Subject: AITSDS/ECD/EXPT

ATMIYA INSTITUTE OF TECHNOLOGY & SCIENCE FOR DIPLOMA STUDIES, RAJKOT

Subject:

BE

To study CRO.

1

Experiment No.

1.

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

CRO AIM:- To study the use of Cathode Ray Oscilloscope (CRO).

Apparatus: - C.R.O, Connecting probe (BNC cable).

Theory:-

An CRO is easily the most useful instrument available for testing circuits at different points. The

best way to investigate any electronic circuit is to monitor or check signal at input and output of each

block, if they are correctly linked or not to next stage.

The function of CRO is to draws graph of voltage against time (V/t), in that voltage is on vertical

or Y-axis and time is on horizontal or X-axis. There are 8 squares or division on the X-axis and 10

squares on the Y-axis. The squares are of 1cm in each direction.

FIGURE :-


Subject:

BE

To study CRO.

2

Experiment No.

1.

DATE:

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AITSDS/ECD/EXPT/

Panel Control :-

Switch

No. Switch Use

1 Power On/Off Push button switch to supplying power to instrument.

2 X 10 MAG When pushed, gives 10 times magnification of the X

signal.

3 XY

4 CH-1 / CH-2 Select between channel 1 (when out) and channel 2

(when pressed)

5 Mono/Dual Selects Mono or Dual trace option.

6 ALT/CHOP/ADD

Selects alternate or chopped in dual mode and enable

for addition or subtraction of channel in mono mode

i.e CH-1± CH-2.

7 EXT. When pressed allows external triggering signal to be

fed.

8 Line When pressed displayed signal is synchronized with

mains line frequency.

9 ALT Selects alternate trigger mode from Ch1 and Ch2. In

this mode both the signals are synchronized.

10 +/- Selects the slope of triggering whether it is positive

going or negative going.

11 AT/NORM

12 Level Controls the trigger level from peak to peak amplitude

of signal.

13 Component tester When pressed starts component testing operation.

14 Pilot Lamp When glow indicates power ON position.

15 X-POS Controls horizontal position of the trace.

16 TB-VAR Controls time speed between two steps of Time/Div

switch, for calibration put it fully anticlockwise.

17 Trace Sep Separate traces X1 & X10 in 4 trace operation.

18 HOLD Off Controls Hold Off time between sweeps used for stable

triggering.

19 TRIG. INP To feed external trigger signal in EXT(external)

Trigger mode.


Subject:

BE

To study CRO.

3

Experiment No.

1.

DATE:

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AITSDS/ECD/EXPT/

20 Intens Controls the brightness of trace.

21 TR Controls alignment of the trace with graticule.

22 Focus Controls sharpness of trace.

23 DC/AC/GD Input coupling switch for each channel.

24 CH1(Y) & CH2(X) BNC connector serve as input connection for CH1 and

CH2.

25 Illume For switching ON/Off graticule illumination.

26 CALOUT Socket provided for square wave output 200mv

27 CT To test any component in CT mode, put one test probe

in this socket and another to ground.

28 INV CH2 When pressed invert polarity of CH2.

29 Digital Readout LCD window displays Volt/Div and Time/Div.

30 Y Pos I & II Controls Vertical Position of signal.

31 Volts/Div Selects Volt/Div step for CH1.

32 Volts/Div Selects Volt/Div step for CH2.

33 NOR/ALT Switch selects Normal or Alternately expanded

simulation position.

34 Time/Div Selects Time/Div step for CH1 and CH2.

Application :-

1) Measurement of magnitude of signal.

2) View different type of signal.

3) Measurement of voltage , time period , frequency of any waveform.

4) To test component.

5) Compare two signal.

6) Measurement of phase difference.

7) To test electronic circuit.

PROCEDURE :-

1) For measurement of Voltage :-

a) Calculate the number of division covered by the entire height of the waveform.


Subject:

BE

To study CRO.

4

Experiment No.

1.

DATE:

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AITSDS/ECD/EXPT/

b) Check the volt/div setting.

c) Now multiply two quantities: number of division covered by signal and reading of

Volt/Div.

Amplitude = Number of Division X Voil/Div.

