Ec 2-simulation-lab

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Document Name: Electronics Circuits II and
Simulation Lab Manual


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ELECTRONICS CIRCUITS II AND SIMULATION LAB

LIST OF EXPERIMENTS

CYCLE I

1. SERIES AND SHUNT FEED BACK AMPLIFIERS

2. DESIGN OF WEIN BRIDGE OSCILLATOR

3. DESIGN OF TRANSISTOR RC PHASE SHIFT OSCILLATOR

4. DESIGN OF LC – HARTLEY AND COLPITTS OSCILLATOR

5. CLASS C TUNED AMPLIFIER

6. INTEGRATORS AND DIFFERENTIATORS

7. CLIPPERS AND CLAMPERS

8. DESIGN OF MONOSTABLE MULTIVIBRATOR

9. DESIGN OF ASTABLE MULTIVIBRATOR

10. DESIGN OF BISTABLE MULTIVIBRATOR

CYCLE II - SIMULATION USING PSPICE

1. DIFFERENTIATE AMPLIFIER

2. ACTIVE FILTER : BUTTERWORTH II ORDER LPF

3. ASTABLE,MONOSTABLE AND BISTABLE MULTIVIBRATOR –
TRANSISTOR BIAS

4. D / A and A/D CONVERTER ( SUCCESSIVE APPROXIMATION )

5. ANALOG MULTIPLIER

6. CMOS INVERTOR , NAND AND NOR



1. FEED BACK AMPLIFIER

AIM:
To design and test the current series and voltage shunt
Feedback Amplifier and to calculate the following parameters with
and without feedback.
1. Mid band gain.
2. Bandwidth and cutoff frequencies.
3. input and output impedance.

APPARATUS REQUIRED:

S.NO ITEM RANGE Q.TY
1 TRANSISTOR BC 107 1
2 RESISTOR 1
3 CAPACITOR

4 CRO (0-30 )MHz 1
5 RPS (0-30) V 1
6 FUNCTION (0 – 1 )MHZ 1
GENERATOR

CURRENT SERIES FEEDBACK

DESIGN: (Without Feedback ):

Given data : Vcc = 15V , β = 0.9, fL = 1kHz, Ic=1mA.
Ω
Stability factor = [2-10], Rs = 680Ω,
Av = 50dB , IE = 1.2mA .
Gain formula is given by
Av = -hfe RLeff / Z i
Assume, VCE = Vcc / 2
RLeff = Rc RL
re = 26mV / IE
hie = β re where re is internal resistance of the
transistor.
hie = hfe re
VE = Vcc / 10


On applying KVL to output loop,
Vcc = IcRc + VCE + IERE
VE = IERE
Rc = ?
Since IB is very small when compared with IC
Ic approximately equal to IE
RE = VE / IE = ?
VB = VBE + VE
VB = VCC . RB2 / RB1 + RB2
S = 1+ (RB /RE )
RB = ?
RB = RB1 RB2
Find
Input Impedance , Zi = ( RB hie )
Coupling and bypass capacitors can be thus found out.
Input coupling capacitor is given by , Xci = Z i / 10
π
Xci = 1/ 2πfCi
Ci = ?
output coupling capacitor is given by ,
Xco=(Rc RL) / 10
π
Xc0 = 1/ 2πfCo
Co = ?
π
By-pass capacitor is given by ,XCE = 1/ 2πfCE
CE = ?
Design ( With feedback ) :
Remove the emitter capacitance ( CE )



β = -1 / RE
Gm = - hfe/ [(hie + RE ) RB]
D = 1+ β Gm
Gmf = Gm / D
Zif = Z iD
Zof = ZoD
CIRCUIT DIAGRAM: WITHOUT FEEDBACK:
+VCC

R1 Rc Co
Cin
B

BC107
E RL
Vo
CRO
CE
Vin R2 RE
F = 1 KHz



WITH FEEDBACK:

+VCC

RB1 Rc Co

Cin
BC107
B
RL
CRO
Vin RB2
RE

Voltage shunt DESIGN: (Without Feedback ):

Given data : Vcc = 15V , fL = 1kHz, Ic=1mA.
Ω
Stability factor = [2-10], Rs = 680Ω,
Av =40 dB .
Av = -hfe RLeff / Z i
RLeff = R c | | RL
re = 26mV / IE
transistor.
hie = hfe re
VE = Vcc / 10



