Download Report

SATHYABAMA UNIVERSITY
DEPARTMENT OF ELECTRONICS AND INSTRUMENTATION
LAB MANUAL
for
II YEAR B.E(EIE) – III SEMESTER
Academic Year 2013-2014
Batch (2012 – 2016)
SECX4048 - Electronic Circuits I Lab
Name : ---------------------------------------------------------------------------
Reg.No :----------------------------------------------------------------------------
LIST OF EXPERIMENTS
1. ANALYSIS OF TRANSISTOR BIASING CIRCUITS
2. DESIGN AND TESTING OF HALF WAVE RECTIFIER CIRCUIT WITHOUT AND WITH
FILTER
3. DESIGN AND TESTING OF FULL WAVE RECTIFIER CIRCUIT WITHOUT AND WITH
FILTER
4. CHARACTERISTICS OF SERIES VOLTAGE REGULATOR
5. CHARACTERISTICS OF SHUNT VOLTAGE REGULATOR
6. DESIGN AND TESTING OF RC COUPLED TRANSISTOR AMPLIFIER
7. DESIGN AND TESTING OF EMITTER FOLLOWER
8. DESIGN AND TESTING OF FET AMPLIFIER
9. DESIGN AND TESTING OF PUSH PULL POWER AMPLIFIER
10. DESIGN AND TESTING OF CLASS A POWER AMPLIFIER
11. STUDY OF PSpice (ORCAD) SOFTWARE AND SIMULATION OF ALL THE ABOVE
EXPERIMENTS
Expt.No:1
ANALYSIS OF TRANSISTOR BIASING CIRCUITS
Aim:
To design and analyse different biasing circuits for a transistor.
Apparatus required:
1. Transistor
2. Resistors
3. DC Voltmeter(0-30)V
4. DC Ammeter(0-30)mA,(0-250)µA
5. Regulated power supply(RPS)
Theory:
The process of giving proper supply voltages and resistance for obtaining the desired Q-point is called
biasing. The circuits used for getting the desired and proper operating point are known as Biasing
circuits .
Fixed bias:
Also known as Base Resistor method. By the proper selection of Rb,which is connected between
positive terminal of supply vcc and base of the transistor, the required zero signal base current can be
made to flow.
Advantages:
 Simplicity
 Small number of components required
 The base current becomes largely independent of the voltage Vbc if the supply voltage is very
large as compared to Vbc of the transistor.
Collector feedback bias:
This circuit is same as base bias circuit expect that Rb is connected to collector rather than to Vcc.
Rb acts as a feedback resistor.
Advantage:
 Considerable improvement in the stability
Voltage Divider Bias:
A very commonly used biasing arrangement is self Bias or Voltage Divider or Emitter Bias.R1 and
R2 acts as potential divider and connected to Vcc for proper Biasing .Re provides stabilization.
Advantage:
 Considerable improvement in the operating point stability
Design:
Fixed Bias:
Given:
β=175, Іc=2.5mA, Vcc=12V, Vbe=0.7V, Vce= 6V
Let
Ic=βІb
Therefore Ib= ?
Apply KVL
Vcc = Ib Rb. +Vbe
Vcc = Ic Rc. +Vce
Therefore
i)Rb = (Vcc -Vbe ) / Ib
Rb= ?
ii)Rc= (Vcc - Vce ) / Ic
Rc= ?
Collector Feedback Bias:
Given :
β=175, Іc=2.5mA, Vcc =12V, Vce=6V
Apply KVL
Vcc = (Ic+Ib)Rc+ IbRb+Vbe
Vce = IbRb+ Vbe
Therefore
i)Rb = (Vce -Vbe)/ Ib
Rb= ?
ii)Rc=(Vcc -Vce)/ (Ib+Ic)
Rc= ?
Voltage Divider Bias / Self Bias:
Given:
β=175, Іc=2.5mA, Vcc=12V, Vbe=0.7V
Let
i)Ve = Vcc/10
Ve = ?
ii)Ie ÷ Ic
Ie = ?
For the given Circuit
Ve = IeRe
Rb2 = βRe/10
Vb=Vbe+IeRe
Vb = (Vcc* Rb2)/(Rb1+Rb2)
Vcc = IcRc + Vce + Ve
Therefore
i)Re=Ve/Ie
Re = ?
iii)Vb=Vbe+IeRe
Vb = ?
v)Rc = (Vcc - Vce - IeRe) / Ic
Rc = ?
ii)Rb2 = βRe/10
Rb2 = ?
iv)Rb1 = ((Vcc/Vb)-1)Rb2
Rb1 = ?
