or

trimpots

Actual pictures of the trimmers

How to calculate the value of fixed resistor using colour code

There are four color bands which are painted on resistors First band indicates first digit second

band indicate second digit and third band indicates the decimal multiplier

1st color band First digit

2nd

color band Second digit

3rd

color band Decimal multiplier

4th color band Tolerance

By using following table we can calculate the fixed resistors values

Capacitor

An electric circuit element which is used to store charge temporarily consisting in general of two

metallic plates (conductors) separated and insulated from each other by a dielectric Also called

condenser

Symbol of Capacitor

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When a voltage potential difference exists between the conductors an electric field is present in the

dielectric An ideal capacitor is characterized by a single constant value capacitance which is

measured in farads This is the ratio of the electric charge on each conductor to the potential

difference between them

Capacitors are widely used in electronic circuits to block the flow of direct current while allowing

alternating current to pass to filter out interference to smooth the output of power supplies and for

many other purposes They are used in resonant circuits in radio frequency equipment to select

particular frequencies from a signal with many frequencies

Types of Capacitors

A) Fixed Capacitors Types of fixed capacitors are

1) Electrolytic capacitors Aluminum Electrolytic Capacitors are polarized and can be used in DC

circuits Typical values range form 01uF to 68000uF Ideal for use in filtering and smoothing

applications in power supplies Also used for coupling and bypassing in audio circuits and as a

timing element in non-critical circuits They have a high reliability and low leakage

2) Paper capacitor In these paper is used as dielectric They are used for high voltage and high

current applications Sometimes on surface of paper vapors deposition of Zn or Al metal is made to

avoid separate winding of metal foil and paper

3) Mica Capacitor Natural mica has significant advantages It is inert It will not change

physically or chemically with age and hence good temperature ability

a) Small mica capacitor

b) Transmitting mica capacitors

4) Glass Capacitor It is stable durable and practically immune to temperature aging voltage

moisture vibrations Aluminum foil is used glass is drawn to 1mm thick flexible layers of foil are

interleaved and then leads are attached Then assembly is fused at high temperature

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5) Ceramic Capacitors These are manufactured in many shapes and sizes depending on

applications Dielectric material for this capacitor is high temperature sintered inorganic

compound

Types of Ceramic capacitors are

1] Disc ceramic capacitors

2] Tubular ceramic capacitors

3] Monolithic Ceramic Capacitors

4] Button Cart wheel door knob ceramic capacitors

6) Aluminum Electronic Capacitors These are electro chemical devices Two aluminum foils

separated by insulting papers are wound into cylinder The roll is impregnated with liquid

electrolyte stabilized

Other types of electrolytic capacitors are

1] Tantalum electrolytic capacitors

2] Tantalum foils electrolytic capacitors

3] Wet slug Tantalum capacitors

4] Solid electrolyte Tantalum capacitors

B) Variable Capacitors

Variable capacitors are mostly used in radio tuning circuits and they are sometimes called tuning

capacitors having very small capacitance values typically between 100pF and 500pF

(100pF = 00001microF)

Actual pictures of variable capacitor and trimmer with its symbols respectively

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How to calculate the value of Capacitor using number coding and colour coding

Most capacitors have numbers printed on their bodies to indicate their electrical characteristics

Some are indicated with XYZ JKM VOLTS V where XYZ represents the capacitance (calculated

as XY x 10Z) the letters J K or M indicate the tolerance (plusmn5 plusmn10 and plusmn20 respectively) and

VOLTS V represents the working voltage

Example

A capacitor with the following text on its body

105 K 330 V has a capacitance of 10 x 105 pF = 1microF (plusmn10) with a working voltage of 330 V

A capacitor with the following text

473 M 100 V has a capacitance of 47 x 103 pF = 47 nF (plusmn20) with a working voltage of 100 V

A number code is often used on small capacitors where printing is difficult

The 1st number is the 1st digit

The 2nd number is the 2nd digit

The 3rd number is the number of zeros to give the capacitance in pF

Ignore any letters - they just indicate tolerance and voltage rating

For example 102 means 1000pF = 1nF (not 102pF)

For example 472J means 4700pF = 47nF (J means 5 tolerance)

It can be difficult to find the values of these small capacitors because there are many types of them

and several different labeling systems

Many small value capacitors have their value printed but without a multiplier so

you need to use experience to work out what the multiplier should be

For example 01 means 01microF = 100nF

Sometimes the multiplier is used in place of the decimal point

For example 4n7 means 47nF

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Color coding

Sr No Color Significant

digits

Multi-

pliers

Capacitance

tolerance

Characte

r-eristic

DC

working

voltage

Operating

temperature

1 Black 0 1 plusmn20 mdash mdash minus55 degC to +70

degC

2 Brown 1 10 plusmn1 B 100 mdash

3 Red 2 100 plusmn2 C mdash minus55 degC to

+85degC

4 Orange 3 1000 mdash D 300 mdash

5 Yellow 4 10000 mdash E mdash minus55 degC to

+125degC

6 Green 5 mdash plusmn5 F 500 mdash

7 Blue 6 mdash mdash mdash mdash minus55 degC to

+150 degC

8 Violet 7 mdash mdash mdash mdash mdash

9 Grey 8 mdash mdash mdash mdash mdash

10 White 9 mdash mdash mdash mdash mdash

11 Gold mdash mdash plusmn05 mdash 1000 mdash

12 Silver mdash mdash plusmn10 mdash mdash mdash

Or plusmn05 pF whichever is greater

A color code was used on polyester capacitors for many years The colors should be read like the

resistor code the top three color bands giving the value in pF Ignore the 4th band (tolerance) and

5th band (voltage rating)

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For example

Brown black orange means 10000pF = 10nF = 001microF

For example

Wide red yellow means 220nF = 022microF

(Note that there are no gaps between the color bands so 2 identical bands

actually appear as a wide band)Inductor

An inductor or a reactor is a passive electrical component that can store energy in a magnetic field

created by the electric current passing through it An inductors ability to store magnetic energy is

measured by its inductance in units of henries Typically an inductor is a conducting wire shaped

as a coil the loops helping to create a strong magnetic field inside the coil due to Faradays Law of

Induction Inductors are one of the basic electronic components used in electronics where current

and voltage change with time due to the ability of inductors to delay and reshape alternating

currents

Symbol of fixed inductor

Types of Inductor

1) Iron core Inductor This classification includes chokes and transformers both of which have

laminated iron cores A choke is a single winding and a transformer has two or more windings

Typical values of inductance for chokes range from 01 of a Henry to 50 henries Lamination

decreases eddy current losses

b) Air core Inductor It consists of number of turns of wire wound on a former made of cardboard

Since air is inside the former the inductor is called as air core inductor The only adjustment

available with air core inductors is by tapping all or part of a turn or by varying the spacing

between turns

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c) Ferrite core Inductor By inserting a ferrite or iron dust core in a coil it is possible to double its

inductance If the core is threaded its position within the coil can be varied to alter the inductance

This type of coil is used throughout the HF range and into the VHF for low-level signal circuits

Losses in the cores make them unsuitable for use in power circuits Values range from a few micro

henries to about a milli Henry

How to calculate the value of Inductor using color code

Some Radio Frequency chokes have their values indicated by a color code similar to that of

resistors

Applications

Filter chokes are used in smoothing pulsating current in rectifier Audio frequency chokes

are used to provide high impedance to audio frequencies Radio frequency chokes are used to block

the radio frequencies in communication systems

Switches

The term switch typically refers to electrical power or electronic telecommunication circuits In

applications where multiple switching options are required (eg a telephone service) mechanical

switches have long been replaced by electronic variants which can be intelligently controlled and

automated

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In the simplest case a switch has two pieces of metal called contacts that touch to make a circuit

and separate to break the circuit

There are different types of standard switches used in electronics

Type of Switch Circuit Symbol Example

1) ON-OFF Single Pole Single Throw =

SPST - A simple on-off switch Such

switches can be used to switch the power

supply to a circuit

SPST toggle switch

(ON)-OFF Push-to-make = SPST

Momentary - A push-to-make switch

returns to its normally open (off) position

when you release the button this is shown

by the brackets around ON This is the

standard doorbell switch

Push-to-make switch

ON-(OFF) Push-to-break = SPST

Momentary- A push-to-break switch

returns to its normally closed (on) position

when you release the button

Push-to-break switch

2) ON-ON Single Pole Double Throw =

SPDT - This switch can be on in both

positions switching on a separate device

in each case It is often called a

changeover switch A SPDT toggle

switch may be used as a simple on-off

switch by connecting to COM and one of

the A or B terminals shown in the

diagram

ON-OFF-ON SPDT Centre Off- A

special version of the standard SPDT

switch It has a third switching position in

the centre which is off Momentary (ON)-

OFF-(ON) versions are also available

where the switch returns to the central off

SPDT toggle switch

SPDT slide switch

(PCB mounting)

SPDT rocker switch

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position when released

3) Dual ON-OFF Double Pole Single

Throw = DPST- A pair of on-off switches

which operate together DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections

DPST rocker switch

Dual ON-ON Double Pole Double

Throw = DPDT- A pair of on-on switches

which operate together (shown by the

dotted line in the circuit symbol) A DPDT

switch can be wired up as a reversing

switch for a motor as shown in the

diagram

ON-OFF-ON DPDT Centre Off -

A special version of the standard SPDT

switch It has a third switching position in

the centre which is off This can be very

useful for motor control because you have

forward off and reverse positions

Momentary (ON)-OFF-(ON) versions are

also available where the switch returns to

the central off position when released

DPDT slide switch

Wiring for Reversing

Switch

Special Switches

Type of Switch Example

1) Push-Push Switch (eg SPST = ON-OFF) - This looks like a

momentary action push switch but it is a standard on-off switch

push once to switch on push again to switch off This is called a

latching action

2) Micro switch (usually SPDT = ON-ON)-Micro switches are

designed to switch fully open or closed in response to small

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

BASIC ELECTRONICS ENGINEERING 15

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

BASIC ELECTRONICS ENGINEERING 16

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

BASIC ELECTRONICS ENGINEERING 17

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

BASIC ELECTRONICS ENGINEERING 18

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

BASIC ELECTRONICS ENGINEERING 19

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

BASIC ELECTRONICS ENGINEERING 20

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

BASIC ELECTRONICS ENGINEERING 22

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BASIC ELECTRONICS ENGINEERING 23

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

BASIC ELECTRONICS ENGINEERING 26

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 2: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 2

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

1) Carbon composition

2) Carbon film

3) Metal film (Thick and Thin film type)

4) Wire-wound (Power and Precision style type)

Symbol of Fixed Resistor

B) Variable Resistor Variable type resistor are used in electronic circuits to adjust the value

of voltages and currents For example it used in Television as volume control brightness

control etc There are three types of variable resistor

1) Potentiometer

2) Rheostat

3) Trimmer

Symbol of Variable resistor

Types of Fixed resistor

1) Carbon composition resistors

It is the most common type as they are cheap general purpose resistor Their resistive element is

manufactured from a mixture of finely ground carbon dust or graphite (similar to pencil lead) and

non-conducting ceramic (clay) powder to bind it all together

Carbon composition resistors are low to medium power resistors with low inductance which makes

them ideal for high frequency application but they can also suffer form noise and stability when

heat is dissipated in temperature

2) Carbon film and Metal film resistors

They are generally made by depositing pure metals such as nickel or an oxide film tin-oxide onto

an insulating ceramic rod or substrate

BASIC ELECTRONICS ENGINEERING 3

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The resistive value of the resistor is controlled by increasing the desired thickness of the film and

then by laser cutting a spiral helix groove type pattern into this film It has much better temperature

stability low noise and is generally better for high frequency or radio frequency applications

3) Wire wound resistors-

Wire wound resistor is made by winding a thin metal alloy wire (Nichrome) or similar wire onto on

insulating ceramic former in the form of a spiral helix similar to the film resistors These types of

resistors are generally only available in very low ohmic high precision values (from 001 to

100Kohm) due to gauge of the wire and number of turns possible on the former making them ideal

for use in measuring circuits and Wheatstone bridge type applications

Types of Variable resistor

1) Potentiometer

A potentiometer (colloquially known as ―pot) is a three terminal resistor with sliding contact that

forms an adjustable voltage divider

Where A and B fixed terminals

W is the variable terminal

2) Rheostat

The most common way to vary the resistance in a circuit is to use a variable resistor or a rheostat

A rheostat is two terminal variable resistors

Symbol of Rheostat Actual picture of Rheostat

They are designed to handle much higher voltage and current Typically these are constructed as a

resistive wire wrapped to form a toroid coil with the moving over the upper surface of toroid

sliding from one turn of the wire to next

BASIC ELECTRONICS ENGINEERING 4

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3) Trimmer

A trimmer is a miniature adjustable electrical component It is called trimmer potentiometer or

trimpots

Actual pictures of the trimmers

How to calculate the value of fixed resistor using colour code

There are four color bands which are painted on resistors First band indicates first digit second

band indicate second digit and third band indicates the decimal multiplier

1st color band First digit

2nd

color band Second digit

3rd

color band Decimal multiplier

4th color band Tolerance

By using following table we can calculate the fixed resistors values

Capacitor

An electric circuit element which is used to store charge temporarily consisting in general of two

metallic plates (conductors) separated and insulated from each other by a dielectric Also called

condenser

Symbol of Capacitor

BASIC ELECTRONICS ENGINEERING 5

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When a voltage potential difference exists between the conductors an electric field is present in the

dielectric An ideal capacitor is characterized by a single constant value capacitance which is

measured in farads This is the ratio of the electric charge on each conductor to the potential

difference between them

Capacitors are widely used in electronic circuits to block the flow of direct current while allowing

alternating current to pass to filter out interference to smooth the output of power supplies and for

many other purposes They are used in resonant circuits in radio frequency equipment to select

particular frequencies from a signal with many frequencies

Types of Capacitors

A) Fixed Capacitors Types of fixed capacitors are

1) Electrolytic capacitors Aluminum Electrolytic Capacitors are polarized and can be used in DC

circuits Typical values range form 01uF to 68000uF Ideal for use in filtering and smoothing

applications in power supplies Also used for coupling and bypassing in audio circuits and as a

timing element in non-critical circuits They have a high reliability and low leakage

2) Paper capacitor In these paper is used as dielectric They are used for high voltage and high

current applications Sometimes on surface of paper vapors deposition of Zn or Al metal is made to

avoid separate winding of metal foil and paper

3) Mica Capacitor Natural mica has significant advantages It is inert It will not change

physically or chemically with age and hence good temperature ability

a) Small mica capacitor

b) Transmitting mica capacitors

4) Glass Capacitor It is stable durable and practically immune to temperature aging voltage

moisture vibrations Aluminum foil is used glass is drawn to 1mm thick flexible layers of foil are

interleaved and then leads are attached Then assembly is fused at high temperature

BASIC ELECTRONICS ENGINEERING 6

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5) Ceramic Capacitors These are manufactured in many shapes and sizes depending on

applications Dielectric material for this capacitor is high temperature sintered inorganic

compound

Types of Ceramic capacitors are

1] Disc ceramic capacitors

2] Tubular ceramic capacitors

3] Monolithic Ceramic Capacitors

4] Button Cart wheel door knob ceramic capacitors

6) Aluminum Electronic Capacitors These are electro chemical devices Two aluminum foils

separated by insulting papers are wound into cylinder The roll is impregnated with liquid

electrolyte stabilized

Other types of electrolytic capacitors are

1] Tantalum electrolytic capacitors

2] Tantalum foils electrolytic capacitors

3] Wet slug Tantalum capacitors

4] Solid electrolyte Tantalum capacitors

B) Variable Capacitors

Variable capacitors are mostly used in radio tuning circuits and they are sometimes called tuning

capacitors having very small capacitance values typically between 100pF and 500pF

(100pF = 00001microF)

Actual pictures of variable capacitor and trimmer with its symbols respectively

BASIC ELECTRONICS ENGINEERING 7

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How to calculate the value of Capacitor using number coding and colour coding

Most capacitors have numbers printed on their bodies to indicate their electrical characteristics

Some are indicated with XYZ JKM VOLTS V where XYZ represents the capacitance (calculated

as XY x 10Z) the letters J K or M indicate the tolerance (plusmn5 plusmn10 and plusmn20 respectively) and

VOLTS V represents the working voltage

Example

A capacitor with the following text on its body

105 K 330 V has a capacitance of 10 x 105 pF = 1microF (plusmn10) with a working voltage of 330 V

A capacitor with the following text

473 M 100 V has a capacitance of 47 x 103 pF = 47 nF (plusmn20) with a working voltage of 100 V

A number code is often used on small capacitors where printing is difficult

The 1st number is the 1st digit

The 2nd number is the 2nd digit

The 3rd number is the number of zeros to give the capacitance in pF

Ignore any letters - they just indicate tolerance and voltage rating

For example 102 means 1000pF = 1nF (not 102pF)

For example 472J means 4700pF = 47nF (J means 5 tolerance)

It can be difficult to find the values of these small capacitors because there are many types of them

and several different labeling systems

Many small value capacitors have their value printed but without a multiplier so

you need to use experience to work out what the multiplier should be

For example 01 means 01microF = 100nF

Sometimes the multiplier is used in place of the decimal point

For example 4n7 means 47nF

BASIC ELECTRONICS ENGINEERING 8

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Color coding

Sr No Color Significant

digits

Multi-

pliers

Capacitance

tolerance

Characte

r-eristic

DC

working

voltage

Operating

temperature

1 Black 0 1 plusmn20 mdash mdash minus55 degC to +70

degC

2 Brown 1 10 plusmn1 B 100 mdash

3 Red 2 100 plusmn2 C mdash minus55 degC to

+85degC

4 Orange 3 1000 mdash D 300 mdash

5 Yellow 4 10000 mdash E mdash minus55 degC to

+125degC

6 Green 5 mdash plusmn5 F 500 mdash

7 Blue 6 mdash mdash mdash mdash minus55 degC to

+150 degC

8 Violet 7 mdash mdash mdash mdash mdash

9 Grey 8 mdash mdash mdash mdash mdash

10 White 9 mdash mdash mdash mdash mdash

11 Gold mdash mdash plusmn05 mdash 1000 mdash

12 Silver mdash mdash plusmn10 mdash mdash mdash

Or plusmn05 pF whichever is greater

A color code was used on polyester capacitors for many years The colors should be read like the

resistor code the top three color bands giving the value in pF Ignore the 4th band (tolerance) and

5th band (voltage rating)