2) For measurement of Currents :-

A CRO is basically a voltage indicating device. For measuring current, it is passed

through a suitable known resistor. Then the potential development across this resistor is

measured and put that value in below equation and the current can be find.

I = V / R

Where, I= current

V= Voltage / potential difference

R= Resistance

3) For measurement of frequency :-

a) Calculate the number of division in horizontal direction that are covered by the 1

complete cycle of waveform.

b) Observe the reading of Time/Div on the CRO front panel.

c) Multiply both , thus

Time period = No. of division X Time/Div

Frequency = 1 / Time period

4) For measurement of Phase Difference :-

a) Put the CRO in dual mode.

b) Apply two signals to CH-1 and CH-2 respectively and adjust the waveform.

c) Measure the time for one complete cycle of the signal, call it T sec.

d) Measure the time difference between the starting points or any same points of the two

signals. Call it t sec.

e) Now the phase difference between two signal is,

Phase Difference = (360 X t) / T.

CONCLUSION :


Subject:

BE

To study FUNCTION GENERATOR

1

Experiment No.

2

DATE:

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AITSDS/ECD/EXPT/

Function Generator: Apparatus :- C.R.O, Function Generator , BNC cable.

Theory:-

The Function generator is a device which is used to generate different kind of waveforms. These

waveforms are used to test different electronic circuit. the function generator is having frequency range

from 2Hz to 2MHz. It can generate different type of waveforms like Sine wave, Square wave, Saw tooth

Wave, Triangle Wave, Pulse Train etc.

Figure:

Panel Control :-

Switch

No. Switch Use

1 Power On/Off Push button switch to switch ON device.

2 Display 7 Segment LED display to see value of Frequency.

3 Duty Cycle To adjust On/OFF time period of square wave.


Subject:

BE


2

Experiment No.

2

DATE:

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AITSDS/ECD/EXPT/

4 Freq. Vari. Adjust to Vary frequency.

5 Amp. Vari Adjust to vary amplitude of signal.

6 DC offset To remove DC component form AC waveform.

7 Attenuation (40 db/20

db) To attenuate amplitude of signal.

8 FM ext ( max 2Vp-p ) To apply FM external input.

9 Frequency range Band selection to generate frequency from 2Hz to

2MHz.

10 Output (50Ω,20Vp-

p,O.C.) Connect output probe to this knob.

11 FM Press it to take external FM input.

Application :-

1) To generate different frequencies.

2) For modulation of any signal.

3) To provide different waveforms.

4) To test any electronic circuit.

PROCEDURE :-

1) Switch ON the power supply.

2) Now select the range of frequency between 2Hz to 200MHz.

3) To change types of waveform select the type.

4) To change frequency preciously just vary frequency variation probe.

5) To change amplitude of waveform vary amplitude variation button.

6) Also can change the duty cycle of waveform.

7) To change DC level of waveform vary DC offset.


Subject:

BE


3

Experiment No.

2

DATE:

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AITSDS/ECD/EXPT/

WAVEFORM :-

CONCLUSION :-


Subject:

BE

To test half wave rectifier

1

Experiment No.

03

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

AIM:- To test half wave rectifier.

Apparatus :- Trainer kit, Variable Voltage DC regulated power supply, Digital Multimeter,

Connecting probes, CRO.

Theory:-

Rectification means conversion of AC into DC. Diode has characteristics such that it allows

current to flow in one direction i.e. only in forward biased condition. AC is a sinusoidal waveform as

shown in Figure. Using positive half cycle current increases from zero to peak value and returns to

zero according to sine wave properly. During negative half cycle current goes to peak and returns to

zero.

Half wave rectifier circuit using diode is shown in Figure. During positive half cycle of AC

diode is forward biased, so it conducts heavily and current flows through the load resistance. During

negative half cycle of AC diode is reverse biased so no current flows through the diode as well as

through load resistance. Only a very small leakage current flows through the circuit. Thus output

voltage appears only during positive half cycles and waveform of voltage across load resistance is as

shown in Figure 3. Peak inverse voltage (PIV) is the maximum voltage across diode reverse bias.