Circuit Diagram
Fixed Bias
Collector Feedback Bias
Voltage Divider Bias
Pin Diagram:
TABULATION
Fixed Bias:
Vcc
Volt
(theo) (prac)
Symbol:
Vce
Volt
(theo) (prac)
Vb
Volt
(theo) (prac)
Ic
mA
(theo) (prac)
Ib
mA
(theo) (prac)
Vb
Volt
(theo) (prac)
Ic
mA
(theo) (prac)
Ib
mA
(theo) (prac)
Collector Feedback Bias:
Vcc
Volt
(theo) (prac)
Vce
Volt
(theo) (prac)
Voltage Divider Bias / Self Bias:
Vcc
Volt
(theo) (prac)
Vce
Volt
(theo) (prac)
Vb
Volt
(theo) (prac)
Ic
mA
(theo) (prac)
Ib
mA
(theo) (prac)
Procedure:
1. Circuit connections are made for all the biasing circuits based on circuit diagram.
2. DC voltages and currents are noted for different biasing circuits.
3. Theoretical and practical values are verified.
Result:
The fixed bias, collector feedback bias and voltage divider bias circuits are verified .
Expt.No:2
DESIGN AND TESTING OF HALF WAVE RECTIFIER CIRCUIT
WITHOUT AND WITH FILTER
Aim:
To design a half wave rectifier circuit with and without filter for desired DC voltage and DC current.
Apparatus Required:
1. Semiconductor diode – 1N4007.
2. Centre Tapped Transformer- Single phase
3. Capacitor
4. Resistor
5. Ammeter (0-30) mA - MC
6. Voltmeter (0-30 )V- MC
7. Multimeter(0-1)V- MI
8. CRO
Theory:
Principle:It is a circuit which converts alternating voltage into pulsating voltage or current for half the
period of input cycle.
Working: During the positive half cycle, the diode D is forward biased offers very small resistance and acts
as closed switch and hence conducts the current through the load resistor R L. During the negative half cycle, the
diode D is heavily reverse biased and offers very high resistance and acts as an open switch and hence does not
conduct any current.
Procedure:
1. Connections are made as shown in the circuit diagram.
2. Using design calculations, the values of resistance, supply voltage and other specifications are fixed.
3. The output waveform of HWR is observed using CRO.
4. The voltmeter and ammeter readings show Vdc and Idc respectively.
5. Using the standard formulas, the values for ripple factor efficiency and regulation are calculated.
6. The above procedure is repeated for various values of RL.
7. For HWR with filter, the capacitor is connected across R and it serves to bypass AC components to
ground.
8. The characteristics of HWR with and without filter are obtained and verified.
Circuit Diagram
HWR without filter
HWR with filter
Pin Diagram
Model Graph
Symbol
Input
Output
TABULATION
Without Filter
Vdc(theo)
Volt
Vdc (prac)
Volt
Idc(theo)
mA
Idc(prac)
mA
MODEL CALCULATION:
Given:
Vdc = 10V,Idc = 10mA
Vdc (th) = Idc * RL
Idc (th) = Vdc/ RL
RL = ?
Vm = Vdc*Π
Vrms= Vm / 2
Ripple = Vac / Vdc
Vdc(theo)
Volt
Vdc(Prac)
Volt
With Filter
Idc(Theo)
Idc(Prac)
mA
mA
Ripple
factor( r )
MODEL CALCULATION
Given:
Vdc = 10V, Idc = 10mA, r =1.1%,f = 50Hz
Vdc = Idc * RL
RL = ?
C = 1/(2√3*f*R L*r)
C=?
Vdc = ( 2f*RL*C)*Vm / ((2f*R L*C)+1)
Vdc = ?
Idc = Vdc/ RL
Idc = ?
Ripple = Vac / Vdc
Result:
Thus the half wave rectifier with and without filter is constructed for the given design specification.
Expt.No:3 DESIGN AND TESTING OF FULL WAVE RECTIFIER CIRCUIT
WITHOUT AND WITH FILTER
Aim:
To design a full wave rectifier circuit with and without filter for desired DC voltage and DC current.
