10esl37_analog electronics lab manual

Analog Electronics Laboratory Manual - 10ESL37

Ex.No:01 HALF WAVE, FULL WAVE AND BRIDGE RECTIFIER HALF WAVE RECTIFIER

AIM:

To study Half Wave Rectifier and to calculate ripple factor, efficiency and

regulation with filter and without filter.

COMPONENTS REQUIRED:

Sl. No. Components Details Specification Qty

1. Diodes BY127 1 No.

2. Capacitor 0.1µf, 470µf Each 1 No.

3. Power Resistance Board 1 No.

4. Step down Transformer 12 V 1 No.

5. CRO, Multimeter, Milliammeter, Connecting Board

THEORY:

Half wave rectifier circuit consists of resistive load, a diode and source of

ac voltage, all connected in series. In half wave rectifier, rectifying element

conducts only during positive half cycle of input ac supply. The negative half

cycles of ac supply are eliminated from the output. The dc output waveform is

expected to be a straight line but the half wave rectifier gives output in the form

of positive sinusoidal pulses. Thus the output is called pulsating dc.

CIRCUIT DIAGRAM:

HALF WAVE RECTIFIER WITHOUT FILTER CAPACITOR

14

C2

0.1UFBY127

A K

RL

AC(230V/50HZ)

12V

12V

0

Step downTransformer

A

Ammeter(0-250mA)

+ -

VODC VOAC


HALF WAVE RECTIFIER WITH FILTER CAPACITOR

DESIGN:

Given

Ripple = r = Vo rms / VO DC = 1.21Design for the filter capacitor

Ripple = 1/(43 f C RL)

Given r = 0.25 C = 1/(43 f r RL)

RL = 50

f = 50Hz

= 461.88F 470F Efficiency = PDC /PAC (I2

DC * RL) / [(Irms)2 * (RL + RF)]

Regulation % Regulation =

15

C2

0.1UFBY127

A K

RL

AC(230V/50HZ)

12V

12V

0


A

Ammeter(0-250mA)

+ -

470UF

+

-

C1

VODC VOAC


PROCEDURE:

1. Connections are made as shown in the circuit diagram

2. Switch on the AC power supply

3. Observe the wave form on CRO across the load resistor and measure the o/p amplitude and frequency.

4. Note down RL, IDC, VODC, VINAC, and VOAC in the tabular column for different load resistances.

5. Calculate the ripple and efficiency and Regulation for each load resistance.

6. Repeat the above procedure with filter capacitor.TABULAR COLUMN:

Sl. No.

RL IDC VO (DC)VIN

(AC)VO (AC) Ripple Efficiency

Regulation

WAVEFORMS:

20

t

0

- 20

0 Vo (Without Filter)

t

Vo (with filter)

t

16

VC

VIN

VO


FULL WAVE RECTIFIER

AIM:

To study the full wave rectifier and to calculate ripple factor and efficiency

and Regulation with filter and without filter.



1. Diodes BY127 2 Nos.





THEORY:

The center tapped full wave rectifier circuit is similar to a half wave

rectifier circuit, using two diodes and a center tapped transformer. Both the input

half cycles are converted into unidirectional pulsating DC.

CIRCUIT DIAGRAM:

FULL WAVE RECTIFIER WITHOUT FILTER CAPACITOR

17

Step down

C2

0.1UFBY127

A K

RL

AC(230V/50HZ)

12V

12V

0

Transformer

A

Ammeter(0-250mA)

+ -

VO(DC)

BY127

A K

VO (AC)


FULL WAVE RECTIFIER WITH FILTER CAPACITOR

DESIGN:

Vin rms = 12VVin m = 2Vin rms = 16.97V

VO DC = 2Vm/ = 10.8V

Given VO DC = 10V

IO DC = 100mA

RL = VO DC / IO DC = 100

Ripple = r = Vo rms / VO DC = 0.48Design for the filter capacitor


Given r = .06 C = 1/(43 f r RL)

RL = 100

f = 50Hz

= 470UF

Efficiency = PDC /PAC (I2DC * RL) / [(Irms)2 * (RL + RF)]


PROCEDURE:




4. Note down RL, IDC, VODC , Vinac, Voac in the tabular column for different load resistances.

18

(230V/50HZ)

C2

0.1UFBY127

A K

RL

AC

12V

12V

0


A

Ammeter(0-250mA)

+ -

470UF

+

-

C1

VO(DC)

BY127

A K

VO(AC)


5. Calculate the ripple and efficiency and regulation for each load resistance.

6. Repeat the above procedure with filter capacitor.

TABULAR COLUMN:

Sl. No.

RL IDC VO (DC)VIN


Regulation

WAVEFORMS:

t

0

-


t

Vo (with filter)

t

19

VC

VIN

VO


BRIDGE RECTIFIER

AIM:

To study the bridge rectifier and to calculate ripple factor and efficiency and

regulation with filter and without filter.



1. Diodes BY127 4 Nos.





THEORY:

The bridge rectifier circuit is essentially a full wave rectifier circuit, using

four diodes, forming the four arms of an electrical bridge. To one diagonal of the

bridge, the ac voltage is applied through a transformer and the rectified dc

voltage is taken from the other diagonal of the bridge. The main advantage of

this circuit is that it does not require a center tap on the secondary winding of

the transformer; ac voltage can be directly applied to the bridge.

The bridge rectifier circuit is mainly used as a power rectifier circuit for

converting ac power to dc power, and a rectifying system in rectifier type ac

meters, such as ac voltmeter in which the ac voltage under measurement is first

converted into dc and measured with conventional meter.

CIRCUIT DIAGRAM:

BRIDGE RECTIFIER WITHOUT FILTER CAPACITOR

20

RL

- +

BRIDGE

1

4

3

2

C2

0.1UF

AC(230V/50HZ)

12V

12V

0


Vo

A

Ammeter(0-250mA)

+ -


BRIDGE RECTIFIER WITH FILTER CAPACITOR

C1

470UF

RL

- +

BRIDGE

1

4

3

2

C2

0.1UF

AC(230V/50HZ)

12V

12V

0


Vo

A

Ammeter(0-250mA)

+ -

+ -

DESIGN:

Vin rms = 12VVin m = 2Vin rms = 16.97V

VO DC = 2Vm/ = 10.8V

Given VO DC = 10V

IO DC = 100mA

RL = VO DC / IO DC = 100

Ripple = r = Vo rms / VO DC = 0.48 Design for the filter capacitor


Given r = .06 C = 1/(43 f r RL)

RL = 100

f = 50Hz

= 470UF

Efficiency = PDC /PAC

= (I2DC * RL) / [(Irms)2 * (RL + RF)]


21


PROCEDURE:




4. Note down RL, IDC, VODC , Vinac, Voac in the tabular column for different load resistances.

5. Calculate the ripple factor, efficiency and regulation for each load resistance.

6. Repeat the above procedure with filter capacitor.TABULAR COLUMN:

Sl. No.

RL IDC VO (DC)VIN


Regulation

WAVEFORMS:

Vin

20

t

0

- 20

Vo


t

Vo (with filter)

VC

t

Ex.No:02 CLAMPING CIRCUITS

22


AIM:

Design a clamping circuit for the given output.



1. Diodes BY127 1 No

2. Capacitors 0.1 F 1 No

Signal generator, Cathode Ray Oscilloscope (CRO) with Probes, Dual Power Supply, Connecting Board

THEORY: A clamper is one, which provides a D.C shift to the input signal. The D.C

shift can be positive or negative. The clamper with positive D.C shift is called

positive clamper and clamper with negative shift is called negative clamper.

