edc_lab_(new)[1]

Lakireddy Bali Reddy College of Engineering (AUTONOMOUS)L.B. Reddy Nagar, Mylavaram – 521 230.

Krishna Dist. (A.P)

Electronic Devices and Circuits Lab (L139)

Name : .........................................................

Regd. No : ........................................................

Course : B.Tech (II - Semester)

Branch : ECE

Academic Year : 2014-2015

DEPT OF ECE 1 EDC LAB

Electronic Devices and Circuits Lab

List of Experiments

1. Course Code : L139

2. Course Title : ELECTRONIC DEVICES AND

CIRCUITS LAB

3. Year in which offered : B. Tech. ECE II-SEM

4. No. of weeks of instruction : 16

5. No. of hours per week : 3 periods

6. Course objectives:

To study the Fundamental characteristics of PN Junction and ZENER

Diode, Input and output characteristics of BJT & FET in different configurations,

Rectifier operation and to verify resistor color coding, signal generation etc by

using LABVIEW simulation software.

7. List of experiments:

1). Study of CRO

2). P-N Junction Diode Characteristics

3). Zener Diode Characteristics

4). Half Wave Rectifiers (with & without filters)

5). Full Wave Rectifiers (with & without filters)

6). Transistor CB Characteristics (input and output)

7). Transistor CE Characteristics (input and output)

8). Transistor CC Characteristics (input and output)

9). Field Effect Transistor Characteristics

10).Uni-junction transistor characteristics

11).Calculation of series & parallel resistance by using

LABVIEW

12). Signal Generation by using LABVIEW

13). Resistor colour coding by using LABVIEW


INDEX

S.No Date Name of the Experiment Page No. Marks Signature

1.Calculation of series & parallel resistance by using

5LABVIEW

2.Signal Generation by using LABVIEW

6

3.Resistor colour coding by using LABVIEW

7

4.Study of CRO

8

5.P-N Junction Diode Characteristics

11

6.Zener Diode Characteristics

16

7.Half Wave Rectifiers (with & without filters)

20

8.Full Wave Rectifiers (with & without filters)

24

9.Transistor CB Characteristics (input and output)

28

10.Transistor CE Characteristics (input and output)

33

11.Transistor CC characteristics(input and output)

38

12.FET characteristics

43

13.UJT Characteristics

48


LABVIEW

INTRODUCTION:

Labview is simulation software developed by national instruments of India.

Labview software is updated in 2010.Labview contains so many functions so that we can use

them easily.

By using labview we can solve so many problems in mathematics .We can solve

matrices, we can evaluate integrations and various types of differentiations. We can plot

various graphs of various functions in 2D and 3D.We can design various electronics circuits

and we can run them. Almost all experiments on various fields can be done here in software

and thus it is called LABVIEW.Other simulation software is MULTISIM/PSPICE.

LABVIEW denotes

LAB –laboratory

V-Virtual

I-Instrumentation

E-Engineering

W-Work bench

When we open Labview software, first we can find a window on a screen. There

we can find blank VI, project module etc. and we can also find various links to national

instruments websites to upload latest version of software, and help regarding this software

and on various matters

If we choose Blank VI , then two windows are opened. One is FRONT panel and the

other is BLOCK diagram

FRONT PANEL:

Front panel is a front view which is used to give the inputs and view the results. For

giving input and getting desired output we need some controls. For example

BLOCK diagram:

It is the VI’s source code, constructed in LabVIEW’s graphical programming

language, G. It is the actual executable program


EXPT 1: CALCULATION OF SERIES AND PARALLELRESISTANCE

AIM:

To calculate the series and parallel resistance value by using LABVIEW software

APPRATUS:

LABVIEW 2010 Software

PROCEDURE:

1) Create control for two resistances values for finding series and parallel values.

2) Create an indicator to display the output.

RESULT:

Thus the series and parallel values of two resistors are calculated by using LABVIEW simulation.


EXPT 2: SIGNAL GENERATION BY USING LABVIEW

AIM:

To generate different types of signals by using LABVIEW software

APPRATUS:


PROCEDURE:

1) First go to block diagram panel right click go to signal processing and select basic

waveform generator.

2) Now generate controls for amplitude frequency and signal type.

3) Now provide an indicator like graph to see the output.

RESULT:

Thus different signals are generated by using LABVIEW.


EXPT 3: RESISTOR COLOUR CODING USING LABVIEW

AIM:

To find the resistance value of the resistor using LABVIEW software

APPRATUS:


PROCEDURE:

1) For the three colors on the resistor, we need three ENUM’S controls and these can

be taken from front panel.

2) Numeric constants like multiplier, adders are constructed on back panel.

3) Necessary connections are made to get resistor value as shown in above figure .

RESULT:

Thus the value of resistor using colour code is calculated by using LABVIEW.


EXPT 4: STUDY OF C.R.O

AIM:- To study the Various front panel controls of Dual Trace Cathode Ray Oscilloscope

and to Measure different frequencies and Voltages.

APPARATUS REQUIRED:-

1.20MHz Dual Trace CRO 1No.

2.Function Generator 1.No.

