20013122-001

Electronics Devices and Circuits Lab

Lab Manuals

Department of Electrical Engineering

Session/Batch: 2020-2024
Student Name: Faryal Naeem
Roll Number: 20013122-001
Course Code: EE-235
Submitted To: Engr.Iftikhar Hussain
20013122-001

CONTENTS

1.Study Common Emitter Amplifier………………………….

2. Study the Darlington pair amplifier…………………………
3. Study Class A amplifier…………………………………….
4.Study Class B amplifier……………………………………..
5. Study Class C amplifier…………………………………...
6. Study Class AB amplifier…………………………………….
7. Study Inverting op-amp…………………………………….
8. Study Non-Inverting op-amp………………………………..
9. Study Summing op-amp…………………………………….
10. Study the Difference amplifier…………………………….
11. Study the integrator amplifier…………………………
12. Design the Monostable multivibrator……………………
13. Design the astable multivibrator…………………………
14. Design the Hartley oscillator……………………………..
15.Design the phase shift oscillator…………………………
16.Design the Voltage controller oscillator…………………
17.Design the Wein bridge oscillator………………………
18. Design the Colpitis oscillator…………………………
19.Design the light active switch……………………………..
20. Design the Instrumentation amplifier………………….
20013122-001

Experiment #1
Title:
“Study the common Emitter Amplifier”
Objective:
1. To design the CE amplifier and check the amplification of signal
2. To determine the frequency response of CE amplifier
Theory:
The common emitter amplifier is a three basic single-stage bipolar junction transistor and is used
as a voltage amplifier. The input of this amplifier is taken from the base terminal, the output is
collected from the collector terminal and the emitter terminal is common for both the
terminals. When a signal is applied across the emitter-base junction, the forward bias across this
junction increases during the upper half cycle. This leads to an increase in the flow of electrons
from the emitter to a collector through the base, hence increases the collector current. The
increasing collector current makes more voltage drops across the collector load resistor RC. The
negative half cycle decreases the forward bias voltage across the emitter-base junction. The
decreasing collector-base voltage decreases the collector current in the whole collector resistor
RC. Thus, the amplified load resistor appears across the collector resistor . The current gain of
the common emitter amplifier is defined as the ratio of change in collector current to the change
in base current.
Current gain = β = ΔIc/ ΔIb
The voltage gain is defined as the ratio of output voltage (Vout) and input voltage (VIN).

CE Amplifier Frequency Response

20013122-001

The voltage gain of a CE amplifier varies with signal frequency. It is because the reactance of the
capacitors in the circuit changes with signal frequency and hence affects the output voltage. The
curve drawn between voltage gain and the signal frequency of an amplifier is known as
frequency response.

At Low Frequencies (< FL): The reactance of coupling capacitor C2 is relatively high and
hence very small part of the signal will pass from the amplifier stage to the load.
Moreover, CE cannot shunt the RE effectively because of its large reactance at low frequencies.
These two factors cause drops off of voltage gain at low frequencies.

At High Frequencies (> FH): The reactance of coupling capacitor C2 is very small and it
behaves as a short circuit. This increases the loading effect of the amplifier stage and serves to
reduce the voltage gain.
Moreover, at high frequencies, the capacitive reactance of base-emitters junction is low which
increases the base current. This frequency reduces the current amplification factor β. Due to
these two reasons, the voltage gain drops off at a high frequency.

At mid Frequencies (FL to FH): The voltage gain of the amplifier is constant. The effect
of the coupling capacitor C2 in this frequency range is such as to maintain a constant voltage
gain. Thus, as the frequency increases in this range, the reactance of CC decreases, which tends
to increase the gain.
Apparatus:
1. Breadboard

2. Resistors

3. Capacitors

4. Connecting Wires

5. Function Generator
20013122-001

6. Power Supply

7. Proteus

Procedure:-
1. Assemble the circuit as shown in the following diagram Figure 1

2. Apply a Frequency, 5mV p-p to 10 mV p-p sinusoidal signal at the input of the transistor.

3. Connect the oscilloscope at the output of the transistor.

4. Now change the frequency of the signal first by lowering it and then increasing it.

5. We can observe the output waveform of the input signal.

Circuit Diagram:

A
BAT1
5V B
R4
R1 3.3k C
100k
C3
D

1uF
vin C2 Q1
2N1711
1uF
C1

R2 R3 10uF
100k 3.6k

Simulation Result:
20013122-001

Frequency response:

Result:
CE amplifier inverts the output waveform and has a phase shift of 180.
20013122-001

VIVA QUESTIONS:
1. How to check type of transistor (NPN or PNP) with help of multi meter?
Connect the positive lead of the multimeter to the Base (B) of the transistor and connect the
negative lead to the Emitter (E) of the transistor. If it is an NPN transistor then meter should
show a voltage drop between 0.45V and 0.9V. If it is a PNP transistor, then it should display see
“OL” (Over Limit)
2. Define current gain of the transistor in CE configuration. What is the DC
current gainyou obtain in this practical?
The current gain of a transistor in CE configuration is defined as the ratio of output current or
collector current (IC) to the input current or base current (I B). The current gain of a transistor
in CE configuration is high. Therefore, the transistor in CE configuration is used for amplifying
the current
3. Tooperate a transistor as amplifier, emitter junction is forward biased and
collector junction is reverse biased. Why?
The emitter to base junction is forward biased and the collector to base junction is reverse biased.
Forward bias on the emitter to base junction causes the electrons to flow from N type emitter
towards the bias. This condition formulates the emitter current (IE).