VE = IERE
Rc = ?
Since IB is very small when compared with Ic
RE = VE / IE = ?
VB = VBE + VE
S = 1+ RB / RE
RB =?
RB = RB1|| RB2
Find
Input Impedance, Zi = (RB || hie )
π
Xci = 1/ 2πf Ci
Ci = ?
X co=(Rc | | RL) / 10
π
Xc0 = 1/ 2πf Co
Co =?
π
By-pass capacitor is given by, XCE = 1/ 2πf CE
CE =?
Design ( With feedback ) :
Connect the feedback resistance (Rf) and feedback
capacitor (Cf) as shown in the figure.
Xcf = Rf / 10



Cf = Rf / 2πf x 10
Ω
Assume, Rf = 68 KΩ
β = -1 / Rf
Trans – resistance Rm = - hfe (RB| | Rf ) (Rc | | Rf ) / (RB| | Rf ) + hie
D = 1+ β Rm
Avf = Rmf / Rs Rmf = Rm / D
Zif = Zi / D
Zof = Zo / D

CIRCUIT DIAGRAM: Voltage shunt feedback
WITHOUT FEEDBACK:

+VCC

R1 Rc Co
Cin
B

BC107
E RL
Vo
CRO
CE
Vin R2 RE
F = 1 KHz



WITH FEEDBACK:
+VCC

RB1 RF Rc Co

RS Cin
BC107
B
RL
CRO
Vin RB2
RE

MODEL GRAPH(WITH & WITHOUT FEEDBACK)

Without feedback
3 dB
GAIN
(db) 3dB With feedback

f3 f1 f2 f4 f(Hz)

f2 – f1 = Bandwidth of without feedback circuit
f4 – f3 = Bandwidth of with feedback circuit
THEORY:
An amplifier whose function fraction of output is fed
back to the input is called feed back amplifier. Depending
upon whether the input is in phase or out of phase with the
feed back signal, they are classified in to positive feed back



and negative feed back. If the feed back signal is in phase
with the input, then the wave will have positive gain. Then
the amplifier is said to have a positive feed back.
If the feed back signal is out of phase with the input
,then the wave will have a negative gain. The amplifier is
said to have a negative feed back. The values of voltage
gain and bandwidth without feed back.

PROCEDURE:

The connections are made as shown in the circuit. The
amplifier is checked for its correct operation .Set the input
voltage to a fixed value. Keeping the input voltage Vary the
input frequency from 0Hz to 1MHz and note down the
corresponding output voltage. plot the graph : gain (dB) vs
frequency .Find the input and output impedances. Calculate
the bandwidth from the graph. Remove RE and follow the
same procedure.

OBSERVATION:
WITH OUT FEEDBACK
Vin = ------------ Volts
S.NO FREQUNCY O/P
voltage Gain
Vo
Av=20 log Vo/Vi

WITH FEEDBACK
S.NO FREQUNCY O/P
voltage Av=20 log Vo/Vi



RESULT:

Theoritical Practical
With F/B Without With F/B Without
F/B F/B
Input Impedance
Output
impedance
Bandwidth
Transconductance
(gm)



2. WEIN BRIDGE OSCILLATOR

Aim : To Design and construct a Wein – Bridge Oscillator for a
given cut-off frequency .

APPARATUS REQUIRED:

1 TRANSISTOR BC107 2
2 RESISTOR
3 CAPACITOR

4 CRO - 1
5 RPS DUAL(0-30) V 1



CIRCUIT DIAGRAM:

R1 RC! CC2
R3 Rc2

+ -

Cc
R2
R4 RE2
CE

R

C

DRB
R

C

GND



MODEL GRAPH:

Design
Given : Vcc = 12V , fo = 2 KHz, Ic1= Ic2 = 1mA.; Stability
factor = [0-10],
fL = 100Hz
When the bridge is balanced,
fo = 1/ 2πRC
Assume, C = 0.1 F
Find, fo = ?
Given data : Vcc = 15V , fL = 50Hz, Ic1= Ic2 = 1mA.; AvT = 3 ;
Av1 =2; Av2 = 1;
Stability factor = [10]
Av = -hfe RLeff / Zi
RLeff = R c2 | | RL