PIV is the same as the peak amplitude of the input voltage as shown in Figure 4.

PROCEDURE :-

1) Connect the circuit as shown in figure-1.

2) Connect the resistance of known value

3) Measure the voltage and observe waveform with the help of CRO.

4) Draw the waveform across diode, supply voltage and output.

CIRCUIT DIAGRAM :-


Subject:

BE

To test half wave rectifier

2

Experiment No.

03

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

Waveform :-

OBSERVATION TABLE :-

CONCLUSION :-

SR

No. V(p-p) Vout (p) PIV = Vm

1.

2.

3.

4.

5.


Subject:

BE

To test full wave rectifier

1

Experiment No.

04

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

AIM:- To test full wave rectifier .

Apparatus :- Trainer kit, Digital Multimeter, Connecting probes, CRO.

Theory:-

In Full wave rectifier circuit, Center tapped transformer is used and two diodes are connected

as shown in Figure 1. During positive half cycle diode D1 conducts and current flows through the

load resistance. In this half cycle diode D2 is reverse biased and the maximum reverse voltage D2 is

the twice of the input peak voltage rating of the diode. During negative half cycle diode D2 conducts

and current flows through the load resistance in the same direction. In this half cycle diode D1

remains reverse biased.

Output from rectifier is pulsating DC. Most of the applications require smooth DC. This

output contains an AC portion, which is called ripple. Filters are used at output of rectifier to give

smooth DC without ripple.

A circuit in which capacitive filter is used as shown in Figure 1. During first quarter cycle in

which output is increasing, capacitor is charged to peak voltage. Then in second quarter cycle output

of rectifier decreases during that time capacitor discharges through the load resistance. But before

capacitor voltage discharges to zero, a next half cycle starts which again charges the capacitor. In this

way capacitive filter keeps the output voltage almost near to peak voltage by not allowing it to fall to

zero value. Thus ripples in rectifier output are filtered out by capacitance filter. Load resistance

provides path for capacitor discharge so it is also called bleeding resistance.

In capacitor filter circuit diodes do not conduct continuously. When output voltage from

transformer becomes larger than capacitor voltage, diode conducts. But most of the times diodes are

subjected to reverse voltage. Diodes must handle high peak current during recharging of capacitor for

a short period and this current increases with the value of capacitance. As the value of capacitor or

bleeding resistance increases ripple is reduced i.e. ripple factor is reduced. It means that load

resistance affects the ripple factor. Ripple factor is defined as the ratio of RMS value of AC

component present at output to DC voltage level at output.

PROCEDURE :-


2) Connect voltmeter across load resistance.

3) Connect the C for capacitor load.

4) Turn ON the power supply

5) Measure voltage from voltmeter that is VDL and observe the output waveform..

6) Keep CRO in AC mode, measure the peak to peak voltage.


Subject:

BE


2

Experiment No.

04

DATE:

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AITSDS/ECD/EXPT/

CIRCUIT DIAGRAM :-

WAVEFORM :-


Subject:

BE


3

Experiment No.

04

DATE:

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AITSDS/ECD/EXPT/


SR

No. VDL Vp-p

1.

2.

3.

4.

5.

CONCLUSION :-


Subject:

BE

To test full wave rectifier bridge rectifier.

1

Experiment No.

05

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

AIM:- To test full wave bridge rectifier .

Apparatus :- Trainer kit, Digital Multimeter, Connecting probes, CRO.

Theory:-

In Full wave rectifier circuit, Center tapped transformer is used and two diodes are connected

as shown in Figure 1. During positive half cycle diode D1 conducts and current flows through the

load resistance. In this half cycle diode D2 is reverse biased and the maximum reverse voltage D2 is

the twice of the input peak voltage rating of the diode. During negative half cycle diode D2 conducts

and current flows through the load resistance in the same direction. In this half cycle diode D1

remains reverse biased.

Output from rectifier is pulsating DC. Most of the applications require smooth DC.This output

contains an AC portion, which is called ripple. Filters are used at output of rectifier to give smooth

DC without ripple.