Apparatus Required:
Semiconductor diode – IN4007.
Center Tapped Transformer- Single phase
Capacitor 10µf-C1.
Ammeter (0-30) mA - MC
Voltmeter (0-30 )V- MC, (0-1) V- MI
Resistor 1K - RL
6.
7. CRO
1.
2.
3.
4.
5.
Theory:
Principle :
It is a circuit which converts alternating voltage or current into pulsating voltage or current during
both half cycle of input. In full wave rectifier current flows through the load in the same direction for both half
cycles of input AC voltage. This can be achieved with two diodes working alternatively.
Working :
During the positive half cycle one diode conducts and supplies current to the load. During the
negative half cycle the other diode conducts and current flows through the load in the same direction. Thus the full
wave rectifier produces continuous pulsating DC output.
Design:
Given Vdc = 10Volts,
Idc = 10mA
With Filter, r = 2.12%
RECTIFIER WITHOUT FILTER
RL
= Vdc / Idc
RL
=?
Vdc = 2Vm/ π
Vdc = ?
Vrms = Vm/√2
Vrms = ?
Ripple = Vac / Vdc
RECTIFIER WITH CAPACITOR FILTER
Idc
Vdc = ( 4f*R L*C)*Vm / ((2f*RL*C)+1)
Vdc = ?
Idc = Vdc/ RL
=?
Ripple Factor for the full-wave rectifier with capacitor filter is given by
r (Theoretical) = 1/(4*√3*f*C* RL ).
r (Practical) = Vac / Vdc.
Procedure:
1.
2.
3.
4.
5.
6.
7.
Connections are made as shown in the circuit diagram
Using design calculations, the values of resistance, supply voltage and other specifications are fixed.
The output waveform of Full Wave Rectifier is observed using a CRO which is a pulsating DC .
The voltmeter and ammeter readings are noted.
Using the standard formulas, the values of ripple factor, the efficiency and regulation are calculated.
The above procedure is repeated for various values of R L.
For FWR with filter, the capacitor is shunt connected across the load. The value of capacitance is obtained
from design calculations.
8. The characteristics of FWR with and without filter are obtained and verified.
Circuit Diagram
FWR without filter
FWR with filter
Model Graph
input
output
TABULATION
Without Filter
Vdc(theo)
Volt
Vdc (prac)
Volt
Idc(theo)
mA
Idc(prac)
mA
MODEL CALCULATION:


Vdc (th) = Idc * RL
Idc (th) = Vdc/ RL
With Filter
Vdc(theo)
Volt
Vdc(Prac)
Volt
Idc(Theo)
mA
Idc(Prac)
mA
Ripple
factor( r )
MODEL CALCULATION:



Vdc (th) = Idc * RL
Idc (th) = Vdc/ RL
Ripple factor ( r ) = Vac / Vdc.
Result:
Thus the full wave rectifier with and without filter is constructed for the given design specification.
Expt.No:4
CHARACTERISTICS OF SERIES VOLTAGE REGULATOR
Aim:
To obtain the regulation characteristics of series voltage regulator.
Apparatus Required:
1.
2.
3.
4.
5.
6.
7.
Transistor 2N3055
Regulated Power Supply (RPS) - (0-30)V
Resister 1KΩ
Zener diode
Decade Resistance Box (DRB)
Voltmeter (0-30)V
Ammeter(0-30)mA
Theory:
A DC power supply which maintains the o/p voltage constant irrespective of the AC mains fluctuations or
load variations is a regulator. It is called as a series voltage regulator because the transistor is in series with the
load.
When a zener diode is operated in the breakdown region it maintains constant voltage across the load. The
series limiting resistance limits the current. As a load current increases, zener diode current increases so that
current through RL is maintained constant. The o/p voltage is given by Vo=Vi-IRL.
Procedure:
Connections are made as shown in circuit diagram. For line regulation the R L is kept constant at some
resistance values and for different values of input, the output is noted. Graphs are drawn between output voltage
and input voltage.
For load regulation, introduce an ammeter between the emitter and the variable resistance. Keep the input
voltage at 10V.For different values of R L measure the output current and voltage. Graphs are drawn between
output voltage and load current.
Design:
Vo = 6.8V,IL = 20mA, η = 71.5%
Let
Vo = Vz
RL = Vo/IL
RL = ?