Consider a clamper circuit shown below.

In the positive half cycle as the diode is forward biased the capacitor charges to

the value with the polarity as shown in the figure. In the negative half

cycle the diode is reverse biased. Hence the output is .

Initially let us assume that the capacitor has charged to i.e.

(5 – 0.5) = 4.5V

Then in the positive half cycle diode is forward biased and applying KVL to

the loop,

Vin –VC –V0 = 0 V0 =Vin –VC

When Vin = 0 V0 = 0 - 4.5 = - 4.5V

Vin = 5V V0 = 5 – 4.5 = 0.5V

In the negative half cycle

When Vin = -5V V0 = -5 – 4.5 = -9.5V

The output shifts between 0.5V and – 9.5V.Here the output has shifted

down by 4.5V

The peak to peak voltage at the output of a clamper is the same as that of

the input.

CIRCUIT DIAGRAM AND DESIGN:

Given Vin = 10V (p-p)

A] In the positive half cycle:

23

D 1

B Y 1 2 7

0 . 1 u

+ -

VoVin

C


Diode is forward biased.

Applying KVL to loop 1

Vin – VC – VD = 0

VC = Vin – VD

= 5 - 0.5 4.5V

In the negative half cycle:

Vin – VC – V0 = 0

V0 = Vin – VC

When Vin = 0 V0 = - 4.5V

When Vin = 5V V0 = 0.5V

When Vin = -5V V0 = -9.5V

B]In the negative half cycle:

Diode is forward biased

Applying KVL to loop 1

Vin + VC + VD = 0

VC = - ( Vin + VD)

VC = - (-5 + 0.5)

= 4.5V

In the positive half cycle:

Diode is reverse biased.

Apply KVL to the loop

Vin + VC – V0 = 0

V0 = Vin + VC

When Vin = 0 V0 = 4.5V

When Vin = 5V V0 = 5 + 4.5 = 9.5V

When Vin = - 5V V0 = - 0.5V

C] Assume VR = 2V


Diode is forward biased.

Apply KVL to loop 1

Vin – VC – VD – VR = 0

VC = Vin – VD – VR

24

Vo

0.1u

D1 BY127

+ -

Vin

C

VR

D 1

B Y 1 2 7

0 . 1 u

+ -

VoVin

C

D 1BY1 2 7

0 .1 u

- +

VoVin

C


= 5 - 0.5 – 2

= 2.5V


Diode is reverse biased

Vin – VC – V0 = 0

V0 = Vin – VC

When Vin = 0V V0 = - 2.5V



D] Assume VR = 2V


Diode is forward biased and the capacitor charges.

Apply KVL to loop 1

Vin – VC – VD + VR = 0

VC = Vin – VD + VR

= 5 –0.5 +2

= 6.5V


Vin – VC – V0 = 0

V0 = Vin – VC



When Vin = -5V V0 = - 11.5V

25

VoD1 BY127

0.1u

C

Vin

-+

VR


E]In the negative half cycle:

Assume VR = 2V

Diode is forward biased and capacitor charges.

Apply KVL to the loop1

Vin + VC + VD + VR = 0

VC = - ( Vin + VR + VD)

= - (- 5 + 0.5 + 2)

= 2.5V

From the fig. we see that

Vin + VC – V0 = 0

V0 = Vin + VC

When Vin = 0 V0 = 2.5V



F] VR = 2V


Diode is forward biased and capacitor charges.

Apply KVL to loop 1

Vin + VC + VD - VR =0

VC = - ( Vin + VD - VR)

= - (- 5 + 0.5 – 2)

= 6.5V

From the circuit we see that,

Vin + VC - V0 =0

V0 = Vin – VC

When Vin =0V V0=6.5V

When Vin = 5V V0= 11.5V

When Vin = - 5V V0= 1.5V

PROCEDURE:

1. Rig up the circuit as shown in the circuit diagram.

2. Give a sinusoidal input of 10V peak to peak

3. Check and verify the output.

26

Vo

0.1u

D1BY127

VR

C

Vin

- +

Vo

0.1u

D1BY127C

Vin

+-

VR


WAVEFORMS:

Vin

5V

0 t - 5V

V0

0.5 0 t

[A] - 4.5

- 9.5

V0

9.5

4.5

[B] 0 t - 0.5

V0

2.5 0

[C] t - 2.5

- 7.5

27


V0

0 t

[D] - 1.5

- 6.5

- 11.5

V0

7.5

2.5

[E] 0 t

- 2.5

V0

11.5

6.5

[F]

1.5

0 t

28


Ex.No:03 CLIPPING CIRCUITS

AIM:

Design a clipping circuit for the given values.



1. Diodes BY127 1 No

2. Resistors 10 K 1 No

THEORY:

The process by which the shape of a signal is changed by passing the

signal through a network consisting of linear elements is called linear wave

shaping. Most commonly used wave shaping circuit is clipper. Clipping circuits

are those, which cut off the unwanted portion of the waveform or signal without

distorting the remaining part of the signal. There are two types of clippers

namely parallel and series. A series clipper is one in which the diode is

connected in series with the load and a parallel clipper is one in which the diode

is connected in parallel with the load.

CIRCUIT DIAGRAM AND DESIGN:

Assume Vin = 10V (Peak to Peak)

(a) Consider the circuit in fig. 1

In the positive half cycle D is forward biased

V0 = Vin – 0.5 = 5 – 0.5 = 4.5 (0.5V is the diode drop)

In the negative half cycle D is reverse biased

V0 = 0V

(b) Consider the circuit in fig. 2

In the positive half cycle D is reverse biased

V0 = 0V

In the negative half cycle D is forward biased

Applying KVL to the loop

Vin + VD – V0 = 0

V0 = Vin + VD = -5 + 0.5 = - 4.5V

29

10k

D 1

BY1 2 7Vin Vo

(a)