A circuit in which capacitive filter is used as shown in Figure 1. During first quarter cycle in

which output is increasing, capacitor is charged to peak voltage. Then in second quarter cycle output

of rectifier decreases during that time capacitor discharges through the load resistance. But before

capacitor voltage discharges to zero, a next half cycle starts which again charges the capacitor. In this

way capacitive filter keeps the output voltage almost near to peak voltage by not allowing it to fall to

zero value. Thus ripples in rectifier output are filtered out by capacitance filter. Load resistance

provides path for capacitor discharge so it is also called bleeding resistance.

In capacitor filter circuit diodes do not conduct continuously. When output voltage from

transformer becomes larger than capacitor voltage, diode conducts. But most of the times diodes are

subjected to reverse voltage. Diodes must handle high peak current during recharging of capacitor for

a short period and this current increases with the value of capacitance. As the value of capacitor or

bleeding resistance increases ripple is reduced i.e. ripple factor is reduced. It means that load

resistance affects the ripple factor. Ripple factor is defined as the ratio of RMS value of AC

component present at output to DC voltage level at output.

PROCEDURE :-


2) Connect voltmeter across load resistance.

3) Connect the C for capacitor load.

4) Turn ON the power supply

5) Measure voltage from voltmeter that is VDL and observe the output waveform..

6) Keep CRO in AC mode, measure the peak to peak voltage.


Subject:

BE


2

Experiment No.

05

DATE:

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AITSDS/ECD/EXPT/

CIRCUIT DIAGRAM :-


SR

No. VDL Vp-p

1.

2.

3.


Subject:

BE


3

Experiment No.

05

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

WAVEFORM:-

CONCLUSION :-


Subject:

BE

TO STUDY P-N JUNCTION IN FORWARD BIAS

1

Experiment No.

6

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

AIM: TO STUDY P-N JUNCTION IN FORWARD BIAS.

APPARATUS: Trainer kit, Variable voltage DC regulated power supply, Voltmeter,

Milli ammeter, Micro ammeter, connecting probes.

THEORY:

When diode is connected in such a way that its P terminal is connected with positive terminal of

battery and N terminal is connect to negative terminal of battery. Diode is forward bias is shown in

fig.2 in forward bias. Diode allows large current to flow in the circuit and voltage is developed across

resistance R1. As supply voltage is increased. Voltage across resistance increases because once diode

is turned on. The voltage across diode does not change appreciably. In forward bias the voltage across

diode is about 0.3V for germanium diode and 0.7V for a silicon diode. The reminder of the applied

voltage appears the resistor connected in series of the diode.

Circuit Diagram:

PROCEDURE:

1. Note down maximum forward current and peak inverse voltage of the diode given by

manufacturer.

2. Connect the circuit as shown in fig.

3. Increase the supply voltage in small steps and measure the current passing through the circuit as

well as voltage across diode. Note down the readings in table.

4. Plot forward current Vs forward voltage.


Subject:

BE

TO STUDY P-N JUNCTION IN FORWARD BIAS

2

Experiment No.

6

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

OBSERVATION TABLE:

Sr.

No. Forward current Forward voltage Reverse current Reverse voltage

V-I characteristic:

CONCLUSION:


Subject:

BE

Obtain the V-I characteristic of zener diode.

1

Experiment No.

07

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

AIM: - Obtain the V-I characteristic of zener diode.

Apparatus: - Trainer kit, Variable Voltage DC regulated power supply, Digital Multimeter, Connecting

probes.

Theory:-

Normal P-N junction diode, in reverse bias carries large amount of current ,so large amount of

power dissipation occurs that damage the P-N junction diode, so does not used in reverse bias. While

Zener diode is highly doped compare to P-N junction diode so it can be used in reverse bias region.

Symbol of Zener diode is shown in Figure-1.

Characteristic of voltage V/S current of zener diode is shown in figure-2. In forward bias zener

diode is same as forward characteristic of normal P-N junction diode. When the diode is reverse-biased, a

small reverse current is remains relatively constant despite an increase in reverse bias, until the Zener

breakdown region, in the vicinity of the Zener voltage Vz, is reached. In this vicinity reverse current starts

rising rapidly because of avalanche effect. Finally Zener breakdown occurs when the Zener voltage Vz is

reached. Zener breakdown need not result in the destruction of the diode.

