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Jawaharlal Nehru Engineering Collage

Laboratory Manual

Electronics Devices and Circuits

For

Second Year Students

Manual made by

M.K.Pawar

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Jawaharlal Nehru Engineering College

Technical Document

This technical document is a series of Laboratory manuals of Electronics and

Telecommunication Department and is a certified document of Jawaharlal Nehru

engineering College. The care has been taken to make the document error-free. But

still if any error is found, kindly bring it to the notice of subject teacher and HOD.

Recommended by,

HOD

Approved by,

Principal

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FOREWORD

It is my great pleasure to present this laboratory manual for second year

engineering students for the subject of Electronic Devices &circuits to understand

and visualize the basic concepts of various circuits using electronic components.

Electronic Devices &circuits cover basic concepts of electronics. This being a core

subject, it becomes very essential to have clear theoretical and designing aspects.

This lab manual provides a platform to the students for understanding the basic

concepts of electronic devices and circuits. This practical background will help

students to gain confidence in qualitative and quantitative approach to electronic

circuits.

Good Luck for your Enjoyable Laboratory Sessions.

H.O.D

ECT Dept

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LABORATORY MANUAL CONTENTS

This manual is intended for the Second Year students of ECT branches in the

subject of Electronic Devices & Circuits. This manual typically contains practical/

Lab Sessions related to Electronic Devices & Circuits covering various aspects

related to the subject for enhanced understanding.

Students are advised to thoroughly go through this manual rather than only topics

mentioned in the syllabus as practical aspects are the key to understanding and

conceptual visualization of theoretical aspects covered in the books.

Good Luck for your enjoyable Laboratory Sessions.

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SUBJECT INDEX:

1. Do’s & Don’ts in Laboratory.

2. Lab Exercises

1. To plot VI characteristic of PN junction diode.

2. For Full wave bridge rectifier with capacitor filter find the ripple factor.

3. To plot the output V-I characteristics of Bipolar Junction Transistor.

4. To study the two stage RC Coupled Amplifier using Transistor to plot a

frequency response.

5. To plot the drain characteristics of N-channel JFET.

6. To plot the drain characteristics of N-channel MOSFET.

7. Study of RC integrator for sine, square wave input.

8. To study the circuit of Colpitts or LC Oscillator & Determine the output

frequency of Oscillator.

3. Quiz

4. Conduction of viva voce examination

5. Evaluation & marking scheme

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Dos and Don’ts in Laboratory :-

1. Do not handle any equipment before reading the instructions /Instruction

manuals.

2. Read carefully the power ratings of the equipment before it is switched ON,

whether ratings 230 V/50 Hz or 115V/60 Hz. For Indian equipment, the power

ratings are normally 230V/50Hz. If you have equipment with 115/60 Hz

ratings, do not insert power plug, as our normal supply is 230V/50Hz., which

will damage the equipment.

3. Observe type of sockets of equipment power to avoid mechanical damage.

4. Do not forcefully place connectors to avoid the damage.

5. Strictly observe the instructions given by the Teacher/ Lab Instructor.

Instruction for Laboratory Teachers:-

1. Submission related to whatever lab work has been completed should be done

during the next lab session.

2. Students should be instructed to switch on the power supply after getting the

checked by the lab assistant / teacher. After the experiment is over, the students

must hand over the circuit board, wires, CRO probe to the lab assistant/teacher.

3. The promptness of submission should be encouraged by way of marking and

evaluation patterns that will benefit the sincere students.

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Exercise No.1 :(2 Hours)

Aim:- To plot VI characteristic of PN junction diode.

Apparatus:- D.C.regulated power supply (0-30V) , Diode(1N4007), Resistance

(1K Ω), voltmeter(0-10V), ammeter (0-25mA), Connecting wires.

Circuit Diagram:-

Procedure:-

1. Connect the circuit as shown in fig.

2. By varying applied voltage measure corresponding reading for voltage &

current.

3. Plot the graph of voltage & forward current.

V Vf

0-10V D Si

DIODE

Vdc

12V

R 0-25mA

mA

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Observations:-

Applied

voltage

Vdc ( V)

O/P Voltage

Vf ( V)

Current

If ( mA)

12V

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Forward V-I Characteristics of PN Junction Diode :-

Conclusion: - Current increases exponentially with respect to voltage after cut in

voltage as seen from the graph.

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Exercise No.2 :( 2 Hours)

Aim: - For Full wave bridge rectifier with capacitor filter find the ripple factor.

Apparatus: - Step Down transformer, 04 Diodes- (1N4007), Resistance (1KΩ),

capacitor (1000 µF), voltmeter, oscilloscope, connecting wires.

Circuit Diagram :-

Procedure:-

1. Connect the circuit as shown in fig.

2. By applying AC input voltage measure corresponding reading for output voltage

(Peak, RMS).