10k

D 1

BY1 2 7Vin Vo


(c) Consider the circuit in fig. 3

Given VR = 2.5V

In the positive half cycle

(i) When |Vin| > |VD + VR|, D is forward biased

Applying KVL, we get

Vin = VD + VR + V0

V0 = Vin – VD – VR

V0 = 5 – 0.5 – 2.5

V0 = 2V

(ii) When |Vin| < |VD + VR|, D is reverse biased

V0 = 0V

In the negative half cycle, D is reverse biased

V0 = 0V

(d) Consider the circuit in fig. 4

Assume VR = 3V

In the positive half cycle, D is reverse biased

V0 = 0V


(i) When |Vin| > |VD + VR|, D is forward biased


Vin = - VD - VR + V0

V0 = Vin + VD + VR

V0 = -5 + 0.5 + 3

V0 = -1.5V

(ii) When |Vin < |VD + VR|, D is reverse biased

V0 = 0V

30

D 1

BY1 2 710k

V R

Vin Vo

V R

10k

D 1

BY1 2 7Vin Vo


(e) Consider the circuit in fig. 5

Assume VR1 = 2.5V and VR2 = 3V

In the positive half cycle, D2 is reverse biased

(i) When |Vin| > |VD1 + VR1|, D1 is forward biased


Vin = VD1 + VR1 + V0

V0 = Vin - VD1 - VR1

V0 = 5 - 0.5 – 2.5

V0 = 2V

(ii) When |Vin < |VD1 + VR1|, D1 is reverse biased

V0 = 0V




Vin = - VD - VR + V0

V0 = Vin + VD2 + VR2

V0 = -5 + 0.5 + 3

V0 = -1.5V

(ii) When |Vin < |VD2 + VR2|, D2 is reverse biased

V0 = 0V

(f) Consider the circuit in fig. 6

During the positive half cycle, D is forward biased

V0 = VD = 0.5V

During negative half cycle, D is reverse biased

V0 = Vin

31

BY1 2 7 V R2

10kBY1 2 7 V R1 VoD 1Vin

1

2

D 2

10k

D 1

BY1 2 7

VoVin


(g) Consider the circuit in fig. 7

During positive half cycle,

D is reverse biased

V0 = Vin

During negative half cycle,

D is forward biased

V0 = -VD = -0.5V

(h) Consider the circuit in fig. 8

During positive half cycle

(i) When |Vin| > |VD + VR|,

D is forward biased

V0 = VD + VR = 0.5 + 2.5

V0 = 3V

(ii) When |Vin| < |VD + VR|, D is reverse biased

V0 = Vin


V0 = Vin

(i)Consider the circuit in fig. 9

Assume VR = 2.5V

During positive half cycle,

D is reverse biased

V0 = Vin

During negative half cycle

(i) When |Vin| > |VD + VR|,

D is forward biased

Applying KVL to the loop, we get

V0 = -VD - VR = - 0.5 - 2.5

V0 = -3V

(ii) When |Vin| < |VD + VR|,

D is reverse biased

V0 = Vin


V0 = Vin

32

10k

D 1BY1 2 7

V R

Vin Vo

10k

D 1BY1 2 7Vin Vo

10k

D 1BY1 2 7

V R

Vin Vo

+

-


(j) Consider the circuit in fig. 10

Assume VR1 = VR2 = 2.5V

During positive half cycle, D2 is reverse biased.


V0 = VD1 + VR1 = 0.5 + 2.5

V0 = 3V

(ii) When |Vin| < |VD1 + VR1|,

D1 is reverse biased

V0 = Vin



(i)When |Vin| > |VD2 + VR2|, D2 is forward biased

Applying KVL to the loop, we get

V0 = -VD2 - VR2 = -0.5 - 2.5

V0 = -3V

(ii) When |Vin| < |VD2 + VR2|, D2 is reverse biased

V0 = Vin

(k) Consider the circuit in fig. 11

Assume VR1 = 3.5V and VR2 = 2V

During positive half cycle

(i) When |Vin| > |VD1 + VR1|

D1 is forward biased and


V0 = VD1 + VR1 = 0.5 + 3.5 = 4 V

(ii) When |Vin| < |VR2 – VD2|

D1 is reverse biased and

D2 is forward biased

V0 = -VD2 + VR2 = - 0.5 + 2 1.5V


D1 is reverse biased and D2 is forward biased

V0 = -VD2 + VR2 = - 0.5 + 2 V0 = 1.5VPROCEDURE:

1. Rig up the circuit as shown in the fig.2. Give a sinusoidal input of 10V peak to peak.3. Check the output at the output terminal.4. To plot the transfer characteristics, connect channel 1 of the CRO to

the output and channel 2 to the input and press the XY knob5. Adjust the grounds of both the channels to the centre.6. Measure the designed values.

33

D 1BY1 2 7

V R1 V R2

10k

BY1 2 7Vin

D 2

Vo

1

Vo

Vin

10k

D1

BY127

VR1

BY127

D2

VR2

Vo


WAVEFORMS:

Series Clipper

Vin

5

3

0 t

- 3.5

- 5

Vo

4.5

(a) 0 t

Vo(b)

0 t

- 4.5

2.0(c)

0 t

(d) 0 t

-1.5

2

(e) 0 t

-1.5

34

Vin

Vo

Vin

Vo

Vin

Vo

3

Vin

Vo

-3.5

Vin

Vo

-3.5

3


Shunt ClipperVin

+5

0 t

+5

(f) 0.5 t

0.5

-5

4.5

(g) 0 t 0.5

VO

3

(h) t

-5

+5

(i) 0 t

-3

+3

(j) 0 t

-3

+4

1.5

( k ) 0 t

35

Vin

Vo

Vin

Vo

Vin

Vo

-3.0

Vin

Vo

3.0

Vin

Vo

Vin

Vo

3.0


Ex.No:04 RC COUPLED AMPLIFIER - BJT

AIM:

Design an RC coupled single stage BJT amplifier and determine its gain

and frequency response, input and output impedances.



1. Transistor SL100 1 No

2. Capacitors 0.1 f , 47µf Each 1 No

3. Resistors 22K, 4.7K, 1.2K, 330 Each 1 No

DC Supply, Signal Generator, CRO with Probe

CIRCUIT DIAGRAM:

To Find Input Impedance

To Find the Output Impedance

DESIGN:

36

DRB

RCCOUPLED

AMPLIFIERI/P VOUT

DRB

RCCOUPLED

AMPLIFIERI/P VOUT

00

R2

SL100

CB

CcR1

Vcc = 12 v

CE

RE

~Vs

B

Vo

Rc

22K

4.7K

1.2 K

330

47 f

0.1 f

0.1 f


Given VCC = 12V, IC = 4mA, = 100.

RE: W.K.T. VRE = VCC / 10 = 12 / 10 = 1.2V ------for biasing

IE IC = 4 mA

From the fig. We see that,

IERE = VRE

RE = 1.2 / (4 x 10-3 ) = 300

Therefore RE 330

RC: VCE = VCC / 2 = 6V ----- for Q point to be in active region.

Applying KVL to output loop

VCC –ICRC-VCE -VRE = 0

12 – 4 x 10-3 RC – 6 -1.2 = 0

Therefore RC = 1.2k

R1 & R2: From biasing circuit

VB = VBE+ VRE

= 0.7 + 1.2

VB = 1.9V

Assume 10 IB flows through R1 and 9 IB flows through R2.

W.K.T. IC = IB

4 x 10-3 = 100 IB

Therefore IB = 40 A

From the fig. we see that,

R1 = VCC – VB / 10 IB = 12 – 1.9 / (10 x 40 x 10-6 ) = 25.25k

Therefore R1 22k

R2 = VB / 9IB = 1.9 / ( 9 x 40 x 10-6 ) = 5.28k

Therefore R2 4.7k

CE, CC, CB : Let CB = CC = 0.1F

XCE = RE/10

Therefore f = 10 / (2 CE RE)

Let f = 100Hz and W.K.T RE = 330

Therefore CE = 10 / 2 f.RE = 48F

Therefore CE 47F.

37


PROCEDURE:

1) To find Q point:

Connect the circuit without Vs and capacitors. Set Vcc= 12V. Measure dc

voltages at the base VB, collector Vc and VE with respect to ground

Determine VCE = VC – VE = --------- V

IC = (VCC-VC)/RC = -------- mA

Q point is Q(VCE,IC)

To check biasing conditions:

With VCC=12V; VCE should be VCC/2 = 6V

VRE should be VCC/10 = 1.2V

VBE = 0.6V

2) Connect the circuit of Fig(1)

3) Feed a sine wave of peak to peak amplitude about 40Mv from signal

generator.

4) Vary the input sine wave frequency from 10Hz to 1MHz in steps and

measure the output voltage VO of the amplifier. Input voltage Vi should

remain constant throughout the frequency range.

5) Tabulate the results.

6) Plot the graph of frequency f versus Gain in dB and determine the GBW

product

Procedure to measure input impedance Zi:

1) Connect the circuit of Fig(2).

2) Set the following:

DRB to zero.

Input sine wave amplitude of 40Mv

Input sine wave frequency to any mid band frequency.

3) Measure Vop-p.