While crossing the P-type material, electrons tend to combine with holes, generally very few,
and constitute the base current (IB). Rest of the electrons cross the thin depletion region and
reach the collector region. This current constitutes collector current (IC).
In other words, the emitter current actually flows through the collector circuit. Therefore, it can
be considered that the emitter current is the summation of the base and the collector current. It
can be expressed as,
IE = IB + IC
4. Foramplification CEis preferred,why?
Common emitter circuit is preferred over a common base circuit in amplifiers because the
resistance of the common emitter circuit is much less than that of the common base circuit.
Also the power gain (voltage gain & current gain) in the common emitter circuit is much higher
than that in a common base circuit.
20013122-001

Experiment#2
Title:
“Design Darlington pair amplifier”
Objective:
1. To construct a Darlington pair amplifier circuit
2. To plot a frequency response
Theory:
A Darlington transistor (also known as a Darlington pair) is an electronics component made via
the combination of two BJTs (Bipolar Junction Transistor) connected in such a way that it allows
a very high amount of current gain. This is achieved through a compounding amplification,
whereby the current is amplified by the first transistor and then further amplified by the second
transistor.As this compound structure is designed from two BJTs, this transistor is also known as
“Darlington Pair”. This transistor behaves as a single unit transistor as it has only one emitter,
collector, and base. The Darlington transistor was invented by Sidney Darlington in 1953.If the
current gain of a transistor is β1 and β2, the overall current gain of Darlington pair is β1β2. The
current gain of this transistor is very high compared to the normal transistor. Therefore, this
transistor is also known as “Super Beta Transistor”. The Darlington Transistor consists of two
PNP transistors or NPN transistors connected back to back. It is a single package with a common
collector terminal for both transistors.The Emitter terminal of the first transistor is connected
with the base terminal of the second transistor. Hence, the base supply is given only to the first
transistor, and the output current is taken only from the second transistor
20013122-001

Apparatus:
1. Breadboard
2. Resistor
3. Capacitor
4. ConnectingWires
5. PowerSupply
6. Transistor
7. CRO(30MHz)
8. Proteus (for online simulation)
Procedure:
1. Connect the circuit as per the circuit diagram.
2. Set Vi 50 mv.
20013122-001

3. Keeping the input voltage constant, vary the frequency from 0 Hz to 1M Hz in regular
steps and note down the corresponding output voltage.
4. Plot the graph; Gain (dB) vs Frequency (Hz).

Circuit Diagram:

R2
10k
BAT1
12

R1 C1 Q1
BC107
680
0.1u Q2
BC107
Vin=5m & F=1M C2 C2(2)
V=0.00432225

47u
R3
15k R4
6K
20013122-001

Frequency Response

Conclusion:
The Darlington transistor pair is a very useful circuit in many applications. It provides a high
level of current gain which can be used in many power applications. Although the Darlington
pair has some limitations, it is nevertheless used in many areas, especially where high frequency
response in not needed.
20013122-001

Experiment#3

Title:
“Design the class A amplifier using NPN transistor”
Objective:
1. To check Amplification of the signal of ClassAamplifier.
Theory:
A class A amplifier is biased so that it conducts over the whole of the cycle of the waveform. It
conducts all of the time, even for very small signals, or when no signal is present. The Class A
amplifier is inherently the most linear form of amplifier, and it is typically biased to ensure that
the output from the device itself, before it is passed through a coupling capacitor or transformer,
sits at half the rail voltage, enabling voltage excursions equally either side of this central point.
This means that the largest signal can be accommodated before it hits either the top or bottom
voltage rail. Normally a class A amplifier will start to become non-linear as the signal
approaches either voltage rail, so operation is normally kept away from this situation. For the
amplifier to operate correctly in its class A condition, the no signal current in the output stage
must be equal to or greater than the maximum load current for the peak of any signal. As the
output device is always conducting this current represents a loss of power in the amplifier. In fact
the maximum theoretical efficiency that a class A amp can achieve is 50% efficiency with
inductive output coupling or just 25% with capacitive coupling. In practice the actual figures
obtained are much less than this for a variety of reasons including circuit losses and the fact that
waveforms do not normally remain at their maximum values, where the maximum efficiency
levels are achieved. Accordingly, the Class A amplifier provides a linear output with the lowest
distortion, but it also has the lowest efficiency level.
20013122-001

The output characteristics with operating point Q are shown in the figure above. Here (Ic)Q and
(Vce)Q represent no signal collector current and voltage between collector and emitter
respectively. When signal is applied, the Q-point shifts to Q1 and Q2. The output current
increases to (Ic) max and decreases to (Ic) min. Similarly, the collector-emitter voltage increases to
(Vce) max and decreases to (Vce) min.

Apparatus:
1. Breadboard
2. Resistor
3. Capacitor
4. Connecting Wires
5. Function Generator
6. Power Supply
7. Proteus(For online simulation)

Procedure:-
1. Assemble the circuit as shown in the following diagram Figure 1 2.
2. Apply a Frequency, 5mVp-p to 10 mV p-p sinusoidal signal at the input of the transistor.
3. Connect the oscilloscope at the output of the transistor.
4. Now change the frequency of the signal first by lowering it and then increasing it.
5. We can observe the output waveform of the input signal.

Circuit Diagram:
20013122-001

A
BAT1
5V B
R4
R1 3.3k C
100k
C3
D

1uF
vin C2 Q1
2N1711
1uF
C1

R2 R3 10uF
100k 3.6k
20013122-001

Conclusion:
Class amplifier is same as common emitter amplifier. it conducts over the whole of the cycle of
the waveform. It inverts the output waveform. The maximum theoretical efficiency of RC
coupled is 25% and that of transformer couple is 50%.
VIVA QUESTIONS
How to check type of transistor (NPN or PNP) with help of multimeter?
Connect the positive lead of the multimeter to the Base (B) of the transistor and connect the
negative lead to the Emitter (E) of the transistor. If it is an NPN transistor then meter should
show a voltage drop between 0.45V and 0.9V. If it is a PNP transistor, then it should display see
“OL” (Over Limit).

Define current gain of the transistor in CE configuration?

The current gain for the common-base configuration is defined as the change in collector current
divided by the change in emitter current when the base-to-collector voltage is constant.