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For example

Brown black orange means 10000pF = 10nF = 001microF

For example

Wide red yellow means 220nF = 022microF

(Note that there are no gaps between the color bands so 2 identical bands

actually appear as a wide band)Inductor

An inductor or a reactor is a passive electrical component that can store energy in a magnetic field

created by the electric current passing through it An inductors ability to store magnetic energy is

measured by its inductance in units of henries Typically an inductor is a conducting wire shaped

as a coil the loops helping to create a strong magnetic field inside the coil due to Faradays Law of

Induction Inductors are one of the basic electronic components used in electronics where current

and voltage change with time due to the ability of inductors to delay and reshape alternating

currents

Symbol of fixed inductor

Types of Inductor

1) Iron core Inductor This classification includes chokes and transformers both of which have

laminated iron cores A choke is a single winding and a transformer has two or more windings

Typical values of inductance for chokes range from 01 of a Henry to 50 henries Lamination

decreases eddy current losses

b) Air core Inductor It consists of number of turns of wire wound on a former made of cardboard

Since air is inside the former the inductor is called as air core inductor The only adjustment

available with air core inductors is by tapping all or part of a turn or by varying the spacing

between turns

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c) Ferrite core Inductor By inserting a ferrite or iron dust core in a coil it is possible to double its

inductance If the core is threaded its position within the coil can be varied to alter the inductance

This type of coil is used throughout the HF range and into the VHF for low-level signal circuits

Losses in the cores make them unsuitable for use in power circuits Values range from a few micro

henries to about a milli Henry

How to calculate the value of Inductor using color code

Some Radio Frequency chokes have their values indicated by a color code similar to that of

resistors

Applications

Filter chokes are used in smoothing pulsating current in rectifier Audio frequency chokes

are used to provide high impedance to audio frequencies Radio frequency chokes are used to block

the radio frequencies in communication systems

Switches

The term switch typically refers to electrical power or electronic telecommunication circuits In

applications where multiple switching options are required (eg a telephone service) mechanical

switches have long been replaced by electronic variants which can be intelligently controlled and

automated

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In the simplest case a switch has two pieces of metal called contacts that touch to make a circuit

and separate to break the circuit

There are different types of standard switches used in electronics

Type of Switch Circuit Symbol Example

1) ON-OFF Single Pole Single Throw =

SPST - A simple on-off switch Such

switches can be used to switch the power

supply to a circuit

SPST toggle switch

(ON)-OFF Push-to-make = SPST

Momentary - A push-to-make switch

returns to its normally open (off) position

when you release the button this is shown

by the brackets around ON This is the

standard doorbell switch

Push-to-make switch

ON-(OFF) Push-to-break = SPST

Momentary- A push-to-break switch

returns to its normally closed (on) position

when you release the button

Push-to-break switch

2) ON-ON Single Pole Double Throw =

SPDT - This switch can be on in both

positions switching on a separate device

in each case It is often called a

changeover switch A SPDT toggle

switch may be used as a simple on-off

switch by connecting to COM and one of

the A or B terminals shown in the

diagram

ON-OFF-ON SPDT Centre Off- A

special version of the standard SPDT

switch It has a third switching position in

the centre which is off Momentary (ON)-

OFF-(ON) versions are also available

where the switch returns to the central off

SPDT toggle switch

SPDT slide switch

(PCB mounting)

SPDT rocker switch

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position when released

3) Dual ON-OFF Double Pole Single

Throw = DPST- A pair of on-off switches

which operate together DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections

DPST rocker switch

Dual ON-ON Double Pole Double

Throw = DPDT- A pair of on-on switches

which operate together (shown by the

dotted line in the circuit symbol) A DPDT

switch can be wired up as a reversing

switch for a motor as shown in the

diagram

ON-OFF-ON DPDT Centre Off -

A special version of the standard SPDT

switch It has a third switching position in

the centre which is off This can be very

useful for motor control because you have

forward off and reverse positions

Momentary (ON)-OFF-(ON) versions are

also available where the switch returns to

the central off position when released

DPDT slide switch

Wiring for Reversing

Switch

Special Switches

Type of Switch Example

1) Push-Push Switch (eg SPST = ON-OFF) - This looks like a

momentary action push switch but it is a standard on-off switch

push once to switch on push again to switch off This is called a

latching action

2) Micro switch (usually SPDT = ON-ON)-Micro switches are

designed to switch fully open or closed in response to small

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

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The resistive value of the resistor is controlled by increasing the desired thickness of the film and

then by laser cutting a spiral helix groove type pattern into this film It has much better temperature

stability low noise and is generally better for high frequency or radio frequency applications

3) Wire wound resistors-

Wire wound resistor is made by winding a thin metal alloy wire (Nichrome) or similar wire onto on

insulating ceramic former in the form of a spiral helix similar to the film resistors These types of

resistors are generally only available in very low ohmic high precision values (from 001 to

100Kohm) due to gauge of the wire and number of turns possible on the former making them ideal

for use in measuring circuits and Wheatstone bridge type applications

Types of Variable resistor

1) Potentiometer

A potentiometer (colloquially known as ―pot) is a three terminal resistor with sliding contact that

forms an adjustable voltage divider

Where A and B fixed terminals

W is the variable terminal

2) Rheostat

The most common way to vary the resistance in a circuit is to use a variable resistor or a rheostat

A rheostat is two terminal variable resistors

Symbol of Rheostat Actual picture of Rheostat

They are designed to handle much higher voltage and current Typically these are constructed as a

resistive wire wrapped to form a toroid coil with the moving over the upper surface of toroid

sliding from one turn of the wire to next

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3) Trimmer

A trimmer is a miniature adjustable electrical component It is called trimmer potentiometer or

trimpots

Actual pictures of the trimmers

How to calculate the value of fixed resistor using colour code

There are four color bands which are painted on resistors First band indicates first digit second

band indicate second digit and third band indicates the decimal multiplier

1st color band First digit

2nd

color band Second digit

3rd

color band Decimal multiplier

4th color band Tolerance

By using following table we can calculate the fixed resistors values

Capacitor

An electric circuit element which is used to store charge temporarily consisting in general of two

metallic plates (conductors) separated and insulated from each other by a dielectric Also called

condenser

Symbol of Capacitor

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When a voltage potential difference exists between the conductors an electric field is present in the

dielectric An ideal capacitor is characterized by a single constant value capacitance which is

measured in farads This is the ratio of the electric charge on each conductor to the potential

difference between them

Capacitors are widely used in electronic circuits to block the flow of direct current while allowing

alternating current to pass to filter out interference to smooth the output of power supplies and for

many other purposes They are used in resonant circuits in radio frequency equipment to select

particular frequencies from a signal with many frequencies

Types of Capacitors

A) Fixed Capacitors Types of fixed capacitors are

1) Electrolytic capacitors Aluminum Electrolytic Capacitors are polarized and can be used in DC

circuits Typical values range form 01uF to 68000uF Ideal for use in filtering and smoothing

applications in power supplies Also used for coupling and bypassing in audio circuits and as a

timing element in non-critical circuits They have a high reliability and low leakage

2) Paper capacitor In these paper is used as dielectric They are used for high voltage and high

current applications Sometimes on surface of paper vapors deposition of Zn or Al metal is made to

avoid separate winding of metal foil and paper

3) Mica Capacitor Natural mica has significant advantages It is inert It will not change

physically or chemically with age and hence good temperature ability

a) Small mica capacitor

b) Transmitting mica capacitors

4) Glass Capacitor It is stable durable and practically immune to temperature aging voltage

moisture vibrations Aluminum foil is used glass is drawn to 1mm thick flexible layers of foil are

interleaved and then leads are attached Then assembly is fused at high temperature

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5) Ceramic Capacitors These are manufactured in many shapes and sizes depending on

applications Dielectric material for this capacitor is high temperature sintered inorganic

compound

Types of Ceramic capacitors are

1] Disc ceramic capacitors

2] Tubular ceramic capacitors

3] Monolithic Ceramic Capacitors

4] Button Cart wheel door knob ceramic capacitors

6) Aluminum Electronic Capacitors These are electro chemical devices Two aluminum foils

separated by insulting papers are wound into cylinder The roll is impregnated with liquid

electrolyte stabilized

Other types of electrolytic capacitors are

1] Tantalum electrolytic capacitors

2] Tantalum foils electrolytic capacitors

3] Wet slug Tantalum capacitors

4] Solid electrolyte Tantalum capacitors

B) Variable Capacitors

Variable capacitors are mostly used in radio tuning circuits and they are sometimes called tuning

capacitors having very small capacitance values typically between 100pF and 500pF

(100pF = 00001microF)

Actual pictures of variable capacitor and trimmer with its symbols respectively

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How to calculate the value of Capacitor using number coding and colour coding

Most capacitors have numbers printed on their bodies to indicate their electrical characteristics

Some are indicated with XYZ JKM VOLTS V where XYZ represents the capacitance (calculated

as XY x 10Z) the letters J K or M indicate the tolerance (plusmn5 plusmn10 and plusmn20 respectively) and

VOLTS V represents the working voltage

Example

A capacitor with the following text on its body

105 K 330 V has a capacitance of 10 x 105 pF = 1microF (plusmn10) with a working voltage of 330 V

A capacitor with the following text

473 M 100 V has a capacitance of 47 x 103 pF = 47 nF (plusmn20) with a working voltage of 100 V

A number code is often used on small capacitors where printing is difficult

The 1st number is the 1st digit

The 2nd number is the 2nd digit

The 3rd number is the number of zeros to give the capacitance in pF

Ignore any letters - they just indicate tolerance and voltage rating

For example 102 means 1000pF = 1nF (not 102pF)

For example 472J means 4700pF = 47nF (J means 5 tolerance)

It can be difficult to find the values of these small capacitors because there are many types of them

and several different labeling systems

Many small value capacitors have their value printed but without a multiplier so

you need to use experience to work out what the multiplier should be

For example 01 means 01microF = 100nF

Sometimes the multiplier is used in place of the decimal point

For example 4n7 means 47nF

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Color coding

Sr No Color Significant

digits

Multi-

pliers

Capacitance

tolerance

Characte

r-eristic

DC

working

voltage

Operating

temperature

1 Black 0 1 plusmn20 mdash mdash minus55 degC to +70

degC

2 Brown 1 10 plusmn1 B 100 mdash

3 Red 2 100 plusmn2 C mdash minus55 degC to

+85degC

4 Orange 3 1000 mdash D 300 mdash

5 Yellow 4 10000 mdash E mdash minus55 degC to

+125degC

6 Green 5 mdash plusmn5 F 500 mdash

7 Blue 6 mdash mdash mdash mdash minus55 degC to

+150 degC

8 Violet 7 mdash mdash mdash mdash mdash

9 Grey 8 mdash mdash mdash mdash mdash

10 White 9 mdash mdash mdash mdash mdash

11 Gold mdash mdash plusmn05 mdash 1000 mdash

12 Silver mdash mdash plusmn10 mdash mdash mdash

Or plusmn05 pF whichever is greater

A color code was used on polyester capacitors for many years The colors should be read like the

resistor code the top three color bands giving the value in pF Ignore the 4th band (tolerance) and

5th band (voltage rating)

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For example

Brown black orange means 10000pF = 10nF = 001microF

For example

Wide red yellow means 220nF = 022microF

(Note that there are no gaps between the color bands so 2 identical bands

actually appear as a wide band)Inductor

An inductor or a reactor is a passive electrical component that can store energy in a magnetic field

created by the electric current passing through it An inductors ability to store magnetic energy is

measured by its inductance in units of henries Typically an inductor is a conducting wire shaped

as a coil the loops helping to create a strong magnetic field inside the coil due to Faradays Law of

Induction Inductors are one of the basic electronic components used in electronics where current

and voltage change with time due to the ability of inductors to delay and reshape alternating

currents

Symbol of fixed inductor

Types of Inductor

1) Iron core Inductor This classification includes chokes and transformers both of which have

laminated iron cores A choke is a single winding and a transformer has two or more windings

Typical values of inductance for chokes range from 01 of a Henry to 50 henries Lamination

decreases eddy current losses

b) Air core Inductor It consists of number of turns of wire wound on a former made of cardboard

Since air is inside the former the inductor is called as air core inductor The only adjustment

available with air core inductors is by tapping all or part of a turn or by varying the spacing

between turns

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c) Ferrite core Inductor By inserting a ferrite or iron dust core in a coil it is possible to double its

inductance If the core is threaded its position within the coil can be varied to alter the inductance

This type of coil is used throughout the HF range and into the VHF for low-level signal circuits

Losses in the cores make them unsuitable for use in power circuits Values range from a few micro

henries to about a milli Henry

How to calculate the value of Inductor using color code

Some Radio Frequency chokes have their values indicated by a color code similar to that of

resistors

Applications

Filter chokes are used in smoothing pulsating current in rectifier Audio frequency chokes

are used to provide high impedance to audio frequencies Radio frequency chokes are used to block

the radio frequencies in communication systems

Switches

The term switch typically refers to electrical power or electronic telecommunication circuits In

applications where multiple switching options are required (eg a telephone service) mechanical

switches have long been replaced by electronic variants which can be intelligently controlled and

automated

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In the simplest case a switch has two pieces of metal called contacts that touch to make a circuit

and separate to break the circuit

There are different types of standard switches used in electronics

Type of Switch Circuit Symbol Example

1) ON-OFF Single Pole Single Throw =

SPST - A simple on-off switch Such

switches can be used to switch the power

supply to a circuit

SPST toggle switch

(ON)-OFF Push-to-make = SPST

Momentary - A push-to-make switch

returns to its normally open (off) position

when you release the button this is shown

by the brackets around ON This is the

standard doorbell switch

Push-to-make switch

ON-(OFF) Push-to-break = SPST

Momentary- A push-to-break switch

returns to its normally closed (on) position

when you release the button

Push-to-break switch

2) ON-ON Single Pole Double Throw =

SPDT - This switch can be on in both

positions switching on a separate device

in each case It is often called a

changeover switch A SPDT toggle

switch may be used as a simple on-off

switch by connecting to COM and one of

the A or B terminals shown in the

diagram

ON-OFF-ON SPDT Centre Off- A

special version of the standard SPDT

switch It has a third switching position in

the centre which is off Momentary (ON)-

OFF-(ON) versions are also available

where the switch returns to the central off

SPDT toggle switch

SPDT slide switch

(PCB mounting)

SPDT rocker switch

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position when released

3) Dual ON-OFF Double Pole Single

Throw = DPST- A pair of on-off switches

which operate together DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections

DPST rocker switch

Dual ON-ON Double Pole Double

Throw = DPDT- A pair of on-on switches

which operate together (shown by the

dotted line in the circuit symbol) A DPDT

switch can be wired up as a reversing

switch for a motor as shown in the

diagram

ON-OFF-ON DPDT Centre Off -

A special version of the standard SPDT

switch It has a third switching position in

the centre which is off This can be very

useful for motor control because you have

forward off and reverse positions

Momentary (ON)-OFF-(ON) versions are

also available where the switch returns to

the central off position when released

DPDT slide switch

Wiring for Reversing

Switch

Special Switches

Type of Switch Example

1) Push-Push Switch (eg SPST = ON-OFF) - This looks like a

momentary action push switch but it is a standard on-off switch

push once to switch on push again to switch off This is called a

latching action

2) Micro switch (usually SPDT = ON-ON)-Micro switches are

designed to switch fully open or closed in response to small

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

BASIC ELECTRONICS ENGINEERING 19

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 4: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 4

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

3) Trimmer

A trimmer is a miniature adjustable electrical component It is called trimmer potentiometer or

trimpots

Actual pictures of the trimmers

How to calculate the value of fixed resistor using colour code

There are four color bands which are painted on resistors First band indicates first digit second

band indicate second digit and third band indicates the decimal multiplier

1st color band First digit

2nd

color band Second digit

3rd

color band Decimal multiplier

4th color band Tolerance

By using following table we can calculate the fixed resistors values

Capacitor

An electric circuit element which is used to store charge temporarily consisting in general of two

metallic plates (conductors) separated and insulated from each other by a dielectric Also called

condenser

Symbol of Capacitor

BASIC ELECTRONICS ENGINEERING 5

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When a voltage potential difference exists between the conductors an electric field is present in the

dielectric An ideal capacitor is characterized by a single constant value capacitance which is

measured in farads This is the ratio of the electric charge on each conductor to the potential

difference between them

Capacitors are widely used in electronic circuits to block the flow of direct current while allowing

alternating current to pass to filter out interference to smooth the output of power supplies and for

many other purposes They are used in resonant circuits in radio frequency equipment to select

particular frequencies from a signal with many frequencies

Types of Capacitors

A) Fixed Capacitors Types of fixed capacitors are

1) Electrolytic capacitors Aluminum Electrolytic Capacitors are polarized and can be used in DC

circuits Typical values range form 01uF to 68000uF Ideal for use in filtering and smoothing

applications in power supplies Also used for coupling and bypassing in audio circuits and as a

timing element in non-critical circuits They have a high reliability and low leakage

2) Paper capacitor In these paper is used as dielectric They are used for high voltage and high

current applications Sometimes on surface of paper vapors deposition of Zn or Al metal is made to

avoid separate winding of metal foil and paper

3) Mica Capacitor Natural mica has significant advantages It is inert It will not change

physically or chemically with age and hence good temperature ability

a) Small mica capacitor

b) Transmitting mica capacitors

4) Glass Capacitor It is stable durable and practically immune to temperature aging voltage

moisture vibrations Aluminum foil is used glass is drawn to 1mm thick flexible layers of foil are

interleaved and then leads are attached Then assembly is fused at high temperature

BASIC ELECTRONICS ENGINEERING 6

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5) Ceramic Capacitors These are manufactured in many shapes and sizes depending on

applications Dielectric material for this capacitor is high temperature sintered inorganic

compound

Types of Ceramic capacitors are

1] Disc ceramic capacitors

2] Tubular ceramic capacitors

3] Monolithic Ceramic Capacitors

4] Button Cart wheel door knob ceramic capacitors

6) Aluminum Electronic Capacitors These are electro chemical devices Two aluminum foils

separated by insulting papers are wound into cylinder The roll is impregnated with liquid

electrolyte stabilized

Other types of electrolytic capacitors are

1] Tantalum electrolytic capacitors

2] Tantalum foils electrolytic capacitors

3] Wet slug Tantalum capacitors

4] Solid electrolyte Tantalum capacitors

B) Variable Capacitors

Variable capacitors are mostly used in radio tuning circuits and they are sometimes called tuning

capacitors having very small capacitance values typically between 100pF and 500pF

(100pF = 00001microF)