4) Increase DRB till VO = Vop-p/2. The corresponding DRB value gives the

input impedance Zi.

Procedure to measure output impedance:

1) Connect as in Fig(3).

2) Set the following:

DRB to maximum value.

Input sine wave amplitude to 40mv.

Input sine wave frequency to any mid band frequency

3) Measure Vop-p.

38


4) Decrease DRB till Vo = Vop-p/2. The corresponding DRB value gives the

output impedance Zo.

WAVEFORM:

Vin

0 t

V0

0 t

OBSERVATION

Vi = ---------------- mV

Freq.

(Hz)

Output

VoltageAV = V0 / Vi AV (dB) = 20log AV

100

.

.

.

1 M

39


FREQUENCY RESPONSE CURVE ( in Semilog )

AV (db)

3db

f1 f2 f

Bandwidth = f2 – f1

40


Ex.No:04 RC COUPLED AMPLIFIER – FET

AIM:

Design an RC coupled single stage FET amplifier and determine its gain

and frequency response, input and output impedances.



1. FET BFW10 1 No

2. Capacitors 0.37 f 2 Nos.

100 µf 1 No

3. Resistors 2.2 M, 1 K, 330, 10 K Each 1 No


CIRCUIT DIAGRAM:

To Determine Input Impedance:

47k

Vin Vout

To Determine Output Impedance:

Vin Vout

DESIGN:

41

VOLTAGE SERIES FEEDBACK AMPLIFIER WITH / WITHOUT FEEDBACK

~


~DRB

0

C1=0.37µf

RD =1 K

BFW10D

GS

RS

330

C2=0.3µf

CS

100µfVINi

RL

10 K

VDD = 12V

RG

2.2M

Vo


Given VDD = 12V, IDss = 10 mA, VGS = - 2V, VP = -6 V

For proper biasing: VDD=12 V; VDS = 6 V;

VRS = VDD/10 = 1.2V

VGS = - 0.7 to -2V

To find RD :

Applying KVL to the output loop of the circuit

VDD = VDS + IDRD + VRS

12 = RD (5 x 10-3 ) + 6 + 1.2

RD = 960 1 k

ID = IDSS (1-VGS/ VP)2

= 10x10-3 (1- 2/6)2

= 4.4 mA 5mA

To find RS :

VRS = ISRS

RS = VRS/IS = 1.2 / 5x10 -3 240 270

Assume RS = 2 M

To find CS :

XS = 0.1 Rs = 27

XS = 1/2fCS

Let f = 50 Hz Therefore CS = 100µf

Let C1 = C2 = C

XD = 10 RD = 10K

XD = 1/2fC therefore C = 0.318µf

TABULAR COLUMN:

Vin = mV

Frequency (Hz)

V0 (V) AV AV (dB)

10

20

.

.

.

.

.

1M


42


AV (db)

3db

f1 f2 f

Bandwidth = f2 – f1

WAVEFORM:

Vin

0 t

V0

0 t

Ex.No:05 HARTLEY OSCILLATOR / COLPITT’S OSCILLATOR

AIM:

Design of Hartley/Colpitts oscillator for a given Radio frequency of f0

=100 KHz using BJT.

43





2. Capacitors0.1 f, 1000 pf 2 No

47µf, 0.0023 µf Each 1 No

3. Resistors 22K, 4.7K, 1.2K, 3301 K Pot

Each 1 No

4. Inductors 100 µH, 1mH, 5mH Each 1 No

DC Supply, CRO with Probe

THEORY :

Oscillators are devices, which generate oscillations. The frequency of

oscillations depends on the feedback network. Feedback may be of two types

namely positive and negative. In positive feedback, the feedback signal is

applied in phase with the input signal thus increasing it. In negative feedback,

the feedback signal is applied out of phase with the input thus reducing it. The

feedback used in oscillators is positive feedback. The oscillators work on the

principle of Barkhausen criteria. This states that for sustained oscillations

i) Loop gain Av must be equal to 1.

ii) The phase shift around the loop must be 0 deg of 360 deg.

Here Av is the gain of the amplifier and is the attenuation of the feedback

network. Consider the feedback network shown in the fig (1) below. Assume an

amplifier with input signal Vin. The output signal VO will be 180 deg out of phase

with Vin. So to get an in phase output, the feedback network provides 180-deg

phase shift. Therefore the output Vf from the feedback network can be made in

phase and equal in amplitude to Vin and Vin can be removed. Even then the

oscillations continue. Practical oscillations do not need any input signal to start

oscillations. They are self-starting due to thermally produced noise in resistors

and other components. Only one frequency (fo) of noise satisfies, Barkhausen

criteria and the circuit oscillates with that frequency. The magnitude of fo keeps

on increasing each time it goes around the loop. The amplification of fo is limited

by circuit’s own non-linearities. Therefore to start oscillations Av > 1 and to

sustain it, the loop gain Av = 1.

Fig 1.

44

B

AvVin

Vf

Vo

Amplifier


The feedback network used here consists of L and C. Consider the circuit

shown below fig 2. This circuit consists of L and C in parallel. The capacitor stores

energy in its electric field whenever there is voltage across it and the inductor

stores energy in its magnetic field whenever there is current through it. Initially

let us assume that the capacitor has charged to V volts. When S is closed c= 0.

When S is closed at t = t0 , capacitor starts charging through the inductor. Thus a

voltage gets built up across the inductor due to the change in current through it.

If the capacitor was changed with the polarity as shown in the fig 2 the current

starts flowing from the positive plate of the capacitor to the negativ4 plate of the

capacitor. As shown the voltage across the capacitor reduces during the

discharge time v reduces and I increases. At time t1 v will be 0 and I will be

maximum as c is fully discharged, the capacitor charges like sinusoidal

oscillations. Thus the circuit oscillates with the frequency

fo = 1/ 2LC

The Hartley oscillator consists of two inductors and a capacitor and Colpitts oscillator consists of two capacitors and an inductor.

The resonant frequency fo for Hartley oscillator is

fo =1/ 2 LeqC ------where Leq = L1 + L2.

The resonant frequency fo for Colpitts oscillator is

fo = 1/ 2LCeq ------where Ceq = C1C2/(C1 + C2)

45

L C

i

+-

S t = to

vFig.2


CIRCUIT DIAGRAM:

HARTLEY OSCILLATOR:

COLPITTS OSCILLATOR:

46

47 f

C = 0.0023 µf

GND

L1 = 100 µH L2 = 1mH

R2 CERE

3.9K470

BC109CB

CcR1

Vcc = 9 v

Rc

18K

1.8 K

0.1 f

0.1 f

VO

Variable1 K Pot

47 f

R2 CERE

3.9K470

BC109CB

CcR1

Vcc = 9 v

Rc

18K

1.8 K

0.1 f

0.1 f

VO

Variable1 K Pot

L = 5mH

GND

C2 = 1000pf C1 = 1000pf


DESIGN:

Given VCC = 9V, IC = 2mA, = 50


IE IC = 2 mA


IERE = VRE

RE = 0.9 / (2 x 10-3 ) = 450

Therefore RE 470

RC: VCE = VCC / 2 = 4.5V ----- for Q point to be in active region.



9 – 2 x 10-3 RC – 4.5 -0.9 = 0

Therefore RC = 1.8k


VB = VBE+ VRE

= 0.7 + 0.9

VB = 1.6V


W.K.T. IC = IB

2 x 10-3 = 50 IB

Therefore IB = 40 A

47



R1 = VCC – VB / 10 IB = 9 – 1.6 / (10 x 40 x 10-6 ) = 18.5k

Therefore R1 18k

R2 = VB / 9IB = 1.6 / ( 9 x 40 x 10-6 ) = 4.44k

Therefore R2 3.9k


XCE = RE/10




Therefore CE 47F.

