ANNA UNIVERSITY TIRUCHIRAPPALLI TIRUCHIRAPPALLI - 620 024 REGULATION-2007

B.E-ELECTRONICS AND COMMUNICATION ENGG

FIRST YEAR ELECTRONICS LAB MANUAL

(COMMON FOR ECE, CSE IT)

J.J. COLLEGE OF ENGINEERING & TECHNOLOGYAMMAPETTAI, POOLANGULATHUPATTI (PO)

TRICHIRAPALLI-620009

LIST OF EXPERIMENTS:

1. Characteristics of PN junction diode

2. Characteristics of Zener diode

3. Characteristics of JFET

4. Characteristics of UJT

5. Characteristics of SCR

6. Characteristics of Photo Diode

7. Characteristics of Phototransistor

8. Characteristics of DIAC

9. Characteristics of TRIAC

10. Characteristics of BJT in CE Configuration

11. Common base configuration

EX.NO:1 CHARACTERISTICS OF PN JUNCTION DIODE

AIM:To study the characteristics of PN junction diode under forward bias condition

and reverse bias condition.

COMPONENTS:

1. PN junction diode IN4001

2. Resistor 1kΩ

3. Voltmeter (0-2)V, (0-30)V

4. Ammeter (0 – 50)MA , (0-500)µA

5. DCPS

6. Bread board

7. Connecting wires

THEORY:

PN junction diode is a two-terminal device. The P and N junctions are referred to

as anode and cathode respectively. A PN junction diode is a one way device offering low

resistance. When forward biased and behaving as an insulator when reverse biased.

Forward bias:

When a semiconductor diode is under forward bias condition, the anode of the

diode is connected to the positive terminal of battery and the cathode of diode is

connected to negative terminal of the battery.

Reverse Bias

Here the anode of the diode is connected to the negative terminal of battery and

cathode of the diode is connected to positive terminal of the battery.

PROCEDURE:

1. Connections are made as shown in the circuit diagram.

2. Input voltage is varied and the corresponding readings of voltmeter and

ammeter

3. For reverse bias the polarity of the diode is reverse and the millimeter is

replaced by a micro ammeter

4. For the tabulated readings the forward and reverse characteristics of the PN

junction diode are drawn with voltage X- axis and current on Y- axis.

RESULT :

Thus the value of reverse saturation current was studied under forward and

reverse bias condition in PN junction diode.

EX.NO:2 CHARACTERISTICS OF ZENER DIODE

AIM:

To study the characteristics of Zener diode under forward bias condition and

reverse bias condition

COMPONENTS:

1. Zener Diode Z 6.8

2. Resistor 560Ω

3. Voltmeter (0-10)V, (0-30)V

4. Ammeter (0 – 50)MA , (0-100)mA

5. DCPS

6. Bread board

7. Connecting wires

THEORY:

Zener diode is heavily doped PNP junction diode. The zener diode is normally

operated in its reverse biased breakdown region, where the voltages across the device

remain constant as the reverse current varies over a large range. Like a fixed voltage

some , this ability to maintain a constant voltage across its terminals, independent of

current makes the device useful as a voltage is called zener voltage.

Forward bias :

When the zener diode is forward biased, the forward current increases with

increase in applied voltage bias condition of ordinary PN junction diode.

Reverse bias:

When the diode is reverse biased a small reverse current called reverse saturation

current starts increasing rapidly with no change in the voltage Vz

PROCEDURE:

1. Connections are made as shown in the circuit diagram.

2. Input voltage is varied and the corresponding readings of voltmeter and

ammeter

3. For reverse bias the polarity of the diode is reverse and the millimeter is

replaced by a micro ammeter

4. For the tabulated readings the forward and reverse characteristics of the PN

junction diode are drawn with voltage X- axis and current on Y- axis.

RESULT :

Thus the value of reverse saturation current was studied under forward and

reverse bias condition in zener diode.