Actual pictures of variable capacitor and trimmer with its symbols respectively

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How to calculate the value of Capacitor using number coding and colour coding

Most capacitors have numbers printed on their bodies to indicate their electrical characteristics

Some are indicated with XYZ JKM VOLTS V where XYZ represents the capacitance (calculated

as XY x 10Z) the letters J K or M indicate the tolerance (plusmn5 plusmn10 and plusmn20 respectively) and

VOLTS V represents the working voltage

Example

A capacitor with the following text on its body

105 K 330 V has a capacitance of 10 x 105 pF = 1microF (plusmn10) with a working voltage of 330 V

A capacitor with the following text

473 M 100 V has a capacitance of 47 x 103 pF = 47 nF (plusmn20) with a working voltage of 100 V

A number code is often used on small capacitors where printing is difficult

The 1st number is the 1st digit

The 2nd number is the 2nd digit

The 3rd number is the number of zeros to give the capacitance in pF

Ignore any letters - they just indicate tolerance and voltage rating

For example 102 means 1000pF = 1nF (not 102pF)

For example 472J means 4700pF = 47nF (J means 5 tolerance)

It can be difficult to find the values of these small capacitors because there are many types of them

and several different labeling systems

Many small value capacitors have their value printed but without a multiplier so

you need to use experience to work out what the multiplier should be

For example 01 means 01microF = 100nF

Sometimes the multiplier is used in place of the decimal point

For example 4n7 means 47nF

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Color coding

Sr No Color Significant

digits

Multi-

pliers

Capacitance

tolerance

Characte

r-eristic

DC

working

voltage

Operating

temperature

1 Black 0 1 plusmn20 mdash mdash minus55 degC to +70

degC

2 Brown 1 10 plusmn1 B 100 mdash

3 Red 2 100 plusmn2 C mdash minus55 degC to

+85degC

4 Orange 3 1000 mdash D 300 mdash

5 Yellow 4 10000 mdash E mdash minus55 degC to

+125degC

6 Green 5 mdash plusmn5 F 500 mdash

7 Blue 6 mdash mdash mdash mdash minus55 degC to

+150 degC

8 Violet 7 mdash mdash mdash mdash mdash

9 Grey 8 mdash mdash mdash mdash mdash

10 White 9 mdash mdash mdash mdash mdash

11 Gold mdash mdash plusmn05 mdash 1000 mdash

12 Silver mdash mdash plusmn10 mdash mdash mdash

Or plusmn05 pF whichever is greater

A color code was used on polyester capacitors for many years The colors should be read like the

resistor code the top three color bands giving the value in pF Ignore the 4th band (tolerance) and

5th band (voltage rating)

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For example

Brown black orange means 10000pF = 10nF = 001microF

For example

Wide red yellow means 220nF = 022microF

(Note that there are no gaps between the color bands so 2 identical bands

actually appear as a wide band)Inductor

An inductor or a reactor is a passive electrical component that can store energy in a magnetic field

created by the electric current passing through it An inductors ability to store magnetic energy is

measured by its inductance in units of henries Typically an inductor is a conducting wire shaped

as a coil the loops helping to create a strong magnetic field inside the coil due to Faradays Law of

Induction Inductors are one of the basic electronic components used in electronics where current

and voltage change with time due to the ability of inductors to delay and reshape alternating

currents

Symbol of fixed inductor

Types of Inductor

1) Iron core Inductor This classification includes chokes and transformers both of which have

laminated iron cores A choke is a single winding and a transformer has two or more windings

Typical values of inductance for chokes range from 01 of a Henry to 50 henries Lamination

decreases eddy current losses

b) Air core Inductor It consists of number of turns of wire wound on a former made of cardboard

Since air is inside the former the inductor is called as air core inductor The only adjustment

available with air core inductors is by tapping all or part of a turn or by varying the spacing

between turns

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c) Ferrite core Inductor By inserting a ferrite or iron dust core in a coil it is possible to double its

inductance If the core is threaded its position within the coil can be varied to alter the inductance

This type of coil is used throughout the HF range and into the VHF for low-level signal circuits

Losses in the cores make them unsuitable for use in power circuits Values range from a few micro

henries to about a milli Henry

How to calculate the value of Inductor using color code

Some Radio Frequency chokes have their values indicated by a color code similar to that of

resistors

Applications

Filter chokes are used in smoothing pulsating current in rectifier Audio frequency chokes

are used to provide high impedance to audio frequencies Radio frequency chokes are used to block

the radio frequencies in communication systems

Switches

The term switch typically refers to electrical power or electronic telecommunication circuits In

applications where multiple switching options are required (eg a telephone service) mechanical

switches have long been replaced by electronic variants which can be intelligently controlled and

automated

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In the simplest case a switch has two pieces of metal called contacts that touch to make a circuit

and separate to break the circuit

There are different types of standard switches used in electronics

Type of Switch Circuit Symbol Example

1) ON-OFF Single Pole Single Throw =

SPST - A simple on-off switch Such

switches can be used to switch the power

supply to a circuit

SPST toggle switch

(ON)-OFF Push-to-make = SPST

Momentary - A push-to-make switch

returns to its normally open (off) position

when you release the button this is shown

by the brackets around ON This is the

standard doorbell switch

Push-to-make switch

ON-(OFF) Push-to-break = SPST

Momentary- A push-to-break switch

returns to its normally closed (on) position

when you release the button

Push-to-break switch

2) ON-ON Single Pole Double Throw =

SPDT - This switch can be on in both

positions switching on a separate device

in each case It is often called a

changeover switch A SPDT toggle

switch may be used as a simple on-off

switch by connecting to COM and one of

the A or B terminals shown in the

diagram

ON-OFF-ON SPDT Centre Off- A

special version of the standard SPDT

switch It has a third switching position in

the centre which is off Momentary (ON)-

OFF-(ON) versions are also available

where the switch returns to the central off

SPDT toggle switch

SPDT slide switch

(PCB mounting)

SPDT rocker switch

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position when released

3) Dual ON-OFF Double Pole Single

Throw = DPST- A pair of on-off switches

which operate together DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections

DPST rocker switch

Dual ON-ON Double Pole Double

Throw = DPDT- A pair of on-on switches

which operate together (shown by the

dotted line in the circuit symbol) A DPDT

switch can be wired up as a reversing

switch for a motor as shown in the

diagram

ON-OFF-ON DPDT Centre Off -

A special version of the standard SPDT

switch It has a third switching position in

the centre which is off This can be very

useful for motor control because you have

forward off and reverse positions

Momentary (ON)-OFF-(ON) versions are

also available where the switch returns to

the central off position when released

DPDT slide switch

Wiring for Reversing

Switch

Special Switches

Type of Switch Example

1) Push-Push Switch (eg SPST = ON-OFF) - This looks like a

momentary action push switch but it is a standard on-off switch

push once to switch on push again to switch off This is called a

latching action

2) Micro switch (usually SPDT = ON-ON)-Micro switches are

designed to switch fully open or closed in response to small

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

BASIC ELECTRONICS ENGINEERING 35

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 5: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 5

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

When a voltage potential difference exists between the conductors an electric field is present in the

dielectric An ideal capacitor is characterized by a single constant value capacitance which is

measured in farads This is the ratio of the electric charge on each conductor to the potential

difference between them

Capacitors are widely used in electronic circuits to block the flow of direct current while allowing

alternating current to pass to filter out interference to smooth the output of power supplies and for

many other purposes They are used in resonant circuits in radio frequency equipment to select

particular frequencies from a signal with many frequencies

Types of Capacitors

A) Fixed Capacitors Types of fixed capacitors are

1) Electrolytic capacitors Aluminum Electrolytic Capacitors are polarized and can be used in DC

circuits Typical values range form 01uF to 68000uF Ideal for use in filtering and smoothing

applications in power supplies Also used for coupling and bypassing in audio circuits and as a

timing element in non-critical circuits They have a high reliability and low leakage

2) Paper capacitor In these paper is used as dielectric They are used for high voltage and high

current applications Sometimes on surface of paper vapors deposition of Zn or Al metal is made to

avoid separate winding of metal foil and paper

3) Mica Capacitor Natural mica has significant advantages It is inert It will not change

physically or chemically with age and hence good temperature ability

a) Small mica capacitor

b) Transmitting mica capacitors

4) Glass Capacitor It is stable durable and practically immune to temperature aging voltage

moisture vibrations Aluminum foil is used glass is drawn to 1mm thick flexible layers of foil are

interleaved and then leads are attached Then assembly is fused at high temperature

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5) Ceramic Capacitors These are manufactured in many shapes and sizes depending on

applications Dielectric material for this capacitor is high temperature sintered inorganic

compound

Types of Ceramic capacitors are

1] Disc ceramic capacitors

2] Tubular ceramic capacitors

3] Monolithic Ceramic Capacitors

4] Button Cart wheel door knob ceramic capacitors

6) Aluminum Electronic Capacitors These are electro chemical devices Two aluminum foils

separated by insulting papers are wound into cylinder The roll is impregnated with liquid

electrolyte stabilized

Other types of electrolytic capacitors are

1] Tantalum electrolytic capacitors

2] Tantalum foils electrolytic capacitors

3] Wet slug Tantalum capacitors

4] Solid electrolyte Tantalum capacitors

B) Variable Capacitors

Variable capacitors are mostly used in radio tuning circuits and they are sometimes called tuning

capacitors having very small capacitance values typically between 100pF and 500pF

(100pF = 00001microF)

Actual pictures of variable capacitor and trimmer with its symbols respectively

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How to calculate the value of Capacitor using number coding and colour coding

Most capacitors have numbers printed on their bodies to indicate their electrical characteristics

Some are indicated with XYZ JKM VOLTS V where XYZ represents the capacitance (calculated

as XY x 10Z) the letters J K or M indicate the tolerance (plusmn5 plusmn10 and plusmn20 respectively) and

VOLTS V represents the working voltage

Example

A capacitor with the following text on its body

105 K 330 V has a capacitance of 10 x 105 pF = 1microF (plusmn10) with a working voltage of 330 V

A capacitor with the following text

473 M 100 V has a capacitance of 47 x 103 pF = 47 nF (plusmn20) with a working voltage of 100 V

A number code is often used on small capacitors where printing is difficult

The 1st number is the 1st digit

The 2nd number is the 2nd digit

The 3rd number is the number of zeros to give the capacitance in pF

Ignore any letters - they just indicate tolerance and voltage rating

For example 102 means 1000pF = 1nF (not 102pF)

For example 472J means 4700pF = 47nF (J means 5 tolerance)

It can be difficult to find the values of these small capacitors because there are many types of them

and several different labeling systems

Many small value capacitors have their value printed but without a multiplier so

you need to use experience to work out what the multiplier should be

For example 01 means 01microF = 100nF

Sometimes the multiplier is used in place of the decimal point

For example 4n7 means 47nF

BASIC ELECTRONICS ENGINEERING 8

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Color coding

Sr No Color Significant

digits

Multi-

pliers

Capacitance

tolerance

Characte

r-eristic

DC

working

voltage

Operating

temperature

1 Black 0 1 plusmn20 mdash mdash minus55 degC to +70

degC

2 Brown 1 10 plusmn1 B 100 mdash

3 Red 2 100 plusmn2 C mdash minus55 degC to

+85degC

4 Orange 3 1000 mdash D 300 mdash

5 Yellow 4 10000 mdash E mdash minus55 degC to

+125degC

6 Green 5 mdash plusmn5 F 500 mdash

7 Blue 6 mdash mdash mdash mdash minus55 degC to

+150 degC

8 Violet 7 mdash mdash mdash mdash mdash

9 Grey 8 mdash mdash mdash mdash mdash

10 White 9 mdash mdash mdash mdash mdash

11 Gold mdash mdash plusmn05 mdash 1000 mdash

12 Silver mdash mdash plusmn10 mdash mdash mdash

Or plusmn05 pF whichever is greater

A color code was used on polyester capacitors for many years The colors should be read like the

resistor code the top three color bands giving the value in pF Ignore the 4th band (tolerance) and

5th band (voltage rating)

BASIC ELECTRONICS ENGINEERING 9

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For example

Brown black orange means 10000pF = 10nF = 001microF

For example

Wide red yellow means 220nF = 022microF

(Note that there are no gaps between the color bands so 2 identical bands

actually appear as a wide band)Inductor

An inductor or a reactor is a passive electrical component that can store energy in a magnetic field

created by the electric current passing through it An inductors ability to store magnetic energy is

measured by its inductance in units of henries Typically an inductor is a conducting wire shaped

as a coil the loops helping to create a strong magnetic field inside the coil due to Faradays Law of

Induction Inductors are one of the basic electronic components used in electronics where current

and voltage change with time due to the ability of inductors to delay and reshape alternating

currents

Symbol of fixed inductor

Types of Inductor

1) Iron core Inductor This classification includes chokes and transformers both of which have

laminated iron cores A choke is a single winding and a transformer has two or more windings

Typical values of inductance for chokes range from 01 of a Henry to 50 henries Lamination

decreases eddy current losses

b) Air core Inductor It consists of number of turns of wire wound on a former made of cardboard

Since air is inside the former the inductor is called as air core inductor The only adjustment

available with air core inductors is by tapping all or part of a turn or by varying the spacing

between turns

BASIC ELECTRONICS ENGINEERING 10

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c) Ferrite core Inductor By inserting a ferrite or iron dust core in a coil it is possible to double its

inductance If the core is threaded its position within the coil can be varied to alter the inductance

This type of coil is used throughout the HF range and into the VHF for low-level signal circuits

Losses in the cores make them unsuitable for use in power circuits Values range from a few micro

henries to about a milli Henry

How to calculate the value of Inductor using color code

Some Radio Frequency chokes have their values indicated by a color code similar to that of

resistors

Applications

Filter chokes are used in smoothing pulsating current in rectifier Audio frequency chokes

are used to provide high impedance to audio frequencies Radio frequency chokes are used to block

the radio frequencies in communication systems

Switches

The term switch typically refers to electrical power or electronic telecommunication circuits In

applications where multiple switching options are required (eg a telephone service) mechanical

switches have long been replaced by electronic variants which can be intelligently controlled and

automated

BASIC ELECTRONICS ENGINEERING 11

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In the simplest case a switch has two pieces of metal called contacts that touch to make a circuit

and separate to break the circuit

There are different types of standard switches used in electronics

Type of Switch Circuit Symbol Example

1) ON-OFF Single Pole Single Throw =

SPST - A simple on-off switch Such

switches can be used to switch the power

supply to a circuit

SPST toggle switch

(ON)-OFF Push-to-make = SPST

Momentary - A push-to-make switch

returns to its normally open (off) position

when you release the button this is shown

by the brackets around ON This is the

standard doorbell switch

Push-to-make switch

ON-(OFF) Push-to-break = SPST

Momentary- A push-to-break switch

returns to its normally closed (on) position

when you release the button

Push-to-break switch

2) ON-ON Single Pole Double Throw =

SPDT - This switch can be on in both

positions switching on a separate device

in each case It is often called a

changeover switch A SPDT toggle

switch may be used as a simple on-off

switch by connecting to COM and one of

the A or B terminals shown in the

diagram

ON-OFF-ON SPDT Centre Off- A

special version of the standard SPDT

switch It has a third switching position in

the centre which is off Momentary (ON)-

OFF-(ON) versions are also available

where the switch returns to the central off

SPDT toggle switch

SPDT slide switch

(PCB mounting)

SPDT rocker switch

BASIC ELECTRONICS ENGINEERING 12

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position when released

3) Dual ON-OFF Double Pole Single

Throw = DPST- A pair of on-off switches

which operate together DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections

DPST rocker switch

Dual ON-ON Double Pole Double

Throw = DPDT- A pair of on-on switches

which operate together (shown by the

dotted line in the circuit symbol) A DPDT

switch can be wired up as a reversing

switch for a motor as shown in the

diagram

ON-OFF-ON DPDT Centre Off -

A special version of the standard SPDT

switch It has a third switching position in

the centre which is off This can be very

useful for motor control because you have

forward off and reverse positions

Momentary (ON)-OFF-(ON) versions are

also available where the switch returns to

the central off position when released

DPDT slide switch

Wiring for Reversing

Switch

Special Switches

Type of Switch Example

1) Push-Push Switch (eg SPST = ON-OFF) - This looks like a

momentary action push switch but it is a standard on-off switch

push once to switch on push again to switch off This is called a

latching action

2) Micro switch (usually SPDT = ON-ON)-Micro switches are

designed to switch fully open or closed in response to small

BASIC ELECTRONICS ENGINEERING 13

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

BASIC ELECTRONICS ENGINEERING 14

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

BASIC ELECTRONICS ENGINEERING 15

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

BASIC ELECTRONICS ENGINEERING 16

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

BASIC ELECTRONICS ENGINEERING 17

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

BASIC ELECTRONICS ENGINEERING 18

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 6: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 6

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

5) Ceramic Capacitors These are manufactured in many shapes and sizes depending on

applications Dielectric material for this capacitor is high temperature sintered inorganic

compound

Types of Ceramic capacitors are

1] Disc ceramic capacitors

2] Tubular ceramic capacitors

3] Monolithic Ceramic Capacitors

4] Button Cart wheel door knob ceramic capacitors

6) Aluminum Electronic Capacitors These are electro chemical devices Two aluminum foils

separated by insulting papers are wound into cylinder The roll is impregnated with liquid

electrolyte stabilized

Other types of electrolytic capacitors are

1] Tantalum electrolytic capacitors

2] Tantalum foils electrolytic capacitors

3] Wet slug Tantalum capacitors

4] Solid electrolyte Tantalum capacitors

B) Variable Capacitors

Variable capacitors are mostly used in radio tuning circuits and they are sometimes called tuning

capacitors having very small capacitance values typically between 100pF and 500pF

(100pF = 00001microF)

Actual pictures of variable capacitor and trimmer with its symbols respectively

BASIC ELECTRONICS ENGINEERING 7

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How to calculate the value of Capacitor using number coding and colour coding

Most capacitors have numbers printed on their bodies to indicate their electrical characteristics

Some are indicated with XYZ JKM VOLTS V where XYZ represents the capacitance (calculated

as XY x 10Z) the letters J K or M indicate the tolerance (plusmn5 plusmn10 and plusmn20 respectively) and