3.BNC to Crocodile Probes 2.No.

PROCEDURE:-

1. Switch the CRO and Select Mono/Dual Operation Observe the Trace on the CTR

2. Now switch on the Function Generator, Select the Sine wave and Connect the

Function Generator output to CH-I or CH-II of CRO.

3. If we measure mill Volts from Function Generator press 20db or 40db or 20db &

40db attenuating switches depending upon the required Voltage. If want in Volts

release the attenuating push buttons in the out position.

For Voltage Variation use amplitude Control.

4. Measure different Signal Voltages and frequencies as per the given tabular Form.

VOLTAGE MEASUREMENT:-

Set the Frequency at 1 KHz

S.No. APPLIED VOLTS/DIVISION NO. OF RESULTANT

VOLAGE. IN VERTICAL VOLTAGE

DIVISIOVS(PP)

1 1V 1V0.05V

1V

2V

2 2V 0.05V

1V

2V

3 3V 1V

2V

5V


4 5V 1V

2V

5V

5 10V 2V

5V

10V

6 15V 5V

10V

20V

7 20V 5V

10V

20V

8 0.5V (500mV) 0.5V

0.2V

0.1V

9 0.1V 0.2V

0.1V

0.05V

10 0.5V (50mV) 0.1V

0.05V

20MV

11 20mV 20V

10V

5Mv


FREQUENCY MEASUREMENT:-

Set the Amplitude at 3V (Cal. Variable Control should be in minimum position)

S.No APPLIED FREQ. TIME/DIVISION NO. OF RESULTANT

IN HORIZONTAL FREQUENCY

DIVISIONS f=1/T

1 1KHz 0.05ms

1 ms

2 ms

2 5Hz 0.5 ms

0.2 ms

0.1 ms

3 10Hz 0.2 ms

0.1 ms

50 ms

4 20Hz 0.1 ms

50µs

20 µs

5 50Hz 50 µs

20 µs

10 µs

6 100Hz 20 µs

10 µs

5 µs

7 500Hz 5 µs

2 µs

1 µs

8 1MHz 2 µs

1 µs

0.5 µs

RESULT:- Studied various front panel controls and measured different voltages and

Frequencies using a CRO.


EXPT 5: PN JUNCTION DIODE CHARACTERISTICS

AIM: 1. To Plot the V-I characteristics of p-n junction diode.

2. To find the static and dynamic resistances in Forward and Reverse Bias.

APPARATUS REQUIRED:

1.IN 4007 Diode 1.No.

2.Resistor 1K 1.No.

3.0-50mA DC Ammeter 1.No.

4.0-500 A DC Ammeter 1.No.

5.0-1V Dc Voltmeter. 1.No.

6.0-30V DC Voltmeter 1.No.

7.0-30V Regulated Power Supply 1.No.

8. Bread Board 1.No.

THEORY:

Forward Bias:

If P-type semiconductor is connected to the positive terminal of the battery and N-

type Semiconductor is connected to negative terminal of the battery, this way of biasing is

called as forward bias. In this biasing current is exponentially increasing with respective to

applied voltage.

Reverse bias:

If P-type semiconductor connected to negative terminal of the battery and N-type

semiconductor is connected to the positive terminal of the battery is known as reverse bias. In

reverse bias the current through the diode is I = -Io whose value is independent on applied

voltages and which depends on minority carrier concentration and temperature. For every 10

degrees raise in temperature reverse saturation current becomes double.

Thus in forward bias diode offers less resistance and in reverse bias diode

offers high resistance. Hence it is known as rectifier.


CIRCUIT DIAGRAMS:

1KΩ(0-50mA)

+A+

RPS,(0-30V) IN4007 V (0-1V)

FORWARD BIAS CHARACTERISTICS

1KΩ(0-500µA)

+ A +

RPS,(0-30V) IN4007 V (0-30V)

REVERSE BIAS CHARACTERISTICS

PROCEDURE :

FORWARD BIAS CHARACTERISTICS:

1. Connect the Circuit as per the Circuit Diagram on the bread board

2. Switch on the regulated Power supply and slowly increase the source voltage and

note the down the voltage across the PN Junction diode insteps of .1Volt and note

down the Corresponding diode current under forward bias Condition as per table

given below.

3. Plot the graph Vf versus If on the graph Sheet to the scale.

4. From the graph find out the static forward bias resistance of the diode

r=Vf/If.

5. From the graph find out the dynamic forward bias resistance of the diode

6. Observe and note down the cut in Voltage of the diode.


TABLE:FORWARD BIAS CHARACTERISTICS:

S.No FORWARD BIAS FORWARD BIASVOLTAGE (Vf) CURRENT (If) IN mA

IN VOLTS

1 0.1

2 0.23. 0.34. 0.45. 0.56. 0.67. 0.7

8. 0.8

REVESE BIAS CHARACTERISTICS:

1. Connect the Circuit as per the Circuit Diagram on the bread board.

2. Switch on the Regulated Power supply and slowly increase the source Voltage

and note the Voltage across the PN Junction diode insteps of 1 Volt. And note the

Corresponding current flowing through the diode under reverse bias Condition as

per table given below.