3. Observe the output DC voltage.

4. Calculate ripple factor.

Equation:-

Ripple Factor: γ = VRMS / VDC

+

-

Vin

T1

+ C

RL

1KΩ

Vout

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Observations:-

Applied input

peak voltage

Vin(peak)

Peak Output

Voltage

Vout(peak)

RMS Output

Voltage

Vout(rms)

DC Output

Voltage

Vout(DC)

Input and Output Waveforms for Full Wave bridge Rectifier with Capacitor

Filter

Result:- Ripple Factor (Calculated)=

Ripple Factor (Measured) =

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Exercise No.3 :(2 Hours):-

Aim: - To plot the output V-I characteristics of Bipolar Junction Transistor.

Apparatus: - Transistor (BC 107), Regulated Power Supply (0-15V), Regulated

Power Supply (0-30V), Voltmeter (0-20V), Ammeter (0-200μA),

Ammeter (0-100mA), Resistors, Bread board, connecting wires.

Circuit Diagram :-

Procedure:-

Output characteristics:

1. Connect the circuit as per the circuit diagram

2. For plotting the output characteristics the input current IB is kept constant at

20μA and for different values of VCE note down the values of IC.

3. Repeat Step 2 for IB at 40μA and 60μA.

4. Tabulate the all the readings.

5. Plot the graph between VCE and IC for constant IB.

PRECAUTIONS:

1. The supply voltage should not exceed the rating of the transistor

2. Meters should be connected properly according to their polarities

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Observations:-

Sr.No IB = 10 μA IB = 20 μA IB = 30 μA

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

1 0.1 0.1 0.1

2 0.2 0.2 0.2

3 0.3 0.3 0.3

4 0.4 0.4 0.4

5 0.5 0.5 0.5

6 0.8 0.8 0.8

7 1.0 1.0 1.0

8 2.0 2.0 2.0

9 3.0 3.0 3.0

10 4.0 4.0 4.0

11 5.0 5.0 5.0

Output Characteristics of BJT:

Conclusion: The output current Ic depends on input current Ib and hence, output

characteristics of a transistor in CE configuration show that a BJT is current

controlled device.

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Exercise No.4 :(2 Hours):-

Aim: - To study the two stage RC Coupled Amplifier using Transistor to plot a

frequency response.

Apparatus: - Function generator, CRO, RC coupled Amplifier kit

Circuit Diagram: -

Procedure:-

1. Connect the signal generator at the input terminals of the circuit.

2. Connect the CRO at the output.

3. Switch on the power supply.

4. Keep the input signal amplitude Vin constant of 100 mV, so that transistors

should not enter in saturation.

5. Now vary the input frequency Fi from 100 Hz to 100 kHz in steps. Observe

& note the corresponding output voltage Vo. Find out the voltage gain Av.

6. Plot the graph between input frequency & voltage gain.

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Observation Table:- Vin =100 mV

Sr. No I/P Frequency

(Hz)

O/P Voltage

(Volts) Gain (Av) =

=

1 100

2 200

3 300

4 500

5 800

6 1K

7 2K

8 3K

9 5K

10 10K

11 20K

12 30K

13 50K

14 100K

Result:-

Bandwidth of R-C Coupled amplifier is:

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Exercise No.5 :(2 Hours):-

Aim: - To plot the drain characteristics of N-channel JFET.

Apparatus: - JFET (BFW10), Regulated Power Supply (0-12V), Regulated

Power Supply (0-30V), 02 Voltmeters (0-20V), Ammeter (0-100mA),

Resistors, Bread board, connecting wires.

Circuit Diagram :-

Procedure:-

Output characteristics:

1. Connect the milliammeter & voltmeters at the respective places.

2. Keep the VGG & VDD at minimum positions.

3. Switch on the power supply.

4. Keep the VGS at fixed value say VGS=0V

5. Now increase the VDD in steps & note down the readings of ID &VDS with the

1V interval of VGS

6. Plot the graph with VDS along x axis & ID along y axis.

7. Repeat the steps from 4 to 6 for different values of VGS

VDD 0-30V

VGG

0-12V

Q1

NJFET

100K

RG

RD 1k

mA

V VDS

0-20V

V VDS

0-20V

0-100mA

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Observations:-

Sr.

No

VGS = 0 VGS = -1V VGS = -2V VGS = -3V

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

1 0.5 0.5 0.5 0.5

2 1.0 1.0 1.0 1.0

3 1.5 1.5 1.5 1.5

4 2.0 2.0 2.0 2.0

5 2.5 2.5 2.5 2.5

6 3.0 3.0 3.0 3.0

7 4.0 4.0 4.0 4.0

8 5.0 5.0 5.0 5.0

9 6.0 6.0 6.0 6.0

10 7.0 7.0 7.0 7.0

11 8.0 8.0 8.0 8.0

Drain Characteristics of JFET:

Conclusion: The output current ID depends on input voltage VGS and hence, drain

characteristics of a JFET show that it is current controlled device.

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Exercise No.6 :(2 Hours):-

Aim: - To plot the drain characteristics of N-channel MOSFET.

Apparatus: - MOSFET (IRF840), Regulated Power Supply (0-12V), Regulated

Power Supply (0-30V), 02 Voltmeters (0-20V), Ammeter (0-100mA),

Resistors, Bread board, connecting wires.