Rb = (Vin – Vz)/IL
Rb = ?
Circuit Diagram
Pin Diagram
Symbol
Model Graph:
Load Regulation
Tabulation:
Line Regulation
RL=
Vi(volts)
ohms
Vo(volts)
Load Regulation
RL (Ω)
Vin =
IL (mA)
volts
Vo (V)
Result:
The regulation characteristics of a series voltage regulator are drawn.
CHARACTERISTICS OF SHUNT VOLTAGE REGULATOR
Expt.No:5
Aim:
To study the characteristics of zener voltage regulator.
Apparatus Required:
1.
2.
3.
4.
5.
Regulated Power Supply RPS (0-30) V
Zener diode
Resistor 1 KΩ
Voltmeter(0-10) V
Ammeter(0-30) mA
Theory:
A power supply consists of transformer and filter. But such a simple system suffers the following defects.
1. Output voltage fluctuates as input changes due to the fluctuation in DC load current.
2. Temperature coefficient of the device causes the change.
The power supply will have better regulation if all the above factors are kept at minimum values.
Consider the Zener shunt regulator shown in the diagram. Since the diode is connected in parallel the circuit
is called the shunt regulator. A resistance is connected in series to limit the current in the circuit. Here R s is
known as the current limiting resistor. For proper operation in reverse break down region, Vin must be
greater than the zener voltage Vz.
1. Varying input voltage:
As the input voltage increases the current also increases. As long as Vin > Vz. the output voltage is constant.
Since Vz. and Rl are fixed IL remains constant. As Is increases, Iz also increases. The value of Rs is chosen
such that Iz does not increase beyond the maximum value.
As input voltage reduces, Is reduces that in turn reduces IsRs . As long as Vs > Vz., VL remains constant. Since
IL is fixed, as Is reduces so that Iz reduces. Rs is chosen such that the current Iz is not below the minimum rated
value so as to keep it in breakdown region.
2. Varying Load Resistance:
As RL increases the load current reduces. This causes Iz to increase. So the value of IS and IS Rs remains
constant. Thus VL is constant.
3. Optimum value of Rs:
The value of Rs must be properly selected to fulfill the following requirements .
1. When input voltage and load current is maximum, sufficient current must be supplied to keep the zener
diode in the breakdown region.
2. The input voltage is maximum and load current is minimum, Zener current must not increase above the
maximum rated value.
Procedure:
1. The circuit connections are made as per the circuit diagram.
2. The input voltage is varied within the limits and the corresponding output voltage is noted down by
keeping RL constant.
3. Similarly the value of RL is varied and the output voltage is noted down by keeping V in
constant. It is noted that the output voltage is constant with respect to input.
Design:
Given:
VS= 16V,VZ = 6.2V,IS = 10mA
Is = (VS - VZ)/RS
RS= ?
Circuit Diagram:
Pin Diagram
Symbol
Model Graph:
Load Regulation
Tabulation:
Line Regulation
RL
= -------- ohms
Vin (V)
Load Regulation
Vin = ------- Volts
RL (Ω)
Result:
Thus the shunt voltage regulator characteristics are studied.
Vout (V)
Expt.No:6
DESIGN AND TESTING OF RC COUPLED TRANSISTOR AMPLIFIER
Aim:
To design a RC coupled amplifier and to plot its frequency response characteristics and to calculate
the gain bandwidth product.
Apparatus Required:
1. Transistor 2N3904
2. Resistors – 120KΩ ,56KΩ ,4.7KΩ ,12KΩ.
3. Capacitors – 0.33µF(2 nos.),470µF
4. Regulated Power Supply (RPS) - (0-30) V
5. CRO
6. Audio Frequency Oscillator (AFO).
Theory:
The RC coupled amplifier is the most popular type of coupling, because it is cheap and provides
excellent audio fidelity over a wide range of frequencies. It is usually employed for voltage
amplification. A coupling capacitor is used to connect the output of first stage to the base of the next
stage and so on. As the coupling from one stage to another stage is achieved by a coupling capacitor
followed by a connection of shunt resistor .This amplifier is called as resistance capacitance coupled
amplifier.
When AC signal is applied to the base of the first transistor, it appears in the amplified form across
its collector load. The amplified signal developed across RC is given to base of the next stage through
the signal. In this way the cascaded stages amplify the signal of low and high frequencies where it is
uniform over mid frequency range.