3. Plot the graph Vr versus Ir on the graph Sheet to the scale.

4. From the graph find out the static reverse bias resistance of the diode

r =Vr/Ir.

5. From the graph find out the dynamic reverse bias resistance of the diode.


REVERSE BIAS CHARACTERISTICS:

REVERSE BIAS REVERSES.No VOLTAGE (Vr) BIAS CURRENT (Ir) IN

IN VOLTS A

1 12 23. 34. 45. 56. 67. 78 89 910 1011 1112 1213 1314 1415 15

MODEL GRAPH:

PRECAUTIONS:

1. Identify the Diode terminals properly while connecting.

2. Keep all COARSE controls of RPS minimum and CURRENT controls in maximum position before switch ON.


RESULT:1. Static forward resistance =

2. Static reverse resistance =

3. Dynamic forward resistance =

4. Dynamic reverse resistance =

The V-I Characteristics of the PN Junction diode are plotted for the Both forward and reverse bias conditions and Calculated the dynamic forward and reverse bias resistance.

VIVA QUESTIONS:

1. What is meant by P- type layer?

2. What is meant by N- type layer?

3. What is the function of p-n junction diode?

4. What is meant by forward bias of p-n junction diode?

5. What is meant by reverse bias of p-n junction diode?

6. Define cut-in voltage of p-n junction diode.

7. What is meant by depletion layer in p-n junction diode?


EXPT 6: ZENER DIODE CHARACTERISTICS

AI M:- 1. To Plot the V-I characteristics of ZENER diode.

2. To find out the Zener Break down Voltage and Zener resistances from the

Characteristics.

APPARATUS REQUIRED:-

1. D.C Regulated Power Supply 0-30V 1No.

2.Zener Diodes 5.1V 1No.

3.Resistor 1 K 1No.

4.DC Ammeter 0-50mA 2No.

5.DC Voltmeters 0-1V,0-30V Each 1No.

6.Bread Board. 1No.

THEORY:

In forward bias it acts as similar to the diode. In the reverse bias it acts as regulator

because its doping concentration is higher than the ordinary diode, due to this a large electric

field intensity is developed at the junction with narrow distance. Thus a large amount of

current is drawn through the diode. This phenomenon is known as Zener Break. The diode

which adopts this is zener diode.

CIRCUIT DIAGRAMS:-

1KΩ

(0-50mA)

+ A +

RPS(0-30V) 5.1V or 9.1V V (0-1V)

FORWARD BIAS CHARACTERISTICS

1KΩ

(0-50mA)

+ A +

RPS(0-30V) 5.1V or 9.1V V (0-30V)

REVERSE BIAS CHARACTERISTICS


PROCEDURE:-Forward bias characteristics:-

1. Connect the Circuit on the Bread Board as per the Circuit Diagram given below.

2. Switch on the D.C regulated power supply and slowly increase the source Voltage

and note the Voltage across the Zener diode in steps of 0.1V and note the

corresponding diode current under forward bias condition as per the tabular form

given below.

3. Repeat the above procedure for 9.1V Zener diode.

4. Draw graph between voltage Across the diode (Vf) Vs current (If) through the

diode on graph sheet for both zener diodes.

Reverse bias characteristics:-

1. Connect the circuit on the Bread Board as per the Circuit Diagram

given above.

2. Switch the DC Regulated power supply and slowly increase the source

Voltage and note down the Voltage across Zener diode insteps of the 1Volt

and note the Corresponding diode current as per table given below.

3. Repeat the above procedure for the 9.1V Zener diode.

4. Draw the graph between Voltage across the Zener diode (Vr)

Vs current (Ir) through the diode on graph sheet for the both zener Diodes.

5. From the graph find out the Zener break down voltage(Zvbr) & Zener resistance. Vr

Z r = Ir .

TABULAR FORMS:-

FORWARD BIAS CHARACTERISTICS:-

For 5.1zener diode ForwardS.No Forward Voltage(Vf) Current(If) in mA

inVolts1 0.12 0.23 0.34 0.45 0.56 0.67 0.78 0.8


REVERSE BIAS CHARACTERISTICS:-

For 5.1zener diode ReverseS.No. Reverse Voltage(Vr) Current(Ir) in

In Volts mA1 12 23 34 45 56 67 78 8

MODEL GRAPH:-

PRECAUTIONS:

1. Identify the Diode terminals properly while connecting.

2. Keep all COARSE controls of RPS minimum and CURRENT controls in maximum position before switch ON.

RESULT:1. Zener Break down Voltage =

2. Zener resistances =

The Characteristics of the Forward and Reverse biased Zener Diode and the Zener Break

Down Voltage from the Characteristics are Observed.


VIVA QUESTIONS:

1.What is meant by Avalanche effect?

2.What is meant by Zener effect?

3.What is meant by static and dynamic resistance of zener

diode?

4.What is meant by Zener break down voltage?How a Zener acts

like a voltage regulator?


EXPT 7: HALF-WAVE RECTIFIER

AIM: To observe the input & output waveforms of Half-Wave Rectifier with and without

filters. And to find the Ripple factor & % Regulation.