CIRCUIT DIAGRAM :-

If

(mA)

Vz (v) Vf (v)

Iz

(mA)

Figure 2. Characteristic of Zener Diode


Subject:

BE

Obtain the V-I characteristic of zener diode.

2

Experiment No.

07

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

PROCEDURE :-


2) Connect regulated DC power supply of 0-18v.

3) Turn ON the power supply and increase slowly supply voltage and measure and note down zener

voltage Vz and zener current Iz.

4) Plot characteristic graph of zener voltage versus zener current.


Sr.

No.

Forward Bias Reverse Bias

Diode Voltage Forward

Current

Diode

Voltage

Reverse current

1. 0.1v 0.5v

2. 0.2v 1v

3. 0.3v 1.5v

4. 0.4v 2v

5. 0.5v 3v

6. 0.6v 4v

7. 0.7v 5v

8. 0.8v 6v

9. 0.9v 7v

CONCLUSION :-


Subject:

BE

To Study Filter

1

Experiment No.

8

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

AIM: To Study Filter.

Apparatus : Trainer kit, CRO, Connecting probes

Theory :

The circuit diagram of the bridge rectifier with filter capacitor is shown in the following figure. When

capacitor charges during the first cycle, surge current flows because initially capacitor acts like a short

circuit. Thus, surge current is very large. If surge current exceeds rated current capacity of the diode it

can damage the diode. To limit surge current surge resistance is used in series as shown in the figure.

Similar surge resistance can be used in half wave as well as center-tapped full wave rectifier also.

Circuit Diagram:

Bridge rectifier package (combination of four diodes in form of bridge) is easily available in the market

for various current capacities ranging from 500 mA to 30A. For laboratory purpose you can use 1A

package.

Advantages:

No center tap is required in the transformer secondary hence transformer design is simple. If

stepping up and stepping down not required than transformer can be eliminated. (In SMPS used

in TV and computer, 230V is directly applied to the input of bridge rectifier).

The PIV of the diode is half than in center tap full wave rectifier

Transformer utilization factor is higher than in center tapped full wave rectifier

Smaller size transformer required for given capacity because transformer is utilized effectively

during both AC cycles.

Disadvantages:

Requires Four diodes (But package is low cost)

Forward voltage drop across two diodes. This will reduce efficiency particularly when low

voltage (less than 5V ) is required.

Load resistance and supply source have no common point which may be earthed.


Subject:

BE

To Study Filter

2

Experiment No.

8

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

Waveform:

Conclusion:


Subject:

BE

TO BUILD AND TEST COLPITTS OSCILLATOR.

1

Experiment No.

09

.

DATE:

DOC. CODE

AIM: TO BUILD AND TEST COLPITTS OSCILLATOR.

Apparatus : Oscilloscope, +12V DC Adapter, Patch Cords.

Circuit Diagram :

Procedure :

1. Connect +12V DC Supply (adapter) to the trainer

2. Now connect +12V terminal to TP2 and Gnd to Gnd as shown in figure.

3. Connect terminals 1 and 2 and similarly 4 and Gnd together.

4. Switch ‘On’ the mains supply. 5. Connect oscilloscope between Vout and Gnd.

6. Measure the value of output frequency on oscilloscope.

7. Calculate the resonance frequency (theoretical) using equation 1.

8. Compare measured frequency with the theoretically calculated value.

9. Switch ‘Off’ the supply.


Subject:

BE

TO BUILD AND TEST COLPITTS OSCILLATOR.

2

Experiment No.

09

.

DATE:

DOC. CODE

Observation Table:

SR. NO. Capacitors Ceq.

(Equivalent

Capacitance)

Output

frequency

(Measured)

Output

frequency

(Theoretical)

CONCLUSION:


Subject:

BE

TO BUILD AND TEST HARTELY OSCILLATOR.

1

Experiment No.

10

.

DATE:

DOC. CODE

AIM: TO BUILD AND TEST HARTELY OSCILLATOR.

APPARATUS: Power Supply.

Trainer kit,

Connecting probe,

CRO.