Design:
The voltage gain of the circuit is Av = hfe (Rc || Rf ) / hfe.
1. For large voltage gain hfe must be high. Therefore Ic will be high. Then Rc will be low. Therefore Av
again reduces.
2. To increase Av if Rc increased, Ic decreases. But a minimum Ic of 500μA is necessary for small
signal operation. Therefore Ic=1mA mostly.
3. Thus for given I c for large Rc,VRC increases ,Vce & Ve decreases. But Vce
should be atleast 3V to ensure that transistor operates in active region.
4. Select Rc<<< RL because RL should have little effect on Av of the circuit.
5. Minimum Ve=5V for good bias stability.
When Vcc = 10V, Ve = 3V (when Vcc <3V it results in poor stability)
Vcc = VRC+Vce+Ve ;
RC = VRC/Ie
Re = Ve / Ic (since Ic=Ie)
BIAS RESISTOR:
Select I2 = Io /10 gives good bias stability
R2 = Vb/ I2
R1 =( Vcc – Vb) / (I2 + Ib)
BY PASS CAPACITORS:
The circuit’s lower 3 dB frequency is determined by C2,
1 /(2*π*f1 *C2) = hfe / ( 1 + hfe) from which C2 can be found.
SHUNTING CAPACITOR:
The circuit’s higher 3 dB frequency is set by including a small capacitor to shunt the output
terminals to ground.
1 /(2*π*f2 *C4)-Re//RL
From which C4 can be found.
COUPLING CAPACITOR:
V1-V2/(Xc2+Z1)*ZL if Xc2 increases, V1 decreases.
Therefore choose Xc1=Z1 /10.
Vo-Vc/(Xc3+RL)*RL, if Xc3 increases, V2 decreses.
Therefore choose Xc3 = RL/10.
Procedure:
1. Connections are made as per the circuit diagram.
2. The input voltage Vin is initially kept constant at a particular values say 0.04volt.
3. By slowly varying the frequency range from a low value say 100Hz to a high valve say 100 Khz,
the corresponding values of the output voltage Va are noted down and tabulated.
4. The gain in db is then calculated using the formula 20 log V o/Vin.
5. A graph is plotted with gain in db along Y axis and frequency along X axis in a semilog sheet.
Pin Diagram
Symbol
Circuit Diagram:
Model graph:
Tabulation:
Vin=-----------volt
S.No
Frequency(Hz)
Vo(Volts)
Gain=Vo/Vin
Gain in dB
Model Calculation:
Calculation of bandwidth:
Bandwidth = (f2 – f1) Hz.
Result:
The frequency response of the RC coupled amplifier is thus obtained.
Band Width - -------------HZ
Expt.No:7
DESIGN AND TESTING OF EMITTER FOLLOWER
Aim:
To design an emitter follower circuit and study the frequency response.
Apparatus Required:
1.
2.
3.
4.
5.
6.
7.
Power Transistor T1 (BC547)
Switching transistor T2 (SL100)
Resistors – 220KΩ ,47KΩ ,270Ω
Capacitors – 0.33µF(2 nos.)
FET voltmeter, Multimeter
Regulated Power Supply (RPS) - (0 – 30)V
Audio Frequency Oscillator (AFO).
Design:
The Darlington emitter follower is an example of DC multistage amplifier. The ideal combination
of discrete transistors for Darlington pair consists of a power transistor driven by low or medium power
transistor. The circuit considered consists of cascaded emitter followers resulting in high input
impedance. Consider the Darlington pair emitter follower formed by connecting two discrete transistors
namely 2N 3904 and 2N 3055 or BC147 and SL100.
1. The following ratings are noted down for both the transistors.
a. Small signal current gain hfe and its corresponding Vcc and Ic.
b. Maximum collector power dissipation at 25°C.
c. Collector - emitter saturation voltage and base - emitter saturation voltage.