APPARATUS:

1. Transformer 230v/6v – 0 – 6v

2. Diodes IN4007

3. Decade resistance Box

4. Multimeter

5. Bread Board

6. 20MHz Dual Trace CRO

7. Connecting wires

THEORY:

As per the circuit diagram, it contains transformer and one diode, DRB, Capacitor.

During the positive swing of power supply, the diode acts as forward bias condition. Hence

it offers very less resistance. Thus whatever the input signal is applied transmitted to the load

resistance when the negative swing of the A.C signal is applied to the diode, it acts as

reverse bias connection Since it offers as high resistance. In this no signal is allowed to the

load. Thus it gives Half wave output signal .The amount of A.C signal is present in output

wave form is measured by ripple factor.

Ripple factor = V rms

V dc

Percentage of Regulation = VNL -VFL X 100

VFL


CIRCUIT DIAGRAMS:-

HALF WAVE WITHOUT FILTER

HALF WAVE WITH FILTER

PROCEDURE:

1. Connecting the circuit on bread board as per the circuit diagram

2. Connect the primary of the transformer to main supply i.e. 230V, 50Hz

3. Connect the decade resistance box and set the RL value to 500Ω

4. connect the Multimeter at output terminals and vary the load resistance (DRB) from

500Ω to 5KΩ and note down the Vac and Vdc as per given tabular form

5. Disconnect load resistance ( DRB) and note down No load voltage Vdc

6. Connect load resistance at 5KΩ and connect Channel – II of CRO at output terminals and

CH – I of CRO at Secondary Input terminals observe and note down the Input and Output

Wave form on Graph Sheet

7. Calculate Ripple Factor γ = Vac

Vdc

8. Calculate Percentage of regulation = Vnoload – Vfull load x 100%

Vfull load


TABULAR FORM: Without filter

V no Load Voltage (Vdc) =S.NO Load Vdc Vac Ripple Factor %of Regulation

Resistance In γ VNC – VFC X 100%Ohms VFL

1 5002 1K

3 2K4 3K5 4K6 5K

TABULAR FORM: With filter

V no Load Voltage (Vdc) =

S.NO Load Vdc Vac Ripple Factor %of RegulationResistance In γ VNC – VFC X 100%

Ohms VFL1 5002 1K3 2K4 3K5 4K6 5K

WAVE SHAPES:

HALF WAVE WITHOUT FILTER


HALF WAVE WITH FILTER

PRECAUTIONS:

1. Don’t touch the Primary side of the Transformer when it is PLUG-IN.

2. Maintain RL(DRB) should be above 100 Ω.

RESULTS: Average Ripple factor without filter :

Average Ripple factor with filter :

Average % Regulation without filter :

Average % Regulation with filter :

Observe Input and Output Wave forms and Calculate ripple factor and percentage of

regulation in Half wave rectifiers with & without filter.

VIVA QUESTIONS:

1. What is the function of half wave rectifier (HWR)?

2. What is meant by voltage regulation of HWR?

3. What are the applications of HWR?

4. What is the value of peak inverse voltage of HWR?

5. What is the value of ripple factor in HWR?


EXPT 8: FULL-WAVE RECTIFIER

AIM: To observe the input & output waveforms of Full- Wave Rectifier with and without

filters. And to find the Ripple factor & % Regulation.

APPARATUS:

1. Transformer 230v/6v – 0 – 6v

2 .Diodes IN4007 - 2 no’s

3. Capacitor 470µf/35v - 1 no.

4. Decade resistance Box

5. Multimeter

6. Bread Board

7. 20MHz Dual Trace CRO

THEORY:

It contains two diodes connected across the load and a center tapped transformer.

When the input is 0 to due to the center tapping we have two waveforms which are in

opposite phase. Diode1 acts as a conductor in 0 to . The diode 2 acts as a non-conductor.

Hence the output is almost equal to input of diode 1.When the primary of transformer is

between to 2 diode 1 acts as non-conductor and diode 2 acts as conductor. Hence the

output signal is almost equal to input signal of diode2 Thus we can observe a continuous

waveform.

CIRCUIT DIAGRAM:

FULL WAVE WITHOUT FILTER


FULL WAVE WITH FILTER

PROCEDURE:

1. Connecting the circuit on bread board as per the circuit diagram

2. Connect the primary of the transformer to main supply i.e. 230V, 50Hz

3. Connect the decade resistance box and set the RL value to 100Ω

4. Connect the multimeter at output terminals and vary the load resistance (DRB)

from 100Ω to 5KΩ and note down the Vac and Vdc as per given tabular form

5. Disconnect load resistance ( DRB) and note down No load voltage Vdc

6. Connect load resistance at 100KΩ and connect CH – I of Dual Trace CRO at

Secondary (Input) terminals, Channel – II of Dual Trace CRO at output terminals

and observe and note down the Input and Output Wave form on Graph Sheet

7. Calculate Ripple Factor γ = Vac

Vdc

8. Calculate Percentage of regulation = Vnoload – Vfull load x 100%

Vfull load

TABULAR FORM: Without filterV no Load Voltage (Vdc) =

S.NO Load Vdc Vac Ripple Factor %of RegulationResistance In γ VNC – VFC X 100%

Ohms VFL1 1002 2003 3004 4005 5006 6007 7008 8009 90010 1K11 2K


TABULAR FORM: With filterV no Load Voltage (Vdc) =

Load Resistance Ripple Factor %of RegulationS.No In Ohms Vdc Vac γ VNC – VFC X 100%