VOLTS V represents the working voltage

Example

A capacitor with the following text on its body

105 K 330 V has a capacitance of 10 x 105 pF = 1microF (plusmn10) with a working voltage of 330 V

A capacitor with the following text

473 M 100 V has a capacitance of 47 x 103 pF = 47 nF (plusmn20) with a working voltage of 100 V

A number code is often used on small capacitors where printing is difficult

The 1st number is the 1st digit

The 2nd number is the 2nd digit

The 3rd number is the number of zeros to give the capacitance in pF

Ignore any letters - they just indicate tolerance and voltage rating

For example 102 means 1000pF = 1nF (not 102pF)

For example 472J means 4700pF = 47nF (J means 5 tolerance)

It can be difficult to find the values of these small capacitors because there are many types of them

and several different labeling systems

Many small value capacitors have their value printed but without a multiplier so

you need to use experience to work out what the multiplier should be

For example 01 means 01microF = 100nF

Sometimes the multiplier is used in place of the decimal point

For example 4n7 means 47nF

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Color coding

Sr No Color Significant

digits

Multi-

pliers

Capacitance

tolerance

Characte

r-eristic

DC

working

voltage

Operating

temperature

1 Black 0 1 plusmn20 mdash mdash minus55 degC to +70

degC

2 Brown 1 10 plusmn1 B 100 mdash

3 Red 2 100 plusmn2 C mdash minus55 degC to

+85degC

4 Orange 3 1000 mdash D 300 mdash

5 Yellow 4 10000 mdash E mdash minus55 degC to

+125degC

6 Green 5 mdash plusmn5 F 500 mdash

7 Blue 6 mdash mdash mdash mdash minus55 degC to

+150 degC

8 Violet 7 mdash mdash mdash mdash mdash

9 Grey 8 mdash mdash mdash mdash mdash

10 White 9 mdash mdash mdash mdash mdash

11 Gold mdash mdash plusmn05 mdash 1000 mdash

12 Silver mdash mdash plusmn10 mdash mdash mdash

Or plusmn05 pF whichever is greater

A color code was used on polyester capacitors for many years The colors should be read like the

resistor code the top three color bands giving the value in pF Ignore the 4th band (tolerance) and

5th band (voltage rating)

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For example

Brown black orange means 10000pF = 10nF = 001microF

For example

Wide red yellow means 220nF = 022microF

(Note that there are no gaps between the color bands so 2 identical bands

actually appear as a wide band)Inductor

An inductor or a reactor is a passive electrical component that can store energy in a magnetic field

created by the electric current passing through it An inductors ability to store magnetic energy is

measured by its inductance in units of henries Typically an inductor is a conducting wire shaped

as a coil the loops helping to create a strong magnetic field inside the coil due to Faradays Law of

Induction Inductors are one of the basic electronic components used in electronics where current

and voltage change with time due to the ability of inductors to delay and reshape alternating

currents

Symbol of fixed inductor

Types of Inductor

1) Iron core Inductor This classification includes chokes and transformers both of which have

laminated iron cores A choke is a single winding and a transformer has two or more windings

Typical values of inductance for chokes range from 01 of a Henry to 50 henries Lamination

decreases eddy current losses

b) Air core Inductor It consists of number of turns of wire wound on a former made of cardboard

Since air is inside the former the inductor is called as air core inductor The only adjustment

available with air core inductors is by tapping all or part of a turn or by varying the spacing

between turns

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c) Ferrite core Inductor By inserting a ferrite or iron dust core in a coil it is possible to double its

inductance If the core is threaded its position within the coil can be varied to alter the inductance

This type of coil is used throughout the HF range and into the VHF for low-level signal circuits

Losses in the cores make them unsuitable for use in power circuits Values range from a few micro

henries to about a milli Henry

How to calculate the value of Inductor using color code

Some Radio Frequency chokes have their values indicated by a color code similar to that of

resistors

Applications

Filter chokes are used in smoothing pulsating current in rectifier Audio frequency chokes

are used to provide high impedance to audio frequencies Radio frequency chokes are used to block

the radio frequencies in communication systems

Switches

The term switch typically refers to electrical power or electronic telecommunication circuits In

applications where multiple switching options are required (eg a telephone service) mechanical

switches have long been replaced by electronic variants which can be intelligently controlled and

automated

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In the simplest case a switch has two pieces of metal called contacts that touch to make a circuit

and separate to break the circuit

There are different types of standard switches used in electronics

Type of Switch Circuit Symbol Example

1) ON-OFF Single Pole Single Throw =

SPST - A simple on-off switch Such

switches can be used to switch the power

supply to a circuit

SPST toggle switch

(ON)-OFF Push-to-make = SPST

Momentary - A push-to-make switch

returns to its normally open (off) position

when you release the button this is shown

by the brackets around ON This is the

standard doorbell switch

Push-to-make switch

ON-(OFF) Push-to-break = SPST

Momentary- A push-to-break switch

returns to its normally closed (on) position

when you release the button

Push-to-break switch

2) ON-ON Single Pole Double Throw =

SPDT - This switch can be on in both

positions switching on a separate device

in each case It is often called a

changeover switch A SPDT toggle

switch may be used as a simple on-off

switch by connecting to COM and one of

the A or B terminals shown in the

diagram

ON-OFF-ON SPDT Centre Off- A

special version of the standard SPDT

switch It has a third switching position in

the centre which is off Momentary (ON)-

OFF-(ON) versions are also available

where the switch returns to the central off

SPDT toggle switch

SPDT slide switch

(PCB mounting)

SPDT rocker switch

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position when released

3) Dual ON-OFF Double Pole Single

Throw = DPST- A pair of on-off switches

which operate together DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections

DPST rocker switch

Dual ON-ON Double Pole Double

Throw = DPDT- A pair of on-on switches

which operate together (shown by the

dotted line in the circuit symbol) A DPDT

switch can be wired up as a reversing

switch for a motor as shown in the

diagram

ON-OFF-ON DPDT Centre Off -

A special version of the standard SPDT

switch It has a third switching position in

the centre which is off This can be very

useful for motor control because you have

forward off and reverse positions

Momentary (ON)-OFF-(ON) versions are

also available where the switch returns to

the central off position when released

DPDT slide switch

Wiring for Reversing

Switch

Special Switches

Type of Switch Example

1) Push-Push Switch (eg SPST = ON-OFF) - This looks like a

momentary action push switch but it is a standard on-off switch

push once to switch on push again to switch off This is called a

latching action

2) Micro switch (usually SPDT = ON-ON)-Micro switches are

designed to switch fully open or closed in response to small

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 7: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

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How to calculate the value of Capacitor using number coding and colour coding

Most capacitors have numbers printed on their bodies to indicate their electrical characteristics

Some are indicated with XYZ JKM VOLTS V where XYZ represents the capacitance (calculated

as XY x 10Z) the letters J K or M indicate the tolerance (plusmn5 plusmn10 and plusmn20 respectively) and

VOLTS V represents the working voltage

Example

A capacitor with the following text on its body

105 K 330 V has a capacitance of 10 x 105 pF = 1microF (plusmn10) with a working voltage of 330 V

A capacitor with the following text

473 M 100 V has a capacitance of 47 x 103 pF = 47 nF (plusmn20) with a working voltage of 100 V

A number code is often used on small capacitors where printing is difficult

The 1st number is the 1st digit

The 2nd number is the 2nd digit

The 3rd number is the number of zeros to give the capacitance in pF

Ignore any letters - they just indicate tolerance and voltage rating

For example 102 means 1000pF = 1nF (not 102pF)

For example 472J means 4700pF = 47nF (J means 5 tolerance)

It can be difficult to find the values of these small capacitors because there are many types of them

and several different labeling systems

Many small value capacitors have their value printed but without a multiplier so

you need to use experience to work out what the multiplier should be

For example 01 means 01microF = 100nF

Sometimes the multiplier is used in place of the decimal point

For example 4n7 means 47nF

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Color coding

Sr No Color Significant

digits

Multi-

pliers

Capacitance

tolerance

Characte

r-eristic

DC

working

voltage

Operating

temperature

1 Black 0 1 plusmn20 mdash mdash minus55 degC to +70

degC

2 Brown 1 10 plusmn1 B 100 mdash

3 Red 2 100 plusmn2 C mdash minus55 degC to

+85degC

4 Orange 3 1000 mdash D 300 mdash

5 Yellow 4 10000 mdash E mdash minus55 degC to

+125degC

6 Green 5 mdash plusmn5 F 500 mdash

7 Blue 6 mdash mdash mdash mdash minus55 degC to

+150 degC

8 Violet 7 mdash mdash mdash mdash mdash

9 Grey 8 mdash mdash mdash mdash mdash

10 White 9 mdash mdash mdash mdash mdash

11 Gold mdash mdash plusmn05 mdash 1000 mdash

12 Silver mdash mdash plusmn10 mdash mdash mdash

Or plusmn05 pF whichever is greater

A color code was used on polyester capacitors for many years The colors should be read like the

resistor code the top three color bands giving the value in pF Ignore the 4th band (tolerance) and

5th band (voltage rating)

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For example

Brown black orange means 10000pF = 10nF = 001microF

For example

Wide red yellow means 220nF = 022microF

(Note that there are no gaps between the color bands so 2 identical bands

actually appear as a wide band)Inductor

An inductor or a reactor is a passive electrical component that can store energy in a magnetic field

created by the electric current passing through it An inductors ability to store magnetic energy is

measured by its inductance in units of henries Typically an inductor is a conducting wire shaped

as a coil the loops helping to create a strong magnetic field inside the coil due to Faradays Law of

Induction Inductors are one of the basic electronic components used in electronics where current

and voltage change with time due to the ability of inductors to delay and reshape alternating

currents

Symbol of fixed inductor

Types of Inductor

1) Iron core Inductor This classification includes chokes and transformers both of which have

laminated iron cores A choke is a single winding and a transformer has two or more windings

Typical values of inductance for chokes range from 01 of a Henry to 50 henries Lamination

decreases eddy current losses

b) Air core Inductor It consists of number of turns of wire wound on a former made of cardboard

Since air is inside the former the inductor is called as air core inductor The only adjustment

available with air core inductors is by tapping all or part of a turn or by varying the spacing

between turns

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c) Ferrite core Inductor By inserting a ferrite or iron dust core in a coil it is possible to double its

inductance If the core is threaded its position within the coil can be varied to alter the inductance

This type of coil is used throughout the HF range and into the VHF for low-level signal circuits

Losses in the cores make them unsuitable for use in power circuits Values range from a few micro

henries to about a milli Henry

How to calculate the value of Inductor using color code

Some Radio Frequency chokes have their values indicated by a color code similar to that of

resistors

Applications

Filter chokes are used in smoothing pulsating current in rectifier Audio frequency chokes

are used to provide high impedance to audio frequencies Radio frequency chokes are used to block

the radio frequencies in communication systems

Switches

The term switch typically refers to electrical power or electronic telecommunication circuits In

applications where multiple switching options are required (eg a telephone service) mechanical

switches have long been replaced by electronic variants which can be intelligently controlled and

automated

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In the simplest case a switch has two pieces of metal called contacts that touch to make a circuit

and separate to break the circuit

There are different types of standard switches used in electronics

Type of Switch Circuit Symbol Example

1) ON-OFF Single Pole Single Throw =

SPST - A simple on-off switch Such

switches can be used to switch the power

supply to a circuit

SPST toggle switch

(ON)-OFF Push-to-make = SPST

Momentary - A push-to-make switch

returns to its normally open (off) position

when you release the button this is shown

by the brackets around ON This is the

standard doorbell switch

Push-to-make switch

ON-(OFF) Push-to-break = SPST

Momentary- A push-to-break switch

returns to its normally closed (on) position

when you release the button

Push-to-break switch

2) ON-ON Single Pole Double Throw =

SPDT - This switch can be on in both

positions switching on a separate device

in each case It is often called a

changeover switch A SPDT toggle

switch may be used as a simple on-off

switch by connecting to COM and one of

the A or B terminals shown in the

diagram

ON-OFF-ON SPDT Centre Off- A

special version of the standard SPDT

switch It has a third switching position in

the centre which is off Momentary (ON)-

OFF-(ON) versions are also available

where the switch returns to the central off

SPDT toggle switch

SPDT slide switch

(PCB mounting)

SPDT rocker switch

BASIC ELECTRONICS ENGINEERING 12

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position when released

3) Dual ON-OFF Double Pole Single

Throw = DPST- A pair of on-off switches

which operate together DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections

DPST rocker switch

Dual ON-ON Double Pole Double

Throw = DPDT- A pair of on-on switches

which operate together (shown by the

dotted line in the circuit symbol) A DPDT

switch can be wired up as a reversing

switch for a motor as shown in the

diagram

ON-OFF-ON DPDT Centre Off -

A special version of the standard SPDT

switch It has a third switching position in

the centre which is off This can be very

useful for motor control because you have

forward off and reverse positions

Momentary (ON)-OFF-(ON) versions are

also available where the switch returns to

the central off position when released

DPDT slide switch

Wiring for Reversing

Switch

Special Switches

Type of Switch Example

1) Push-Push Switch (eg SPST = ON-OFF) - This looks like a

momentary action push switch but it is a standard on-off switch

push once to switch on push again to switch off This is called a

latching action

2) Micro switch (usually SPDT = ON-ON)-Micro switches are

designed to switch fully open or closed in response to small

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

BASIC ELECTRONICS ENGINEERING 15

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

BASIC ELECTRONICS ENGINEERING 16

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

BASIC ELECTRONICS ENGINEERING 17

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

BASIC ELECTRONICS ENGINEERING 18

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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BASIC ELECTRONICS ENGINEERING 23

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

BASIC ELECTRONICS ENGINEERING 24

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 8: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 8

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Color coding

Sr No Color Significant

digits

Multi-

pliers

Capacitance

tolerance

Characte

r-eristic

DC

working

voltage

Operating

temperature

1 Black 0 1 plusmn20 mdash mdash minus55 degC to +70

degC

2 Brown 1 10 plusmn1 B 100 mdash

3 Red 2 100 plusmn2 C mdash minus55 degC to

+85degC

4 Orange 3 1000 mdash D 300 mdash

5 Yellow 4 10000 mdash E mdash minus55 degC to

+125degC

6 Green 5 mdash plusmn5 F 500 mdash

7 Blue 6 mdash mdash mdash mdash minus55 degC to

+150 degC

8 Violet 7 mdash mdash mdash mdash mdash

9 Grey 8 mdash mdash mdash mdash mdash

10 White 9 mdash mdash mdash mdash mdash

11 Gold mdash mdash plusmn05 mdash 1000 mdash

12 Silver mdash mdash plusmn10 mdash mdash mdash

Or plusmn05 pF whichever is greater

A color code was used on polyester capacitors for many years The colors should be read like the

resistor code the top three color bands giving the value in pF Ignore the 4th band (tolerance) and

5th band (voltage rating)

BASIC ELECTRONICS ENGINEERING 9

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For example

Brown black orange means 10000pF = 10nF = 001microF

For example

Wide red yellow means 220nF = 022microF

(Note that there are no gaps between the color bands so 2 identical bands

actually appear as a wide band)Inductor

An inductor or a reactor is a passive electrical component that can store energy in a magnetic field

created by the electric current passing through it An inductors ability to store magnetic energy is

measured by its inductance in units of henries Typically an inductor is a conducting wire shaped

as a coil the loops helping to create a strong magnetic field inside the coil due to Faradays Law of

Induction Inductors are one of the basic electronic components used in electronics where current

and voltage change with time due to the ability of inductors to delay and reshape alternating

currents

Symbol of fixed inductor

Types of Inductor

1) Iron core Inductor This classification includes chokes and transformers both of which have

laminated iron cores A choke is a single winding and a transformer has two or more windings

Typical values of inductance for chokes range from 01 of a Henry to 50 henries Lamination

decreases eddy current losses

b) Air core Inductor It consists of number of turns of wire wound on a former made of cardboard

Since air is inside the former the inductor is called as air core inductor The only adjustment

available with air core inductors is by tapping all or part of a turn or by varying the spacing

between turns

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c) Ferrite core Inductor By inserting a ferrite or iron dust core in a coil it is possible to double its

inductance If the core is threaded its position within the coil can be varied to alter the inductance

This type of coil is used throughout the HF range and into the VHF for low-level signal circuits

Losses in the cores make them unsuitable for use in power circuits Values range from a few micro

henries to about a milli Henry

How to calculate the value of Inductor using color code

Some Radio Frequency chokes have their values indicated by a color code similar to that of

resistors

Applications

Filter chokes are used in smoothing pulsating current in rectifier Audio frequency chokes

are used to provide high impedance to audio frequencies Radio frequency chokes are used to block

the radio frequencies in communication systems

Switches

The term switch typically refers to electrical power or electronic telecommunication circuits In

applications where multiple switching options are required (eg a telephone service) mechanical

switches have long been replaced by electronic variants which can be intelligently controlled and

automated

BASIC ELECTRONICS ENGINEERING 11

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In the simplest case a switch has two pieces of metal called contacts that touch to make a circuit

and separate to break the circuit

There are different types of standard switches used in electronics

Type of Switch Circuit Symbol Example

1) ON-OFF Single Pole Single Throw =

SPST - A simple on-off switch Such

switches can be used to switch the power

supply to a circuit

SPST toggle switch

(ON)-OFF Push-to-make = SPST

Momentary - A push-to-make switch

returns to its normally open (off) position

when you release the button this is shown

by the brackets around ON This is the

standard doorbell switch

Push-to-make switch

ON-(OFF) Push-to-break = SPST

Momentary- A push-to-break switch

returns to its normally closed (on) position

when you release the button

Push-to-break switch

2) ON-ON Single Pole Double Throw =

SPDT - This switch can be on in both

positions switching on a separate device

in each case It is often called a

changeover switch A SPDT toggle

switch may be used as a simple on-off

switch by connecting to COM and one of

the A or B terminals shown in the

diagram

ON-OFF-ON SPDT Centre Off- A

special version of the standard SPDT

switch It has a third switching position in

the centre which is off Momentary (ON)-

OFF-(ON) versions are also available

where the switch returns to the central off

SPDT toggle switch

SPDT slide switch

(PCB mounting)

SPDT rocker switch

BASIC ELECTRONICS ENGINEERING 12

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

position when released

3) Dual ON-OFF Double Pole Single

Throw = DPST- A pair of on-off switches

which operate together DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections

DPST rocker switch

Dual ON-ON Double Pole Double

Throw = DPDT- A pair of on-on switches

which operate together (shown by the

dotted line in the circuit symbol) A DPDT

switch can be wired up as a reversing

switch for a motor as shown in the

diagram

ON-OFF-ON DPDT Centre Off -

A special version of the standard SPDT

switch It has a third switching position in

the centre which is off This can be very

useful for motor control because you have

forward off and reverse positions

Momentary (ON)-OFF-(ON) versions are

also available where the switch returns to

the central off position when released

DPDT slide switch

Wiring for Reversing

Switch

Special Switches

Type of Switch Example

1) Push-Push Switch (eg SPST = ON-OFF) - This looks like a

momentary action push switch but it is a standard on-off switch

push once to switch on push again to switch off This is called a

latching action

2) Micro switch (usually SPDT = ON-ON)-Micro switches are

designed to switch fully open or closed in response to small

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

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For example

Brown black orange means 10000pF = 10nF = 001microF

For example

Wide red yellow means 220nF = 022microF

(Note that there are no gaps between the color bands so 2 identical bands

actually appear as a wide band)Inductor

An inductor or a reactor is a passive electrical component that can store energy in a magnetic field

created by the electric current passing through it An inductors ability to store magnetic energy is

measured by its inductance in units of henries Typically an inductor is a conducting wire shaped

as a coil the loops helping to create a strong magnetic field inside the coil due to Faradays Law of

Induction Inductors are one of the basic electronic components used in electronics where current

and voltage change with time due to the ability of inductors to delay and reshape alternating

currents

Symbol of fixed inductor

Types of Inductor

1) Iron core Inductor This classification includes chokes and transformers both of which have

laminated iron cores A choke is a single winding and a transformer has two or more windings

Typical values of inductance for chokes range from 01 of a Henry to 50 henries Lamination

decreases eddy current losses

b) Air core Inductor It consists of number of turns of wire wound on a former made of cardboard

Since air is inside the former the inductor is called as air core inductor The only adjustment

available with air core inductors is by tapping all or part of a turn or by varying the spacing

between turns

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c) Ferrite core Inductor By inserting a ferrite or iron dust core in a coil it is possible to double its

inductance If the core is threaded its position within the coil can be varied to alter the inductance

This type of coil is used throughout the HF range and into the VHF for low-level signal circuits

Losses in the cores make them unsuitable for use in power circuits Values range from a few micro

henries to about a milli Henry

How to calculate the value of Inductor using color code

Some Radio Frequency chokes have their values indicated by a color code similar to that of

resistors

Applications

Filter chokes are used in smoothing pulsating current in rectifier Audio frequency chokes

are used to provide high impedance to audio frequencies Radio frequency chokes are used to block

the radio frequencies in communication systems

Switches

The term switch typically refers to electrical power or electronic telecommunication circuits In

applications where multiple switching options are required (eg a telephone service) mechanical

switches have long been replaced by electronic variants which can be intelligently controlled and

automated

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In the simplest case a switch has two pieces of metal called contacts that touch to make a circuit

and separate to break the circuit

There are different types of standard switches used in electronics

Type of Switch Circuit Symbol Example

1) ON-OFF Single Pole Single Throw =

SPST - A simple on-off switch Such

switches can be used to switch the power

supply to a circuit

SPST toggle switch

(ON)-OFF Push-to-make = SPST

Momentary - A push-to-make switch

returns to its normally open (off) position

when you release the button this is shown

by the brackets around ON This is the

standard doorbell switch

Push-to-make switch

ON-(OFF) Push-to-break = SPST

Momentary- A push-to-break switch

returns to its normally closed (on) position

when you release the button

Push-to-break switch

2) ON-ON Single Pole Double Throw =

SPDT - This switch can be on in both

positions switching on a separate device

in each case It is often called a

changeover switch A SPDT toggle

switch may be used as a simple on-off

switch by connecting to COM and one of

the A or B terminals shown in the

diagram

ON-OFF-ON SPDT Centre Off- A

special version of the standard SPDT

switch It has a third switching position in

the centre which is off Momentary (ON)-

OFF-(ON) versions are also available

where the switch returns to the central off

SPDT toggle switch

SPDT slide switch

(PCB mounting)

SPDT rocker switch

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position when released

3) Dual ON-OFF Double Pole Single

Throw = DPST- A pair of on-off switches

which operate together DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections

DPST rocker switch

Dual ON-ON Double Pole Double

Throw = DPDT- A pair of on-on switches

which operate together (shown by the

dotted line in the circuit symbol) A DPDT

switch can be wired up as a reversing

switch for a motor as shown in the

diagram

ON-OFF-ON DPDT Centre Off -

A special version of the standard SPDT

switch It has a third switching position in

the centre which is off This can be very

useful for motor control because you have

forward off and reverse positions

Momentary (ON)-OFF-(ON) versions are

also available where the switch returns to

the central off position when released

DPDT slide switch

Wiring for Reversing

Switch

Special Switches

Type of Switch Example

1) Push-Push Switch (eg SPST = ON-OFF) - This looks like a

momentary action push switch but it is a standard on-off switch

push once to switch on push again to switch off This is called a

latching action

2) Micro switch (usually SPDT = ON-ON)-Micro switches are

designed to switch fully open or closed in response to small

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 10: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 10

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

c) Ferrite core Inductor By inserting a ferrite or iron dust core in a coil it is possible to double its

inductance If the core is threaded its position within the coil can be varied to alter the inductance

This type of coil is used throughout the HF range and into the VHF for low-level signal circuits

Losses in the cores make them unsuitable for use in power circuits Values range from a few micro

henries to about a milli Henry

How to calculate the value of Inductor using color code

Some Radio Frequency chokes have their values indicated by a color code similar to that of

resistors

Applications

Filter chokes are used in smoothing pulsating current in rectifier Audio frequency chokes

are used to provide high impedance to audio frequencies Radio frequency chokes are used to block

the radio frequencies in communication systems

Switches

The term switch typically refers to electrical power or electronic telecommunication circuits In

applications where multiple switching options are required (eg a telephone service) mechanical

switches have long been replaced by electronic variants which can be intelligently controlled and

automated

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In the simplest case a switch has two pieces of metal called contacts that touch to make a circuit

and separate to break the circuit

There are different types of standard switches used in electronics

Type of Switch Circuit Symbol Example

1) ON-OFF Single Pole Single Throw =

SPST - A simple on-off switch Such

switches can be used to switch the power

supply to a circuit

SPST toggle switch

(ON)-OFF Push-to-make = SPST

Momentary - A push-to-make switch

returns to its normally open (off) position

when you release the button this is shown

by the brackets around ON This is the

standard doorbell switch

Push-to-make switch

ON-(OFF) Push-to-break = SPST

Momentary- A push-to-break switch

returns to its normally closed (on) position

when you release the button

Push-to-break switch

2) ON-ON Single Pole Double Throw =

SPDT - This switch can be on in both

positions switching on a separate device

in each case It is often called a

changeover switch A SPDT toggle

switch may be used as a simple on-off

switch by connecting to COM and one of

the A or B terminals shown in the

diagram

ON-OFF-ON SPDT Centre Off- A

special version of the standard SPDT

switch It has a third switching position in

the centre which is off Momentary (ON)-

OFF-(ON) versions are also available

where the switch returns to the central off

SPDT toggle switch

SPDT slide switch

(PCB mounting)

SPDT rocker switch

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position when released

3) Dual ON-OFF Double Pole Single

Throw = DPST- A pair of on-off switches

which operate together DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections

DPST rocker switch

Dual ON-ON Double Pole Double

Throw = DPDT- A pair of on-on switches

which operate together (shown by the

dotted line in the circuit symbol) A DPDT

switch can be wired up as a reversing

switch for a motor as shown in the

diagram

ON-OFF-ON DPDT Centre Off -

A special version of the standard SPDT

switch It has a third switching position in

the centre which is off This can be very

useful for motor control because you have

forward off and reverse positions

Momentary (ON)-OFF-(ON) versions are

also available where the switch returns to

the central off position when released

DPDT slide switch

Wiring for Reversing

Switch

Special Switches

Type of Switch Example

1) Push-Push Switch (eg SPST = ON-OFF) - This looks like a

momentary action push switch but it is a standard on-off switch

push once to switch on push again to switch off This is called a

latching action

2) Micro switch (usually SPDT = ON-ON)-Micro switches are

designed to switch fully open or closed in response to small

BASIC ELECTRONICS ENGINEERING 13

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

BASIC ELECTRONICS ENGINEERING 14

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

BASIC ELECTRONICS ENGINEERING 15

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

BASIC ELECTRONICS ENGINEERING 16

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

BASIC ELECTRONICS ENGINEERING 17

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

BASIC ELECTRONICS ENGINEERING 18

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

BASIC ELECTRONICS ENGINEERING 19

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

BASIC ELECTRONICS ENGINEERING 20

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

BASIC ELECTRONICS ENGINEERING 21

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CONCLUSION

BASIC ELECTRONICS ENGINEERING 22

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BASIC ELECTRONICS ENGINEERING 23

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

BASIC ELECTRONICS ENGINEERING 24

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

BASIC ELECTRONICS ENGINEERING 25

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

BASIC ELECTRONICS ENGINEERING 26

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 11: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 11

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

In the simplest case a switch has two pieces of metal called contacts that touch to make a circuit

and separate to break the circuit

There are different types of standard switches used in electronics

Type of Switch Circuit Symbol Example

1) ON-OFF Single Pole Single Throw =

SPST - A simple on-off switch Such

switches can be used to switch the power

supply to a circuit

SPST toggle switch

(ON)-OFF Push-to-make = SPST

Momentary - A push-to-make switch

returns to its normally open (off) position

when you release the button this is shown

by the brackets around ON This is the

standard doorbell switch

Push-to-make switch

ON-(OFF) Push-to-break = SPST

Momentary- A push-to-break switch

returns to its normally closed (on) position

when you release the button

Push-to-break switch

2) ON-ON Single Pole Double Throw =

SPDT - This switch can be on in both

positions switching on a separate device

in each case It is often called a

changeover switch A SPDT toggle

switch may be used as a simple on-off

switch by connecting to COM and one of

the A or B terminals shown in the

diagram

ON-OFF-ON SPDT Centre Off- A

special version of the standard SPDT

switch It has a third switching position in

the centre which is off Momentary (ON)-

OFF-(ON) versions are also available

where the switch returns to the central off

SPDT toggle switch

SPDT slide switch

(PCB mounting)

SPDT rocker switch

BASIC ELECTRONICS ENGINEERING 12

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position when released

3) Dual ON-OFF Double Pole Single

Throw = DPST- A pair of on-off switches

which operate together DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections

DPST rocker switch

Dual ON-ON Double Pole Double

Throw = DPDT- A pair of on-on switches

which operate together (shown by the

dotted line in the circuit symbol) A DPDT

switch can be wired up as a reversing

switch for a motor as shown in the

diagram

ON-OFF-ON DPDT Centre Off -

A special version of the standard SPDT

switch It has a third switching position in

the centre which is off This can be very

useful for motor control because you have

forward off and reverse positions

Momentary (ON)-OFF-(ON) versions are

also available where the switch returns to

the central off position when released

DPDT slide switch

Wiring for Reversing

Switch

Special Switches

Type of Switch Example

1) Push-Push Switch (eg SPST = ON-OFF) - This looks like a

momentary action push switch but it is a standard on-off switch

push once to switch on push again to switch off This is called a

latching action

2) Micro switch (usually SPDT = ON-ON)-Micro switches are

designed to switch fully open or closed in response to small

BASIC ELECTRONICS ENGINEERING 13

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

BASIC ELECTRONICS ENGINEERING 14

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

BASIC ELECTRONICS ENGINEERING 15

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

BASIC ELECTRONICS ENGINEERING 16

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 12: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 12

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

position when released

3) Dual ON-OFF Double Pole Single

Throw = DPST- A pair of on-off switches

which operate together DPST switch is

often used to switch mains electricity

because it can isolate both the live and

neutral connections

DPST rocker switch

Dual ON-ON Double Pole Double

Throw = DPDT- A pair of on-on switches

which operate together (shown by the

dotted line in the circuit symbol) A DPDT

switch can be wired up as a reversing

switch for a motor as shown in the

diagram

ON-OFF-ON DPDT Centre Off -

A special version of the standard SPDT

switch It has a third switching position in

the centre which is off This can be very

useful for motor control because you have

forward off and reverse positions

Momentary (ON)-OFF-(ON) versions are

also available where the switch returns to

the central off position when released

DPDT slide switch

Wiring for Reversing

Switch

Special Switches

Type of Switch Example

1) Push-Push Switch (eg SPST = ON-OFF) - This looks like a

momentary action push switch but it is a standard on-off switch

push once to switch on push again to switch off This is called a

latching action

2) Micro switch (usually SPDT = ON-ON)-Micro switches are

designed to switch fully open or closed in response to small

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

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movements They are available with levers and rollers attached

3) Key switch - A key operated switch The example shown is

SPST

4) Tilt Switch (SPST) - Tilt switches contain a conductive liquid

and when tilted this bridges the contacts inside closing the

switch They can be used as a sensor to detect the position of an

object

5) Reed Switch (usually SPST) - The contacts of a reed switch

are closed by bringing a small magnet near the switch They are

used in security circuits for example to check that doors are

closed Standard reed switches are SPST (simple on-off) but

SPDT (changeover) versions are also available

6) DIP Switch (DIP = Dual In-line Parallel) - This is a set of

miniature SPST on-off switches the example shown has 8

switches The package is the same size as a standard DIL (Dual

In-Line) integrated circuit This type of switch is used to set up

circuits eg setting the code of a remote control

7) Multi-pole Switch - The picture shows a 6-pole double throw

switch also known as a 6-pole changeover switch It can be set

to have momentary or latching action Latching action means it

behaves as a push-push switch push once for the first position

push again for the second position etc

8) Multi-way (Rotary) Switch - Multi-way switches have 3 or

more conducting positions (Several poles contact sets) A

popular type has a rotary action and it is available with a range of

contact arrangements from 1-pole 12-way to 4-pole 3 way

Multi-way rotary switch

1-pole 4-way switch symbol

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

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9) Tactile Switch

These switches used in instruments keyboards

Connectors

An electrical connector is a conductive device for joining electrical circuits together The

connection may be temporary as for portable equipment or may require a tool for assembly and

removal or may be a permanent electrical joint between two wires or devices Connectors may join

two lengths of flexible wire or cable or may connect a wire or cable to an electrical terminal

There are hundreds of types of electrical connectors Out of that some of the connecters given

below

1) Battery clips and holders

The standard battery and battery holders such as the 6 times AA cell holder shown Battery holders are

also available with wires attached with pins for PCB mounting or as a complete box with lid

switch and wires

2) Terminal blocks and PCB terminals

Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with

a sharp knife large wire cutters or a junior hacksaw They are sometimes called chocolate blocks

because of the way they can be easily cut to size PCB mounting terminal blocks provide an easy

way of making semi-permanent connections to PCBs

PCB Terminal block

terminal

block

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3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 15: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 15

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

3) Crocodile clips

The standard crocodile clip has no cover and a screw contact However miniature insulated

crocodile clips are more suitable for many purposes including test leads

Crocodile clips

4) 4mm plugs sockets and terminals

These are the standard single pole connectors used on meters and other electronic equipment They

are capable of passing high currents (typically 10A) and most designs are very robust

Plugs

Plugs may have a screw or solder terminal to hold the cable

Sockets

these are usually described as panel mounting because they are designed to be fitted to a case

Terminals

In addition to a socket these have provision for attaching a wire by threading it through a hole (or

wrapping it around the post) and tightening the top nut by hand

4mm terminal and solder tag

5) DC power plugs and sockets

These 2-pole plugs and sockets ensure that the polarity of a DC supply cannot be accidentally

reversed The standard sizes are 21 and 25mm plug diameter Standard plugs have a 10mm shaft

long plugs have a 14mm shaft

6) Jack plugs and sockets

BASIC ELECTRONICS ENGINEERING 16

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These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

BASIC ELECTRONICS ENGINEERING 17

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

BASIC ELECTRONICS ENGINEERING 19

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

BASIC ELECTRONICS ENGINEERING 20

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

BASIC ELECTRONICS ENGINEERING 21

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CONCLUSION

BASIC ELECTRONICS ENGINEERING 22

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BASIC ELECTRONICS ENGINEERING 23

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

BASIC ELECTRONICS ENGINEERING 24

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

BASIC ELECTRONICS ENGINEERING 25

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

BASIC ELECTRONICS ENGINEERING 26

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

BASIC ELECTRONICS ENGINEERING 27

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

BASIC ELECTRONICS ENGINEERING 28

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

BASIC ELECTRONICS ENGINEERING 30

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

BASIC ELECTRONICS ENGINEERING 31

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

BASIC ELECTRONICS ENGINEERING 32

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

BASIC ELECTRONICS ENGINEERING 33

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

BASIC ELECTRONICS ENGINEERING 35

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 16: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 16

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

These are intended for audio signals so mono and stereo versions are available The sizes are

determined by the plug diameter frac14 (63mm) 35mm and 25mm The 25mm size is only

available for mono

frac14 (63mm) jack plug and socket 35mm jack plug and socket 35mm jack line socket

(for fitting to a cable)

35mm jack plug and socket connections

(the R connection is not present on mono plugs)

L = left channel signal R = right channel signal COM = common (0V screen) (Do not use jack

plugs for power supply connections because the contacts may be briefly shorted as the plug is

inserted Use DC power connectors for this)

7) Phono plugs and sockets

These are used for screened cables carrying audio and video signals Stereo connections are made

using a pair of phono plugs and sockets

8) Coax plugs and sockets

These are similar to the phono plugs and sockets described above but they are designed for use with

screened cables carrying much higher frequency signals such as TV aerial leads They provide

better screening because at high frequencies this is essential to reduce electrical noise

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Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

BASIC ELECTRONICS ENGINEERING 20

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

BASIC ELECTRONICS ENGINEERING 21

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CONCLUSION

BASIC ELECTRONICS ENGINEERING 22

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BASIC ELECTRONICS ENGINEERING 23

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

BASIC ELECTRONICS ENGINEERING 24

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

BASIC ELECTRONICS ENGINEERING 25

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

BASIC ELECTRONICS ENGINEERING 26

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

BASIC ELECTRONICS ENGINEERING 27

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

BASIC ELECTRONICS ENGINEERING 28

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

BASIC ELECTRONICS ENGINEERING 30

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

BASIC ELECTRONICS ENGINEERING 31

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

BASIC ELECTRONICS ENGINEERING 32

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

BASIC ELECTRONICS ENGINEERING 33

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 17: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 17

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Construction of a screened cable

9) BNC (Bayonet Neill-Concelman) plugs and sockets

These are designed for screened cables carrying high frequency signals where an undistorted and

noise free signal is essential for example oscilloscope leads BNC plugs are connected with a push

and twist action to disconnect you need to twist and pull

Plugs and sockets are rated by their impedance (50 or 75 ) which must be the same as the

cables impedance

11) D connectors

These are multi-pole connectors with provision for screw fittings to make semi-permanent

connections for example on computer equipment The D shape prevents incorrect connection