2. Choose a value of R e such that its power rating is ( IE2)R2.
3. Now Vcc = Ic2 * Re + Vce2. Find the operating voltage of the transistor
4.Find the current through the base of the transistor T2, which is
IB2- IC2/2 (Select 2 from data Sheet)
5.Find the current through the emitter of the transistor T2,which is
IB1- IB2
6.The current through the base of the transistor T2 is same as through the
emitter of the transistor T1.which is
IB1- IC1/1- IE1/1
7.The potential at the base of T1 with respect to the ground. which is
VB1-VBE3+VBE2+IE2* Re
8.The potential at the collector of T1 with respect to the emitter of T2 is R 1
(I2/IB2) = (VCC-VB1)/R1
9.The coupling capacitors C1 and C2 are selected such that their
impedances are negligible compared with the input resistance of the
amplifier. Take 20 Hz as the value of the lowest frequency used in
finding the amplifier frequency response.
XC1=XC2=1/2FC2<<<(1*2* Re) ||R2 ||R2 .
Design:
Given:
Vcc – 12v, f – 50Hz, Ie – 1mA, hfe – 100, hie – 1K, Vbe – 0.7v,
Let R1 – 10k
Procedure:
The circuit connections were made using the computed values of the components. The RPS unit
was turned ON and its voltage level is adjusted to the value of V cc needed.AFO was switched on and its
voltage level is adjusted to a suitable value of V s. This level was maintained constant throughout the
experiment. The frequency of the oscillator was varied over its working range in suitable steps. For each
frequency setting the corresponding value of the output voltage was noted. The voltage gain A v given by
20 log (Vo / Vs) was computed for each frequency setting. The frequency response curve is plotted.
Circuit Diagram:
Pin Diagram
Symbol
SL100
Tabulation:
Vin = …………V
S.No
Frequency(Hz)
Output
Voltage(V)
Voltage
gain=
V0/Vin
Gain in dB
Model calculation:
Calculation of bandwidth: Bandwidth = (f2-f1) Hz.
Model graph:
Result:
The frequency response curve for the designed Darlington pair emitter follow amplifier was noted.
Expt.No:8
Aim:
DESIGN AND TESTING OF PUSH –PULL AMPLIFIER
To study the operation of the push amplifier.
Apparatus Required:
1.
2.
3.
4.
5.
6.
Power Transistor T 1 – ZN3904,ZN3906.
Resistors 10KΩ (2), 4.7KΩ(2).
Diodes
Audio Frequency Oscillator(AFO)
Cathode Ray Oscillator (CRO)
Regulated Power Supply (RPS) - ( 0-30 V)
Theory:
The push pull amplifier is a power amplifier frequently used in the output stage of an electronic circuit. It is
used whenever high output power at high efficiency and little distortion is required. In a class B amplifier the
collector current flows for the duration of the positive half cycle of the input signal only. In the push pull amplifier
both PNP and NPN transistors are used. So the collector current for each transistor flows for each half cycle.
Procedure:
Connections are made as per the circuit diagram. The input voltages and frequency supplied by AFO is kept
constant. A load resistance is varied and the corresponding power output is measured. The value of R L for
minimum output is measured. With the minimum value of R L obtained, the frequency is varied in steps and the
power output is measured. The frequency at which maximum power is to be determined. With R Lmax and Fmax the
input voltage from AFO is varied in steps and the corresponding power output is measured.
Circuit Diagram:
Pin Diagram
Symbol
Model graph:
Tabulation:
Vin = -------- volts
S.No
Frequency(Hz)
Vo(Volts)
Gain= Vo/Vin
Result:
The operation of the push pull amplifiers are studied.
Gain in dB
Expt.No:9
DESIGN AND TESTING OF FET AMPLIFIER
Aim:
To construct and test FET amplifier
Apparatus Required:
1. FET(BFW11)
2. Resistors – 1.5M,6.8K,100K,1M,6.8K
3. Capacitors – 0.1µF( 2 ),10µF
4. Audio Frequency Oscillator (AFO)
5. Cathode Ray Oscilloscope (CRO)
6. Regulated Power Supply (RPS) – (0-30)V.
7. Decade Resistance Box (DRB)
8. FET Voltmeter.
Theory:
FET amplifier is a low noise amplifier. It can be used as amplifier in common source mode or common
drain mode. The input signal is applied to gate. The gate is always reverse biased with respect to source.
Procedure:
The connections are made as per the circuit diagram. RPS is switched on. The input voltage is set on
the oscillator at a constant value, varying the frequency of input signal, the output amplitude is noted. The gain is
then calculated. A graph is drawn for frequency versus gain.