To operate a transistor as amplifier, emitter junction is forward biased and

collector junction is reverse biased. Why?
With the base-emitter junction is forward biased and the base-collector junction is reversed
biased, the transistor can amplify voltage because the collector to emitter voltage is greater than
the base to emitter voltage and is also in between the cutoff and saturation states.

For amplification CE is preferred, why?

Common emitter circuit is preferred over a common base circuit in amplifiers because the
resistance of the common emitter circuit is much less than that of the common base circuit. Also
the power gain in the common emitter circuit is much higher than that in a common base circuit.

What is Class A power amplifier?

A Class A power amplifier is one in which the output current flows for the entire cycle of the AC
input supply.
20013122-001

Experiment#4
Title:
“Design and Study the Class B amplifier”
Objective:
1. To design the Class B amplifier
2. To observe the effect of Cross-over distortion at output waveform.
Theory:
Class B amplifier is a type of power amplifier where the active device (transistor) conducts only
for one half cycle of the input signal. That means the conduction angle is 180° for a Class B
amplifier. Since the active device is switched off for half the input cycle, the active device
dissipates less power and hence the efficiency is improved. Theoretical maximum efficiency of
Class B power amplifier is 78.5%. Since the active elements start conduction only after the input
signal amplitude has risen above 0.7V, the regions of the input signal where the amplitude is less
than 0.7V will be missing in the output signal and it is called cross over distortion. The
schematic representation of cross-over distortion is shown in the figure below. In the figure, you
can see that the regions of the input waveform which are under 0.7V are missing in the output
waveform.
20013122-001

Apparatus: -
1. Function Generator
2. Dual Trace Oscilloscope
3. NPN Transistor, 2N3904
4. PNP Transistor, 2N3906
5. Resistors
6. Proteus Software
Procedure: -
1-Connect the circuit as shown in figure for class B amplifier.
2- Connect the signal source and apply a 1 kHz sine at 5 volts peak. Look at the load voltage and
capture the oscilloscope image. There should be considerable notch or crossover distortion.
Circuit Diagram:

R1(1)

R1
10k
A

C1 Q1
B

NPN C
0.25u R2 D
10k

V1 C3
VSINE
R3
10k 20u

C2 Q2 R5
PNP 100k
0.25u

R4
10k
20013122-001

Conclusion:

We have concluded that Class-B amplifiers amplify the signal with two active devices; each
operates over one half of the cycle. Efficiency is much improved over class-A amplifiers. Class-
B amplifiers are also favoured in battery-operated devices, such as transistor radios. Class B has
a maximum theoretical efficiency of π/4 (≈ 78.5%).
20013122-001

Experiment#5

Title:
“Design Class C amplifier and study its characteristics”
Objective:
1. To design the class C amplifier
2. To observe the distortion at output wave-form
Theory:
Class C power amplifier is a type of amplifier where the active element (transistor) conducts for
less than one half cycle of the input signal. Less than one half cycles means the conduction angle
is less than 180° and its typical value is 80° to 120°. The reduced conduction angle improves the
efficiency to a great extend but causes a lot of distortion. Theoretical maximum efficiency of a
Class C amplifier is around 90%. Due to the huge amounts of distortion, the Class C
configurations are not used in audio applications. The most common application of the Class C
amplifier is the RF (radio frequency) circuits like RF oscillator, RF amplifier etc. where there are
additional tuned circuits for retrieving the original input signal from the pulsed output of the
Class C amplifier and so the distortion caused by the amplifier has little effect on the final
output. Input and output waveforms of a typical Class C power amplifier are shown in the figure
below.

Apparatus:
1. Oscilloscope
2. NPN Transistor
3. Resistors
4. proteus Software
5. inductor
6. capacitor
Procedure:
20013122-001

1. Connect all the components according to the circuit.

2. Supply Vac=5.
3. Apply DC supply=10V in between capacitor and inductor.
4. Afterwards take the output or connect oscilloscope at the output capacitors.
5. Observe the difference between input and output signals, and draw the output waveform.
Circuit Diagram:

C1(1)

L1 B
C1 100mH
10uF C

Q1
NPN R1
1k

V1 R2
VSINE 1k

Simulation Results:
20013122-001

Conclusion:
Class C amplifiers present higher efficiencies than class A, B or AB. However, their conduction
angle is very low between 0° and 180°, meaning that they conduct only a fraction of the signal.
Class C has maximum theoretical efficiency is 90%.
VIVA QUESTIONS:
What is the use of class C Amplifier?
The Class C amplifier is used in the applications like RF oscillators, RF amplifier, FM
transmitters, Booster amplifiers, High frequency repeaters and Tuned amplifiers. The main
advantage of the Class C amplifier is, it has a Lowest physical size for a given power output.
What are advantages and disadvantages of class C amplifier?
Not fit in audio applications. It creates a lot of RF interference. It is difficult to obtain coupling
transformers and ideal inductors. The dynamic range will be reduced. The Class C amplifier is
used in the applications like RF oscillators, RF amplifier, FM transmitters, Booster amplifiers,
High frequency repeaters and Tuned amplifiers. The main advantage of the Class C amplifier is,
it has a Lowest physical size for a given power output.
Why class C amplifier is called tuned amplifier?
In Modulators a high-frequency signal is controlled by a low-frequency signal. Therefore, Class
C amplifiers are also called Tuned Amplifiers. Resonant circuit load, so the resistive load is used
only for the purpose of illustrating the concept.On for only a small percentage of the input cycle.
20013122-001