Standard D-connectors have 2 rows of contacts (top picture) 9 15 and 25-way versions are the

most popular

12) IDC communication connectors

These multi-pole insulation displacement connectors are used for computer and

telecommunications equipment They automatically cut through the insulation on wires when

installed and special tools are required to fit them They are available as 4 6 and 8-way versions

They are called BT (British Telecom) connectors

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

BASIC ELECTRONICS ENGINEERING 20

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

BASIC ELECTRONICS ENGINEERING 21

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CONCLUSION

BASIC ELECTRONICS ENGINEERING 22

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BASIC ELECTRONICS ENGINEERING 23

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

BASIC ELECTRONICS ENGINEERING 24

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

BASIC ELECTRONICS ENGINEERING 25

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

BASIC ELECTRONICS ENGINEERING 26

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

BASIC ELECTRONICS ENGINEERING 27

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

BASIC ELECTRONICS ENGINEERING 28

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

BASIC ELECTRONICS ENGINEERING 30

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

BASIC ELECTRONICS ENGINEERING 31

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

BASIC ELECTRONICS ENGINEERING 32

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

BASIC ELECTRONICS ENGINEERING 33

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

BASIC ELECTRONICS ENGINEERING 35

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 18: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 18

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13) USB Connector

The Universal Serial Bus is a serial bus standard to interface devices founded in 1996

Relays

A relay is an electrically operated switch Current flowing through the coil of the relay creates a

magnetic field which attracts a lever and changes the switch contacts The coil current can be on or

off so relays have two switch positions and they are double throw (changeover) switches Relays

allow one circuit to switch a second circuit which can be completely separate from the first For

example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit There is

no electrical connection inside the relay between the two circuits the link is magnetic and

mechanical

Following figure shows a working of relay with its coil and switch contacts You can see a

lever on the left being attracted by magnetism when the coil is switched on This lever moves the

switch contacts There is one set of contacts (SPDT) in the foreground and another behind them

making the relay DPDT

Circuit symbol for a relay Picture of a relay

The relays switch connections are usually labeled COM NC and NO

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COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

BASIC ELECTRONICS ENGINEERING 20

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

BASIC ELECTRONICS ENGINEERING 22

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BASIC ELECTRONICS ENGINEERING 23

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

BASIC ELECTRONICS ENGINEERING 24

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

BASIC ELECTRONICS ENGINEERING 25

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

BASIC ELECTRONICS ENGINEERING 26

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

BASIC ELECTRONICS ENGINEERING 27

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

BASIC ELECTRONICS ENGINEERING 28

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

BASIC ELECTRONICS ENGINEERING 30

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

BASIC ELECTRONICS ENGINEERING 31

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

BASIC ELECTRONICS ENGINEERING 32

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

BASIC ELECTRONICS ENGINEERING 33

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 19: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 19

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

COM = Common always connect to this it is the moving part of the switch

NC = Normally Closed COM is connected to this when the relay coil is off

NO = Normally Open COM is connected to this when the relay coil is on

Connect to COM and NO if you want the switched circuit to be on when the relay coil is

on

Connect to COM and NC if you want the switched circuit to be on when the relay coil is

off

Advantages of relays

Relays can switch AC and DC transistors can only switch DC

Relays can switch high voltages transistors cannot

Relays are a better choice for switching large currents (gt 5A)

Relays can switch many contacts at once

Disadvantages of relays

Relays are bulkier than transistors for switching small currents

Relays cannot switch rapidly (except reed relays) transistors can switch many times per

second

Relays use more power due to the current flowing through their coil

Relays require more current than many ICs can provide so a low power transistor may

be needed to switch the current for the relays coil

Transformer

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductorsmdashthe transformers coils A varying current in the first or primary

winding creates a varying magnetic flux in the transformers core and thus a varying magnetic field

through the secondary winding This varying magnetic field induces a varying electromotive force

(EMF) or voltage in the secondary winding This effect is called mutual induction

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

BASIC ELECTRONICS ENGINEERING 21

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CONCLUSION

BASIC ELECTRONICS ENGINEERING 22

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BASIC ELECTRONICS ENGINEERING 23

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

BASIC ELECTRONICS ENGINEERING 24

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

BASIC ELECTRONICS ENGINEERING 25

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

BASIC ELECTRONICS ENGINEERING 26

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

BASIC ELECTRONICS ENGINEERING 27

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

BASIC ELECTRONICS ENGINEERING 28

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

BASIC ELECTRONICS ENGINEERING 30

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

BASIC ELECTRONICS ENGINEERING 31

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

BASIC ELECTRONICS ENGINEERING 32

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

BASIC ELECTRONICS ENGINEERING 33

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

BASIC ELECTRONICS ENGINEERING 35

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 20: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

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Symbol of transformer

If a load is connected to the secondary an electric current will flow in the secondary winding and

electrical energy will be transferred from the primary circuit through the transformer to the load In

an ideal transformer the induced voltage in the secondary winding (VS) is in proportion to the

primary voltage (VP) and is given by the ratio of the number of turns in the secondary (NS) to the

number of turns in the primary (NP) as follows

By appropriate selection of the ratio of turns a transformer thus allows an alternating current (AC)

voltage to be stepped up by making NS greater than NP or stepped down by making NS less than

NP

Actual pictures of transformer

Types of Transformer

1) Step-up Transformer

2) Step-down Transformer

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

BASIC ELECTRONICS ENGINEERING 24

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 21: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

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CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

BASIC ELECTRONICS ENGINEERING 24

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

BASIC ELECTRONICS ENGINEERING 25

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 22: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 22

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BASIC ELECTRONICS ENGINEERING 23

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Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

BASIC ELECTRONICS ENGINEERING 24

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 23: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 23

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 02 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

To Study Different Electronics Measuring Components

AIM a) Study of settings of DMM and Measurement of parameters like AC DC voltage

current

b) Study of controls of CRO Measurement of frequency Phase AC and DC Voltages

using CRO

c) Study of controls of Function Generator

a) Study of settings of DMM and Measurement of parameters like AC DC voltages currents

PREREQUISITE

Knowledge of different measuring instruments

Difference between AC DC voltages and currents

Basic concept of diode and transistors

Internal construction of CRO and how it works

Use of function generator and power supply

Basic knowledge of different types of waveforms

OBJECTIVE

Use of DMM for measuring various types of components and parameters

Use of each and every control on front panel of CRO

Use of front panel control of function generator and power supply

EQUIPMENTS amp COMPONENTS

1) Digital Multimeter

2) Connecting Probes

3) Cathode Ray Oscilloscope

4) Function Generator

5) Power Supply

6) Multimeter

BASIC ELECTRONICS ENGINEERING 24

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THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

BASIC ELECTRONICS ENGINEERING 25

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

BASIC ELECTRONICS ENGINEERING 26

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

BASIC ELECTRONICS ENGINEERING 27

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

BASIC ELECTRONICS ENGINEERING 28

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 24: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 24

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

Digital multimeters are usually referred to as digital-multi-meters abbreviated DMM A

multimeter can be a handheld device useful for basic fault finding and field service work or a bench

instrument which can measure to a very high degree of accuracy Such an instrument will

commonly be found in a calibration lab and can be used to characterize resistance and voltage

standards or adjust and verify the performance of multi-function calibrators

By using mentioned DMM we can measure resistance AC DC voltage and current and diode and

transistor testing

Control Panels

1) LCD Display

A 3 frac12 digit display (maximum reading 1999) indicates measured values and features symbols

indicating ranges low Battery

2) Function Selector

To select ACV DCV ACA DCA RESISTANCE Diode Continuity ampTransistor test

3) Input Jacks

Test leads are inserted into these jacks for voltage resistance current measurements continuity and

diode checks

4) Input socket for transistor test

NPN or PNP transistors are inserted in the sockets provided to measure their ratings

PROCEDURE

1) Measuring voltage and current with DMM-

1 Select a range with a maximum greater than you expect the reading to be

2 Connect the meter making sure the leads are the correct way round

Digital meters can be safely connected in reverse but an analog meter may be damaged

3 If the reading goes off the scale immediately disconnect and select a higher range

2) Testing diode with a DMM-

Digital multimeters have a special setting for testing a diode usually labeled with the diode

symbol

BASIC ELECTRONICS ENGINEERING 25

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Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

BASIC ELECTRONICS ENGINEERING 26

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

BASIC ELECTRONICS ENGINEERING 27

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

BASIC ELECTRONICS ENGINEERING 28

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

BASIC ELECTRONICS ENGINEERING 30

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

BASIC ELECTRONICS ENGINEERING 31

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

BASIC ELECTRONICS ENGINEERING 32

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

BASIC ELECTRONICS ENGINEERING 33

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

BASIC ELECTRONICS ENGINEERING 35

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 25: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 25

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Connect the red (+) lead to the anode and the black (-) to the cathode The diode should

conduct and the meter will display a value (usually the voltage across the diode in mV

1000mV = 1V)

Reverse the connections The diode should NOT conduct this way so the meter will display

off the scale (usually blank except for a 1 on the left)

a=anode

k=cathode

3) Testing a transistor with DMM-

Set a digital multimeter to diode test and an analog multimeter to a low resistance range

such as times 10 as described above for testing a diode

The base-emitter (BE) junction should behave like a diode and conduct one way only

The base-collector (BC) junction should behave like a diode and conduct one way only

The collector-emitter (CE) should not conduct either way

The diagram shows how the junctions behave in an NPN transistor The diodes are reversed

in a PNP transistor but the same test procedure can be used

Diodes

BASIC ELECTRONICS ENGINEERING 26

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FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

BASIC ELECTRONICS ENGINEERING 27

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

BASIC ELECTRONICS ENGINEERING 28

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

BASIC ELECTRONICS ENGINEERING 30

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

BASIC ELECTRONICS ENGINEERING 31

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

BASIC ELECTRONICS ENGINEERING 32

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

BASIC ELECTRONICS ENGINEERING 33

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

BASIC ELECTRONICS ENGINEERING 35

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 26: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 26

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

FRONT PANEL CONTROLS

Measurements

1 Resistance

2 AC Voltage

3 DC Voltage

4 AC Current

5 DC Current

BASIC ELECTRONICS ENGINEERING 27

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b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

BASIC ELECTRONICS ENGINEERING 28

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

BASIC ELECTRONICS ENGINEERING 30

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

BASIC ELECTRONICS ENGINEERING 31

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

BASIC ELECTRONICS ENGINEERING 32

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 27: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 27

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Study of controls of CRO Measurement of frequency Phase AC and DC voltages

using CRO

THEORY

The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides

accurate time and amplitude measurements of voltage signals over a wide range of frequencies Its

reliability stability and ease of operation make it suitable as a general purpose laboratory

instrument The heart of the CRO is a cathode-ray tube shown schematically in Fig1

The cathode ray is a beam of electrons which are emitted by the heated cathode (negative electrode)

and accelerated toward the fluorescent screen The assembly of the cathode intensity grid focus

grid and accelerating anode (positive electrode) is called an electron gun Its purpose is to generate

the electron beam and control its intensity and focus Between the electron gun and the fluorescent

screen there are two pair of metal plates - one oriented to provide horizontal deflection of the beam

and one pair oriented to give vertical deflection to the beam These plates are thus referred to as the

horizontal and vertical deflection plates The combination of these two deflections allows the beam

to reach any portion of the fluorescent screen Wherever the electron beam hits the screen the

phosphor is excited and light is emitted from that point This conversion of electron energy into

light allows us to write with points or lines of light on an otherwise darkened screen

BASIC ELECTRONICS ENGINEERING 28

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 28: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 28

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FRONT PANEL DIAGRAM

FRONT PANEL CONTROLS

1) Power ON OFF Push button switches for supplying power to instrument

2) X amp Y-POS Controls horizontal amp vertical position of the trace

3) Time Base -VAR controls the time speed in between two steps of TIMEDIV switch For

calibration put this fully anticlockwise

4) X10 MAG Switch when pushed gives 10 times magnification of the signal X

5) XY Switch when pressed cuts off the time base (XY Display) amp allows access the ext

horizontal signal to be feed through CH2

6) CH-1CH-2 Selects channel from Channel 1 and channel 2

7) MONODUAL Switch selects mono or dual trace operation

8) ALTCHOPADD Switch selects alternate or chopped in DUAL mode If mono is

selected then this switch enable addition or subtraction of channel ie CH1 +-CH2

9) EXT Switch when pressed allows external triggering signal to be feed from the socket

marked TRIGINP

10) LINE switch when pressed display signal synchronized with mains line frequency

11) ALT Selects alternate trigger mode from CH1 amp CH2 In this mode both the signal are

synchronized

12) LEVEL Controls the trigger level from peak to peak amplitude of signal

13) COMPONENT TESTER Switch when pressed starts Component testing operation

14) INTENS Controls the brightness of the trace

15) TR Controls the alignment of the trace with latitude

16) FOCUS Controls the sharpness of the trace

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

BASIC ELECTRONICS ENGINEERING 30

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

BASIC ELECTRONICS ENGINEERING 31

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

BASIC ELECTRONICS ENGINEERING 32

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

BASIC ELECTRONICS ENGINEERING 33

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

BASIC ELECTRONICS ENGINEERING 35

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 29: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 29

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17) DCACGD Input coupling switch for each channel In AC the signal is coupled through

01MFD capacitor

18) CH1 amp CH 2 BNC connectors serve as input connection for CH 1 and Ch 2 Channel 2

input connections also serve as Horizontal External Signal

19) INV CH2 Switch when pressed invert polarity of CH2

20) DIGITAL READOUT LCD window for displaying digital readout for VDiv amp

TimeDiv Settings

21) VOLTSDIV Switch selects VDiv for channel 1 amp 2

PROCEDURE

1 DC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on DC position

iii) Apply test voltage to CRO input probe

iv) Measure the shift of beam from reference level

v) Calculate the DC voltage

DC Voltage = No of Divisions on Y-Axis VoltsDiv

2 AC Voltage Measurements

i) Adjust beam to reference level

ii) Keep ACDC selector switch on AC position

iii) Apply test voltage to CRO input probe

iv) Measure the peak to peak voltage

v) Calculate the AC voltage

AC Voltage = No of Divisions on Y-Axis VoltsDiv

3 Frequency Measurements

i) Adjust beam to reference level

ii) Apply test voltage to CRO input probe

iii) Measure the time period required to complete one cycle

iv) Calculate the frequency

Frequency = 1 (No of Divisions on X-axis TimeDiv)

4 Phase Measurements

i) Adjust beam to reference level

ii) Apply test voltages to both CRO input channels

iii) Measure the difference between the two waves on X-axis (i e Δt)

iv) Measure the time period required to complete one cycle of channel ndash 1 (ie t1)

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v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

BASIC ELECTRONICS ENGINEERING 61

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 30: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 30

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

v) Calculate the Phase

Phase (Φ) = (Δt 180) (t1)

(Channel ndash 2 is having the phase shift of Φ with channel - 1)

Observation Table

Sr No Parameter Actual Value Observed Value

1 DC Voltage

2 AC Voltage

3 Frequency

4 Phase

BASIC ELECTRONICS ENGINEERING 31

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c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

BASIC ELECTRONICS ENGINEERING 32

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

BASIC ELECTRONICS ENGINEERING 33

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

BASIC ELECTRONICS ENGINEERING 35

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 31: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 31

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

c) Study of controls of Function Generator

THEORY

A function generator is a device that can produce various patterns of voltage at a variety of

frequencies and amplitudes The electrical leads from the device are attached to the ground and

signal input terminals of the device under test

FRONT PANEL CONTROLS

Front panel controls

Waveform key Selects the waveform sine square and triangle

TTL activation Activates TTL output

Numerical keys Specifies frequency

Frequency unit selection Specifies the frequency unit MHz kHz or Hz

Cursor selection Moves the cursor (frequency editing point)left or right

-40db attenuation Attenuates amplitude by-40db

FrequencyVoltage display selection Switches the display between frequency and

voltage

Shift key Selects the 2nd

function associated to the entry keys The LED lights when Shift is

activated

Output OnOff key Turns the output OnOff The LED lights when the output is on

Frequency Editing knob Increases (right turn) or decreases (left turn) the frequency

Main output Outputs sine square and triangle waveform BNC 50 output impedance

TTL output Outputs TTL waveform

BASIC ELECTRONICS ENGINEERING 32

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Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

BASIC ELECTRONICS ENGINEERING 33

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

BASIC ELECTRONICS ENGINEERING 35

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 32: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 32

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Amplitude control Sets the sinesquaretriangle waveform amplitude Turn left (decreases)or right

(increase)

DC offset control When pulled out sets the DC offset level for sinesquaretriangle waveform

Turn left (decrease) or right (increase)The range is-5v +5v in 50 load

Duty cycle control When pulled out sets the square or TTL wave duty cycle Turn left

(decrease)or right (increase)

Power switch Turns the main power OnOff

PROCEDURE

1) Connect sinesquaretriangular waveform from function generator to the CRO

2) Take down the various observations by varying the various controls of function generator

on CRO screen

3) Plot the changes in waveform on graph paper

CONCLUSION

BASIC ELECTRONICS ENGINEERING 33

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Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 33: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 33

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 03 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Regulated Power Supply using Bridge Rectifier Capacitor Filter And

Three Terminal Regulator

AIM a) Identify pins of rectifier diode (Such as 1N4001) and study of its data sheet specification

b) Identify pins of three pin regulator (such as LM 78XX or LM 79XX) and study of its data

sheet specifications

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

a) Identify pins of rectifier diode(Such as 1N4001)and study of its data sheet specification

PREREQUISITE

Basics of diode rectifier diode

Basics of voltage regulator

Basics of transformer Bridge rectifier

OBJECTIVE

To study working principle of rectifier diode

To study working of voltage regulators

To study amp measure voltages amp observe waveforms of transformer secondary output of

bridge rectifier output regulator

EQUIPMENTS amp COMPONENTS

1) 1N4001

2) Multimeter

3) Trainer kit

4) CRO

5) CRO probes connecting wires

BASIC ELECTRONICS ENGINEERING 34

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THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

BASIC ELECTRONICS ENGINEERING 35

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 34: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 34

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

THEORY

1N4001 - 1N4007

Figure a Typical Diode

A diode is a two-terminal electronic component with asymmetric transfer characteristic with low