hfe2 = 200 (from multimeter )
re2 = 26mV / IE2 = 26
hie2 = hfe2 re 2 = 200 x 26 = 5.2kW
From dc bias analysis , on applying KVL to the outer loop, we get
Vcc = Ic2Rc2 + VCE2+VE2
VcE2 = Vcc/2 ; VE2 = Vcc / 10 ; Ic2 = 1mA
Rc2 = ?
Av2 = -hfe2 RLeff / Zi2
Find RL|| Rc2 from above equation
Since Rc2 is known , Calculate RL.
VE2 = IE2RE2
Calculate RE2
S = 1+ RB2 / RE2
RB 2 =?
RB 2 =R3 || R4
VB2 = VCC . R4 / R3 + R4
VB2 = VBE2 + VE2
R3 =?
Find R4
Zi2 = (RB2 || hie2 )
Zi2 = ?
Rleff1 = Zi2|| Rc1
|
Find Rleff1 from the gain formula given above
Av1 = -hfe1 RLeff 1/ Zi1
RLeff1 = ?



On applying KVL to the first stage, we get
Vcc = Ic1 Rc1 + VCE1 +VE1
VCE1 = VCC / 2 ; VE1 = VCC / 10
Rc1 = ?
Find Ic1 approximately equal to IE1
R6 = RE1=?
S = 1+ RB1 / RE1
RB 1 =?
RB 1 =R1 || R2
VB1 = VCC . R2 / R1 + R2
VB1 = VBE2 +VE2
Find R1 = ?
Therefore find R2 = ?
Zi1 = (RB1 || hie1 )
R5 = RL – R6
π
Xci = 1/ 2πf Ci
Ci = ?
X co=(Rc2 | | RL2) / 10
π
Xc0 = 1/ 2πf Co
Co =?
By-pass capacitor is given by, XCE = RE2 / 10
π
XCE 1/ 2πf CE2
CE =?



THEORY:

In wein bridge oscillator, wein bridge circuit is connected
between the amplifier input terminals and output terminals. The
bridge has a series rc network in one arm and parallel network in
the adjoining arm. In the remaining 2 arms of the bridge resistors
R1and Rf are connected . To maintain oscillations total phase
shift around the circuit must be zero and loop gain unity. First
condition occurs only when the bridge is balanced . Assuming
that the resistors and capacitors are equal in value, the resonant
frequency of balanced bridge is given by

Fo = 0.159 RC

PROCEDURE:

1. The circuit is constructed as per the given circuit
diagram.
2. Switch on the power supply and observe the output on
the CRO( sine wave)
3. Note down the practical frequency and compare it with
the theoretical frequency.



RESULT :

Frequency f = 1 / 2 Π RC



3. TRANSISTOR PHASE SHIFT OSCILLATOR
AIM:
To design and construct the transistor Phase shift oscillator.
APPARATUS REQUIRED:

2 RESISTOR
3 CAPACITOR
4 CRO ( 0 – 30 ) MHz 1
5 RPS (0-30) V 1
6 FUNCTION (0-1 )MHz 1
GENERATOR

CIRCUIT DIAGRAM:



MODEL GRAPH:

DESIGN:
Given : Vcc = 12V , fo = 1 KHz,C = 0.01µF; IE = 5mA.;
Stability factor = 10
f = 1/ 2πRC Find R
R1 = (Ri – R)
R >> Rc
Βeta = -1 / 29
Amplifier Design :
Av = -hfe RLeff / hie ( Av = 29, design given )
RLeff = R c | | RL
re = 26mV / IE



transistor.
hie = hfe re
VE = Vcc / 10
VE = IERE
Rc = ?
RE = VE / IE = ?
VB = VBE + VE
S = 1+ RB / RE
RB =?
RB = RB1|| RB2
Find RB1 & RB2
π
Xci = 1/ 2πf Ci
Ci = ?
π
Xc0 = 1/ 2πf Co
Co =?
π
By-pass capacitor is given by, XCE = 1/ 2πf CE
CE =?



THEORY:
The Transistor Phase Shift Oscillator produces a sine wave
of desired designed frequency. The RC combination will give a
° °
60° phase shift totally three combination will give a 180° phase
shift. . The BC107 is in the common emitter configuration.
° °
Therefore that will give a 180° phase shift totally a 360° phase
shift output is produced. The capacitor value is designed in order
to get the desired output frequency. Initially the C and R are
connected as a feedback with respect to input and output and this
will maintain constant sine wave output. CRO is connected at the
output.
PROCEDURE:
1. The circuit is constructed as per the given circuit diagram.
2. Switch on the power supply and observe the output on the
CRO( sine wave)
3. Note down the practical frequency and compare it with the
theoretical frequency.