EX.NO:3 CHARACTERISTICS OF JFET

AIM:

To draw the drain and transfer characteristics of JFET.

COMPONENTS:

1. JFET BFW10

2. Voltmeter (0-39)v,(0-10)v

3. Ammeter (0-50)ma

4. DCPS

5. Bread board

6. Connecting wires

THEORY:

The field effect transistor like bipolar junction transistor is a three terminal

semiconductor device. It is called unipolar device because the current through it results

from the flow of only one of the two kinds of charge carriers namely holes or electrons

whichever is the majority carriers.

PROCEDURE:

If a battery Vds is connected across the channel , the electrons in the n- channel

move towards the positive terminal of the battery.

Drain control characteristics:

Keeping the voltage between gate and source (Vgs) constant, the drain source

voltage (Vds) is varied and the corresponding values of Vds and drain current (Id) are

noted drawn. This is repeated for different constant values of Vgs. A graph is drawn

between Vds and Id for different constant values of Vgs. This gives the drain

characteristics. The slope of the characteristics given, drain resistance of JFET

Transfer characteristics:

Keeping Vds constant, Vgs is varied and the corresponding values of Vgs and Id

are noted down. This is repeated for different constant values of Vds. A graph is drawn

between Vgs and Id for different values of Vds. This gives the transfer characteristics

from the transfer characteristics. The Trans conductance of JFET is determined.

RESULT:

Thus JFET has a very high input resistance and amplification factor greater than

unity.

EX.NO:4 CHARACTERISTICS OF UJT

AIM:

To draw the emitter characteristics of UJT and to determine intrinsic stand off

ratio.

COMPONENTS:

Power supply (0-30)v

Ammeter (0-50) m A

Voltmeter (0-30) v,(0-10)v

UJT ZN2646

Resistor 22kΩ

FORMULA:

Intrinsic Stand Off Ratio η = Vp-Vd./VB1.VB2

Where V p=peak voltage

V d=diode forward voltage(v)

VB1B2=Voltage across the terminals B1 and B2.

THEORY:

It is a three terminal semiconductor switching device. There are one emitter and

two bases. The emitter is heavily doped, it is a p-region having two many holes .It is

diffused in n-region which is lightly doped.

PROCEDURE:

To determine the emitter characteristics of UJT, VB1,VB2 are kept constant and

voltage across B1 and Vet is varied and emitter current (Ie) is noted. A graph is drawn by

taking Ie along x-axis and Vbe along y-axis. From the characteristics curve intrinsic stand

off ratio is calculated.

RESULT:

Thus the intrinsic stand off ratio is calculated from emitter characteristics of UJT

EX.NO:5 CHARACTERISTICS OF SCR

AIM:

To draw the characteristics of SCR and to calculate gate current(IG)

COMPONENTS:

Power supply (0-30)v-2

Resistor 1KΩ-2

Ammeter (0-50) m A-2

SCR-1

Voltmeter (0-30) v -1

THEORY:

SCR acts as a switch when it is forward biased when the gate is kept open

IG=0.Operation of SCR is similar to PN diode .When IG>0, the amount of reverse

Bias applied.I2 decreased very low voltage such that the characteristics of SCR is similar

to that of of ordinary PN diode.

Once the SCR is turned ON , the gate loses control the gate cannot be used to

switch the device off.

PROCEDURE:

1. Connections are made as shown in the circuit diagram.

2. Power supply and voltage to gate is increased to make the voltmeter reading

zero.

3. The voltmeter is used to get supply and it is increased

4. The corresponding voltmeter and ammeter readings are noted.

5. A graph is plotted by taking voltage along x-axis and current along Y- axis.

Result:

Thus the firing characteristics of SCR and the calculations of gate current are

studied.

EX.NO:6 CHARACTERISTICS OF PHOTO DIODE

AIM:

To determine the characteristics of photo diode.