VFL1 1002 2003 3004 4005 5006 6007 7008 8009 90010 1K11 2K

WAVE SHAPES:

FULL WAVE WITHOUT FILTER

FULL WAVE WITH FILTER


PRECAUTIONS:

1. Don’t touch the Primary side of the Transformer when it is PLUG-IN.

2. Maintain RL(DRB) should be above 100 Ω.

RESULTS: : Average Ripple factor without filter =

Average Ripple factor with filter =

Average % Regulation without filter =

Average % Regulation with filter =

Observe Input and Output Wave forms and Calculate ripple factor and percentage of

regulation in Full wave wave rectifiers with & without filter

VIVA QUESTIONS:

1. What is the function of full-wave rectifier (FWR)?

2. What is meant by voltage regulation of FWR?

3. What are the applications of FWR?

4. What is the value of peak inverse voltage of FWR?

5. What is the value of ripple factor in FWR?


EXPT 9: COMMON BASE TRANSISTORCHARACTERISTICS

AIM: 1. To observe the input & output characteristics of a transistor connected in CB

configuration.

2. To find input and output resistance from the characteristics.

APPARATUS:

1. Transistor BC 107 or SL 100 1No.

2. Resistor 1K 1No.

3. Ammeter 0-50mA 2No.

4. Voltmeter 0-1V, 0-30V 2No.

5. 0-30V, 1A Dual Channel power supplies 1No.

6. Bread Board, 1No.

7. Connecting wires

THEORY:

In a common Base transistor base terminal is connected common to both the nput

(Emitter – Base) voltage and the output (collector –base) voltage . Voltmeters and Ammeters

are connected to measure the input and output voltages and currents.

Input Characteristics:

To determine the input characteristics, the output (Collector-Base) Voltage is

maintained constant ,and the input (Emitter-Base) voltage is set at several

convenient levels. For each level of the input voltage, the input current (Emitter

current) is recorded.

(a) Input Resistance ( Ri ) :

The Emitter current increases rapidly with small increase in VBE . This means

that input resistance is small. It is defined by the ratio of VBE to change in IE

at constant VCB.

Ri = ΔVBE at constant VCB IE


Output Characteristics:

To determine the output characteristics the input (Emitter) Current is held

constant at each of several fixed levels. For each fixed level of IE, the output

voltage VCB is adjusted in convenient steps, and the corresponding levels of

collector current are recorded.

(a) Output resistance (R O) : It is the ratio of change in output voltage to

corresponding change in output current at constant VCB.

RO = ΔVCB at constant IE

IC

(b) Current Amplification Factor ( α ) : It is ratio of change in output current to

change in input current at constant VCB

α = IC at constant VCB IE

CIRCUIT DIAGRAM:


PROCEDURE:Input characteristics:

1. Connect the circuit as in the circuit Diagram.

2. Make VCB open and Vary the 5V Supply (Channel-1) and note the Values

of IE and VBE by increasing the IE in steps of 0.5mA

3. Adjust VCB = 1V (Channel -2) Power supply.

4. Vary the 0-5V(Channel -1)power Supply and the Values of IE and VEB.

5. Repeat the steps 3 & 4 For VCB = 2V , 3V, 4V.

6. Calculate Input resistance Zi= ΔVBE at constant VCB

ΔIE

TABULAR FORM:-

S.No VCB Open VCB = 1V VCB = 2V

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

1 0.1 0.1 0.12 0.2 0.2 0.23 0.3 0.3 0.34 0.4 0.4 0.45. 0.5 0.5 0.56 0.6 0.6 0.67. 0.7 0.7 0.78. 0.8 0.8 0.8

Output characteristics:-

1. Connect the circuit as shown in circuit Diagram.

2. Adjust the 0 – 5V (Channel – 1) power supply and fix the value I E =0.5mA

3. Vary the 0 – 20 V (Channel – 2) power supply and note the value of I c andVCB

4. Vary the VCB inspects of 1v

5. Repeat steps 2 to 4 for IE = 1mA, 1.5mA, 2mA, 2.5mA

6. Calculate output resistance Zo= ΔVCB at constant IE

IC


TABULAR FORM:-

S.No.

IE=1mA IE=2mA IE=3mA

VcB(v) Ic(mA) VcB(v) Ic(mA) VcB(v) Ic(mA)

1 1 1 12 2 2 23 4 4 44 8 8 85 12 12 126 16 16 167 20 20 208 25 25 25

GRAPH:-

INPUT CHARACTERISTICS

OUTPUT CHARACTERISTICS

1. Plot the input characteristics by taking IE on y – axis and VEB on X – axis

2. Plot the output characteristics by taking Ic on y – axis and VcB on X – axis


PRECAUTIONS:

1. Keep all COARSE controls of RPS minimum and CURRENT controls in maximum

position before switch ON.

