EC2155-Circuits and Devices lab

7/28/2019 EC2155-Circuits and Devices lab

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1

VERIFICATION OF KIRCHHOFFS CURRENT LAW

CIRCUIT DIAGRAM

TABULATION:

S.no Supply Voltage (V) I1 (mA) I2 (mA) I3 (mA)I2 + I3

(mA)

1

2

3


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Expt.No:1

Verification of KCL and KVL

Aim:

To verify a) Kirchhoffs Current Law

b) Kirchhoffs Voltage Law

Materials Required:

S.No Components/Equipments Range Quantity

1 RPS (0-15)V 1

2 Ammeter (0-30)mA 3

3 Voltmeter (0-30)V 2

4 Resistors 5001K

3.3K

11

2

5 Bread Board 16 Connecting Wires As reqd.

Theory:

Kirchhoffs Current Law (KCL)

Kirchhoffs Current Law states that the algebraic sum of all currents at any node in a

circuit is zero.

i.e. sum of currents entering a node = sum of currents leaving the node

Procedure:

Kirchhoffs Current Law (KCL)

1. Make connections as per the circuit diagram.2. Switch on the power supply.3. Note down the ammeter readings and verify KCL.4. Repeat the experiment with different values of supply voltages.


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VERIFICATION OF KIRCHHOFFS VOLTAGE LAW

CIRCUIT DIAGRAM

TABULATION:

S.no Supply Voltage (V) V1 (V) V2 (V) V3 (V) V1 + V2 + V3

1

2

3


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Theory:

Kirchhoffs Voltage Law (KVL)

Kirchhoffs Voltage Law states that the algebraic sum of all voltages across any set of

branches in a closed loop is zero.

i.e. sum of voltage drop = sum of voltage rise

Procedure:

Kirchhoffs Voltage Law (KVL)

1. Make connections as per the circuit diagram.2. Switch on the power supply.3. Note down the voltmeter readings and verify KVL.4. Repeat the experiment with different values of supply voltages.

Result:

Thus Kirchhoffs Current and Voltage laws were verified.


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VERIFICATION OF THEVENINS THEOREM

CIRCUIT DIAGRAM

Figure 1:

Figure 2:

Figure 3:


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Expt.No:2

Verification of Thevenin and Nortons Theorem

Aim:

To verify a) Thevenins Theorem

b) Nortons Theorem

Materials Required:


1 RPS (0-30)V 1

2 Ammeter (0-1)mA 1


4 DRB (0-1)M 1

5 Resistors 560

1K470

10K5.6K

1

21

32

6 Bread Board 1

7 Connecting Wires As reqd.

Theory:

Thevenins Theorem

Thevenins theorem states that any two-terminal linear network having a number of

voltage, current sources and resistances can be replaced by a simple equivalent circuit consisting

of a single voltage source in series with a resistance, where the value of the voltage source is

equal to the open circuit voltage across the two terminals of the network and resistance is equalto the equivalent resistance measured between the terminals with all the energy sources replaced

by their internal resistances.

Procedure:

Thevenins Theorem

1. Connect the circuit as shown in the circuit diagram.2. Measure the voltage across the load (VL) using a voltmeter or multimeter after switching

on the power supply.

To find Thevenins Equivalent Circuit:

3. Remove the load resistance and measure the open circuited voltage VTH across the outputterminal (as in figure 2).

4. Remove the voltage source and measure the resistance RTH across the output (as in figure3) using multimeter.

5. Connect the Thevenin equivalent circuit as in figure 4.6. Measure the value of load voltage VL across the load resistance.


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Figure 4:

THEVENINS EQUIVALENT CIRCUIT

TABULATION:

S.No VS RL VL RTH VTH VL


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VERIFICATION OF NORTONS THEOREM

CIRCUIT DIAGRAM

Figure 5:

Figure 6:

Figure 7:


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Theory:

Nortons Theorem

Nortons theorem states that any two-terminal linear network with current sources,

voltage sources and resistances can be replaced by a simple equivalent circuit consisting of a

current source in parallel with a resistance. The value of the current source is the short circuit

current between the two terminals of the network and the resistance is the equivalent resistance

measured between the terminals of the network with all the energy sources replaced by their

internal resistances.