(ideally zero) resistance to current in one direction and high (ideally infinite) resistance in the

other A semiconductor diode the most common type today is a crystalline piece of semiconductor

material with a p-n junction connected to two electrical terminals

Features

Diffused Junction

High Current Capability and Low Forward Voltage Drop

Surge Overload Rating to 30A Peak

Low Reverse Leakage Current

Lead Free Finish

BASIC ELECTRONICS ENGINEERING 35

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 35: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 35

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Figure b Maxratings of Electrical characteristics of 1N4001 Diode

BASIC ELECTRONICS ENGINEERING 36

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b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 36: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 36

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Identify pins of three pin regulator(such as LM 78XX or LM 79XX)and study of its data

sheet specifications

LM 78LXX

The LM78LXX series of three terminal positive regulators is available with several fixed

output voltages making them useful in a wide range of applications When used as a zener

dioderesistor combination replacement the LM78LXX usually results in an effective output

impedance improvement of two orders of magnitude and lower quiescent current These regulators

can provide local on card regulation eliminating

the distribution problems associated with single point regulation

The voltages available allow the LM78LXX to be used in logic systems instrumentation

HiFi and other solid state electronic equipment

The LM78LXX is available in the plastic TO-92 (Z) package

LM 78L05

Features

LM78L05 in micro SMD package

Output voltage tolerances of plusmn5 over the temperature range

Output current of 100 mA

Internal thermal overload protection

Output transistor safe area protection

Internal short circuit current limit

Available in plastic TO-92 and plastic SO-8 low profile packages

No external components

Output voltages of 50V 62V 82V 90V 12V 15V

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 37: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 37

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Figure c Maxratings of Electrical characteristics of LM78L05

LM78L09

Features

3-Terminal Regulators

Output Current Up to 100 mA

No External Components Required

Internal Thermal-Overload Protection

Internal Short-Circuit Current Limiting

Direct Replacement for Motorola MC79L00

BASIC ELECTRONICS ENGINEERING 38

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Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

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CONCLUSIONS

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BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 38: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 38

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Theory

This series of fixed negative-voltage integrated-circuit voltage regulators is designed for a

wide range of applications These include on-card regulation for elimination of noise and

distribution problems associated with single-point regulation In addition they can be used to

control series pass elements to make high-current voltage-regulator circuits One of these regulators

can deliver up to 100 mA of output current The internal current-limiting and thermal-shutdown

features make them essentially immune to overload When used as a replacement for a zener-diode

and resistor combination these devices can provide emf current

Figure c Maxratings of Electrical characteristics of LM79L05

BASIC ELECTRONICS ENGINEERING 39

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c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

BASIC ELECTRONICS ENGINEERING 51

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 39: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 39

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

c) To measure voltages and observe waveforms at transformer secondary output of bridge

rectifier output regulator

CIRCUIT DIAGRAM

THEORY

For positive half cycle of the input voltage diodes D1 and D2 forward biased and conduct

current During this time diodes D3 and D4 are reverse biased For negative half cycle of the input

voltage diodes D3 and D4 forward biased and conduct current During this time diodes D1and D2

are reverse biased Capacitor C1 and C2 are used as filter capacitor IC 7805 is positive voltage

regulator and Ic 7905 is negative voltage regulator Capacitors C3 and C4 are required if the

regulator is located at an appreciable distance from the power supply filter and capacitors C5 and

C6 are used to improve the transient response of the regulator

PROCEDURE

1 Make the connections as shown in the circuit diagram

2 Vary the load resistance and measure the corresponding load voltage and ripple voltage

values

3 Observe and study the output waveforms on CRO

BASIC ELECTRONICS ENGINEERING 40

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OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 40: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 40

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

OBSERVATION TABLE

Without Filter With Filter

Load

Current

IL(mA)

Load

Voltage

VL (V)

Vm

(V)

Load

current

Il (mA)

Load

Voltage

Vl (mA)

Vrpp

(V)

CALCULATIONS

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 41: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 41

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CONCLUSIONS

BASIC ELECTRONICS ENGINEERING 42

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BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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BASIC ELECTRONICS ENGINEERING 61

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 42: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 42

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

BASIC ELECTRONICS ENGINEERING 43

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Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 43: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 43

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 04 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Bipolar Junction Transistor (BJT)

AIM Single stage BJT Common Emitter amplifier

a To identify pins of a BJT (BC547) and study of its data sheet amp

specifications

b To measure voltages and observe waveforms at input and output

terminals of single stage BJT Common Emitter amplifier circuit

c Calculate voltage gain of the amplifier

PREREQUISITE

Basics of Bipolar Junction Transistor (BJT) amp its biasing methods

Basics of gain of amplifier

OBJECTIVE

To study Characteristics and parameters of BJT

Equipments amp COMPONENTS

1) Transistor 2) Bread Board 3) Function Generator 4) CRO 5) CRO Probes 6) Connecting

Probes

a Identify pins of a BJT (BC547) and study of its data sheet specifications

THEORY

Transistor is a three terminal active device made from different semiconductor materials that can

act as either an insulator or a conductor by the application of a small signal voltage The

transistors ability to change between these two states enables it to have two basic functions

―Switching amp ―amplification (analog electronics)

There are two types of BJT

BASIC ELECTRONICS ENGINEERING 44

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PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 44: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 44

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PNP transistor

NPN transistor

The Bipolar Junction Transistorlsquos basic construction consists of two PN-junctions producing three

connecting terminals with each terminal being given a name to identify it from the other two

These three terminals are known and labeled as the Emitter (E) the Base (B) and the Collector (C)

respectively The principle of operation of the two transistor types PNP and NPN is exactly the

same only difference is in their biasing and the polarity of the power supply for each type The

BJT construction is shown in figure1

(a) NPN Transistor (b) PNP Transistor

Figure1BJT Construction

The middle region of each type is called the base of the transistor This region is very thin and

lightly doped The process by which the impurities are added in a pure semiconductor is called

doping The remaining two regions are called emitter and collector The emitter and collector are

heavily doped But the doping level in emitter is slightly greater than that of collector and the

collector region area is slightly more than that of emitter Relative doping levels in the base emitter

and collector junctions must be satisfied to work that device as a transistor Two normal pn-junction

diodes cannot satisfy this requirement

In figure1 the symbol of NPN and PNP transistors are shown Arrow head on a transistor symbol

indicate the conventional current which is opposite to the direction of electron current in emitter

The transistor has two pn-junctions One junction is between the emitter and the base is called

emitter-base junction or simply the emitter junction The other junction is between the base and the

collector and is called collector-base junction or simply collector junction

BASIC ELECTRONICS ENGINEERING 45

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Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 45: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 45

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Bipolar Transistors are current regulating devices that control the amount of current flowing

through them in proportion to the amount of biasing voltage applied to their base terminal acting

like a current-controlled switch

b To measure voltages and observe waveforms at input and output terminals of single

stage BJT Common Emitter amplifier circuit

THEORY

In CE-configuration input is applied between base and emitter and output is taken from collector

and emitter Here emitter of the transistor is common to both input and output circuits and hence

the name common emitter configuration CE-configuration for both NPN and PNP transistor are

shown in figure2

Configurations

(a) NPN Transistor (b) PNP Transistor

Figure2CE-Configuration

Circuit Diagram

As shown in figure 3below the bias voltage VBB forward biases the base-emitter junction and VCC

is used to reverse bias the collector-base junction The input voltage in the CE-configuration is

the base-emitter voltage and the output voltage is the collector-emitter voltage The input current

is IB and the output current is IC

BASIC ELECTRONICS ENGINEERING 46

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Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

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voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 46: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 46

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Figure3Transistor currents and voltages in CE-Configuration

Characteristics of transistor in CE-Configuration

a Input Characteristics

It is the curve between input current IB (base current) and input voltage VBB (base-emitter

voltage) at constant collector-emitter voltage VCE The base current is taken along Y-axis and

VBB is taken along X-axis as shown in figure4

Figure4Input Characteristics of the transistor in CE-Configuration

From this characteristic we observe the following important points

1 As the input to a transistor in the CE configuration is between the base-to- emitter

junction the CE input characteristics resembles a family of forward biased diode curves

A typical set of CE input characteristics for an npn transistor is shown in figure4

2 For a fixed value of VBE IB decreases as VCE is increased A large value of VCE results in

a large reverse bias at collector-base pn-junction This increases the depletion region and

reduces the effective width of the base Hence there are fewer recombinations in the base

region reducing the base current IB

b Output Characteristics

1 This characteristic shows the relationship between the collector current IC and collector

BASIC ELECTRONICS ENGINEERING 47

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 47: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 47

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

voltage VCE for various fixed values of IB This characteristic is often called collector

characteristics as shown in figure5

Figure5 Output characteristics of the transistor in CE configuration

2 The value of βdc of the transistor can be found at any point on the characteristics by

taking the ratio IC to IB at that point

βdc = IC IB

3 The output characteristics of CE configuration consists of three regions

a Active Region - the transistor operates as an amplifier and IC = βdcIB

b Saturation - the transistor is fully-ON operating as a switch and

Ic=I(saturation)

c Cut-off - the transistor is fully-OFF operating as a switch and Ic=0

PROCEDURE

a Input Characteristics

Give 10v from power supply 1 to the input side amp 50mv from power supply 2 to

the output side

Vary base current from 0 to 30microA in steps of 5microA by using the input pot amp take

corresponding VBE reading

Repeat the above step for VCE=100mv and VCE=150mv

Plot the graphs corresponding to these set of readings on the graph paper

b Output Characteristics

Apply 10v from power supply 1 to the input side amp adjust IB using input pot to

0microA

Vary the output of power supply 2 ie VCE in steps of 1v from 0 to 15v Take

corresponding IC reading

Repeat the above step for IB=5microA 10microA amp15microA

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 48: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 48

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Plot the graphs corresponding to these set of readings on the graph paper

OBSERVATION TABLE

a Input Characteristics

VCE IB microA VBE

50mv

0

5

15

20

25

30

100mv

0

5

15

20

25

30

b Output Characteristics

IB VCE Ic microA

5 microA

0

2

4

6

8

10

10 microA 0

2

4

6

8

10

BASIC ELECTRONICS ENGINEERING 49

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c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 49: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 49

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

c Calculate voltage gain of the amplifier

THEORY

In electronics gain is a measure of the ability of a circuit (often an amplifier) to increase the

power or amplitude of a signal from the input to the output It is usually defined as the mean

ratio of the signal output of a system to the signal input of the same system It may also be

defined on a logarithmic scale in tens of the decimal logarithm of the same ratio (dB gain)

A gain greater than one (zero dB) that is amplification is the defining property of an active

component or circuit while a passive circuit will have a gain of less than one

PROCEDURE

Voltage Gain Measurement

Apply VCC=9v

Adjust the AC input frequency to 10 KHz and connect the source to the circuit

Observe the amplifier output on CRO

Adjust the AC input voltage so as to get maximum undistorted output

Calculate voltage gain AV = VO Vin

Draw the waveform for input and output on graph paper

OBSERVATION TABLE

ip Voltage op Voltage AV = VO Vin dB=20log10AV

CONCLUSION

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

BASIC ELECTRONICS ENGINEERING 65

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 50: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 50

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BASIC ELECTRONICS ENGINEERING 51

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Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 51: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 51

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 05 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Operational Amplifier

AIM Op-amp based Summing amplifier and difference amplifier

a) Identify pins of an op-amp (such as LM 741)

b) Implement given voltage equation for two inputs with Op-amp based Summing and

Difference amplifier (such as V0 = 2V1 + 3V2) and V0 = 4V1 ndash V2)

PREREQUISITE

Knowledge of different parameters of op-amp

Brief description of Summing and Difference amplifier

OBJECTIVE

Pin Diagram of LM 741

Application of Summing and Difference amplifier

EQUIPMENTS amp COMPONENTS

1) IC 741

2) Bread board

3) Resistor (As Specified)

4) Connecting wires

5) DC Power supply (+12V)

6) CRO

BASIC ELECTRONICS ENGINEERING 52

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a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

BASIC ELECTRONICS ENGINEERING 65

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 52: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 52

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify Pins of an Op-amp LM 741

THEORY

The LM 741 is a high performance operational amplifier The high gain and wide range of

operating voltage provides superior performance in many applications

Pin No Pin

Abbreviation

Pin description

1 OFFSET

NULL (-)

Offset voltage is the differential dc voltage required

between the inputs to force the output to zero volts Offset

voltage is nulled by application of a voltage of opposite

polarity to the offset

2 INVERTED

INPUT

All input signals at this pin will be inverted at output pin 6

3 NON-

INVERTED

INPUT

All input signals at this pin will be processed normally

without inversion

4 VEE It is the negative supply voltage terminal Desired operating

range is -5V to -15V

5 OFFSET

NULL (+)

Same as pin 1 except opposite polarity

6 OUTPUT Output voltage polarity will be opposite to that of input

terminal if the input signal is applied at op-amplsquos inverting

point

7 VCC It is the positive supply voltage terminal It specified

operation voltage range is +5V to +15 V

8 NC It stands for NO CONNECTION Nothing is connected to

this pin It is just there to make it standard 8-pin package

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

BASIC ELECTRONICS ENGINEERING 65

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 53: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 53

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CIRCUIT DIAGRAM

Fig 51 Symbol of Op-amp 741

Fig 52 Pin Diagram of Op-amp 741

BASIC ELECTRONICS ENGINEERING 54

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b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

BASIC ELECTRONICS ENGINEERING 65

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 54: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 54

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Implement given voltage equation for 2 inputs with Op-Amp based Summing and

difference amplifier

THEORY

I Summing Amplifier

It has two or more inputs and its output voltage is proportional to the negative of the

algebraic sum of its input voltages It is also called as ―summing inverter or ―Voltage adder The

amplifier is connected with feedback to produce a closed loop operation

CIRCUIT DIAGRAM

Fig 53 Circuit diagram of Summing Amplifier

Fig 54 Circuit diagram of Summing Amplifier with N inputs

BASIC ELECTRONICS ENGINEERING 55

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Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

BASIC ELECTRONICS ENGINEERING 65

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 55: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 55

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Summing Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

Since Vout = -IF RF

Vout = - (I1 + I2) RF

Vout = - (

)

If all the three resistors are equal (R1 = R2 = RF= R) then

Vout = - (

)

Vout = - (Vin1 + Vin2)

General expression for unity gain summing amplifier with N inputs

Vout = - ( )

General expression for gain greater than unity with N inputs

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in

the circuit diagram

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2 mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

BASIC ELECTRONICS ENGINEERING 65

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 56: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 56

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CALCULATIONS

1 Implement following equation using difference amplifier Vout = - (10V1 + 5V2)

2 Given the value of RF = 10KΩ Therefore

Vout = - (

)

3 Calculate R1 and R2 using the equation

4 From the equation of the output voltage we obtain R1 and R2

5 Implement the values obtained through calculation on the circuit and calculate theoretical as

well as practical values of output voltage

II Difference Amplifier

For the subtraction of two input voltages or to amplify the difference between two voltages

subtractor or Difference amplifier is employed The output voltage is proportional to the difference

between the two input voltages

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 57: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 57

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CIRCUIT DIAGRAM

Fig 55 Circuit diagram of Difference amplifier

Difference Amplifier Equation

Applying Kirchhofflsquos current equation at node A (which is virtual ground)

IF = I1 + I2

I1 =

I2 =

IF= ( )

VB = (

)

Summing point VA= VB

If VB =0 then Vout(A) = -V1(

)

BASIC ELECTRONICS ENGINEERING 58

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If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

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3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

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BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 58: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 58

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

If VA = 0 then Vout (B) = -V2(

) (

)

Vout= Vout(A) + Vout(B)

Vout = -V1(

) + V2(

) (

)

When Resistors R1= R2 then

Vout =

( )

PROCEDURE

1 Make the connection for summing amplifier on breadboard as shown in the Fig

53

2 Apply 12 V dual supply to the summing amplifier

3 Apply input voltages as Vin1 = 2mV and Vin2 = 5 mV

4 Measure the value of output voltage using DMM

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

Output voltage

CALCULATIONS

1 Implement following equation using summer amplifier Vout = 4(V1 - V2)

2 Given the value R1= 1KΩ RF = 4KΩ Therefore

Vout =

( )

BASIC ELECTRONICS ENGINEERING 59

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

BASIC ELECTRONICS ENGINEERING 61

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 59: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 59

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

3 With the help of step 2 and step 3 we will implement the values obtained through

calculation on the circuit and calculate theoretical as well as practical values of output

voltage

CONCLUSION

BASIC ELECTRONICS ENGINEERING 60

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

BASIC ELECTRONICS ENGINEERING 61

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

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Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

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Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

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Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

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PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

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4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

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8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 60: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 60

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

BASIC ELECTRONICS ENGINEERING 61

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Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

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a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

BASIC ELECTRONICS ENGINEERING 65

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

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The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

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Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 61: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 61

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 06 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Timer IC 555

AIM Study of Timer IC 555 circuit

a) Identify pins of Timer IC 555

b) Observe output waveform and measure frequency of output wave for Timer IC 555 used

in Astable mode

PREREQUISITE

Knowledge of Timer IC 555

Knowledge of Astable Multivibrator along with derivation of duty cycle

OBJECTIVE

Pin Diagram of Timer IC 555

Working of Astable multivibrator

EQUIPMENTS amp COMPONENTS

1) Timer IC 555

2) Bread board

3) Resistor (As Specified)

4) Capacitor (As Specified)

5) Connecting wires

6) DCPower supply

7) CRO

BASIC ELECTRONICS ENGINEERING 62

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

BASIC ELECTRONICS ENGINEERING 63

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

BASIC ELECTRONICS ENGINEERING 65

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

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Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 62: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 62

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify Pins of TIMER IC 555

THEORY

The connection of the pins for a DIP package as follows

Pin

No

Pin

Abbreviation

Pin description

1 GND Ground All voltages are measured with respect to this

terminal

2 TRIG Trigger it depends upon the amplitude of the external

trigger pulse applied to this pin If the voltage at this pin

is greater than 23 VCC output is LOW and if greater

than 13 VCC then output is HIGH

3 OUT Output Load can be connected between pin 3 and pin

1(ground) or between pin 3 and pin 8 (Supply voltage)

depending upon the nature of output whether high or low

4 RESET Reset Timer IC 555 can be reset (disabled) by applying

negative pulse to this pin If reset not in use it should be

connected to +VCC

5 CTRL Control voltage An external voltage applied to this pin

changes the threshold as well as the trigger voltage

6 THR Threshold It is non inverting input terminal of

comparator which monitors the voltage across the

external capacitor

7 DIS Discharge It is connected internally to the collector of

transistor

8 +VCC Supply Voltage The positive supply voltage between

+5V to +18V with respect to ground

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CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