Circuit Diagram:
Pin Diagram
Symbol
Model Graph:
Tabulation:
Vin = ----------- Volts
S.No
Frequency (Hz)
Vo(V)
Gain=Vo/Vin
Model Calculation:
Calculation of Bandwidth:
Bandwidth = (f2-f1) Hz.
Result:
The FET amplifier was tested. The various graphs are drawn.
Gain in dB=20log (Vo/Vin)
Expt No: 10
DESIGN AND TESTING OF CLASS A POWER AMPLIFIER
Aim:
To Study the operation of the Class A Power amplifier.
Apparatus Required:
1.
2.
3.
4.
5.
6.
7.
Power Transistors (SL100)
Resistors – 560Ω ,22KΩ,120KΩ ,1KΩ ,100KΩ
Capacitors – 0.1µF,0.01µF,100µF,10µF.
Inductors 30H(DIB)
CRO
RPS (0-30V)
AFO
Theory:
The class A amplifier is a small signal amplifier that has been designed so that output voltage can vary in
response to both positive and negative inputs that is the amplifier is biased such that under normal operation the
output never saturates or ends off. In this type of amplifier the output remains in the active region during complete
cycle. This principle advantage of Class A amplifier is that it generally produces less signal distortion than some
of the other, more efficient classes.
Procedure:
Connections are made as per the circuit diagram the input voltages and frequency supplied by Audio
Oscillator is kept constant. A Load Resistance is varied and the corresponding power output is measured. The
valve of RL for maximum output is measured. With the maximum valve of RL obtained, the frequency is varied
in step and the power output is measured. The frequency at which maximum power is to be determined. With RL
max F max the input voltage from Audio Oscillator is varied in step and the corresponding power output is
measured.
Circuit Diagram
Pin Diagram
Symbol
BC107
BC107
Model graph
Tabulation:
Vin=----------volt
S No
Frequency(Hz)
V0(volts)
Result:
The operation of Class A Power amplifier is studied.
Gain=V0/Vin
Gain in dB
SPICE
(Simulation Program with Integrated Circuit Emphasis)
Electronic circuits design requires accurate methods for evaluating circuit’s performance.Because of
the enormous complexity of modern integrated circuits, computer-aided analysis is essential and can provided
information about circuit’s performance that is almost impossible to obtain with laboratory prototype
measurements.Computer-aided analysis permits.
1. Evaluating the effect of variation in elements such as resistors, transistors, transformers, and so on.
2. The assessment of performance improvements or degradation.
3. Evaluating the effect of noise and signal distortion without the need of expensive measuring instruments.
4. Fourier analysis without expensive wave analyzers.
5. Evaluating the effect of nonlinear elements on the circuit’s performance.
6. Optimizing the design of electronic circuit’s in the term of circuit’s parameters.
SPICE is a general-purpose circuits program that simulates electronic circuits. SPICE can perform various
analyses of electronic circuits: the operating (or quiescent) points of transistor, a time-domain response, a smallsignal frequency response, and so on. SPICE contains models for common circuits elements, active as well as
passive, and it is capable of simulating most electronic circuits. It is a versatile program and is widely used in
industries and universities. The acronym SPICE stands for Simulation Program With Integrated Circuit
Emphasis.
PSpice,which uses the same algorithm as SPICE and is a member of the SPICE family,is equally useful
for simulating all types of circuits in a wide range of application.
PSpice allows various types of analysis.
DC Analysis is used for circuits with time-invariant sources (e.g., steady-state dc source). It calculates all
node voltages and branch currents over a range of values, and their quiescent (dc) values are the outputs.
Transient analysis is used for circuits with time-variant sources (e.g., ac sources and switched dc sources). It
calculates all node voltages and branch currents over a time interval, and their instantaneous values are the
output.
AC Analysis is used for small-signal analysis of circuits with sources of variable frequencies. It calculates all
node voltages and branch currents over a range of frequencies, and their magnitude and phase angles are the
outputs.
Limitations of PSpice:
1. As a circuit’s simulator, PSpice
is restricted to circuits with 10 transistors only. However, the
professional DOS(or production)version can simulate a circuit with up to 2000 bipolar transistors(or 150
MOSFETs)
2. The program is not interactive; thats, the circuits cannot be analyzed for various component values
without editing the program statements.