48


HARTLEY OSCILLATOR:

Attenuation = Vf/Vo = IXL1/IX L2 = XL1 / X L2 = 2 foL1/2foL2 = L1/L2

For sustained oscillations Av = 1 -------- Av = 1/ = L2/L1

For oscillations to start Av > 1 -----------Av > L2/L1

COLPITTS OSCILLATOR:

Attenuation = Vf / Vo = IXC1/IXC2 = XC1/ XC2 = (1/ 2foC1)/(1/2foC2) = C1/C2

For sustained oscillations Av = 1 ---------- Av = C1/C2

For oscillations to start Av > 1----------Av > C1/C2

DESIGN OF TANK CIRCUIT

Assume = fo = 100 KHz

HARTLEY OSCILLATOR

fo = 1/ (2 LeqC) ------where Leq = L1 + L2.

Assume L1 = 100 µH, L2 =1mH LEQ = fO =1/ (2 2*10-3 C) C = 0.0023 µf (Decade capacitance box)

COLPITTS OSCILLATOR

fO = 1/ (2LCeq ) ------where Ceq = (C1C2)/(C1 + C2)

Assume C1 = C2 = 1000 pF

Ceq =

fO = 1/ 2L * .05*10 - 6

L = 5 mH (Use decade inductance box)

49


PROCEDURE:

1. Rig up the circuit as shown in the circuit diagram.

2. Before connecting the feedback network, check the circuit for biasing conditions i.e. check VCE, and VRE.

3. After connecting the feedback network. Check the output.

4. Check for the sinusoidal waveform at output. Note down the frequency of the output waveform and check for any deviation from the designed value of the frequency.

5. To get a sinusoidal waveform adjust 1K potentiometer.

6. DCB/DIB can be varied to vary the frequency of the output waveform.

TABULAR COLUMN

HARTLEY OSCILLATOR COLPITTS OSCILLATOR

SL NO C fo SL NO L fo

WAVEFORM:

Vo

0

t

T

frequency fo = 1/T

50


Ex.No:06 CRYSTAL OSCILLATOR

AIM:

To design a crystal oscillator to oscillate at the specified crystal frequency.




2. Capacitors0.1 f 2 No

47µf 1 No


Each 1 No

4. Crystal 2 MHz or 1.8 MHz 1 No


CIRCUIT DIAGRAM:

51

2 MHz

1.8 MHz

47 f

R2 CERE

3.9K470

BC109CB

CcR1

Vcc = 9 v

Rc

18K

1.8 K

0.1 f

0.1 f

VO

Variable1 K Pot


DESIGN:Given VCC = 9V, IC = 2mA, = 50


IE IC = 2 mA


IERE = VRE

RE = 0.9 / (2 x 10-3 ) = 450

Therefore RE 470

RC: VCE = VCC / 2 = 4.5V ----- for Q point to be in active region.



9 – 2 x 10-3 RC – 4.5 -0.9 = 0

Therefore RC = 1.8k


VB = VBE+ VRE

= 0.7 + 0.9

VB = 1.6V


W.K.T. IC = IB

2 x 10-3 = 50 IB

Therefore IB = 40 A


R1 = VCC – VB / 10 IB = 9 – 1.6 / (10 x 40 x 10-6 ) = 18.5k

Therefore R1 18k

R2 = VB / 9IB = 1.6 / ( 9 x 40 x 10-6 ) = 4.44k

Therefore R2 3.9k


XCE = RE/10




Therefore CE 47F.

52


PROCEDURE:1. Rig up the circuit as shown in the circuit diagram.

2. Before connecting the feedback network, check the circuit for biasing conditions i.e. check VCE, and VRE.

3. After connecting the feedback network. Check the output.

4. Check for the sinusoidal waveform at output. Note down the frequency of the output waveform and check for any deviation from the designed value of the frequency.

5. To get a sinusoidal waveform adjust 1K potentiometer.

WAVEFORM:

Vo

0

t

T

frequency fo = 1/T

53


Ex.No:07 RC PHASE SHIFT OSCILLATOR

AIM:

Design a circuit, which generates repetitive waveform (Sinusoidal signal)

of frequency 7 KHz.




2. Capacitors 0.001 f 3 NoS.

0.1 f 2 Nos.

47µf 1 No


Each 1 No

6.8K 3 Nos.


THEORY:

RC Phase shift oscillator consists of a single transistor amplifier and a

RCphase shift network. The Phase shift network consists of three RC sections.

Here a fraction of the output of the amplifier is passed through a phase shift

network before feeding back to the input. The phase shift in each section is 600

so that the total phase shift is 1800.Another 1800 phase shift is provided by the

transistor amplifier and therefore the total phase shift of the oscillator is 360 0

.The frequency of oscillations is given by

fo = 1 / [26(RC)]

Let us consider a RC circuit..

Let I be the current flowing through both R and C. Then using I as the

reference vector,Vo is in phase with I while Vc ,the voltage across the capacitor

is 900 behind as shown in the figure.

Vi is the sum of Vo and Vc.Hence Vc is degrees ahead of Vi and represents a

phase shift of degrees

Vo = IR, Vc =IXc

Tan =Vc/Vo =Ixc/IR = Xc/R = 1/(2fCR)

Therefore f = 1/(2fCR Tan )

If there are 3 sections each must give approximately 600

i.e. = 600 Tan =3 =1.73

f= 1/(2CR3)

54


The above phase discussion ignored the additional current I that flows

through C for other sections, so that Vc is actually larger than the value

indicated,which means f is smaller.

More accurately f = 1/26(RC)

CIRCUIT DIAGRAM:

DESIGN:

Given VCC = 12V, IC = 4mA, = 100.


IE IC = 4 mA


IERE = VRE

RE = 1.2 / (4 x 10-3 ) = 300

Therefore RE 330




12 – 4 x 10-3 RC – 6 -1.2 = 0

Therefore RC = 1.2k


VB = VBE+ VRE

= 0.7 + 1.2

55

Q11

23

R 4700.1u

1k

VCC(12V)

A B C

R1=22K

R2=4.7 K

RC=1.2K

RE=330 CE=47µf

Cc

CC=0.1µf

SL100 0.02µf

C

0.02µf

C

0.02µf

C

R 470 R 470

D


VB = 1.9V


W.K.T. IC = IB

4 x 10-3 = 100 IB

Therefore IB = 40 A


R1 = VCC – VB / 10 IB = 12 – 1.9 / (10 x 40 x 10-6 ) = 25.25k

Therefore R1 22k

R2 = VB / 9IB = 1.9 / ( 9 x 40 x 10-6 ) = 5.28k

Therefore R2 4.7k


XCE = RE/10




Therefore CE 47F.

DESIGN OF TANK CIRCUIT:

We know that f=1/(2 RC6)

Given fO = 7 KHz

Assume C = 0.02 F

R = 1/(2 x 0.02 x 10-6 x 7 x 10+3 x 6) =527 470

PROCEDURE:

1. Make the connections as shown in the circuit diagram.

2. Check the circuit for biasing.

3. Adjust the 1k potentiometer to get sinusoidal waveform at the output.

4. To measure the phase shift

Method 1:

Connect the channel 1 of the CRO to point D and channel 2 to point A.

We will get two sine waves with a phase difference

Measure the difference by converting the time into angle.