Procedure:

Nortons Theorem

1. Connect the components as shown in the given circuit. (Figure 5).2. Measure the current through the load IL using an ammeter or multimeter.

To find Nortons equivalent circuit:3. Remove the load resistance and short circuit the output terminal. Measure the current IN

through the short circuited terminals.

4. Remove the voltage source and measure the resistance across the output terminal.5. Connect the components as in the equivalent circuit where Veq = IN . RN volt.6. Measure the load current IL through the load resistorRL.7. Verify if IL = IL.


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Figure 8:

Figure 9:

NORTONS EQUIVALENT CIRCUIT

TABULATION:

S.NoVS(V)

IL

(mA)

IN

(mA)

RN

(K)Veq = IN.RN

(V)

IL(mA)


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Result:

Thus Thevenins and Nortons theorems were verified.


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VERIFICATION OF SUPERPOSITION THEOREM

CIRCUIT DIAGRAM

Figure 1:

Figure 2:

Figure 3:


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Expt.No:3

VERIFICATION OF SUPERPOSITION THEOREM

Aim:

To verify Superposition theorem.

Components Required:


1 RPS (0-30)V 1


3 DRB (0-1)M 1

4 Resistors 330

470

1

1

5 Bread Board 1


Theory:Superposition Theorem

It states that in any linear resistive network, the voltage across or current through any

resistor or source may be calculated by adding algebraically all the individual voltages or

currents caused by separate independent sources acting alone, with all the other independent

voltage sources replaced by short circuits and all other independent current sources replaced by

open circuits. However, superposition theorem is not applicable to unbalanced bridge circuits.

The theorem is applicable only to linear circuits. The theorem cannot be used to measure power

and it is applicable only for circuits having more than one source.

Procedure:

1. Connect the circuit as in the given circuit (Figure1).2. Switch on the power supply.3. Adjust the DRB to a certain value and measure the ammeter reading, I.4. Set V2 to a certain value and short circuit the voltage source V1 as in Figure 2, and

measure the ammeter reading, I1.

5. Set V1 at a certain value and short circuit the second voltage source V2 (as in Figure 3).Measure the ammeter reading, I2.

6. Verify if I = I1 + I2.7.

Repeat the experiment for different DRB values.


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TABULATION:

S.No

DRB

value

()

I

(mA)

I1

(mA)

I2

(mA)I1 + I2(mA)

Theoretical Practical Theoretical Practical Theoretical Practical

1

2

3


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Result:

Thus Superposition theorem was verified.


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VERIFICATION OF MAXIMUM POWER TRANSFER THEOREM

CIRCUIT DIAGRAM:

TABULATION:

S.No DRB Value, R

()Current, I

(mA)

Power, P= I2R

(W)

1.

2.

3.

4.

5.

MODEL GRAPH:


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Expt.No:4

VERIFICATION OF MAXIMUM POWER TRANSFER & RECIPROCITY THEOREMS

Aim:

To verify Maximum Power transfer and Reciprocity theorems.



1 RPS (0-10)V 1


3 DRB (0-1)M 1

4 Resistors 3.3K

2.2K1K

1

11

5 Bread Board 1


Maximum Power Transfer Theorem

Theory:

Maximum Power Transfer theorem states An independent voltage source in series with a

resistance RS, delivers a maximum power to that loads resistance RL for which RL = RS .

Maximum Power Transfer theorem can also be stated in terms of Thevenin equivalent

resistance of the network as A network delivers the maximum power to a load resistance RL

when RLis equal to the Thevenin equivalent resistance of the network.

Procedure:

1. Connect the circuit as shown in figure.2. Find the Thevenin equivalent resistance of the circuit.3. Adjust the DRB for different values of resistances and note down the ammeter readings.4. Calculate the power for the corresponding resistance and current readings.5. Verify if power is maximum for RL = RTH.