Components:

Photo diode

Voltmeter (0-10) v

Ammeter (0-25) ma

Resistor 1kΩ

DCPS

Connecting wires

Lamp

Theory

Photo diode consists of PN diode embedded in clear plastic. It is constructed so

that it can be exported to light when reverse biased, it behaves as photo conductive device

because its resistance result in a change in reverse leakage current. The reverse leakage

current is conventional diode is due to thermally generated minority carriers that are

swept at the depletion region by carrier voltage.

PROCEDURE:

1. Connections are made as shown in the circuit diagram.

2. the photo diode is reverse biased

3. the distance between the lamp and corresponding voltmeter and ammeter

readings are noted

4. this is repeated for different constant distance

5. A graph is plotted by taking voltage along x-axis and current along Y- axis.

Result :

Thus the characteristics of photo diode is plotted and verified.

EX.NO:7 CHARACTERISTICS OF PHOTOTRANSISTOR

AIM:

To determine the characteristics of photo transistor

COMPONENTS:

Phototransistor

Voltmeter (0-30)v

Ammeter (0-20)ma

Lamps

Dcps

Bread board

Connecting wires.

Theory:

The phototransistor is a much more sensitive semiconductor photo device than the

PN photodiode . the phototransistor is usually connected in a common emitter

configuration with base open and radiation is concentrated on the region near the

collector junction. The emitter junction is lightly forward biases and collector junction is

reverse biased. When there is no light and collector junction is reverse biased. When

there is no light incident on the phototransistor, the thermally generated minority carriers

constitute the reverse saturation current ICO. The collector current is given as IC =(1+B)

ICO. When B is current gain of common emitter amplifier. If light is turned on current

gain of common emitter amplifier.

Procedure:

Connections are made as shown in the circuit diagram. The distance between the

light source and the photo transistor is kept constant . the collector emitter voltage is

varied and the collector current is noted down . this is repeated for different and

phototransistor . A graph is drawn with VCE in x-axis and IC in y-axis.

Result:

The characteristics of photo transistor is drawn.

EX.NO:8 CHARACTERISTICS OF DIAC

AIM:

To study, the characteristics of DIAC.

COMPONENTS:

DIAC Db3

Voltmeter (0-300)v

Ammeter

Bread board

Connecting wires

THEORY:

A DIAC is a two terminal, three layer bi-directional device, which can be

switched from its OFF state to ON state for either polarity voltage. A DIAC is a two-

terminal, three layer bi-directional device, which can be switched from its OFF state to

ON state for either polarity of applied voltage.

The DIAC can be constructed in either npn and pnp from the two leads are

connected to p-region of silicon separated by an n-region. The structure of DIAC is very

much similar to that of a transistor.

OPERATION:

When a –ve voltage or +ve voltage is applied across the terminals of a DIAC ,

only a small leakage current. as the applied voltage is increased the leakage current will

continue to flow until the voltage reaches the break over voltage VBO.

Procedure:

Connections are made as shown in the diagram.

For applied +ve voltage less than +VBO and –ve voltage less than –VBO, small

leakage current (-+IBO) flows through the device.

the voltage +VBO and –VBO are the break down voltages and usually have a

range of 30 to 50v

Result:

When the +ve or –ve applied voltage is equal to or greater than break down

voltage, DIAC begins to conduct and the voltage drop across it becomes a few

volts. Conduction then continues until the device current drops below its holding

its holding current. Note that the break over voltage and holding current values

are identical for the forward and reverse regions of operation.

EX.NO:9 CHARACTERISTICS OF TRIAC

Aim:

To draw, VI - C characteristics of the given TRIAC

Components:

TRIAC BJT 136

DCPS (0-30)V,(0-300)V

Resistors 10k,1k,2.2k/10w

Voltmeter (0-300)v

Ammeter (0-25)ma, (0-100) ma

Bread board

Connecting wires

Theory

A TRIAC is a three terminal semiconductor device, which can control alternating

current in a load. TRIAC is an abbreviation for triode ac switch . tri- indicates that the

device has three terminals and ac means that the device controls alternating current in

either direction .