Method 2:

a] Connect channel 1 to point D and channel 2 to point A.

Press the XY knob and measure the phase shift.

56


=Sin-1 (a/b) (approx.=600)

b] Connect channel 2 to point B the graph is as shown

= Sin-1(a/b)

Phase angle =1800- (approx. = 1200)

C] Connect channel 2 to point C

The transfer function will be almost a straight line and =00 and

therefore phase angle =1800 - 00 = 1800

WAVEFORM:

0 t

f = 1 / T

57

b

a

b

a


Ex.No:08 VOLTAGE SERIES FEEDBACK AMPLIFIER USING BJT

AIM:

To design and test a two stage voltage series feedback amplifier using BJT

and to determine gain, frequency response, input and output impedance with

and without feedback.



1. Transistor SL100 2 Nos.

2. Capacitors 0.47 f 3 Nos

10µf 2 Nos

3. Resistors 12K, 2.7K, 2.2K, 560 Each 2 No

4.7 K, 100 Each 1 No

4. Variable Resistor 1K Pot 1 No.


THEORY:

The high gain amplifier is widely used in analog circuit design and will

serve as the step to the next higher level of complex analog systems. The

philosophy behind the high gain amplifier is based on the concept of feedback. In

analog circuits we must be able to precisely define transfer function. A familiar

representation of this concept is illustrated in the block diagram below:

xs + xi A x0

_

xf

Here x voltage or current

A High Gain Amplifier

Feedback Network

xs Input signal (source)

xi Input signal to amplifier

xf Feedback signal

58


The overall gain of the amplifier with feedback is given by

Af = x0 / xs = A / (1 + A)

The high gain amplifier is defined by

A = x0 / xi

The gains defined above may be current gain or voltage gain.

In the circuit shown below, the feedback signal is the voltage V f across R1

and the sampled signal is the output voltage V0 across R. It is called voltage

series feedback amplifier because a part of the output voltage is fed back in

series with the input.

CIRCUIT DIAGRAM:

WITHOUT FEEDBACK

WITH FEEDBACK

59

10 K

10 fR2

SL100

CcR1

CE

RE

B

Vo

Rc12K

2.7K

2.2 K

560

0.47 f

R2

SL100

CcR1

CB

Vcc = 12 v

CE

RE

Rc12K

2.7K

2.2 K

560

0.47 f0.47 f

Vcc = 12 v

10 f

~Vs

10 fR2

SL100

CcR1

CE

RE

B

Vo

Rc12K

2.7K

2.2 K

560

0.47 f

R2

SL100

CB

CcR1

CERE

Rc

12K

2.7K

2.2 K

560

0.47 f

0.47 f

100 RF

R

~Vs


To Determine Input Impedance

47k

Vin Vout

To Determine Output Impedance

Vin Vout

DESIGN:

Given VCC = 12V, IC = 2mA, = 25.


IE IC = 2 mA


IERE = VRE

RE = 1.2 / (2 x 10-3 )

RE 560




12 – 2 x 10-3 RC – 6 -1.2 = 0

Therefore RC = 2.2k


VB = VBE+ VRE

= 0.7 + 1.2

VB = 1.9V


W.K.T. IC = IB

2 x 10-3 = 100 IB

Therefore IB = 20 A

60


~


~DRB



R1 = VCC – VB / 10 IB = 12 – 1.9 / (10 x 20 x 10-6 )

Therefore R1 12k

R2 = VB / 9IB = 1.9 / ( 9 x 20 x 10-6 )

R2 2.7k


XCE = RE/10



Therefore CE = 10 / 2 f.RE = 10f

Therefore CE 10f.

DESIGN FEED BACK CIRCUIT

Let β = 0.02

β = Rf/ Rf + R

Rf = β R / 1 – β

Let R = 4.7 K

Therefore Rf = 100

PROCEDURE:

1. Rig the circuit as shown in the fig.

2. Check the circuit for biasing i.e. check VDD, VDS and VRS.

3. Give a sinusoidal input of 10kHz from signal generator. Adjust the

amplitude of this sine wave such that the output doesn’t get clipped.

4. Observe the output waveform on the CRO.

5. Measure the output voltage using AC milli voltmeter.

6. Measure the output voltage for different frequencies of the input and

tabulate the readings as shown in the tabular column.

7. Plot the graph of gain vs frequency on a semilog graph sheet as shown

in the fig.

8. To measure input impedance connect a resistor of 47k in series with

the signal generator.

9. Measure the voltage at the input point (VS) and at the point after the

resistor (Vin).

10.Current through the resistor is given by the expression

I = ( VS – Vin ) / 47k

11.Input impedance is given by Zin = Vin / 47k

61


12.To measure output impedance connect a DRB in parallel with the

output.

13.Adjust all the knobs of the DRB to maximum.

14.Start reducing the resistance in the DRB from a large value until the

output reduces to half.

15.The resistance in the DRB is the output impedance.

TABULAR COLUMN:

Without FeedbackVin = constant

Frequency (Hz)

V0 (V) AV AV (dB)

10

20

.

.

.

.

.

1M

With FeedbackVin = constant

Frequency (Hz)

V0 (V) AV AV (dB)

10

20

.

.

.

.

.

.

1M

62


EXPECTED GRAPH:

AV

Without feedback

With feedback

0 f

WAVEFORM:

Vin

0 t

V0

0 t

63


Ex.No:09THEVININ’S THEOREM AND

MAXIMUM POWER TRANSFER THEOREM

AIM: To State and verify the thevenin’s theorem for the given circuit. COMPONENTS REQUIRED:


1. Resistors 1 K 4 Nos.

DC Supply, Multimeter, Ammeter (0-10)mA

THEORY:

Any Linear, bilateral network containing energy sources and impedances

can be replaced with equivalent circuit consisting of a voltage source in series

with an impedance.

The Value of voltage source is open circuit voltage between terminals of a

network and value of impedance is the impedance measured between the two

terminal of a network with all energy sources eliminated.

Circuit diagram:

RL

+

R31 k

R11k R2

-

B

1k

FIG 1

A

5v 1k

R1

Vo

1k R2

A

A

0-10mA

IL

FIG 2

1k

B

+

1 k

1k

-5v

-

R3 + RL

64

Vo-

+

-

FIG 3

+

-

0-10mA

I

-

A

+

B

R11k R2

5v

A+

1k

1k

R3


Procedure:

1. Connection are made as shown in the fig(2).

2. Supply voltage is adjusted to 5v and the ammeter reading IL is noted down.

3. Open circuit the terminal A & B , Voltmeter reading Vo is measure which is the thevenin’s voltage. Vo=VTH= ___________Volts .

4. To find the Thevenin’s impedance, connections are made as shown in the fig (3)

5. The reading of voltmeter V and ammeter I are noted . the thevenin’s Impedance

ZTH=V/I W

ZTH=_____________ W

6. Thevenin’s equivalent circuit connection are made as shown in the fig (4)

7. The supply voltage is set to Vth as measured above.

8. The ammeter reading Ith is noted.

If Ith=IL, Thevenin’s theorem is verified.

65

0-10mA

RL

1kVTH

ZTHA

+

Ith

_


(2) MAXIMUM POWER TRANSFER THEOREM:

Aim: (i) To state and verify maximum power transfer theorem.

(ii) To determine maximum power and the value of RL for Maximum power

transfer.



1. Resistors 1 K 1 No.

DC Supply, DRB, Multimeter, Ammeter (0-10)mA

Circuit diagram:

I10v

Rs0-10mA

-A

_

-+

1k

VR l

1 0 k p o t

+

Circuit for measuring source resistance:

Rs

A

1k

-0-10mA

Is

+

_-

Vs+

+

10v

66


Procedure:1. Connection are made as shown in the fig(i).