Experiment#6
Title:
“Design the class AB amplifier”
Objective:
1. To design the class AB amplifier
2. To observe the output waveform
Theory:
As its name suggests, the Class AB Amplifier is a combination of the “Class A” and the “Class
B” type amplifiers we have looked at above. The AB classification of amplifier is currently one
of the most common used types of audio power amplifier design. The class AB amplifier is a
variation of a class B amplifier as described above, except that both devices are allowed to
conduct at the same time around the waveforms crossover point eliminating the crossover
distortion problems of the previous class B amplifier.The two transistors have a very small bias
voltage, typically at 5 to 10% of the quiescent current to bias the transistors just above its cut-off
point. Then the conducting device, either bipolar of FET, will be “ON” for more than one half
cycle, but much less than one full cycle of the input signal. Therefore, in a class AB amplifier
design each of the push-pull transistors is conducting for slightly more than the half cycle of
conduction in class B, but much less than the full cycle of conduction of class A.In other words,
the conduction angle of a class AB amplifier is somewhere between 180o and 360o depending
upon the chosen bias point as shown.The advantage of this small bias voltage, provided by series
diodes or resistors, is that the crossover distortion created by the class B amplifier characteristics
is overcome, without the inefficiencies of the class A amplifier design. So the class AB amplifier
is a good compromise between class A and class B in terms of efficiency and linearity, with
conversion efficiencies reaching about 50% to 60%.

Apparatus:
1. Diodes
2. Resistors
3. Transistors
20013122-001

4. Vsine
5. Capacitors
6. Ground
7. Oscilloscope
8. Proteus(for online simulation)
Procedure:
1. Connect all the components according to the circuit.
2. Supply Vac=5V.
3. Apply DC supply=10V in between capacitor and inductor.
4. Afterwards take the output or connect oscilloscope at the output capacitors.
5. Observe the difference between input and output signals, and draw the output waveform.
Circuit Diagram:

R1(1)

R1
100
A

B
Q1
NPN
C1 C

D
10u
D1 C3
1N4007
V1
VSINE 2mF
R3
C2 D2 5
1N4007
Q2
PNP
10u

R2
100

Simulation Results
20013122-001

Conclusion:
Class AB amplifiers are one of the most preferred audio power amplifier designs due to their
combination of reasonably good efficiency and high-quality output as they have low crossover
distortion and a high linearity similar to the Class A amplifier design.
20013122-001

Experiment#7
Title:
“Design the inverting operational amplifier”
Objective:
1. To design the inverting amplifier characteristics
2. To observe the inverted wave at output
Theory:
An inverting amplifier (also known as an inverting operational amplifier or an inverting op-amp)
is a type of operational amplifier circuit which produces an output which is out of phase with
respect to its input by 180o.This means that if the input pulse is positive, then the output pulse
will be negative and vice versa. The figure below shows an inverting operational amplifier
built by using an op-amp and two resistors.

;
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Apparatus:
1. IC-741
2. Bread board
3. Resistor
4. Feedback resistor
5. Ground
6. Voltage source
7. Proteus(For online simulation)
Procedure:
1. Connect the circuit as shown in the circuit diagram.
2. Use the Vsine to supply a 1 kHz 5 V to 10 v peak-to-peak sine wave input as Vin.
3. Note particularly the phase relationship between output (which is the amplifier input) and
the amplifier output.
Circuit Diagram:
20013122-001

+15

U1
A

7
3
B
6
R1 2
C
1k
D

4
1
5
741
V1
VSINE

-15

R2
10k

Simulation Results:
20013122-001

Conclusion:
In case of inverting op-amp, there are no current flows into the input terminal; also the input
Voltage is equal to the feedback voltage across two resistors as they both share one common
virtual ground source and give output as inverted waveform

VIVA QUESTIONS
What is operational amplifier?
An operational amplifier is an integrated circuit that can amplify weak electric signals. An
operational amplifier has two input pins and one output pin. Its basic role is to amplify and
output the voltage difference between the two input pins.
What is op amps used for?
In the most basic circuit, op-amps are used as voltage amplifiers, which can be broadly divided
into no inverting and inverting amplifiers. Voltage followers (also simply called buffers) are a
type of commonly used no inverting amplifiers. Op-amps are also used as differential amplifiers,
integrator circuits, etc.
What are the applications of op-amp?
Op amps are used in a wide variety of applications in electronics. Some of the more common
applications are: as a voltage follower, selective inversion circuit, a current-to-voltage converter,
active rectifier, integrator, a whole wide variety of filters, and a voltage comparator.

What is a voltage follower?

A voltage follower (also known as a buffer amplifier, unity-gain amplifier, or isolation amplifier)
is an op-amp circuit whose output voltage is equal to the input voltage (it “follows” the input
voltage)
20013122-001

Experiment#8
Title:
“Study the non-inverting operational amplifier”
Objective:
1. To study the characteristics of operational amplifier
Theory:
Non-inverting amplifier is an op-amp-based amplifier with positive voltage gain. A non-
inverting operational amplifier or non-inverting op-amp uses an op-amp as the main element.
The op amp has two input terminals (pins). One is inverting denoted with a minus sign (-), and
other is non-inverting denoted with a positive sign (+).When we apply any signal to the non –
inverting input, it does not change its polarity when it gets amplified at the output terminal. So,
in that case, the gain of the amplifier is always positive.

Apparatus:
1. Breadboard
2. 741 IC Operational Amplifier
3. Resistors
20013122-001

4. Connecting wires
5. Vsine
6. Oscilloscope
7. Ground
Procedure:
1. Connect the circuit as shown in the circuit diagram.
2. Use the Vsine to supply a 1 kHz 5 V to 10 v peak-to-peak sine wave input as Vin.
3. Note particularly the phase relationship between output (which is the amplifier input) and
the amplifier output
Circuit Diagram:

+15

U1
A
7

3
B
6
R1 2
C
V1 1k
VSINE D
4
1
5

741

-15

R2
10k

Simulation Result:
20013122-001

Conclusion:
A non-inverting amplifier produces an output signal that is in phase with the input signal