THEORY: Any circuit generates an alternating voltage is called an oscillator. To generate AC voltage, the circuit. is

supplied energy from a DC source. Main application of positive feedback is oscillator. If output signal varies

sinusoidally, the circuit is referred to as a sinusoidal oscillator. If output voltage rises quickly to one voltage

level and later drops quickly to another voltage level, the circuit. is generally referred to as a pulse or square

wave oscillator.

Consider the feedback circuit, which is shown in the fig. When the switch at the amplifier input is open, no

oscillation occurs. Consider that we have a input (Vi). This results in an output voltage Vo = AVi after the

amplifier stage and in a voltage Vf = B (AVi) after the feed back stage. Thus, we have a feedback voltage Vf =

BAVi where BA is referred to as the loop gain if the circuit of the base amplifier and feedback network provide

BA of correct magnitude and phase, Vf can be made equal to Vi. Then when the switch is closed and voltage Vi

is removed, the circuit will continue operating since the feedback voltage is sufficient to drive the amplifier and

feedback circuit resulting in a proper input voltage to sustain the loop operation. The output waveform will still

exist after the switch is closed.

We derive the expression for the over all voltage gain of the amp. can be written as

Af=A/1-A.

It can now be seen that if AB =1, so Af= . The gain becoming infinity means that there is a output without any

input. In other words, the amp. Becomes an oscillator. The condition,

AB=1 is known as barkhausen critetion of oscillation.

As shown in the fig. of Hartley oscillator, two inductors L1 &L2 are placed across a capacitor C. Frequency is

determine by L1,L2 and C (tank circuit).

When the circuit is turned ON, the capacitor is charged. When this capacitor is fully charged it discharges

through coils L1 and L2.The output voltage of the ampere appears across L1 and feedback voltage across L2.

The voltage across L2 is 180 out of phase with the voltage developed across L1. It is easy to see that voltage

feedback to the transistor provides positive feedback. A phase shift of 180 is produced by the transistor and the

L1-L2 voltage divider produces further phase shift of 180, in this way feedback is continuous un-damped

oscillation.

PROCEDURE: 1. Assemble the circuit as shown in the fig.

2. Connect the CRO at the output terminals and observed the sine wave output.

3. Measure the output frequency on CRO.

OBSERVATION TABLE:

No. Inductor

(L)

Capacitor

(C1)

Capacitor

(C2)

Observed

frequency

Theoretical

frequency

1.

2.

3.


Subject:

BE

TO BUILD AND TEST HARTELY OSCILLATOR.

2

Experiment No.

10

.

DATE:

DOC. CODE

Circuit diagram:

CONCLUSION:


Subject:

BE

To understand working of transistor as a switch.

1

Experiment No.

11

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

AIM: To understand working of transistor as a switch.

Introduction: Transistor can be operated in three region: cut-off region, active region and saturation region. While

using transistor in amplifier circuit, we are using active region. If transistor operated in cut-off and

saturation region in amplifier, clipping of waveforms will occur. When we use transistor as a switch,

only two regions cut-off and saturation are used. In saturation region transistor acts as ON switch. In cut-

off region, transistor acts as OFF switch. We are using only two points of DC load line while using

transistor as a switch.

Circuit diagram:

Experiment Procedure to obtain input characteristics:

Connect circuit as shown in the circuit diagram for input characteristics

Adjust collector supply Vcc = +12V and base supply VBB=+5V

You may use base voltage supply switch instead of switch shown in the circuit diagram.

Measure base current when switch is OFF (It will be zero). Measure collector current and voltage

between collector and emitter. LED is off because transistor is in cut-off region,

Now apply base voltage +5V, LED will be ON. Measure collector current and collector-emitter

voltage. Transistor is in saturation region.


Subject:

BE

To understand working of transistor as a switch.

2

Experiment No.

11

DATE:

DOC. CODE

AITSDS/ECD/EXPT/

Observations:

[1] Switch off (VBB=0): Ib = _________ VCE = __________ Ic = ________

[2] Switch ON (VBB=+5V): Ib = _________ VCE = __________ Ic = ________

Conclusion:

Subject: AITSDS/ECD/EXPT

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