2. Supply voltage V is set to 10V, the potentiometer RL is kept at maximum.

3. The readings of voltmeter (V) and ammeter (I) are noted down in the table.

4. RL is decreased in steps and at each steps readings of V and I are tabulated in the table.

5. A graph of RL versus power is plotted, the maximum power Pmax and value of RL for maximum power transfer are noted from graph PMAX

=_______W, RL = .

6. To measure source resistance the connection are made as shown in the fig (2)

7. Supply is set to 10V, the ammeter reading I and voltmeter reading are noted down.

The source resistance RS=V/I =__________

If RS = RL, MPT Theorem is verified

V (volts) I mAmps P = VI in W RL= V/I

67

RL, RL, for PMAX

PMAX

Power , Watts


Ex.No: 10 SERIES AND PARALLEL RESONANCE SERIES RESONANCE CIRCUIT

Aim : To obtain the frequency response of an RLC series circuit and hence to determine

a) Resonance frequency fob) Band width ,Upper and Lower half power frequency c) Q-factor.



1. Resistors 100 1 No.

2. Capacitor 0.22µf 1 No.

3. Inductor 1 mH 1 No.

Signal generator, Multimeter

Circuit diagram:

DESIGN:

fo = 1/2LC Let L = 1mHC = 1/42Lfo2

C = 0.22μfR = 100Find fo

Procedure:1. Connections are made as shown in the circuit diagram.2. AC Supply is switched on. oscillator output voltage is adjusted to about

maximum i.e 10V P-P3. The frequency is gradually varied from zero hertz and for different value

of “ f”, voltage is noted down. The results are tabulated in the tabular column.

4. Frequency response i.e a graph of frequency versus voltage is drawn.

68

L

C

R VO


5. From the graph , resonant frequency “fo” is noted down at which voltage is maximum(Vo).

6. Lower half power frequency “f1” and upper half power frequency “f2” are noted corresponding to a voltage of Vo/ 2

Band width=f2-f1=_____________ hertz

7. The Q-factor =fo/f2-f1

Tabular column

69

f in hz V in VOLTS



70

0

BW

f1 f0 f2 f, Hz

VO

VOmax

VOmax/2


PARALLEL RESONANCE CIRCUIT:

Aim : To obtain the frequency response of an RLC series circuit and hence to determine

a) Resonance frequency fob) Band width ,upper and lower half power frequencyc) Q-factor.



1. Resistors 100 1 No.

2. Capacitor 0.22µf 1 No.

3. Inductor 1 mH 1 No.

Signal generator, Multimeter

Circuit diagram:

Frequency response

Vo

Vomin x 2

Vomin

71

f1 fO f2 fin Hz

BW

0

L C

R VO


Procedure:1. Connections are made as shown in the circuit diagram.2. AC Supply is switched on. oscillator output voltage is adjusted to about

maximum i.e 10V P-P3. The frequency is gradually varied from zero hertz and for different value

of “ f”, voltage is noted down. The results are tabulated in the tabular column.

4. Frequency response i.e a graph of frequency versus voltage is drawn.5. From the graph , resonant frequency “fo” is noted down at which voltage

is minimum (Vo).6. Lower half power frequency “f1” and upper half power frequency “f2” are

noted corresponding to a voltage of VOmin x 2.a. Band width = f2 - f1=_____________ Hz

7. The Q-factor =fo/f2-f1

72


Ex.No: 11 DARLINGTON EMITTER FOLLOWER

AIM:

To design and test a Darlington emitter follower circuit with and without

boot strapping and determine the gain, input and output impedance for both the

circuits.



1. Transistor SL100 2 Nos.

2. Capacitors10 f 1 No

0.47µf 2 Nos.

3. Resistors 1 M, 2.2 M, 1.5 K, 10 K, 47K Each 1 No

DC Supply, CRO with Probe, Signal generator, AC millivoltmeter

THEORY:

Normally transistors are used as amplifiers. But there are some

applications in which, matching of impedance is required between two circuits

without any gain or attenuation. In such applications emitter followers are used.

Emitter followers have large input impedance and small output impedance.

Darlington emitter follower has two transistors connected in cascade such that

the emitter of first transistor is connected to the base of second transistor. The

voltage gain of the darlington emitter follower is close to unity. The major

drawback of this circuit is that the second transistor amplifies leakage current of

the first transistor and overall leakage current becomes high. The output is

observed at the emitter terminal of the second transistor. Hence it is called an

emitter follower.

73


CIRCUIT DIAGRAM:

Darlington emitter follower without bootstrapping

Darlington emitter follower with bootstrapping

DESIGN:

Given IC = 4mA, VCC = 12V, VBE = 0.6V, 1 = 2 = 100

To find RE:

Applying KVL to the output loop of the second transistor, we get

VCC = VCE + VRE

Therefore VRE = VCC – VCE = 12 – 6

Therefore VRE = 6V

W.K.T RE = VRE / IE2

Here IE2 = IC2

Therefore RE = 6 / 4 x 10-3

RE = 1.5k

74

QSL100

RE

SL100

Vin

Vcc = 12V

Q1

Vo

R1

Cb = 0.47µf

1 M

R2

2.2 M

1.5 K

CE = 0.47µf

CE = 0.47µf

R3


To find R1 & R2:

From the circuit we have

VA = VBE1 + VBE2 + VRE

= 0.6 + 0.6 + 6 = 7.2V

W.K.T. IC = IB

Therefore IB = (4 x 10-3)/ 100 = 40 A

Let 10IB be the current through R1 and 9IB be the current through R2.

From the fig. we see that

R1 = (VCC – VA) / 10IB

Therefore R1 = 12K

From the fig. R2 = VA / 9IB

Therefore R2 = 20 K 22K

W.K.T. CC = 10 / XRE = 10 / ( 2..f.RE)

Assume f = 50Hz

Therefore CC = 21.2F 47 F

W.K.T. Cb = 10 / XRB = 10 / ( 2..f.RB ) where RB = R1 || R2 = 7.5k

Therefore Cb = 4.2F 4.7F

Chose R3 = 10 K, CB = 10µf for bootstrapping

PROCEDURE:

1. Rig up the circuit as shown in the fig.

2. Check the circuit for biasing, i.e. check VCE, VCC and VRE.

3. Give a sinusoidal input signal of 1KHz from a signal generator.

4. Set the input signal to a value such that the output doesn’t get clipped.

5. For different frequencies of the input signal, read the output on the voltmeter and verify that the gain is 1.

6. To measure input impedance, connect a resistor of 47k in series with the signal generator.

7. Measure the voltage at the input point (VS) and at the point after the resistor (VIN).

8. Current through the resistor is given by the expression I = (VS - VIN) / 47K.

9. Input impedance is given by ZIN = VIN / 47 K

10.To measure output impedance, connect a DRB in parallel with the output.

11.Adjust all the knobs of the DRB to maximum.

12.Start reducing the resistance in the DRB from a large value until the output reduces to half.

13.The resistance in the DRB is the output impedance.TABULAR COLUMN:

75


VIN = __________ constant

Frequency(Hz)

V0 (V) AV AV (dB)

WAVEFORM:

Vin

Vin 0 t

V0

0 t Vin

76


Ex.No: 12 TRANSFORMERLESS CLASS-B PUSH PULL POWER AMPLIFIER

Aim: Testing of a transformer less class-B push pull power amplifier and determination of its conversion efficiency.