RESULT :
Frequency f = 1 / 2 Π RC √6RC



4. LC OSCILLATOR – HARTLEY and COLPITT OSCILLATOR

AIM :
To Design and construct the given Oscillator at the given
operating frequency.
APPARATUS REQUIRED:
2 RESISTOR 1

3 CAPACITOR
4 CRO (0 – 30)MHZ 1
5 RPS (0-30) V 1

6 FUNCTION (0- 1 ) MHz 1
GENERATOR
7 DlB, DRB 1

CIRCUIT DIAGRAM :
+VCC

RB1 Rc Co
C
Cin B
BC107
E
RL
RB2 CRO
RE CE

+ L1 - - L2 +



CIRCUIT DIAGRAM:
+VCC

RB1 RC
µ
0 .01µF
Cin C
B
BC107
RL
E
CRO
RE CE
RB2

C1 C2

L

MODEL GRAPH:

Design of Feedback Network ( Hartely Oscillator ) :
Given : L1 = 1mH ; f = 800kHz; Vcc = 12V ; Av =50 ; fL = 1Khz



Av = 1 / β = -L1 / L2
F = 1/2π√(L1 + L2)C; C=?
Design of Feedback Network ( Colpitt Oscillator ) :

Given : C1 = 0.1 F;f =800kHz; Vcc = 12V ; Av = 50 ; S = 10
IE = 5mA; fi = 1kHz
Av = Av = 1 / β = C2 / C1
f = 1/2π√(C1 + C2) / LC1C2
L=?
Amplifier Design :
Av = -hfe RLeff / hie ( Av = 29, design given )
RLeff = R c | | RL
re = 26mV / IE
transistor.
hie = hfe re
VE = Vcc / 10
VE = IERE
Rc = ?;RL = ?
RE = VE / IE = ?
VB = VBE + VE



S = 1+ RB / RE
RB =?
RB = RB1|| RB2
Find RB1 & RB2
π
Xci = 1/ 2πf Ci
Ci = ?
Xc0 = (Rc ‫׀׀‬RL) / 10
π
Xc0 = 1/ 2πf Co
Co =?
By-pass capacitor is given by, XCE = RE / 10
π
XCE = 1/ 2πf CE
CE =?
THEORY:
LC oscillator consisting of a tank circuit for generating
sine wave of required frequency. Rectifying Barkhausen
β β
criteria Aβ for a circuit containing reactance Aβ must be
positive and greater than or equal to unity.
PROCEDURE :
1. The circuit connection is made as per the circuit
diagram.
2. Switch on the power supply and observe the output
on the CRO(sine wave ).
3. Note down the practical frequency and compare it
with the theoretical frequency.
THEORETICAL FREQUENCY FOR HARTLEY OSCILLATOR:



THEORETICAL FREQUENCY FOR COLPITT OSCILLATOR:
fc = 1/2π√(C1 + C2) / LC1C2

PRACTICAL :
Observed Values:
Time Period =
Frequency =

RESULT :
Thus the LC oscillator is designed for the given
frequency and the output response is verified.

Frequency Hartley Colpitt Hartley Colpitt



5. CLASS C SINGLE TUNED AMPLIFIER
AIM:
To study the operation of class c tuned amplifier.
APPARATUS REQUIRED:
2 RESISTOR Ω Ω Ω Ω
4.2KΩ, 500Ω, 197KΩ, 2.2KΩ, 1
3 CAPACITOR 0.1µfµ 2
µ µ
0.001µf, 100µf 1
4 CRO - 1
5 RPS (0-30) V 1
6 FUNCTION - 1
GENERATOR

+VCC = 10 V

CIRCUIT DIAGRAM:
µ
10µF
Ω
10KΩ

Ω
47KΩ

µ
47µF C
B Ω
100KΩ
BC107 CRO

E

Vin = 1 V Ω
120KΩ Ω
2.2kΩ +
F = 1 KHz µ
100µF
-



MODEL GRAPH:

THEORY:
The amplifier is said to be class c amplifier if the Q Point and the
input signal are selected such that the output signal is obtained
for less than a half cycle, for a full input cycle Due to such a
selection of the Q point, transistor remains active for less than a
half cycle .Hence only that much Part is reproduced at the output
for remaining cycle of the input cycle the transistor remains cut
off and no signal is produced at the output .the total
Angle during which current flows is less than 180..This angle is
called the conduction angle, Qc

PROCEDURE:
1.The connections are given as per the circuit diagram.
2. Connect the CRO in the output and trace the waveform.
3.calculate the practical frequency and compare with the
theoretical Frequency
4.plot the waveform obtained and calculate the bandwidth

RESULT:
Thus a class c single tuned amplifier was designed and its
bandwidth is Calculated.



6. INTEGRATOR USING OP-AMP
AIM:
To study the output waveform of integrator using op-amp.

APPARATUS REQUIRED:
APPARATUS NAME RANGE QUANTITY
AUDIO OSCILLATOR 1
CRO 1
RESISTORS 1K,10K 1
CAPACITOR µ
0.1µF 1
OP-AMP IC741 1
BREADBOARD
RPS

THEORY:
A simple low pas RC circuit can also work as an integrator when
time constant is very large. This requires very large values of R and
C.The components R and C cannot be made infinitely large because of
practical limitations. However in the op-amp integrator by MILLER’s
theorem, the effective input capacitance becomes Cf (1-Av), where Av is
the gain of the op-amp. The gain Av is the infinite for an ideal op-amp, so
the effective time constant of the opamp integrator becomes very large
which results perfect integration.

PROCEDURE:

1.Connections are given as per the circuit diagram.
2.The resistance Rcomp is also connected to the (+) input terminal
to minimize the effect of the input bias circuit.
3.It is noted that the gain of the integrator decreases with
increasing frequency.
4.Thus the integrator circuit does not have any high frequency
problem.



CIRCUIT DIAGRAM: µ
0.1µF

Ω
10kΩ
+Vcc=12V

2 7
-

3 IC741

+ CRO
4

-Vee=-12V

Ω
1kΩ



MODEL GRAPH:
Vi

t (msec)

Vo t(msec)

RESULT:- Thus the integrator using op-amp is studied.



7.CLIPPER & CLAMPER CIRCUITS

AIM : To observe the clipping waveform in different clipping
configurations.

APPARATUS REQUIRED :

1 DIODE IN4001 1
2 RESISTOR 1KΩΩ 1
10 KΩΩ 1

3 CAPACITOR 0.1µF 1

4 FUNCTION (0-1) MHz 1
GENERATOR
5 CRO - 1



CLIPPER CIRCUIT DIAGRAM :
1KOHM

IN4001
Vout
1KHz
5V 2V

1KOHM

IN4001
Vout
1KHz
5V 2V

Procedure :
1. Connections are given as per the circuit .
2. Set input signal voltage (5v,1kHz ) using function
generator.
3. Observe the output waveform using CRO.
4. Sketch the observed waveform on the graph sheet.



CLAMPING CIRCUITS

Aim:
To study the clamping circuits
(a). Positive clamper circuit (b) Negative clamper circuit


1 DIODE IN4001 1
2 RESISTOR 1KΩΩ 1
10 KΩΩ 1

3 CAPACITOR 0.1µF 1

4 FUNCTION (0-1) MHz 1
GENERATOR
5 CRO - 1

DESIGN :

Given f = 1kHz
T = 1 / f = 1x 10- 3 Sec RC
Assuming, C = 0.1µF
R = 10 KΩ Ω



Circuit Diagram : Positive clamper
C =0.1µF

I/P IN4001 10K o/p Vo

Negative clamper

C = 0.1µF

I/P IN4001 10K o/p Vo

Procedure :
1.Connections are given as per the circuit .
2. Set input signal voltage (5v,1kHz ) using function
generator.
3. Observe the output waveform using CRO.
4. Sketch the observed waveform on the graph sheet.



Result :
Thus the waveforms are observed and traced .for clipper
and clamper circuits .