2. Carefully connect the transistor terminals.

RESULT:Input resistance Zi =Output resistance Zo =

Input and out put characteristics of CB Transistor are plotted.

VIVA QUESTIONS:

1. Explain Early effect in CB configuration?

2. Give the relation between IB and IC .

3. Define large signal current gain.

4. Define input and output characteristics for CB.


EXPT 10: COMMON EMITTER TRANSISTORCHARACTERISTICS

AIM: 1. To observe the input & output characteristics of a transistor connected in CE

configuration.

2. To find input and output resistance from the characteristics.

APPARATUS:

1.Transistor BC 107 or SL 100 1No.

2.Resistor 1K 1No.

3.Ammeter 0-50mA, 0-500µA 2No.

4.Voltmeter 0-1V, 0-30V 2No.

5.0-30V,1A Dual Channel power supply 1No.

6.Bread Board, 1No.

7.Connecting wires

THEORY:

In a common Emitter transistor Emitter terminal is connected common to both the

input (Emitter – Base) voltage and the output (Collector – Emitter) voltage . Voltmeters

and Ammeters are connected to measure the input and output voltages and currents.

Input Characteristics:

To determine the input characteristics, the output (Collector- Emitter) Voltage

is maintained constant ,and the input (Emitter-Base) voltage is set at several

convenient levels. For each level of the input voltage, the input current (Base-

current) is recorded.

(b) Input Resistance ( Ri ) :

The Base current increases rapidly with small increase in VBE . This means

that input resistance is small. It is defined by the ratio of VBE to change in IB

at constant VCE.

Ri = ΔVBE at constant VCE IB


Output Characteristics:

To determine the output characteristics the input (Base) Current is held

constant at each of several fixed levels. For each fixed level of IB, the output

voltage VCE is adjusted in convenient steps, and the corresponding levels of

collector current are recorded.

(b) Output resistance (R O) : It is the ratio of change in output voltage to

corresponding change in output current at constant VCB.

RO = ΔVCE at constant IB

IC

(b) Current Amplification Factor ( α ) : It is ratio of change in output current to

change in put current at constant VCB

α = IC at constant VCE

IB

CIRCUIT DIAGRAM:

PROCEDURE :

1. Connect the Circuit as shown in the Circuit Diagram.

2. Make VcE Open and Vary the 5 V Supply(Channel 1) and note the Values of IB

and VcE, By increasing the IB in Steps of 0.5mA.

3. Adjust VCE = 1V in Channel 2 Power supply.

4. Vary the 0-5V (Channel 1) power Supply and note the Values of IB and

VBE 5.Repeat the Steps 3 and 4 for VCE = 2V ,3V,4V.

6. Need not Connect 0-2mA(IC Measurement), Ammeter while taking the input

Characteristics.

7. Calculate Input resistance Zi= ΔVBE at constant VCE

ΔIB


TABULAR FORM :

at constant IB

S.No. VcE Open VCE = 1V VcE = 2V

VBE(V) IB(mA) VBE(V) IB(mA) VBE(V) IB(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 0.6 0.6 0.6

7 0.7 0.7 0.7

8 0.8 0.8 0.8

OUTPUT CHARACTERISTICS :

1.Connect the Circuit as shown in the Circuit Diagram.

2.Connect 0-500 A Ammeter in place of 0-20mA.

3.Adjust 0-5V (Channel -1) power Supply and fix the Values of IB = 10 A

4.Vary the VCE 0-20V (Channel -2) power supply and note down the Values of

the Ic and VCE. Vary in the Steps of 1V.

5.Repeat the steps 3 & 4 for IB = 30 A, 40 A, 50 A .

6.Calculate Input resistance Zo= ΔVBE

ΔIC


TABULAR FORM :

IB = 100 A IB = 200 A IB = 300 A

S.No. VCE(mA) IC(mA) VCE(mA) IC(mA) VCE(mA) IC(mA)

1 1 1 1

2 2 2 2

3 3 3 3

4 4 4 4

5 5 5 5

6 6 6 6

7 7 7 7

8 8 8 8

GRAPH :

1. Plot the input characteristics by taking IB on Y-Axis and VBE on X-Axis.

2. Plot the output characteristics by taking IC on the Y-Axis and VCE on X - Axis

INPUT CHARACTERISTICS


OUTPUT CHARACTERISTICS

PRECAUTIONS:



2. Carefully connect the transistor terminals.

RESULT: Input resistance Zi =

Output resistance Zo =

Input and out put characteristics of CE Transistor are plotted.

VIVA QUESTIONS:

1. Give the relation between IB, IC and IE

2. Give the relation between ICEO and ICBO.

3. Define the transport factor.

4. Define saturation region, cut-off region and active region.


EXPT 11: CHARACTERISTICS OF EMITTER FOLLOWER(CC) CIRCUIT

AIM: To draw the input and output characteristics of transistor connected in CC

(Common Collector) or Emitter follower configuration.