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VERIFICATION OF RECIPROCITY THEOREM

CIRCUIT DIAGRAM

Figure 1:

Figure 2:

TABULATION:

S.NoVoltage, V1

(V)

Current I1

(mA)V1 / I1

Voltage, V2

(V)

Current I2

(mA)V2 / I2

1.

2.

3.

4.

5.


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Reciprocity Theorem

Theory:

Reciprocity theorem states In any passive linear bilateral network, if the single voltage

source Vx in the branch x produces the current response Iy in the branch y, then the removal of

the voltage source from the branch x and its insertion in the branch y will produce the current

response Iy in the branch x.

In other words, In a linear network, if the position of the excitation and response are

interchanged, their ratio remains the same.

Procedure:

1. Connect the circuit as in figure 1.2. For different values of V1, note down the corresponding values of I1 in the ammeter.3. Calculate the values of V1/I1 and tabulate them.4. Now change the circuit as in figure 2.5.

For different values of V2, note down the corresponding values of I2 in the ammeter.

6. Calculate the values of V2/I2 and tabulate them.7. Verify if V1/I1 = V2/I2.

Result:

Thus Maximum power transfer theorem and reciprocity theorems were verified.


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SERIES RESONANCE CIRCUIT

CIRCUIT DIAGRAM:

TABULATION:

S.NoInput Frequency

(Hz)

Output Voltage

(V)

MODEL GRAPH:


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Expt.No:5

FREQUENCY RESPONSE OF SERIES AND PARALLEL RESONANCE CIRCUITS

Aim:

To find the resonant frequency of series and parallel RLC circuits.



1 Function Generator (0-1)MHz 1


3 Resistor 1K 1

4 Capacitor 1F 1

5 Inductor 50mH 1

6 Bread Board 1

7 Connecting Wires As Reqd.,

Theory:The resonance of a series RLC circuit occurs when the inductive and capacitive reactance

are equal in magnitude but cancel each other because they are 180 apart in phase. It has

minimum impedance at resonance frequency and the phase angle at resonance is equal to zero.

In parallel RLC circuits the circuit behaves purely resistive at resonance. Since inductive

and capacitive reactance currents are equal and opposite in phase, they cancel one another at

parallel resonance. If a capacitor and an inductor, each with negligible resistance are connected

in parallel and the frequency is adjusted such that the reactances are exactly equal, current will

flow through the inductor and capacitor, but the total current will be negligible. The impedance

of parallel RLC circuit is almost infinite.

Formula Used:

Resonant frequency, fr=

(Hz)

Procedure:

1. The connections are made as per the circuit diagram.2. Vary the input frequency and tabulate the corresponding voltage readings.3. Plot the graph and note down the resonant frequency from the graph.4. Verify if the resonant frequency from the graph is equal to the theoretical resonant

frequency.


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PARALLEL RESONANCE CIRCUIT

CIRCUIT DIAGRAM

TABULATION:

S.NoInput Frequency

(Hz)

Output Voltage

(V)

MODEL GRAPH:


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Result:

Thus series and parallel resonant circuits were constructed and their frequency response

curves were drawn.

Resonant frequency of series RLC circuit =

Resonant frequency of parallel RLC circuit =


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CHARACTERISTICS OF PN-JUNCTION DIODE

CIRCUIT DIAGRAM:

FORWARD BIAS:

REVERSE BIAS:

CIRCUIT SYMBOL:

MODEL GRAPH


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Expt.No:6

CHARACTERISTICS OF P-N JUNCTION DIODE AND ZENER DIODE

Aim:

To plot the V-I characteristics of the given PN junction diode and Zener diode under

forward bias and reverse bias.



1 PN junction diode 1N4001 1

2 Zener diode 1

3 Ammeter (0-50)mA

(0-500)A

1

1

4 Voltmeter (0-1)V

(0-30)V

1

1

5 Resistor 1K 16 RPS (0-15)V 1


PN Junction Diode

Theory:

If donor impurities are introduced into one side and acceptor into the other side of a

single crystal of a semiconductor, a p-n junction is formed. Initially there are only p-type carriers

to the left of the junction and only n-type carriers to the right of the junction.