8. MONOSTABLE MULTI VIBRATOR
AIM:
To Design the monostable multivibrator and plot the
waveform.

APPARATUS REQUIRED:
1 IC NE555 1
2 RESISTOR Ω
9KΩ 1

3 CAPACITOR µ
0.01µF 1
µ
0.1µF 1
4 RPS (0-30) V 1
5 CRO - 1

THEORY:
A monostable multivibrator has one stable state
and a quasistable state. When it is triggered by an
external agency it switches from the stable state to
quasistable state and returns back to stable state. The
time during which it states in quasistable state is
determined from the time constant RC. When it is
triggered by a continuous pulse it generates a square
wave. Monostable multi vibrator can be realized by a pair
of regeneratively coupled active devices, resistance
devices and op-amps.



DESIGN :
Given Vcc = 12V ; VBB = - 2 V; Ic = 2 mA; VCE(sat) = 0.2 V ; h FE =
200 ;
f = 1kHz.
RC = VCC – VCE(sat) / IC = 12 – 0.2 / 2x 10 –3 = 5. 9 KΩ
Ω
IB 2(min) = Ic2 / hfe = 2mA / 200 = 10 µA
Select IB 2 > IB 1(min) (say 25 µA )
Then R = VCC – VBE(sat) / I B 2 = 12 – 0.7 / 25 x 10 -6 = 452 KΩ
Ω
T = 0.69 RC
1x10-3 = 0.69 x 452 x 10 3
C
C = 3.2 nF
VB1 = VBB R1 / R1 + R2 + VCE(sat) R2 / R1+R2
Since Q1 is off state, VB1 less than equal to 0.
Then VBB R1 / R1 + R2 = VCE(sat) R2 / R1+R2
VBB R1 = VCE(sat) R2
2R1 = 0.2R2
Assume Ω Ω
R1 = 10 KΩ. Then R2 = 100 KΩ
C1 = 25pF( Commutative capacitor )
procedure :
1. Connect the circuit as per circuit diagram.
2. Switch on the regulated power supply and observe the
output waveform at
the collector of Q1 and Q2 and plot it.



3. Trigger the monostable multivibrator with a pulse and
observe the change in waveform.
4. Plot the waveform and observe the changes before and
after triggering the input to the circuit.
CIRCUIT DIAGRAM :

+ VCC = +12v

5.9K 452k 5.9k
10k
3.2nf

22pf
C C
B B B
Vo1 BC107 BC107 VO2

E 100k E
-VBB

PROCEDURE:
The connections are made as per the diagram.
Ω
The value of R is chosen as 9kΩ. The DCB is set to the
designed value. The power supply is switched on and set
to +5V.
The output of the pulse generator is set to the desired
frequency. Here the frequency of triggering should be
greater than width of ON period (i.e.) T >W. The output is
observed using CRO and the result is compared with the


theoretical value. The experiment can be repeated for
different values of C and the results are tabulated.

OBSERVATION

C (uf) Theoritical(T=1.095 RC(ms))) Practical
T(ms)

RESULT: Thus the monostable multivibrator using IC555 is
designed and its output waveform is traced.



9.ASTABLE MULTIVIBRATOR
AIM :
To design a astable multivibrator and study the
waveform.

1 TRANSISTOR BC107 2
2 RESISTOR Ω
980KΩ 2
Ω
4.9KΩ 2

3 CAPACITOR 0.74nF 2

4 RPS (0-30) V 1
5 CRO - 1

THEORY :
Astable multivibrator has no stable state, but has two
quasi – stable states. The circuit oscillates between the
states (Q1 ON , Q2 OFF) and (Q2 ON , Q! OFF). The output
at the collector of each transistor is a square wave.
Therefore this circuit is applied as a square wave
generator. Refer to the fig each transistor has a bias
resistance RB and each base is capacitor coupled to the
collector of other transistor. When Q1 is ON and Q2 is
OFF, C1 is charged to ( Vcc – VBE1) positive on the right
side. For Q2 ON and Q! OFF, C2 is charged to (Vcc – VBE2)
positive on the left side.



CIRCUIT DIAGRAM : + VCC = +10v

Ω
4.9KΩ Ω
980KΩ Ω
980KΩ Ω
4.9KΩ

0.74nF 0.74nF

C C
B B
Vo1 BC107 BC107 VO2

E E

Design
Given Vcc = 10V ; Ic = 2 mA; h FE = 200 ; f = 1 kHz
R ≤ h FE Rc
RC = VCC – VC2(sat) / IC = 10 – 0.2 / 2x 10 –3 =4. 9 KΩ
Ω
R ≤ 200 x 4.9 x 103 = 980 KΩ
Ω
T = 1.38 RC
1 x 10-3 = 1.38 x 980 x 103 x C
C =0.74 nF



Waveforms :

PROCEDURE :
1. The connections are given as per the circuit
diagram.
2. Switch on the power supply.
3. Observe the waveform both at bases andcollectors
of Q1 and Q2.
4. Connect the CRO in the output of Q1 and Q2 and
trace the square waveform.