1. TransistorSL100 1 No.

SK100 1 No.

2. Diode BY127 2 Nos.

3. Capacitors47 f 2 Nos.

470 µf 1 No.

4. Resistors220 2 No

DRB 1 No

DC Supply, CRO with Probe, Signal generator, AC millivoltmeter

Theory: In class B operation, to obtain output for the full cycle of signal, it is necessary to use two transistors and have each conduct on opposite half cycle, the combined operation providing a full cycle of output signal. Since one part of the circuit pushes the signal high during one half cycle and the other part pulls the signal low during the other half cycle, the circuit is referred to as a push pull circuit.

Circuit diagram:

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DESIGN:

Given Vcc =2.5V; RL= 10 Ω; IDC = 3mA

To Find R1 & R2:Applying KVL at the input circuit; We get ; Vcc = 2VR1 + 1.4Therefore; VR1 = 0.55V; VR1 =IDCR1 = 0.55V; R1 = 183Ω.Choose; R1 = R2 = 220Ω.

To Find Ci :Input coupling capacitor is given by, Xci >Zieff/10 >1.1K/10Xci > 1/2πfCi ;Ci >28μF; Choose Ci = 47μF

To Find CO:Output coupling capacitor is given by, Xco = 10Xco > 1/2πfCoCo > 318μF; Choose; Co = 470μFPoac=Vo2/8RL Pidc=VccIdc

Calculate circuit efficiency, η = Po (ac)/Pi(dc) = (π/4)Vo/Vcc = ?

Procedure:1. Connect the circuit as per the circuit diagram.2. Set VI = 3V, using the signal generator.3. Keeping the input voltage constant, vary the load resistor and note down

the readings of the ammeter and peak to peak output voltage.4. Calculate PDC, PAC and % efficiency η.5. Draw the plot of resistance versus output power.

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Resistance(Ω)

Po (watts)


Tabulation

Vi = ----------------

RL () VO (v) IDC(mA) PAC PDC %

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VIVA-VOCE QUESTIONS

1. What are conductors, insulators, and semi-conductors? Give examples.2. Name different types of semiconductors.3. What are intrinsic semiconductors and extrinsic semiconductors?4. How do you get P-type and N-type semiconductors?5. What is doping? Name different levels of doping.6. Name different types of Dopants.7. What do you understand by Donor and acceptor atoms?8. What is the other name for p-type and N-type semiconductors?9. What are majority carriers and minority carriers?

10. What is the effect of temperature on semiconductors?11. What is drift current?12. What is depletion region or space charge region?13. What is junction potential or potential barrier in PN junction?14. What is a diode? Name different types of diodes and name its applications 15. What is biasing? Name different types w.r.t. Diode biasing16. How does a diode behave in its forward and reverse biased conditions?17. What is static and dynamic resistance of diode?18. Why the current in the forward biased diode takes exponential path?19. What do you understand by Avalanche breakdown and Zener breakdown?20. Why diode is called unidirectional device.21. What is PIV of a diode22. What is knee voltage or cut-in voltage?23. What do you mean by transition capacitance or space charge capacitor?24. What do you mean by diffusion capacitance or storage capacitance?25. What is a transistor? Why is it called so?26. Name different types, of transistors?27. Name different configurations in which the transistor is operated28. Mention the applications of transistor. Explain how transistor is used as switch 29. What is transistor biasing? Why is it necessary?30. What are the three different regions in which the transistor works?31. Why thermistor is called current controlled device?32. What is FET? Why it is called so?33. What are the parameters of FET?34. What are the characteristics of FET?35. Why FET is known as voltage controlled device?36. What are the differences between BJT and FET?37. Mention applications of FET. What is pinch offVoltage, VGS(of J) and lDss38. What is an amplifier? What is the need for an amplifier circuit?39. How do you classify amplifiers? ,40. What is faithful amplification? How do you achieve this?41. What is coupling? Name different types of coupling42. What is operating point or quiescent point?43. What do you mean by frequency response of an amplifier?44. What are gain, Bandwidth, lower cutoff frequency and upper cutoff frequency?45. What is the figure of merit of an amplifier circuit?46. What are the advantages of RC coupled amplifier?47. Why a 3db point is taken to calculate Bandwidth?48. What is semi-log graph sheet? Why it is used to plot frequency response?49. How do you test a diode, transistor, FET?

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50. How do you identify the terminals of Diode, Transistor& FET? Mention the type number of the devices used in your lab.

51. Describe the operation of NPN transistor. Define reverse saturation current.52. Explain Doping w.r.t. Three regions of transistor53. Explain the terms hie/hib, hoel/hob, hre/hrb, hre/hfb.54. Explain thermal runaway. How it can be prevented?55. Define FET parameters and write the relation between them.56. What are Drain Characteristics and transfer characteristics?57. Explain the construction and working of FET58. What is feedback? Name different types.59. What is the effect of negative feedback on the characteristics of an amplifier?60. Why common collector amplifier is known as emitter follower circuit?61. What is the application of emitter follower ckt?62. What is cascading and cascoding? Why do you cascade the amplifier circuits?63. How do you determine the value of capacitor?64. Write down the diode current equation.65. Write symbols of various passive and active components66. How do you determine the value of resistor by color code method?67. What is tolerance and power rating of resistor?68. Name different types of resistors.69. How do you c1assify resistors?70. Name different types of capacitors..71. What are clipping circuits? Classify them.72. Mention the application of clipping circuits.73. What are clamping circuits? Classify them74. What is the other name of clamping circuits?75. Mention the applications of clamping circuits.76. 'What is Darlington emitter follower circuit?77. Can we increase the number of transistors in Darlington emitter follower circuit?

Justify your answer.78. What is the different between Darlington emitter follower circuit & Voltage

follower circuit using Op-Amp? Which is better?79. Name different types of Emitter follower circuits.80. What is an Oscillator? Classify them.81. What are The Blocks, which forms an Oscillator circuits?82. What are damped & Un-damped Oscillations?83. What are Barkhausen's criteria?84. What type of oscillator has got frequency stability?85. What is the disadvantage of Hartley & Colpiit's Oscillator?86. Why RC tank Circuit Oscillator is used for AF range?87. Why LC tank Circuit Oscillator is used for RF range?88. What type of feedback is used in Oscillator circuit?89. In a Transistor type No. SL 100 and in Diode BY 127, what does SL and BY stands

for90. Classify Amplifiers based on: operating point selection.91. What is the efficiency of Class B push pull amplifier?92. What is the drawback of Class B Push pull Amplifier? How it is eliminated.93. What is the advantage of having complimentary symmetry push pull amplifier?94. What is Bootstrapping? What is the advantage of bootstrapping?95. State Thevenin's Theorem and Maximum power transfer theorem.96. What is the figure of merit of resonance circuit?

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97. What is the application of resonant circuit?98. What is a rectifier? Classify.99. What is the efficiency of half wave and full wave rectifier?

100. What is the advantage of Bridge rectifier of Centre tapped type FWR101. What is the disadvantage of Bridge rectifier?102. What is a filter?103. Name different types of filter circuits?104. Which type of filter is used in day to day application and why?105. What is ripple and ripple factor? 106. What is the theoretical value of ripple for Half Wave and Full wave rectifier?107. What is need for rectifier circuits?108. Why a step down transformer is used at the input of Rectifier ckt.109. What is TUF? 110. What is regulation w.r.t rectifier? And how it is calculated?111. What is figure of merit of Rectifier circuit?

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10esl37_analog electronics lab manual

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