The control circuit of a TRIAC can be adjusted to pass the desired portions of

positive and negative half-cycle of a.c supply from Ө to 1800

Procedure:

Connections are made as shown in the diagram.

For applied +ve voltage less than +VBO and –ve voltage less than –VBO, small

leakage current (-+IBO) flows through the device.

the voltage +VBO and –VBO are the break down voltages and usually have a

range of 30 to 50v

Result:

When the +ve or –ve applied voltage is equal to or greater than break down

voltage, TRIAC begins to conduct and the voltage drop across it becomes a few volts.

Conduction then continues until the device current drops below its holding its holding

current. Note that the break over voltage and holding current values are identical for the

forward and reverse regions of operation

EX.NO:10 CHARACTERISTICS OF BJT IN CE CONFIGUATION

AIM:

To draw the input and output characteristics of a BJT in CE configuration.

Components:

Transistor BC 547

Voltmeter (0-3) v, (0-10) v

Ammeter (0-500)ma, (0-50)ma

Resistor 1K(2)

DCPS

Bread broad

Connecting wires

Theory:

The transistor has there regions namely emitter, base and collector. The base is

much thinner than the emitter while the collector is wider than both. The emitter is

heavily doped that it can inject a large number of charge carriers into the base. The

Base is lightly doped and very thin so it passes most of the emitter injected charge

carriers to the collector. The collector is moderated doped. The emitter base junction is

always forward biased while the collector base junction is always reversing biased.

The four parameters of a transistor configuration are input voltage , input current ,

output voltage and output current

CE configuration denoted that emitter is common to both input and output, the

input is applied across base and emitter and output is taken collector and emitter.

PROCEDURE:

1. Connections are made as shown in the circuit diagram

2. Keeping the output voltage (Vce) constant, the input power supply is varied and

the corresponding.

3. input voltage (vbe) and input current (Ib)are noted

4. the same is repeated for different constant values of output voltage (vce)

5. from the readings, the input characteristic is drawn with input voltage (Vbe) on

the x-axis and input current Next the input current (Ib) is kept constant and the

output power supply is carried and the corresponding variation in output

voltage(vce) and output current (IC) are noted . The same is repeated for different

constant values of input current (Ib)

6. from the readings the output characteristics is drawn with output current (Ic) on

y-axis and output voltage (vce) on x- axis.

Result :

Transistor with common emitter configuration has low input resistance and high

output resistance and current gain greater than unity.

input resistance=

Output resistance=

Current amplification factor=

EX.NO:11 COMMON BASE CONFIGURATION

AIM:

To draw the input and output characteristics of a BJT in CB configuration.

Components:

Transistor BC 547

Voltmeter (0-3) v, (0-10) v

Ammeter (0-500)µa, (0-50)ma

Resistor 1K(2)

DCPS

Bread broad

Connecting wires

THEORY:

Common base configuration denotes that base is common to both input and

output. The input is applied across emitter and base and output is taken across collector

and base. The input current and voltage are Ie and vbe respectively. The common base

current gain is less than or equal to unity.

The output resistance of CB circuit is very high, of the order of several tens of

kilo ohms

PROCEDURE:

1. Connections are made as shown in the circuit diagram

2. Keeping the output voltage (VCB) constant, the input power supply is varied and

the corresponding.

3. input voltage (vEB) and input current (Ie)are noted

4. the same is repeated for different constant values of output voltage (vcb)

5. from the readings, the input characteristic is drawn with input voltage (Veb) on

the x-axis and input current Next the input current (Ie) is kept constant and the

output power supply is carried and the corresponding variation in output

voltage(vcb) and output current (IC) are noted . The same is repeated for different

constant values of input current (Ie)

6. from the readings the output characteristics is drawn with output current (Ic) on

y-axis and output voltage (vcb) on x- axis.

Result :

Transistor with common base configuration has low input resistance and high

output resistance and current gain greater than unity.

input resistance=

Output resistance=

Current amplification factor=