VIVA QUESTIONS:
What is an op amp circuit?
An operational amplifier is an integrated circuit that can amplify weak electric signals. An
operational amplifier has two input pins and one output pin. Its basic role is to amplify and
output the voltage difference between the two input pins.
Why we use op-amp as non-inverting amplifier?
As the input impedance is extremely high, the unity gain buffer (voltage follower) can be used to
provide a large power gain as the extra power comes from the op-amps supply rails and through
the op-amps output to the load and not directly from the input.
What is non-inverting operational amplifier?
A non-inverting op amp is an operational amplifier circuit with an output voltage that is in phase
with the input voltage.
20013122-001

Experiment#9
Title:
“Design the summing amplifier”
Objective:
1. To design the summing amplifier
2. To observe the output waveform
Theory:
The term summing amplifier is also named as adder, which is used to add two signal voltages.
The circuit of the voltage adder is so simple to construct and it enables to add many signals
together. These kinds of amplifiers are used in a wide range of electronic circuits. For instance,
on a precise amplifier you have to add a small voltage to terminate the offset error of
the operational amplifier. An audio mixer is another example to add the waveforms together
from various channels before sending the mixed signal to a recorder. 
Vout=V1+V2+V3
Apparatus:
1. Breadboard
2. 741 IC Operational Amplifier
3. Resistors
4. Connecting wires
5. Vsine
6. Ground
7. Oscilloscope
8. Proteus(for online simulation)
Procedure:
1. Connect the circuit as shown in the circuit diagram.
2. Use the sine wave to supply a 1 kHz 2 to 4peak-to-peak different sine wave inputs as Vin
3. Note particularly the summing output amplifier wave which is the sum of all inputs wave.
Circuit:
+15

R5 U1
7

1k
3
V1=2V 6
R1 2
3k
V2=3V
R2
4
1
5

741 -9.00
3k Volts

V3=4V
R3
R4
-15
3k
3k
20013122-001

+15

R5 U1

7
1k
3
A
V1=2V 6
R1 2
B
3k
V2=3V
R2 C

4
1
5
741
3k D
V3=4V
R3
R4
-15
3k
3k

Simulation result:

Conclusion:
We have concluded that summing amplifier combine the voltages present on two or more inputs
into a single output voltage.
20013122-001

Experiment#10

Title:
“Design the Difference amplifier”
Objective:
1. To design the difference amplifier
2. To study the characteristics of difference amplifier and observe the output waveform
Theory:
A differential amplifier (also known as a difference amplifier or op-amp subtracter) is a type of
electronic amplifier that amplifies the difference between two input voltages but suppresses any
voltage common to the two inputs. A differential amplifier is an analog circuit with two inputs
(V1 and V2) and one output (V0) in which the output is ideally proportional to the difference
between the two voltages. The formula for a simple differential amplifier can be expressed:

Apparatus:

1. Breadboard
2. 741 IC Operational Amplifier
3. Resistors
4. Oscilloscope
5. Connecting wires
6. Vsine
7. Proteus(for online simulation)

Procedure:
20013122-001

1. Connect the circuit diagram as shown in figure.

2. Use the Vsine to supply a 1 kHz 5 V to 10 v peak-to-peak different sine wave input as
VIN.
3. Note particularly the output wave which is difference between the inputs wave.

Circuit:

R4
10k
-15

U1
4
1
5
R1(1)
R1 2
A

10k 6
B
R2(1) 3
R2
C
10k
7

741 D

R3
10k

+15

Simulation Result:
20013122-001

Conclusion:
A difference amplifier is a special purpose amplifier designed to measure differential signals,
otherwise known as a subtracter. A key feature of a difference amplifier is its ability to remove
unwanted common mode signals, known as common mode rejection (CMR).
VIVA QUESTIONS
What are applications of difference amplifier?
Unlike most types of amplifiers, difference amplifiers are typically able to measure voltages
beyond the supply rails, and are used in applications where large dc or ac common-mode
voltages are present. They are ideal for current and voltage monitoring.

Why we use difference amplifier?

A difference amplifier is a special purpose amplifier designed to measure differential signals,

otherwise known as a subtracter. A key feature of a difference amplifier is its ability to remove
unwanted common mode signals, known as common mode rejection (CMR).

Experiment#11
20013122-001

Title:
“Design the integrator amplifier”
Objective:
1. To design the integrator amplifier and discuss its characteristics
Theory:
Operational amplifier can be configured to perform calculus operations such as differentiation
and integration. In an integrating circuit, the output is the integration of the input voltage with
respect to time. A passive integrator is a circuit which does not use any active devices like op-
amps or transistors but only passives like resistors and capacitors.An integrator circuit, which
consists of active devices, is called an Active Integrator. An active integrator provides a much
lower output resistance and higher output voltage than it is possible with a simple RC circuit.Op-
amp differentiating and integrating circuits are basically inverting amplifiers, with appropriately
placed capacitors. Integrator circuits are usually designed to produce a triangular wave output
from a square wave input.Integrating circuits have frequency limitations while operating on sine
wave input signals.

Apparatus:
1. Breadboard
2. 741 IC Operational Amplifier
3. Resistors
4. Capacitors
5. Connecting wires
6. Oscilloscope
7. Signal generator
8. Ground
9. Proteus(for online simulation)
Procedure:
1. Connect the circuit as shown in the circuit diagram.
2. Use the function generator to supply a 1 kHz 5 V to 10 v peak-to-peak sine wave input
as VIN.
3. Note particularly the output wave which is the integrating wave of the input signal.

Circuit Diagram:
20013122-001

+15

U1 A

7
B
3
6
R1 2
C

10k D
+

4
1
5
741

-
AM FM

C1
-15

1uF
Simulation Result:

Conclusion:
20013122-001

The mathematical operation “integration” can be realized by an electronic circuit called an

integrator, which is based on an operational amplifier working in inverting configuration with a
reactive component in its feedback loop.
VIVA QUESTIONS:
Why low pass circuit is called as an integrator?
At low frequencies, the LPF has finite output and at high frequencies the output is nil, which is
same for an integrator circuit. Hence low pass filter can be said to be worked as an integrator.
What are the applications of integrator?
The integrator circuit is mostly used in analog computers, analog-to-digital converters and wave-
shaping circuits. A common wave-shaping use is as a charge amplifier and they are usually
constructed using an operational amplifier though they can use high gain discrete transistor
configurations.
What is difference between differentiator and integrator?
A differentiator circuit produces a constant output voltage for a steadily changing input
voltage. An integrator circuit produces a steadily changing output voltage for a constant input
voltage.