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b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

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2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

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Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

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a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

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NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

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b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

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PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 63: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 63

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

CIRCUIT DIAGRAM

Fig 61 Pin Diagram of TIMER IC 555

Fig 62 Internal diagram of TIMER 555 IC

BASIC ELECTRONICS ENGINEERING 64

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

BASIC ELECTRONICS ENGINEERING 65

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

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5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

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The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 64: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 64

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Observe waveform and measure frequency of output waveform for Timer IC 555 used in

Astable Mode

THEORY

Timer IC 555 is a timing circuit that can produce an accurate and highly stable time

delays or oscillations Its timing varies from microseconds to hours It operates on +5V to + 18V

supply voltage The timer basically operates in one of the two modes either as Astable (Free

Running) Multivibrator or as Monostable (one shot) Multivibrator

An Astable Multivibrator is a rectangular wave generating circuit It does not require

an external triggering pulse to change the state of the output Hence the name Astable

Multivibrator The time during which output remains high is determined by external resistors

RA and RB and capacitor C

Initially when output is high the capacitor C starts charging towards +VCC through RA

and RB However as soon as voltage across capacitor reaches 23 VCC upper comparator triggers

the Flip-Flop and Output Switches low Now Comparator C starts discharges through RB and

internal discharge transistor When voltage across capacitor reaches 13 VCC Lower comparator

triggers the Flip-Flip and output switches High

CIRCUIT DIAGRAM

Fig 63 Circuit diagram of Astable multivibrator

PROCEDURE

1 Make the connection for Astable multivibrator on breadboard as shown in the circuit

diagram with RA = 1K ohm RB = 2Kohm and C= 01microF

BASIC ELECTRONICS ENGINEERING 65

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

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With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 65: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 65

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

2 Connect DC power supply of 5VConnect CRO at the output terminals of 555 IC and

measure the value of output frequency

3 Sketch the waveforms on graph paper Measure ON and OFF time periods of waveform

on CRO

4 Calculate the Frequency of Oscillations (fO) practically and verify with

theoretical frequency

OBSERVATION TABLE

PARAMETER THEORITICAL PRACTICAL

tON (microsec)

tOFF (microsec)

T (microsec)

FO (KHz)

CALCULATIONS

1 The timing during which capacitor C starts charges from 13 Vcc to 23 Vcc (tC) is

equal the time when output is HIGH (tON) The tON Charge ONlsquo time It is calculated as

tON = tC = 069 (RA +RB) C

2 The timing during which capacitor discharges from 23 Vcc to 13 Vcc(td) is equal to the time

when output is HIGH (tOFF) The tOFF Discharge OFFlsquo time It is calculated as

tOFF = td = 069 (RB) C

3 The total time period (T) of the output waveform is given by

T = tON + tOFF

T= tC + td = 069 (RA + 2RB) C

4 The output frequency (fO) of the output waveform is given as

fO = 1T

BASIC ELECTRONICS ENGINEERING 66

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 66: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 66

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

5 Duty cycle for the Astable multivibrator is the ratio of the ―ON time divided by the

Total time (tON + tOFF) It can be calculated as

Duty cycle = tON (tON + tOFF) = RA + RB

RA + 2RB

CONCLUSION

BASIC ELECTRONICS ENGINEERING 67

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 67: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 67

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 07 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Digital Circuits

AIM a) Identify pins of Digital Logic Gates ICs such as AND OR NOT XOR NAND

b) Implement Half amp Full adder circuits with basic logic gate ICs

PREREQUISITE

Basic knowledge regarding digital circuits

Knowledge of various binary operations

OBJECTIVE

Identify pins of Digital Logic Gates

Practically building amp testing half adder and full adder circuits

Verification of their respective truth tables

EQUIPMENTS amp COMPONENTS

1) ICs7408 (AND) 7432(OR) 7404(NOT) 7486(EX-OR) 7400(NAND)

7402(NOR)

2) Power Supply

3) Digital trainer Kit

4) Connecting wires etc

BASIC ELECTRONICS ENGINEERING 68

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 68: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 68

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

a) Identify pins of Digital Logic Gates ICs such as ANDORNOTEX-ORNAND

PIN DIAGRAMS

NOT GATE Truth tableY=A

OR GATE Truth tableY=A+B

AND GATE Truth tableY=AB

Input Output

A Y

0 1

1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 1

Inputs Output

A B Y

0 0 0

0 1 0

1 0 0

1 1 1

BASIC ELECTRONICS ENGINEERING 69

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 69: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 69

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

NOR GATE Truth table Y=A+B

NAND GATE Truth table Y=AB

EX-OR GATE Truth tableAB+AB

Inputs Output

A B Y

0 0 1

0 1 0

1 0 0

1 1 0

Inputs Output

A B Y

0 0 1

0 1 1

1 0 1

1 1 0

Inputs Output

A B Y

0 0 0

0 1 1

1 0 1

1 1 0

BASIC ELECTRONICS ENGINEERING 70

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 70: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 70

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

b) Implement Half amp Full adder circuits with basic logic gate ICs

THEORY

Binary Addition In the binary number system we have only two digits 0lsquo and 1lsquo During the

addition of two binary digits total four cases are involved Let us have binary addition of these four

cases as

Observe carefully these cases What is your observation We see here that Sum=0 When both

inputs are equal (same) and Sum = 1 when inputs are unequal (not same) In digital electronics we

come across a two input gate whose output is 1 for unequal inputs while output is 0 for equal

inputs It is the exclusive-ORlsquo (X-OR) gate It means that X-OR gate has output equal to the sum

of its inputs But this addition is incomplete because it does not produce proper carry as appeared

in the last case The careful observation for producing carry 1lsquo is nothing but AND ing both inputs

Therefore the Boolean expression for sum and carry will be

Sum = A B Carry = AB

The Half Adder Half adder is an electronic circuit which can add two binary digits and producing

its sum with proper carry From the above discussion it is clear that an X-OR gate and an AND gate

is required for its construction The fig 1 shows half adder constructed from one X-OR and single

AND gate

The half adder adds two binary digits but it has a disadvantage that it is not useful during the

addition two binary numbers having more than one binary digit This is because if there is any carry

produced during the addition of LSB there is no provision for such carry in the addition of next

LSB So this circuit can add two single bit binary numbers only

1) 0

+ 0

0 Sum

carry

2) 0

+ 1

1 Sum

3) 1

+ 0

1 Sum

4) 1

+ 1

Carry 1 0 Sum

BASIC ELECTRONICS ENGINEERING 71

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 71: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 71

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Circuit diagram for Half adder

TRUTH TABLE FOR HALF ADDER

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

FULL ADDER The full adder is a circuit which can add three binary bits This circuit becomes

essential during the addition of two binary numbers containing more than one bit This is because

the third input is useful carrylsquo generated in the addition of previous binary digits

Now look at the sum of three binary digits given below

There are total eight different possible combinations of inputs but we will consider five of them

which are quite illustrative

1 0 + 0 + 0 = 0 where sum is 0 and carry is 0

2 1 + 0 + 0 = 1 where sum is 1 and carry is 0

3 1 + 1 + 0 = 10 where sum is 0 and carry is 1

4 1 + 0 + 1 = 10 where sum is 0 and carry 1

5 1 + 1 + 1 = 11 where sum is 1 and carry is 1

Basically we have a circuit to add the two binary digits called half adderlsquo To add three

bits we will add the third bit in the addition of sum of the first two binary digits Let us observe

now what happens to this addition if we proceed in this manner

BASIC ELECTRONICS ENGINEERING 72

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 72: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 72

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The first case 0

+ 0

No first carry 0 Sum

+ 0

No second carry 0 Final Sum

Therefore Final sum=0 but final carry = 0

The second case

1

+ 0

No first carry 1 Sum

+ 0

No second carry 1 Final Sum

Therefore final Sum = 1 but final carry = 0

The third case

1

+ 1

First carry 1 0 Sum

+ 0

No second carry 0 final Sum

Therefore final sum = 0 but final carry = 1

The fourth case 1

+ 0

No first carry 1 Sum

+ 1

Second carry 1 0 final Sum

Therefore final sum = 0 but final carry = 1

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 73: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 73

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

The fifth case

1

+ 1

First carry 1 0 Sum

+ 1

Second carry 1 1 final Sum

Therefore final Sum = 1 but final carry = 1

It is observed from these five different sum that final sum is obtained by adding third bit in the sum

of two bits and final carry is obtained by ORing the carries produced at two stages Therefore the

circuit for addition of 3 bits have two half adders and a OR gate having arrangement as shown in

following Figure

Circuit diagram for Full adder

Sum = A B C Carry = AB+AC+BC

INPUT OUT PUT

A B C Sum Carry

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 74: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 74

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Half Adder

1) Select one EX-OR gate from IC 7486 and one AND gate from IC 7408

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from AND gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

Full Adder

1) Select two EX-OR gate from IC 7486two AND gate from IC 7408 one OR gate from IC 7432

2) Connect A and B inputs to the inputs of two gates as shown in figure

3) Connect output of both gates to logic indicators

4) Connect supply wires to appropriate pins of each IC

5) Connect both inputs A and B to ground switch on the power supply

6) Note output from X-OR gate as sumlsquo of inputs A and B while output from OR gate as carrylsquo

7) By changing inputs A and B complete the truth table from and observed output states for all

possible combinations of inputs

CONCLUSION

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 75: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 75

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Department of Electronics amp Telecommunication

Experiment No 08 Date of Performance -----------------

Name of the student ---------------------------------------------------------------------------------------------

Division --------------- Roll No ---------------

Soldering Techniques

AIM Build and test an application circuit of IC such as Timer IC 555 Prepare a report on it

PREREQUISITE

Find an importance of soldering in any electronic application

Knowledge of good and bad soldering

OBJECTIVE

To study different soldering techniques

Procedure and precautions to be considered while soldering

EQUIPMENTS amp COMPONENTS

1) Soldering Iron 2) Soldering Metal 3) Flux 4) Timer IC 555 4) DMM 5) CRO

THEORY

Theory for Soldering

What is solder

Solder is an alloy (mixture) of tin and lead typically 60 tin and 40 lead It melts at a

temperature of about 200degC Coating a surface with solder is called tinning because of the tin

content of solder Lead is poisonous and you should always wash your hands after using solder

Solder for electronic components contains tiny cores of flux like the wires inside a mains flux The

flux is corrosive like an acid and it cleans the metal surfaces as the solder melts This is why you

must melt the solder actually on the joint not on the iron tip Without flux most joints would fail

because metals quickly oxidize and the solder itself will not flow properly into dirty oxidized

metal surface The best size of solder for electronics is 22swg (swg = standard wire gauge)

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 76: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 76

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Reels of solder

Flux

Flux reacts with or removes oxide and other contamination on the surface to be soldered Dissolve

the metal salts formed during the reaction with the metal oxides Protect the surface from

reoxidation before soldering occurs Provide a thermal blanket to spread the heat evenly during

soldering Reduce the interfacial surface tension between the solder and the substrate in order to

enhance wetting

Flux provides several benefits

bull Cleans the base metal (copper trace)

bull Protects the solder and base metal from oxidizing during the soldering process

bull Promotes wetting action of the melted solder

Flux represents some trade offs

bull Can become entrained in the joint

bull Is corrosive and so must be removed

Soldering Techniques

To achieve a soldered joint the solder and the base metal must be heated above the melting point of

the solder used The method by which the necessary heat is applied depends among other things

on ndash nature and type of the joint melting temperature of the solder and fluxGenerally applied

soldering methods are iron soldering torch soldering mass soldering electrical soldering (high

frequency soldering resistance soldering) furnace soldering and other methods Here we shall

have a closer look at the iron soldering and the mass soldering

1) Iron soldering

2) Mass soldering

a Dip soldering

b Wave soldering

c Drag soldering

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 77: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 77

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

PROCEDURE

Preparing the soldering iron

Place the soldering iron in its stand and plug in

The iron will take a few minutes to reach its operating temperature of about 400degC

Dampen the sponge in the stand

The best way to do this is to lift it out the stand and hold it under a cold tap for a moment

then squeeze to remove excess water It should be damp not dripping wet

Wait a few minutes for the soldering iron to warm up

You can check if it is ready by trying to melt a little solder on the tip

Wipe the tip of the iron on the damp sponge

This will clean the tip

Melt a little solder on the tip of the iron

This is called tinning and it will help the heat to flow from the irons tip to the joint It only

needs to be done when you plug in the iron and occasionally while soldering if you need to

wipe the tip clean on the sponge

You are now ready to start soldering

Hold the soldering iron like a pen near the base of the handle

Imagine you are going to write your name Remember to never touch the hot element or

tip

Touch the soldering iron onto the joint to be made

Make sure it touches both the component lead and the track Hold the tip there for a few

seconds and

Feed a little solder onto the joint

It should flow smoothly onto the lead and track to form a volcano shape as shown in the

diagram Apply the solder to the joint not the iron

Remove the solder then the iron while keeping the joint still

Allow the joint a few seconds to cool before you move the circuit board

Inspect the joint closely

It should look shiny and have a volcano shape If not you will need to reheat it and feed in

a little more solder This time ensure that both the lead and track are heated fully before

applying solder

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 78: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 78

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Good Soldering Bad Soldering

Using a heat sink

Some components such as transistors can be damaged by heat when soldering so if you are not an

expert it is wise to use a heat sink clipped to the lead between the joint and the component body

You can buy a special tool but a standard crocodile clip works just as well and is cheaper

Crocodile clip

How to solder Actual components on board

Soldering Advice for Components

It is tempting to start soldering components onto the circuit board straight away but please take

time to identify all the parts first You are much less likely to

make a mistake if you do this

1 Stick all the components onto a sheet of paper using

sticky tape

2 Identify each component and write its name or value

beside it

3 Add the code (R1 R2 C1 etc) if necessary

Many projects from books and magazines label the

components with codes (R1 R2 C1 D1 etc) and you

should use the projects parts list to find these codes if they are given

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 79: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 79

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

4 Resistor values can be found using the resistor colour code which is explained on our

Resistors page You can print out and make your own Resistor Colour Code Calculator to

help you

5 Capacitor values can be difficult to find because there are many types with different

labelling systems The various systems are explained on our Capacitors page

For most projects it is best to put the components onto the board in the order given below

Components Pictures Reminders and Warnings

1 IC Holders

(DIL sockets)

Connect the correct way round by

making sure the notch is at the correct end

Do NOT put the ICs (chips) in yet

2 Resistors

No special precautions are needed with

resistors

3

Small value

capacitors

(usually less than

1microF)

These may be connected either way round

Take care with polystyrene capacitors

because they are easily damaged by heat

4

Electrolytic

capacitors

(1microF and greater)

Connect the correct way round They

will be marked with a + or - near one lead

5 Diodes

Connect the correct way round

Take care with germanium diodes (eg

OA91) because they are easily damaged

by heat

6 LEDs

Connect the correct way round

The diagram may be labelled a or + for

anode and k or - for cathode yes it really

is k not c for cathode The cathode is the

short lead and there may be a slight flat on

the body of round LEDs

7 Transistors

Connect the correct way round

Transistors have 3 legs (leads) so extra

care is needed to ensure the connections

are correct Easily damaged by heat

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 80: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 80

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

8

Wire Links

between points on

the circuit board

single core wire

Use single core wire this is one solid wire

which is plastic-coated

If there is no danger of touching other

parts you can use tinned copper wire this

has no plastic coating and looks just like

solder but it is stiffer

9

Wires to parts off

the circuit board

including switches

relays

variable resistors

and loudspeakers

stranded wire

You should use stranded wire which is

flexible and plastic-coated Do not use

single core wire because this will break

when it is repeatedly flexed

De-soldering

At some stage you will probably need to desolder a joint to remove or re-position a wire or

component There are two ways to remove the solder

Using a desoldering pump (solder sucker)

1 With a desoldering pump (solder sucker)

Set the pump by pushing the spring-loaded plunger down until it locks Apply both the

pump nozzle and the tip of your soldering iron to the joint

Wait a second or two for the solder to melt

Then press the button on the pump to release the plunger and suck the molten solder into

the tool

Repeat if necessary to remove as much solder as possible

The pump will need emptying occasionally by unscrewing the nozzle

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 81: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 81

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

With solder remover wick (copper braid)

Solder remover wick

Apply both the end of the wick and the tip of your soldering iron to the joint

As the solder melts most of it will flow onto the wick away from the joint

Remove the wick first then the soldering iron

Cut off and discard the end of the wick coated with solder

After removing most of the solder from the joint(s) you may be able to remove the wire or

component lead straight away (allow a few seconds for it to cool) If the joint will not come apart

easily apply your soldering iron to melt the remaining traces of solder at the same time as pulling

the joint apart taking care to avoid burning yourself

Precautions

First a few safety precautions

Never touch the element or tip of the soldering iron

They are very hot (about 400degC) and will give you a nasty burn

Take great care to avoid touching the mains flux with the tip of the iron

The iron should have a heatproof flex for extra protection An ordinary plastic flux will

melt immediately if touched by a hot iron and there is a serious risk of burns and electric

shock

Always return the soldering iron to its stand when not in use

Never put it down on your workbench even for a moment

Work in a well-ventilated area

The smoke formed as you melt solder is mostly from the flux and quite irritating Avoid

breathing it by keeping you head to the side of not above your work

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS

Page 82: Department of Electronics & Telecommunication. ELECTRONICS ENGINEERIN… · BASIC ELECTRONICS ENGINEERING 2 Shree Ramchandra College of Engineering, Lonikand, Pune - 412 216. 1) Carbon

BASIC ELECTRONICS ENGINEERING 82

Shree Ramchandra College of Engineering Lonikand Pune - 412 216

Wash your hands after using solder

Solder contains lead which is a poisonous metal

First Aid for Burns

Most burns from soldering are likely to be minor and treatment is simple

Immediately cool the affected area under gently running cold water

Keep the burn in the cold water for at least 5 minutes (15 minutes is recommended) If ice

is readily available this can be helpful too but do not delay the initial cooling with cold

water

Do not apply any creams or ointments

The burn will heal better without them A dry dressing such as a clean handkerchief may

be applied if you wish to protect the area from dirt

Seek medical attention if the burn covers an area bigger than your hand

To reduce the risk of burns

Always return your soldering iron to its stand immediately after use

Allow joints and components a minute or so to cool down before you touch them

Never touch the element or tip of a soldering iron unless you are certain it is cold

CONCLUSIONS


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