Circuit Diagram :-

Procedure:-

Output characteristics:

1. Connect the milliammeter & voltmeters at the respective places.

2. Keep the VGG & VDD at minimum positions.

3. Switch on the power supply.

4. Keep the VGS at fixed value say VGS=3V

5. Now increase the VDD in steps & note down the readings of ID &VDS with the

1V interval of VGS

6. Plot the graph with VDS along x axis & ID along y axis.

7. Repeat the steps from 4 to 6 for different values of VGS

VDD 0-30V

VGG

0-12V

NJFET

1K

RG

RD 1k

mA

V VDS

0-20V

V VDS

0-20V

0-100mA

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Observations:-

Sr.No VGS = 3V VGS = 4V VGS = 5V

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

1 0.1 0.1 0.1

2 0.2 0.2 0.2

3 0.3 0.3 0.3

4 0.4 0.4 0.4

5 0.5 0.5 0.5

6 0.8 0.8 0.8

7 1.0 1.0 1.0

8 2.0 2.0 2.0

9 3.0 3.0 3.0

10 4.0 4.0 4.0

11 5.0 5.0 5.0

Drain Characteristics of MOSFET:

Conclusion: The output current ID depends on input voltage VGS and hence, drain

characteristics of a MOSFET show that it is current controlled device.

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Exercise No.7 :(2 Hours):-

Aim: - Study of RC integrator for sine, square wave input.

Apparatus: - Function generator, CRO, Breadboard, Resister (1 kΩ), Capacitor

(0.01 µF)

Circuit diagram: -

Procedure:-

1. Mount the components on bread board as per circuit diagram.

2. Give input from function generator as sine wave of frequency 5 kHz and

observe the output on CRO.

3. Draw input and output waveforms on graph paper.

4. Repeat the procedure for square wave input.

Observations:-

1. Shape of output waveform for sine wave input:

2. Shape of output waveform for square wave input:

Conclusion:- From integrator circuit we know that it is acting as low pass filter

and is able to generate triangular waveforms at high frequencies for square wave

input.

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Exercise No.8 :(2 Hours):-

Aim: - To study the circuit of Colpitts or LC Oscillator & Determine the output

frequency of Oscillator.

Apparatus: - Colpitts oscillator trainer kit, CRO, Probes, connecting wires.

Circuit Diagram :-

Procedure:-

1. Study the circuit provided on the front panel of the kit.

2. Connect CRO at O/P Vo terminal.

3. Now switch ON the power supply note different voltages as per observation

table.

4. Observe & note the frequency of oscillation & amplitude on CRO.

Cc2

Ce

Vcc

Cc1

Q1

NPN

C2 C2

C1 IFT

Re R2

R1 Rc

Vo

56pf 100pf

100pf

L=1.3mH

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5. Calculate the theoretical frequency of oscillation using formula.

6. Compare theoretical & practical frequency of oscillation.

7. Change the values of capacitor C2 & repeat above procedure.

Equation:-

Where,

Observations:-

1) With C2=56pf, observed frequency of oscillation FO = ------KHz

2) With C2=100pf, observed frequency of oscillation FO = ------KHz

Result:- 1) With C2=56pf, frequency of oscillations is ------------ Hz(Calculated)

and ----- Hz(Observed)

2) With C2=100pf, frequency of oscillations is ----------- Hz (Calculated)

and ----- Hz (Observed)

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3.Quiz on the subject:-

Q:1 When a pn-junction is forward biased

(a) electrons in the n region enter into the p region

(b) holes in the p region enter into the n region

(c) both a and b

(d) none of these

Q:2 under normal operating voltage , the reverse current in a silicon diode is about

(a) 10mA

(b) 1μA

(c) 1000 μA

(d) none of these

Q:3 The most commonly used transistor circuit arrangement is

(a) CB

(b) CE

(c) CC

(d) none of these

Q:4 The emitter of transistor is doped

(a) heavily

(b) lightly

(c) moderately

(d) none of these

Q:5 The biasing circuit which gives best stability to the Q point is

(a) base resistor biasing

(b) feedback resistor biasing

(c) potential divider biasing

(d) emitter resistor biasing

Q:6 The ideal value of stability factor is

(a) 1

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(b) 5

(c) 10

(d) 100

Q:7 A practical constant current source should have internal resistance as

(a) zero

(b) low

(c) high

(d) none of these

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4. Conduction of Viva-Voce Examinations:

Teacher should conduct oral exams of the students with full preparation. Normally,

the objective questions with guess are to be avoided. To make it meaningful, the

questions should be such that depth of the students in the subject is tested. Oral

examinations are to be conducted in cordial environment amongst the teachers

taking the examination. Teachers taking such examinations should not have ill

thoughts about each other and courtesies should be offered to each other in case of

difference of opinion, which should be critically suppressed in front of the

students.

5. Evaluation and marking system:

Basic honesty in the evaluation and marking system is absolutely essential and in

the process impartial nature of the evaluator is required in the examination system

to become. It is a primary responsibility of the teacher to see that right students

who are really putting up lot of hard work with right kind of intelligence are

correctly awarded.

The marking patterns should be justifiable to the students without any ambiguity

and teacher should see that students are faced with just circumstances.