Experiment#12
20013122-001

Title:
“Design the Monostable multivibrator using 555 timer”
Objective:
1. To design the Monostable multivibrator
2. To discuss its characteristics and observe the input and output waveforms
Theory:
A monostable multivibrator (MMV) often called a one-shot multivibrator, is a pulse generator
circuit in which the duration of the pulse is determined by the R-C network,connected externally
to the 555 timer. In such a vibrator, one state of output is stable while the other is quasi-stable
(unstable). For auto-triggering of output from quasi-stable state to stable state energy is stored by
an externally connected capacitor C to a reference level. The time taken in storage determines the
pulse width. The transition of output from stable state to quasi-stable state is accomplished by
external triggering.The width of this output pulse depends upon the RC time constant. Hence it
depends on the values of R1C1. The duration of pulse is given by
T=0.69R1C1
The schematic of a 555 timer in Monostable mode of operation is shown in figure.

Material Required:
1. Resistor
2. Capacitor
3. 555 timer
4. Oscilloscope
5. LED
6. Power supply
7. Proteus
Procedure:
1. Firstly select 555 timers from proteus library.
2. Make connections of resistors, capacitors and Vcc with the pins of 555_Timer as shown in
circuit diagram.
3. After that put values of resistors, capacitors and Vcc.
20013122-001

4. Then connect the oscilloscope at input and output terminal to observe waveformrespectively.
Circuit Diagram:
VCC

R1 B
10k
U1
C

8
R2
R3 4
R Q
3
D

VCC
10k 220
7
DC
5
CV
D1
LED-BLUE
C2

GND
0.01u 2 6
TR TH

1
555
C1
100uF

GND

Conclusion:
We can conclude that, in the Monostable multivibrator using 555 timers, the o/p stays in a low
state until it gets a trigger i/p. This type of operation is used in push to operate systems. When
the input is triggered, then the o/p will go to high state & comes back to its original state.
Experiment#13
20013122-001

Title:
“Design the astable multivibrator using 555 timer”
Objective:
1. To design the astable multivibrator
2. To discuss its characteristics and observe the output waveform.
Theory:
An Astable Multivibrator is an oscillator circuit that continuously produces rectangular wave
without the aid of external triggering. So a stable Multivibrator is also known as Free Running
Multivibrator. It has no stable states and continuously switches between the two states without
application of any external trigger. The IC 555 can be made to work as an astable multivibrator
with the addition of three external components: two resistors (R 1 and R2) and a capacitor. The
pins 2 and 6 are connected and hence there is no need for an external trigger pulse. It will self-
trigger and act as a free running multivibrator (oscillator). The rest of the connections are as
follows: pin 8 is connected to supply voltage (VCC). Pin 3 is the output terminal and hence the
output is available at this pin. Pin 4 is the external reset pin. A momentary low on this pin will
reset the timer. Hence, when not in use, pin 4 is usually tied to VCC... The control voltage applied
at pin 5 will change the threshold voltage level.

Material Required:
1. Resistor
2. Capacitor
3. 555 timer
4. Oscilloscope
5. LED
6. Power supply
7. Proteus
Procedure:
1. Firstly select 555 timers from proteus library.
2. Make connections of resistors, capacitors and Vcc with the pins of 555_Timer as shown in
circuit diagram.
3. After that put values of resistors, capacitors and Vcc.
4. Then connect the oscilloscope at input and output terminal to observe waveform respectively.
20013122-001

Circuit Diagram:
VCC

R1 B
1k
U1
C

8
4 3
R Q D

VCC
DC
7 R3
220
5
CV

C1 R2
2 GND 6
TR TH 2.2k
220uF D1
555
1

LED-BLUE

GND

Conclusion:
The 555 timer can be connected to run as an Astable multivibrator. When used in this way, the
555 timer has no stable states, which implies that it cannot remain indefinitely in either state.
Stated in another way, it oscillates when operated in the Astable mode and produces a Square or
Rectangular output signal.
Experiment#14
20013122-001

Title:
“Implementation of Hartley oscillator”
Objective:
1. To design the Hartley oscillator
2. To discuss its characteristics and observe the output waveform.
Theory:
A Hartley Oscillator (or RF oscillator) is a type of harmonic oscillator. The oscillation frequency
for a Hartley Oscillator is determined by an LC oscillator (i.e. a circuit consisting of capacitors
and inductors). Hartley oscillators are typically tuned to produce waves in the radiofrequency
band (which is why they are also known as RF oscillators).Hartley Oscillators were invented in
1915 by American engineer Ralph Hartley. The distinguishing feature of a Hartley oscillator is
that the tuning circuit consists of a single capacitor in parallel with two inductors in series (or a
single tapped inductor), and the feedback signal needed for oscillation is taken from the center
connection of the two inductors. Here the RC is the collector resistor while the emitter resistor RE
forms the stabilizing network. Further the resistors R1 and R2 form the voltagedivider
bias.Network for the transistor in common-emitter CE configurationon acquiring the maximum
charge feasible, C starts to discharge via the inductors L1 and L2. These charging and discharging
cycles result in the damped oscillations in thetank circuit.The oscillation current in the tank
circuit produces an AC voltage across the inductors L1 and L2 which are out of phase by 180o as
their point of contact are grounded.