RESULT :
Thus the square wave forms are generated using
astable multivibrator.



10.BISTABLE MUITIVIBRATOR
AIM:
To design a bistable multivibrator and study the output
waveform.

Apparatus Required:

2 RESISTOR Ω
4.7KΩ 2
22KΩΩ 2

3 CAPACITOR µ
0.022µf 2
µ
10µf 2
100Pf 2
4 CRO - 1
5 RPS (0-30) V 1
6 FUNCTION - 1
GENERATOR

THEORY:
The bistable multivibrator is a switching circuit with a
two stable state either Q1 is on and Q2 is off (or)Q2 is on and Q1
is off. The circuit is completely symmetrical. load resistors RC1
and RC2 all equal and potential
Divider (R1,R2)and (R1′ and′R2 ′) from identical bias Network at the
′
transistor bases. Each transistor is biased from the collector of
the other
Device when either transistor is ON and the other transistor is
biased OFF.C1andC2 operate as speed up capacitors or memory
capacitors.

Design :


Given Vcc = 12V ; VBB = -12v; Ic = 2mA; VC(sat) = 0.2 V
VBE(sat) = 0.7V
Assume Q1 is cut-off Vc1 = VCC(+12V)
Q2 is in saturation (ON) Vc2 = Vc(sat) (0.2 V)
Using superposition principle,
VB1 = VBB[ R1 / R1 + R2 ] + Vc2[ R2 / R1+R2 ] << 0 .7
Let us consider VB1 = -1V
Then -1 = [-12R1/R1+R2 ] + [ 0.2R2 / R1+R2 ]
Ω
Assume R1 = 10KΩ such that it ensures a loop gain in excess of unity
during the transition between states. The inequality
R1 < hfe Rc
Ω
R2 = 91.67 KΩ
Test for conditions : Q1 = cut-off (Vc1 = 12V )
Q2 = Saturation / (ON) (VC2 = 0.2V)
Minimum base current, IB (min) must be less than the base current (IB)
i.e.,
IB (min) < IB
Calculate hfe from multimeter (say = 200)
IB 2(min) = Ic2 / hfe
Ic2 = Ic – I3
Ic2 = ( 2 – 0.12 )mA = 1.88 mA
IB 2(min) = 1.88mA / 200 = 9.4 µA
IB 2 = I1 – I2
IB 2 = (0.71 – 0.14 )mA = 0.57 mA
Since IB 2 > IB 2(min) ,Q2 is ON
C1 = 25 pF ( Commutative capacitor )



IC = VCC – Vc2 / RC
RC = VCC – Vc2 / IC = 12 – 0.2 / 2x 10 –3 = 5.9 KΩ
Ω
I3 = Vc2 - VBB / R1 + R2 = 0.2 + 12 / ( 10 + 91.6 )K = 0.12mA
I1 = Vc1 - VBE / RC + R1 = 12 – 0.7 / ( 5.9 + 10 ) K = 0.71mA
I2 = VBE - VBB / R2 = 0.7 + 12 / 91.6K = 0.14 mA
Procedure :
1. Connect the cir cuit as per circuit diagram.
2. Switch on the regulated power supply and observe the output
waveform at the collector of Q1 and Q2.
3. Sketch the waveform.
4. Apply a threshold voltage and observe the change of states of Q1
and Q2.
5. Sketch the waveform.



CIRCUIT DIAGRAM :
+ Vcc = +12 V

Ω
5.9KΩ Ω
5.9KΩ
I1 I3
10 KΩΩ 10KΩΩ

50pF 50pF

C C CRO
CRO B B
BC107
22 BC107
91.67k E
10 E I4 I2 91.67k µ
10µF

TRIGGER
TRIGGER IP
-VBB

OBSERVATION :

VOLTAGE Time Period Frequency Amplitude
VC1

Vc2

RESULT:
Thus the bistable multivibrator is designed and the
square waveforms are generated at the output.



