Electric Circuits Experiment No 8 Session: 2016
DEPARTMENT OF ELECTRICAL ENGINEERING
Electric Circuits
Lab Manual
Experiment No 8
Dr. Syed Shah Irfan Hussain Umer Shahid
Assistant Professor Lecturer
Student Name: ____________________________________________
Registration Number: ____________________________________________
Section: ____________________________________________
Important Instructions
Every student should have lab manual in the lab; otherwise there will no evaluation
and attendance.
Every student should fill his/her own manual in the lab complete in all respects,
otherwise there will be deduction of marks, and no excuse will be accepted.
Student should read the manual before coming to the lab.
Waveforms should be made with pencils preferably and should be on proper scale.
Plot at least two cycles of each waveform.
Familiarize yourself with any software for circuit simulation like LT spice, Multisim
or Proteus
UNIVERSITY OF ENGINEERING AND TECHNOLOGY, LAHORE
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Electric Circuits Experiment No 8 Session: 2016
Experiment No 8
Introduction to Operational Amplifier (OP AMP) Voltage Follower and
Non-inverting Amplifier circuits
Objective:
In this experiment we will be able to achieve following advantages
1. Hands on experience to implement a practical AC electric circuit using Op-Amp on a
breadboard.
2. To use how to implement Op AMP as Voltage follower
3. To use how to implement Op AMP in Non-inverting configuration
Apparatus:
Resistors(Use resistor of standard value available in the Lab)
Breadboard
Op-amp LM741
Signal Generator
CRO
Theoretical Background
Read out uses of op-amp as voltage follower and non-inverting amplifier from CH4 of your book.
Download datasheet of op-amp IC 741 from this link http://www.ti.com/lit/ds/symlink/
lm741.pdf and read its features before coming to the lab. An operational amplifier (often op-amp
or opamp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and,
usually, a single-ended output. In this configuration, an op-amp produces an output potential
(relative to circuit ground) that is typically hundreds of thousands of times larger than the potential
difference between its input terminals. Operational amplifiers had their origins in analog
computers, where they were used to perform mathematical operations in many linear, non-linear
and frequency-dependent circuits. The popularity of the op-amp as a building block in analog
circuits is due to its versatility. Due to negative feedback, the characteristics of an op-amp circuit,
its gain, input and output impedance, bandwidth etc. are determined by external components and
have little dependence on temperature coefficients or manufacturing variations in the op-amp itself.
Op-amps are among the most widely used electronic devices today, being used in a vast array of
consumer, industrial, and scientific devices. Op-amps may be packaged as components, or used as
elements of more complex integrated circuits. Fig.1 shows the 8-DIP package of a 741 Type OP-
AMP with its terminals labeled.
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Electric Circuits Experiment No 8 Session: 2016
Fig.1: Pin configuration of Op-Amp LM741
Important Note:
Strictly follow the lab instructions while using signal generator, CRO and operation amplifier for
proper usage and working.
Laboratory Tasks
1) Calibrate both of the channels of CRO as instructed in the lab.
2) Build the circuit shown in Fig. 2 on your breadboard. This is a voltage divider. It will be
connected to a voltage follower circuit shown in Fig. 2a. Voltage division works only if no
current is drawn from the nodes. A voltage follower connected to the voltage divider draws no
current. (1)
3) Connect the non-inverting terminal, V+, of the voltage follower to nodes a, b, c, d of the
voltage divider and measure the output voltage. Also measure I1 and I2 and find I+. Record the
results in Table 1. (2)
4) Connect the circuit as shown in Fig. 4 on your breadboard. This is called a non-inverting
configuration. Measure the output for following input voltages. Remember that terminals 7 and
4 have to be connected to + 12V and 12V respectively. (1)
5) Provide a 1V pk-pk sinusoidal signal of 1kHz frequency at the input of the circuit and observe
the input and output of the circuit at the screen. (1)
6) Calculate its gain and phase difference between the output and input signals. Change the value
of Rf=3.3 k from 1k to 10k and observe the effect of resistance on the gain of amplifier,
phase difference . Note down the value of output peak-to-peak value, gain and phase of the
output at different values of Rf in Table 3. (2)
7) Plot the input and output waveform on your manuals for the highest gain. (1)
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Electric Circuits Experiment No 8 Session: 2016
Observations & Calculations:
Table 1
V+ Vout I1 I2 I3
Va
Vb
Vc
Vd
Table 2
Rf (K) Vin Vout Gain Phase
1
1.5
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Electric Circuits Experiment No 8 Session: 2016
2.7
3.3
4.3
5.6
7.5
10
Plot of input and output of OP AMP in non inverting configuration as seen on the oscilloscope for
the highest gain (1)
Laboratory Report (To be submitted next week)
Q1 Comments on the results in Table 1 by comparing theoretical with practical results (2)
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Electric Circuits Experiment No 8 Session: 2016
Q2 Comment on the results in Table 2 by comparing theoretical with practical results (2)
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