Material required:
1. Proteus software.
2. BC547.
3. Capacitors.
4. DC supply.
5. Resistors.
6. Inductors.
7. Oscilloscope.
Procedure:
1. Select NPN transistor from proteus library.
20013122-001

2. Now make connections of resistors, capacitors, inductors and Vcc with the NPN as shown in
circuit diagram.
3. Now set the values of resistors, capacitors, inductors.
4. At last, connect the oscilloscope at output terminal to observe outputWaveformrespectively.
Circuit Diagram:
R1(1)

R3
R1 3.6k
10k
C1
L1 A
5mH
22uF
C3 Q1
B

NPN C
22uF
D
C4
1uF

R2
4.7k
R4
2.7k C2 L2
10uF 3mH

Conclusion:
It is used to produce a sine wave of desired frequency. Mostly used as a local oscillator in radio
receivers. It is also used as R.F. Oscillator.
20013122-001

Experiment#15

Title:
“Implementation of phase shift oscillator”
Objective:
1. To design the phase shift oscillator
2. To discuss its characteristics and observe the output waveform
Theory:
Phase shift oscillators are the oscillators that generate a stable sinusoidal signal at the output.
Basically, the circuit has, an amplifier unit like transistor or op-amp along with a feedback
network comprising of resistors and capacitors. Thus, is also known as RC phase shift
oscillator.The RC network is present in the feedback path is connected in ladder fashion thus also
known as ladder RC phase shift oscillator. We know for an RC circuit; the output voltage leads
the input for a sinusoidal waveform. The amplifier circuit generates a phase shift of 180⁰. So, in
order to achieve sustained oscillations, in RC phase shift oscillator, the feedback path must also
provide a phase shift of 180⁰. Thus the achieved overall phase shift can be either 0 or 360⁰. Also,
loop gain equal to 1 can be achieved by tuning the gain of the amplifier and feedback circuit.

Material Required:

1. Resistor
2. Capacitor
3. Transistor
4. Proteus
5. Power supply

Procedure:

1. Select NPN transistor from proteus library.

2. Now make connections of resistors, capacitors and Vcc with the NPN as shown in circuit
diagram.
3. Now set the values of resistors, capacitors.
20013122-001

4. At last, connect the oscilloscope at output terminal to observe outputWaveformrespectively.

Circuit Diagram:
R3(1)

R3 A
1k
R1 B
1k
C

D
C3 C2 C1 Q1
NPN
1uF 1uF 1uF

R6
1k R5
1k

R2 R4 C4
1k 1k 22uF

Conclusion:
Phase shift oscillator is used to generate the signals over an extensive range of frequency. They
used in musical instruments, GPS units, & voice synthesis. The applications of this phase shift
oscillator include voice synthesis, musical instruments, and GPS units.
20013122-001

Experiment#16

Title:
“Implementation of voltage controller oscillator”
Objective:
1. To design the voltage controller oscillator
2. To discuss its characteristics and observe the output waveform
Theory:
A voltage-controlled oscillator (VCO) is an electronic oscillator whose oscillation frequency is
controlled by a voltage input. The applied input voltage determines the instantaneous oscillation
frequency. Consequently, a VCO can be used for frequency modulation (FM) or phase
modulation (PM) by applying a modulating signal to the control input. A VCO is also an integral
part of a phase-locked loop. VCOs are used in synthesizers to generate
a waveform whose pitch can be adjusted by a voltage determined by a musical keyboard or other
input. A voltage-to-frequency converter (VFC) is a special type of VCO designed to be very
linear in frequency control over a wide range of input control voltages. A voltage-controlled
oscillator (VCO) is a key component in both wireless and wire line communication systems. For
RF applications as in wireless communication systems, the local oscillator is an essential
component to provide a local carrier to the mixer for up- or down-conversion. VCO is
predominantly employed as the local oscillator for such applications, either as a free-running
circuit or as part of a PLL. Local oscillators should meet stringent phase noise requirement to
avoid the reciprocal mixing, or spectral overlap between two adjacent frequency-converted
signals. To reduce the phase noise, it is important to have high-performance devices besides
optimized circuit design. As it is well known that the phase noise is highly correlated with the
1/f noise.

Material Required:

1. Resistor, Variable resistor

2. Capacitor
3. Voltage controller
4. Proteus
5. Power supply

Procedure:
20013122-001

1. Select VCO from proteus library.

2. Now make connections of resistors, capacitors and Vcc with the VCO as shown in
circuit diagram.
3. Now set the values of resistors, capacitors.
4. At last, connect the oscilloscope at output terminal to observe output Waveform
respectively.

Circuit Diagram:

R2 R1 U1 D
2.2k 4.7k 8
C1
B1 V+
12V 5 3
CTRL SQR
0.01uF 6
RT
7 4
RV1 CT TRI
GND
R4
C2 R3 10k
1 LM566CN
47uF 10k

10k

Conclusion:

Voltage controller is used to produce an output signal whose frequency varies with the voltage
amplitude of an input signal over a reasonable range of frequencies
20013122-001

Experiment#17

Title:
“Implementation of wein-bridge oscillator”
Objective:
1. To design the wein-bridge oscillator
2. To observe the output waveform
Introduction:
One of the simplest sine wave oscillators which use a RC network in place of the conventional
LC tuned tank circuit to produce a sinusoidal output waveform is called a Wien Bridge
Oscillator. The Wien Bridge Oscillator is so called because the circuit is based on a frequency-
selective form of the Wheatstone bridge circuit. The Wien Bridge oscillator is a two-
stage RC coupled amplifier circuit that has good stability at its resonant frequency, low distortion
and is very easy to tune making it a popular circuit as an audio frequency oscillator but the phase
shift of the output signal is considerably different from the previous phase shift RC Oscillator.
The Wien Bridge Oscillator uses a feedback circuit consisting of a series RC circuit connected
with a parallel RC of the same component values producing a phase delay or phase advance
circuit depending upon the frequency. At the resonant frequency ƒr the phase shift is 0o