Forward Bias:

The P-type of the semiconductor is connected to the positive of the battery and N-type tothe negative of the battery.

Width of the depletion region decreases with increase in the bias voltage. Hence there is gradual increase in current with increasing voltage.

Reverse Bias:

The P-type of the semiconductor is connected to the negative of the battery and N-type tothe positive of the battery.


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P-N JUNCTION DIODE

TABULATION:

FORWARD BIAS:

S.No Forward Voltage

VF (V)

Forward Current

IF (V)

REVERSE BIAS:

S.No Reverse Voltage

VR(V)

Reverse Current

IR(V)


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Width of the depletion region increases with increase in bias voltage which results in highresistance.

Hence minimum current flows through the diode.Formula Used:

Resistance = V / I (ohms)

Procedure:

1. Make connections as per the circuit diagram.2. Vary the voltage in the regulated power supply and note down the corresponding

ammeter and voltmeter readings.

3. Tabulate the readings and plot the graph with voltage in X-axis and current in Y-axis.4. Calculate the value of forward resistance.


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CHARACTERISTICS OF ZENER DIODE

CIRCUIT DIAGRAM:

FORWARD BIAS:

REVERSE BIAS:

CIRCUIT SYMBOL:

V-I CHARACTERISTICS:


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ZENER DIODE

Theory:

The zener diode uses a p-n junction in reverse bias to make use of the zener effect

(breakdown phenomenon) which holds the voltage close to a constant value called the zener

voltage. The constant reverse voltage VZ of the zener diode makes it a valuable component for

the regulation of the output voltage against both variations in the input voltage from an

unregulated power supply or variations in the load resistance.

Procedure:

1. Make connections as per the circuit diagram.2. Vary the voltage in the regulated power supply and note down the corresponding

ammeter and voltmeter readings.

3. Tabulate the readings and plot the graph with voltage in X-axis and current in Y-axis.4. Note down the value of zener voltage VZ.


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ZENER DIODE

TABULATION:

FORWARD BIAS:

S.No Forward Voltage

VF (V)

Forward Current

IF (V)

REVERSE BIAS:

S.No Reverse Voltage

VR(V)

Reverse Current

IR(V)


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CHARACTERISTICS OF CE CONFIGURATION

CIRCUIT DIAGRAM:

INPUT CHARACTERISTICS:

OUTPUT CHARACTERISTICS:


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Expt.No:7

CHARACTERISTICS OF CE CONFIGURATION

Aim:

To plot the input and output characteristics of a given BJT in CE configuration and

determine its hybrid parameters.



1 Bipolar Junction Transistor BC 107 1

2 Ammeter (0-10)mA

(0-500)A

1

1

3 Voltmeter (0-5)V

(0-10)V

1

1

4 Resistor 10K 1

5 RPS (0-15)V 26 Connecting Wires As Reqd.,

Theory:

In CE configuration, the base is taken as input terminal, collector is taken as output

terminal and emitter is taken as common terminal. The input characteristics are drawn for

different values of IB and VBE with VCE constant. The output characteristics are drawn for

different values of IC and VCE with IB constant.

Procedure:

1. Make connections as per the circuit diagram.2. To obtain the input characteristics, keep the value of VCE constant. For different values of

VBE, tabulate the corresponding values of IB.

3. Repeat the procedure for various constant values of VCE.4. Plot the graph and calculate the hybrid parameters.5. To obtain the output characteristics, keep the value of IB constant. For different values of

VCE, tabulate the corresponding values of IC.

6. Repeat the procedure for various constant values of IB.7. Plot the graph and calculate the hybrid parameters.

Formula Used:

1. Input Impedance (hie) =

, VCE = constant

2. Forward Current Gain (hfe) =

, VCE = constant


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PIN DIAGRAM SYMBOL

TABULATION:


S.NoVCE = V VCE = V VCE = V

VBE (V) IB (A) VBE (V) IB (A) VBE (V) IB (A)


S.NoIB = A IB = A IB = A

VCE (V) IC (mA) VCE (V) IC (mA) VCE (V) IC (mA)


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3. Reverse Voltage Gain (hre) =

, IB = constant

4. Output Conductance (hoe) =

, IB = constant

Result:

Thus the input and output characteristics of the given BJT were obtained for CE

configuration.