APPARATUS:

Transistor (SL100 or BC107)

R.P.S (O-30V) 2Nos

Voltmeters (0-20V) 2Nos

Ammeters (0-200µA) 2Nos

(0-200mA)

Resistors 100Kohm

Bread board and connecting wires

THEORY:

A transistor is a three terminal device. The terminals are emitter, base,

collector. In emitter follower configuration, input voltage is applied between base and

ground terminals and out put is taken across the emitter and collector terminals.

The input characteristics resemble that of a forward biased diode curve. This

is expected since the Base-Emitter junction of the transistor is forward biased.

The output characteristics are drawn between IE and VCE at constant IB. the

emitter current varies with VCE unto few volts only. After this the emitter current

becomes almost constant, and independent of VCE. The value of VCE up to which the

collector current changes with V CE is known as Knee voltage. The transistor always

operated in the region above Knee voltage, IE is always constant and is approximately

equal to IB.

Dept of ECE 38

CIRCUIT DIAGRAM:

PROCEDURE:

INPUT CHARECTERSTICS:

1. Connect the circuit as per the circuit diagram.

2. For plotting the input characteristics the output voltage VCE is kept constant at 2V and

note down values of VCB for each value of IB

3. Change VCE to 10 V and repeat the above step.

4. Disconnect the voltmeter from input circuit.

5. plot the graph between VCB and IB for constant VCE

OUTPUT CHARACTERSTICS:

1. Connect the circuit as per the circuit diagram

2. With IB set at 0µA, vary VCE and note down the corresponding IE value.

39

3. Set IB at 40µA, 80µA and repeat the above step.

4. Plot the output characteristics between VCE and IE for constant IB.

OBSERVATIONS:

INPUT CHARACTERISTICS:

VCE = 2V VCE = 4V VCE = 10 VS.NO

VCB(V) IB(µA) VCB(V) IB(µA) VCB(V) IB(µA)

OUT PUT CHAREACTARISTICS:

IB = 0 µA IB = 30 µA IB = 40 µAS.NO

VCE(V) IE(mA) VCE(V) IE(mA) VCE(V) IE(mA)

40

MODEL GRAPHS:

INPUT CHARACTERSTICS:

OUTPUT CHARECTERISTICS:

41

PRECAUTIONS:

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

2. Meters should be connected properly according to their polarities

VIVA QUESTIONS:

1. What are the input and output impedances of CC configuration?

2. Identify various regions in the output characteristics?

3. Why CC configuration is preferred for buffering?

4. What is the phase relation between input and output?

5. Draw diagram of CC configuration for PNP transistor? What are the applications of CC configuration?

42

EXPT 12: FET CHARACTERISTICS

AIM: To plot Output Characteristics and Transfer Characteristics of Field Effect Transistor (FET)

APPARATUS:1. FET BFW – 10/11 1 No.

2. Resisters – 470 Ώ 2 No.

3. Connecting Wires

4. Ammeter 0 – 20 Ma 1 No.

5. Multimeter (volt meter 0-10v) 2 No.

6. 0 – 30v, 1A Dual Channel Power Supply 1 No.

7. Bread Board Trainer 1 No.

THEORY:

A junction field effect (JFET) consists of a P – type or N – type silicon bar .

The bar is the conducting channel for the charge carriers. If the bar is made up of N-

type material it is known as N- channel FET and if the bar is made up of P- type

material it is known as P- channel FET.To form a J FET two junction diodes are

connected internally . There are three terminals in FET, namely Source, GATE , and

Drain. GATE is the common terminal to both input and output. In JFET , the gate

source diode is always reverse biased so the input applied to FET is reverse biased.

The source and drain terminals are interchangeable.

When a reverse voltage VGS is applied between the source and gate, the width

of the depletion layer is increased. Thus reduces the width of the channel , there by

increased the resistance of N –type bar, As a result, the current from source to drain is

decreased the width of the depletion layers also decreases. This increases the width of

the conducting channel. As a result the current from source to drain is increased.

DRAIN CHARACTERSTICS:-

This is the curve drawn between the drain – source voltage (VDS) and the drain

current (ID) at constant gate source voltage. The drain current Id rises rapidly with

drain source voltage VDS . After reaching some value, it becomes constant.


FORMULAE:

TRANSCONDUCTANCE : (gm) = ΔID/ΔVGS At constant VDS

DRAIN RESISTANCE: (rd) = ΔVDS/ΔID At constant Vgs

AMPLIFICATION FACTOR : (μ) = rd*gm

CIRCUIT DIAGRAM:

(0-20mA)Ω

A470

+

470 Ω + (0-30V)BFW10 V

(0-5V) (0-20V)

(0-30V) V+

FET CHARACTERISTICS

PROCEDURE:

OUTPUT (Drain) CHARACTERISTICS

1. Connect the circuit as shown in the diagram 2. Make VGS =0v, by adjusting 0 – 5v (Channel – I) power supply

3. Adjust the 0 – 30v (Channel – II) power supply and note the values of ID and VDS with the variation of VDS in step of 1v, as per table given below

4. Repeat the above procedure for VGS=0.5v and 1v

TABULAR FORM (OUTPUT CHARACTERISTICS):