Material Required:
1. Proteus software
2. Op-amp 741
3. Resistor
4. Capacitor
5. Oscilloscope
6. Power supply
Procedure:
1. Select op-amp from proteus library.
2. Now make connections of resistors, capacitors and Vcc with the op-amp as shown in
circuit diagram.
3. Now set the values of resistors, capacitors.
4. At last, connect the oscilloscope at output terminal to observe output Waveform
respectively
20013122-001

Circuit Diagram:

R3 C2

10.2k
U1(V+) 1u
A

B
U1
C

7
3
D
6
R1 C1 2
1k 1u

4
1
5
741

R4
100k

R2
47k
U1(V-)

Conclusion:

The Wien Bridge is one of many common bridges. Wien's bridge is used for precision
measurement of capacitance in terms of resistance and frequency. It was also used to measure
audio frequencies.
20013122-001

Experiment#18

Title:
“Implementation of colpitis oscillator”
Objective:
1. To design the colpitis oscillator
2. To observe the output waveform
Introduction:
In many ways, the Colpitis oscillator is the exact opposite of the Hartley Oscillator. Just like the
Hartley oscillator, the tuned tank circuit consists of an LC resonance sub-circuit connected
between the collector and the base of a single stage transistor amplifier producing a sinusoidal
output waveform.The basic configuration of the Colpitis Oscillator resembles that of
the Hartley Oscillator but the difference this time is that the center tapping of the tank sub-circuit
is now made at the junction of a “capacitive voltage divider” network instead of a tapped
autotransformer type inductor as in the Hartley oscillator.The Colpitis oscillator uses a capacitive
voltage divider network as its feedback source. The two capacitors, C1 and C2 are placed across
a single common inductor, L as shown. Then C1, C2 and L form the tuned tank circuit with the
condition for oscillations being: XC1 + XC2 = XL, the same as for the Hartley oscillator circuit.
The advantage of this type of capacitive circuit configuration is that with less self and mutual
inductance within the tank circuit, frequency stability of the oscillator is improved along with a
more simple design. As with the Hartley oscillator, the Colpitis oscillator uses a single stage
bipolar transistor amplifier as the gain element which produces a sinusoidal output.

Apparatus:
1. Proteus software
2. transistor
3. Resistor
4. Capacitor
5. Oscilloscope
6. Power supply
7. Inductor
Procedure:
1. Select transistor from proteus library.
2. Now make connections of resistors, capacitors, inductor and Vcc with the transistor as
shown in circuit diagram.
3. Now set the values of resistors, capacitors, and inductor.
20013122-001

4. At last, connect the oscilloscope at output terminal to observe output Waveform

respectively

Circuit diagram

Conclusion:

Colpitis oscillator can generate sinusoidal signals of very high frequencies. It can withstand high
and low temperatures. The frequency stability is high. Frequency can be varied by using both the
variable capacitors.
20013122-001

Project#1

Title: “Make the light activated switch”

Objective:
1. To make the light activated switch
Theory:
Dark sensor is also known as automatic street light sensor. It is a simple and powerful concept,
which uses transistor as a switch to switch ON and OFF the street light system automatically. It
automatically switches ON lights when the sunlight goes below the visible region of our
eyes.Dark sensor works in the way that then the LDR comes to the darkness, or in other words, if
no light falls on it, the transistor turns on. Then transistor turns on, it lets the current flow
through it and also the right branch of the circuit is now active. LED starts emitting.
Apparatus:
1. Resistor
2. LED
3. Diode
4. Transistor
5. LDR
6. Relay
7. Op-amp
Procedure:
1. First of all connect the negative pin of op-amp in between terminals of LDR and resistor
2. Secondly connect the positive pin op-amp in between terminal of two resistors which are
in parallel.
3. Connect 11 and 4 pin with power supply.
4. Connect the output of op-amp with the three resistors, one resistor that is connecting with
the base of transistor, one with the resistor that is grounded and one with feedback
resistor.
5. Connect the collector with diode and relay and then relay with LED while emitter is
grounded.
Circuit Diagram

R3
1

10k R6 RL1
LDR1 D1 12V
TORCH_LDR 10k 1N4148

BAT1
12V
2

U1:A
4

3
R1 Q1 L1
1 2N3866
2 12V
1k
11

LM324
R5 R4
20k 10k R2
10k

Conclusion: We have made a light activated switch and it is successfully running.

20013122-001

Project#2

Title: “Design the instrumental amplifier”

Objective:
1. To make the instrumental amplifier
Theory:
An instrumentation amplifier allows an engineer to adjust the gain of an amplifier circuit without
having to change more than one resistor value. An instrumentation amplifier (sometimes
shorthanded as in-amp or In Amp) is a type of differential amplifier that has been outfitted with
input buffer amplifiers, which eliminate the need for input impedance matching and thus make
the amplifier particularly suitable for use in measurement and test equipment. Additional
characteristics include very low DC offset, low drift, low noise, very high open-loop gain, very
high common-mode rejection ratio, and very high input impedances. Instrumentation amplifiers
are used where great accuracy and stability of the circuit both short- and long-term are required.

Apparatus:
1. Op-amplifier
2. Resistor
3. Power supply
4. Oscilloscope
Procedure:
1. Take three op-amps; connect their 4th and 7th pin with negative and positive power supply
respectively.
2. Make connections of Resistors as the circuit given above
3. Connect the oscilloscope at inputs and output to observe the output waveform.
20013122-001

Circuit Diagram:

U1(V+)
R6
10k

U1
U1(POS IP)

7
3 U3(V+)
6
2
A

R4 B

4
1
5
741
R1 5k U3 C
10k

7
D
3
6
2
R2 R5
5k

4
1
5
5k 741 +88.8
U1(V-)

Volts

U2(V-)
R7
10k

U3(V-)
U2(POS IP) U2 R3
10k
4
1
5

2
6
3
7

741
U2(V+)

Conclusion:
Instrumentation amplifiers have uses in nearly every field of electronics; they fulfill a specific
role in circuits needing the advantages of high input impedance with good gain while providing
common mode noise rejection and fully differential inputs.