Input Impedance (hie) =

Forward Current Gain (hfe) =

Reverse Current Gain (hre) =

Output Conductance (hoe) =


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CHARACTERISTICS OF CB CONFIGURATION

CIRCUIT DIAGRAM:




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Expt.No:8

CHARACTERISTICS OF CB CONFIGURATION

Aim:

To plot the input and output characteristics of a given BJT in CB configuration and

determine its hybrid parameters.



1 Bipolar Junction Transistor BC 107 1


3 Voltmeter (0-5)V

(0-25)V

1

1

4 Resistor 100 1

5 RPS (0-15)V 2


Theory:

In CE configuration, the emitter is taken as input terminal, collector is taken as output

terminal and base is taken as common terminal. The input characteristics are drawn for different

values of IE and VBE with VCB constant. The output characteristics are drawn for different values

of IC and VCB with IE constant.

Procedure:

1. Make connections as per the circuit diagram.2. To obtain the input characteristics, keep the value of VCB constant. For different

values of VBE, tabulate the corresponding values of IE.

3. Repeat the procedure for various constant values of VCB.4. Plot the graph and calculate the hybrid parameters.5. To obtain the output characteristics, keep the value of IE constant. For different values

of VCB, tabulate the corresponding values of IC.

6. Repeat the procedure for various constant values of IE.7. Plot the graph and calculate the hybrid parameters.

Formula Used:

1. Input Impedance (hib) =

, VCB = constant

2. Forward Current Gain (hfb) =

, VCB = constant


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PIN DIAGRAM SYMBOL

TABULATION:


S.NoVCB = V VCB = V VCB = V

VEB (V) IE (mA) VEB (V) IE (mA) VEB (V) IE (mA)


S.NoIE = mA IE = mA IE = mA

VCB (V) IC (mA) VCB (V) IC (mA) VCB (V) IC (mA)


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CHARACTERISTICS OF UJT

CIRCUIT DIAGRAM:

CHARACTERISTIC CURVE: Symbol Pin Diagram

TABULATION:

S.No

VB1B2 = (V) VB1B2 = (V)

VB1E (V) IE (mA) VB1E (V) IE (mA)


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Expt.No.9

CHARACTERISTICS OF UJT AND SCR

Aim:

To obtain the characteristics of UJT and SCR.



1 UJT 2N2646 1

2 SCR 2P4M 1

3 Resistor 1K

470

330

11

1

4 RPS (0-5)V 2

5 Ammeter (0-20)mA

(0-100)mA

1

1

6 Voltmeter (0-5)V(0-20)V

11


UJT

Theory:

UJT is a three terminal semiconductor switching device. As it has one PN junction, it is

called Uni Junction Transistor. The heavily doped P region is called emitter E and lightly doped

n region constitute base B1 and B2. The negative resistance property of UJT enables it to be

employed in various applications namely relaxation oscillator, sawtooth generator, switching,

timing and phase control circuits.

Procedure:

1. Connect the circuit as per the circuit diagram.2. Vary the value of input voltage and note down the corresponding emitter current IE and

VBE with VB1B2 constant.

3. Plot the graph with VBE against IE.4. Calculate the intrinsic stand-off ratio using formula.

Formula Used:

1. Intrinsic Stand-off ratio, = Intrinsic stand-off ratio = (VP-VD)/VB1B22. Negative Resistance =


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CHARACTERISTICS OF SCR

CIRCUIT DIAGRAM:

CHARACTERISTICS CURVE: SYMBOL

PIN DIAGRAM

TABULATION:

Before Triggering:

IG = mA

VAK(V) IA (mA)

After Triggering:

IG = mA

VAK(V) IA (mA)


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SCR

Theory:

SCR is a four layer PNPN device. It is a rectifier with a control element. It has three

diodes connected back to back. It is widely used as a switching device in power control

applications. It has three terminals namely Anode (A), Cathode (K) and Gate (G). The gate

controls the firing of the SCR.