3. PSpice does not support an interactive method of solution. If the elements of circuits are specified, the
output can be predicted. On the other hand, if the output is specified, PSpice cannot be uses to synthesize
the circuit’s elements.
4. The PC version needs 512 kilobytes of memory(RAM) to run.
5. Distortion analysis is not available in Spice. SPICE2 allows distortion analysis, but it gives wrong
answers.
6. The student version will run with or without the floating-point co-processor (8087,80287,or 80387). If the
co-processor is present, the program will run at full speed; otherwise it will run 5 to 15 times slower. The
professional version requires a co-processor; it is not optional.
Expt.No:11
SIMULATION OF HALF WAVE RECTIFIER AND FULL WAVE RECTIFIER
Aim:
To simulate a half wave and full wave rectifier circuit using PSpice.
Apparatus Required:
System with ORCAD software.
Procedure:
1. Start
Programs
2. File
New Project.
ORCAD 9.1
CIS Capture.
3.Select Analog or Mixed Signal Circuit wizard
Choose required libraries.
4.Place parts from the corresponding libraries
Wire them.
5.Create new simulation profile
Edit Simulation profile.(Choose the corresponding analysis
type).
6.Place the corresponding markers(Voltage, Current or dB magnitude probes).
7.Run the simulation and view the simulation results.
Result:
The given circuits are analysed using Pspice.
Expt.No:12
SIMULATION OF VOLTAGE REGULATORS
Aim:
To simulate a series voltage regulator and a shunt voltage regulator circuit using PSpice.
Apparatus Required:
System with ORCAD software.
Procedure:
1. Start
Programs
2. File
New Project.
ORCAD 9.1
CIS Capture.
3.Select Analog or Mixed Signal Circuit wizard
Choose required libraries.
4.Place parts from the corresponding libraries
Wire them.
5.Create new simulation profile
Edit Simulation profile.(Choose the corresponding analysis
type).
6.Place the corresponding markers(Voltage, Current or dB magnitude probes).
7.Run the simulation and view the simulation results.
Result:
The given circuits are analysed using Pspice.
Expt.No:13 SIMULATION OF TRANSISTOR BIASING CIRCUITS & RC COUPLED AMPLIFIER
Aim:
To simulate different biasing circuits for a transistor and also simulate RC coupled amplfier using PSpice.
Apparatus Required:
System with ORCAD software.
Procedure:
1. Start
Programs
2. File
New Project.
ORCAD 9.1
CIS Capture.
3.Select Analog or Mixed Signal Circuit wizard
Choose required libraries.
4.Place parts from the corresponding libraries
Wire them.
5.Create new simulation profile
Edit Simulation profile.(Choose the corresponding analysis
type).
6.Place the corresponding markers(Voltage, Current or dB magnitude probes).
7.Run the simulation and view the simulation results.
Result:
The given circuits are analysed using Pspice.
Expt.No:14
SIMULATION OF EMITTER FOLLOWER & PUSH PULL AMPLIFIER
Aim:
To simulate an emitter follower and push -pull amplifier circuit using Pspice and study their frequency
response
Apparatus Required:
System with ORCAD software.
Procedure:
1. Start
Programs
2. File
New Project.
ORCAD 9.1
CIS Capture.
3.Select Analog or Mixed Signal Circuit wizard
Choose required libraries.
4.Place parts from the corresponding libraries
Wire them.
5.Create new simulation profile
Edit Simulation profile.(Choose the corresponding analysis
type).
6.Place the corresponding markers(Voltage, Current or dB magnitude probes).
7.Run the simulation and view the simulation results.
Result:
The given circuits are analysed using Pspice.
Expt.No:15
SIMULATION OF FET AMPLIFIER & CLASS-A POWER AMPLIFIER
Aim:
To simulate FET amplifier and Class-A power amplifier using Pspice and to study their frequency response.
Apparatus Required:
System with ORCAD software.
Procedure:
1. Start
Programs
2. File
New Project.
ORCAD 9.1
CIS Capture.
3.Select Analog or Mixed Signal Circuit wizard
Choose required libraries.
4.Place parts from the corresponding libraries
Wire them.
5.Create new simulation profile
Edit Simulation profile.(Choose the corresponding analysis
type).
6.Place the corresponding markers(Voltage, Current or dB magnitude probes).
7.Run the simulation and view the simulation results.
Result:
The given circuits are analysed using Pspice.