VGS=0v VGS=1v VGS=2v

VDS(V) ID(mA) VDS(V) ID(mA) VDS(V) ID(mA)0 0 01 1 12 2 23 3 34 4 45 5 56 6 67 7 78 8 89 9 910 10 10


PROCEDURE:

INPUT (Transfer) CHARACTERISTICS

1. Connect the circuit as shown in the diagram

2. Make VGS =1v, by adjusting 0 – 30v (Channel – II) power supply

3. Adjust the 0 – 5v (Channel – I) power supply and note the values of ID and VDS

with the variation of VGS in step of 0.2v, as per table given below

4. Repeat the above procedure for VDS=2v and 3v

TABULAR FORM (INTPUT CHARACTERISTICS):

VDS=1v VDS=1.5v VDS=2v

VGS(V) ID(mA) VGS(V) ID(mA) VGS(V) ID(mA)0 0 0

0.2 0.2 0.20.4 0.4 0.40.6 0.6 0.60.8 0.8 0.81.0 1.0 1.01.2 1.2 1.21.4 1.4 1.41.6 1.6 1.61.8 1.8 1.82.0 2.0 2.0

GRAPH:

OUT PUT CHARACTERISTICS


TRANSFER CHARACTERISTICS

GRAPH :

1. Plot the Output Characteristics by taking ID on Y-axis and VDS on X-axis for

constant values of VGS

2. Plot the Transfer Characteristics by taking ID on Y-axis and VGS on X-axis for

constant values of VDS

PRECAUTIONS:



2. Carefully connect the FET terminals.

RESULT: Thus the Drain & Transfer Characteristics of the given JFET are studied

and the following parameters are found out.

1. TRANS CONDUCTANCE :

2. DRAIN RESISTANCE :

3. AMPLIFICATION FACTOR :


VIVA QUESTIONS:

1. What are the merits of FET as compared with BJT?

2. What is the drawback of FET as compared with BJT?

3. Define pinch-off voltage.

4. Why the name field effect transistor?

5. Name the regions in static characteristics of FET?


EXPT 13: UJT CHARACTERISTICS

AIM: To observe the characteristics of UJT and to calculate the Intrinsic Stand-Off Ratio (η).

APPARATUS:

Regulated Power Supply (0-30V, 1A) - 2Nos

UJT 2N2646

Resistors 1k_, 100_

Multimeters - 2Nos

Breadboard and connecting Wires

CIRCUIT DIAGRAM

48

THEORY:

A Unijunction Transistor (UJT) is an electronic semiconductor device that

has only one junction. The UJT Unijunction Transistor (UJT) has three terminals an

emitter (E) and two bases (B1 and B2). The base is formed by lightly doped n-type bar

of silicon. Two ohmic contacts B1 and B2 are attached at its ends. The emitter is of p-

type and it is heavily doped. The resistance between B1 and B2, when the emitter is

open-circuit is called interbase resistance.The original unijunction transistor, or UJT, is

a simple device that is essentially a bar of N type semiconductor material into which P

type material has been diffused somewhere along its length. The 2N2646 is the most

commonly used version of the UJT.

Circuit symbol

The UJT is biased with a positive voltage between the two bases. This causes a

potential drop along the length of the device. When the emitter voltage is driven

approximately one diode voltage above the voltage at the point where the P diffusion

(emitter) is, current will begin to flow from the emitter into the base region. Because the

base region is very lightly doped, the additional current (actually charges in the base

region) causes (conductivity modulation) which reduces the resistance of the portion of

the base between the emitter junction and the B2 terminal. This reduction in resistance

means that the emitter junction is more forward biased, and so even more

49

current is injected. Overall, the effect is a negative resistance at the emitter terminal.

This is what makes the UJT useful, especially in simple oscillator

circuits.When the emitter voltage reaches Vp, the current startsto increase

and the emitter voltage starts to decrease.This is represented by negative

slope of the characteristics which is reffered to as the negative resistance

region,beyond the valleypoint ,RB1 reaches minimum value and this

region,VEB propotional to IE.

PROCEDURE:

1. Connection is made as per circuit diagram.

2. Output voltage is fixed at a constant level and by varying input voltage

corresponding emitter current values are noted down.

3. This procedure is repeated for different values of output voltages.

4. All the readings are tabulated and Intrinsic Stand-Off ratio is calculated using

η = (Vp-VD) / VBB

5. A graph is plotted between VEE and IE for different values of VBE.

MODEL GRAPH:

50

OBSERVATIONS:

VBB=1V VBB=2V VBB=3V

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

CALCULATIONS:

VP = ηVBB + VD

η = (VP-VD) / VBB

η = ( η1 + η2 + η3 ) / 3

VIVA QUESTIONS

1. Wha is the symbol of UJT?

2. Draw the equivalent circuit of UJT?

3. What are the applications of UJT?

4. Formula for the intrinsic stand off ratio?

5. What does it indicates the direction of arrow in the UJT?

6. What is the difference between FET and UJT?

7. Is UJT is used an oscillator? Why?

8. What is the Resistance between B1 and B2 is called as?

9. What is its value of resistance between B1 and B2?

10. Draw the characteristics of UJT?

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