Procedure:

1. Connections are made as per the circuit diagram.2. Keep IG = 0mA.3. Vary the power supply and note down the anode to cathode voltage V AK and the anode

current IA.

4. Increase the gate current till the SCR gets triggered and keep IG constant.5. Now vary the power supply and note down the corresponding anode to cathode voltage

VAKand the anode current IA.6. Note down the holding current IH and break-over voltage (VBO).7. Plot the graph.

Result:

Thus the characteristics of UJT and SCR were obtained.

SCR:

Holding Current IH =

Break-over Voltage VBO =


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CHARACTERISTICS OF JFET

CIRCUIT DIAGRAM:


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Expt.No.10

CHARACTERISTICS OF JFET AND MOSFET

Aim:

To determine and plot the drain and transfer characteristics of the given JFET and

MOSFET



1 JFET BFW10 1

2 MOSFET 1

3 Resistor 1K 1

4 RPS (0-10)V 1

5 Ammeter (0-15)mA

(0-50)mA

1

1

6 Voltmeter (0-3)V

(0-10)V(0-25)V

(0-30)V

1

11

1


JFET

Theory:

FET is a semiconductor switching device in which the flow of electron in the

conducting region is controlled by an external electric field. As current conduction is only

by majority carriers, FET is said to be a unipolar device.

A Junction Field Effect Transistor (JFET) has three terminals namely source (S),

Drain (D) and Gate (G). Source S is connected to negative of the battery. Drain D isconnected to positive of the battery. A PN junction is formed which is the Gate G.

Procedure:

1. Connect the circuit as per the circuit diagram.2. To obtain drain characteristics:

i. Keep voltage VGS constant.ii. Increase the voltage VDS in a number of steps and note the corresponding

drain current ID.

iii. Repeat the procedure for various constant values of VGS.iv. Plot the graph with VDS against ID.

3. To obtain transfer characteristics:i. Keep the voltage VDS constant.

ii. Increase the voltage VGS in a number of steps and note the correspondingdrain current ID.

iii. Repeat the procedure for various constant values of VDS.iv. Plot the graph with VGS against ID for various constant values of VDS.


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TABULATION:

Drain Characteristics:

S.NoVGS = (V) VGS = (V)

VDS (V) ID (mA) VDS (V) ID (mA)

Transfer Characteristics:

S.NoVDS = (V) VDS = (V)

VGS (V) ID (mA) VGS (V) ID (mA)


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v. Determine the values of drain resistance, transconductance, amplificationfactor, pinch-off voltage and drain-source saturation current.

Formula Used:

1. Drain Resistance, rd = VDS / ID , VGS = constant2. Trans-conductance, gm = ID / VGS , VDS = constant3. Amplification factor, = rd * gm


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CHARACTERISTICS OF MOSFET

CIRCUIT DIAGRAM:

DRAIN CHARACTERISTICS TRANSFER CHARACTERISTICS

SYMBOL PIN DIAGRAM


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MOSFET

Theory:

Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) is also called Insulated

Gate Field Effect Transistor (IGFET). MOSFET can be of two types namely depletion type

MOSFET and enhancement type MOSFET. MOSFET has only one P region which is called

substrate (SS). The Gate (G) is insulated from the conducting channel by metal oxide insulating

film. When a negative bias is applied at the gate, it acts as depletion MOSFET and when a

positive bias is applied at the gate, it acts as enhancement type MOSFET.

Procedure:

1. Connect the circuit as per the circuit diagram.2. To obtain drain characteristics:

i. Keep voltage VGS constant.ii. Increase the voltage VDS in a number of steps and note the corresponding

drain current ID.iii. Repeat the procedure for various constant values of VGS.iv. Plot the graph with VDS against ID.