CYCLE II
SIMULATION LAB

1. Differential Amplifier

Aim : Calculate the dc voltage gain , the input resistanceand the
output resistance of a differential amplifier with a transistor
current source.
Specifications: The input voltage is 0.1v. The model parameters
of the bipolar transistors are BF = 50,RB = 70, RC = 40.

Circuit Diagram :

R2 R3
10K 10K

V2
Q1A 12v
R1 Q1A

R7
1.5k R6
20K
1.5K

V1 R4 R5 0
150 K 150K
0
0

Q1A V3
12v

Q1A Q1A



Program :

Vcc 11 0 12v
VEE 0 10 12v
VIN 1 0 DC 0.25v
RC1 11 3 10k
RC2 11 5 10k
RE1 4 12 150
RE2 7 12 150
RS1 1 2 1.5k
RS2 6 0 1.5k
Rx 11 8 20k

Q1 3 2 4 QN
Q2 5 6 7 QN
Q3 12 8 9 QN
Q4 9 9 10 QN
Q5 8 9 10 QN

. TF V (3,5) VIN
END
The results of the transfer – function analysis by the .TF
commands are given below



ACTIVE LOW BUTTER FILTER
R1
0
1k 0.586 RF
VCC
0

7
12VDC
3 5

V+
+ OS2
1K R2 1K R3 6
OUT
2 1

V-
- OS1
uA741
1VAC 0VDC VIN VEE

4
C1 C2 0
12VDC
1n 1n
0
0

PROGRAM:

LOW PASS FILTER
VCC 6 0 DC 12V
VEE 0 7 DC 12V
VIN 1 0 AC 1V
R1 4 0 1K
R2 1 2 1K
R3 2 3 1K
RF 4 5 0.586K
C2 2 5 0.079 UF
C3 3 0 0.079UF
X1 4 3 6 7 5 UA 741
.LIB NOB .LIB
.AC DEC 10HZ 100HZ 1MEGHZ
.PROBE
.END



PROGRAM FOR FREE RUNNING MULTIVIBRATOR

VCC 6 0 DC 12V
VEE 0 7 DC 12V
R1 1 0 100K
R2 2 3 100K
R3 2 3 10K
C1 3 0 0.1 UF IC = -5V
XA1 1 3 6 7 2 UA741
.LIB EVAL .LIB
.TRANS 10US 4MS UIC
.PROBE
.END

100K R2

VCC 0
7

U2 12V
3 5
V+

+ OS2
100K R1 6
OUT
2 1
V-

- OS1
AD741
4

VEE VOT
0
-12V

10K R3

0.1 UF C1

0



A CMOS INVERTER

VDD 2 0 5V
VIN 1 0 DC 5V PULSE (0 5V 0 1NS 1NS 20US 40US)
RL 3 0 100k
M1 3 1 2 2 PMOD L=1U W= 20U
M2 3 1 0 0 NMOD L=1U W= 5U
.TRAN 1US 80US
.TF V(3) VIN
.OP
.PLOT TRAN V(3) V(1)
.PROBE
.END

2 VDD = 5

PMOS M1

3
1

NMOS M2
RL 100K

0



ANALOG MULTIPLIER
V1 1 0 1V
V2 4 0 1V
R1 1 2 1K
R2 4 5 1K
R3 3 7 1K
R4 6 7 1K
R5 7 8 1K
R6 10 0 1K
D1 2 3 DA
D2 5 6 DA
D3 8 9 DA
.MODEL DA D
X1 2 0 3 IOP
X2 5 0 6 IOP
X3 7 0 8 IOP
X4 9 0 10 IOP
.SUBCKT IOP M P V0
RI M P 1G
E V0 0 P M 2E5
.ENDS
.DC V1 -1 1 0.1
.PROBE
.END



7
R17 U2
3 5

V+
V8 + OS2 R26
0V 1k
6
OUT R26
1k
2 1

V-
- OS1

7
U2
0 1k
AD741 3 5

V+
+ OS2

7
D1 U2

4
6 1 2 3 5

V+
OUT + OS2
0 1N4376
2 1 6

V-
- OS1 OUT
AD741 2 1

V-
- OS1

4
AD741
R27

4
R17 U2 7
3 5 1k
V+
V8 + OS2
0V 1k 0
6
OUT
2 1 0
V-

- OS1
0 AD741 0
4

0


Ec 2-simulation-lab

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