3. To obtain transfer characteristics:i. Keep the voltage VDS constant.

ii. Increase the voltage VGS in a number of steps and note the correspondingdrain current ID.

iii. Repeat the procedure for various constant values of VDS.iv. Plot the graph with VGS against ID for various constant values of VDS.

4. Determine the values of drain resistance, transconductance, amplification factor,pinch-off voltage and drain-source saturation current.


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TABULATION:

Drain Characteristics:

S.NoVGS = (V) VGS = (V)

VDS (V) ID (mA) VDS (V) ID (mA)

Transfer Characteristics:

S.NoVDS = (V) VDS = (V)

VGS (V) ID (mA) VGS (V) ID (mA)


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Result:

Thus the characteristics of JFET and MOSFET were obtained.

JFET:

Drain resistance, rd =

Transconductance, gm =

Amplification factor, =

Pinch-off voltage, VP =

Drain-source Saturation Current IDSS =

MOSFET:

Drain resistance, rd =

Transconductance, gm =

Amplification factor, =

Drain-source Saturation Current IDSS =


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CHARACTERISTICS OF DIAC

CIRCUIT DIAGRAM:

MT1 negative with respect to MT2 V-I CHARACTERISTICS

MT2 negative with respect to MT1 VBO

TABULATION:

MT1 positive with respect to MT2

S.NoVoltage V

(V)

Current I

(mA)

MT2 positive with respect to MT1

S.NoVoltage V

(V)

Current I

(mA)


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Expt.No:11

CHARACTERISTICS OF DIAC AND TRIAC

Aim:

To determine the characteristics of the given DIAC and TRIAC.



1 DIAC DB3 1

TRIAC BT136 1

2 Resistor 1K 1

3 RPS (0-60)V 1

4 Ammeter (0-10)mA

(0-50)mA

(0-100)mA MC

1

1

1

5 Voltmeter (0-15)V

(0-100)V MC

1

1


DIAC

Theory:

A diac is a two terminal bidirectional semiconductor device that can be switched from

OFF state to ON state for either polarity of applied voltage. When a positive or negative voltage

is applied across the terminals, a small amount of leakage current flows. As the applied voltage

is increased, the leakage current will continue to flow until the voltage reaches the break-over

voltage VBO. At this point, avalanche breakdown occurs and the device exhibits negative

resistance.

Procedure:

1. Connect the circuit as per the circuit diagram.2. MT1 is kept positive with respect to MT2.3. Vary the supply voltage and note down the corresponding voltmeter and ammeter

readings.

4. Plot the graph with V against I.5. Repeat the procedure with MT2 kept negative with respect to MT1.


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CHARACTERISTICS OF TRIAC

CIRCUIT DIAGRAM:

V-I CHARACTERISTICS:

TABULATION:

S.No

IG1= (mA) IG2 = (mA)

VAK(V) IA (mA) VAK(V) IA (mA)


56/56

56

TRIAC

Theory:

A TRIAC is a three terminal semiconductor switching device which can control

alternating current in a load. It consist of 2 SCRs connected in anti-parallel, so its characteristics

in I and III quadrants are essentially identical to those of an SCR in the I quadrant. The TRIAC

can be operated with either positive or negative gate control voltage, but in normal operation

usually the gate voltage is positive in I quadrant and negative in III quadrant. The supply voltage

at which the TRIAC is turned ON depends on the gate current. The greater the gate current, the

smaller the supply voltage at which the TRIAC is turned ON.

Procedure:

1. Connect the circuit as per the circuit diagram.2. To set the gate current IG, set VMT1, VMT2 and vary VG till VAK suddenly drops. Note

down the corresponding gate current IG.

3.

Set the gate current equal to firing current and vary the anode to cathode voltage.4. Vary VAKin steps and note down the corresponding ammeter readings.5. Open the gate terminal and decrease VAK.6. Plot the graph.

Result:

Thus the characteristics of DIAC and TRIAC were determined.

DIAC:

Date post:	03-Apr-2018
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EC2155-Circuits and Devices lab

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