ELECTRONICS (ETEN1000)
Department of Electrical and Computer Engineering
Laboratory 6
(2017: Rev.1.0)
Laboratory 6: Amplifier Design to Drive a Speaker
1.
Introduction
In this mini project, you will design and implement an amplifier with the following
specifications:




2.
Variable gain and a maximum gain of 12 dB
Input impedance greater than 30 k
Load impedance of 8-16
Input signal range 0 – 1 V pk-pk
Tasks
a) Design an amplifier to drive a very low power speaker that can have the above
specifications using an operational amplifier. Note that the gain in dB can be obtained
20
.
using
(Hint: Use lecture notes on Operational amplifiers as a guide in designing the
amplifier. You may use OPA551 operational amplifier and the data sheet can
be downloaded)
(30 Marks)
b) Select the resistors to meet the gain using standard resistor values.
(10 Marks)
c) Connect up the designed amplifier circuit on a breadboard. Use a signal generator
with a sinusoidal waveform of 1V peak to peak at a frequency of 1 kHz as a test
signal. Also, use a 1k load resistor for testing purposes. Observe the input and
output waveforms using the oscilloscope. Measure the peak to peak voltage of the
(20 Marks)
output signal and confirm the voltage gain of the amplifier.
d) Discuss the problems associated with the input and output waveforms observed.
Suggest any changes to the designed circuit. (Hint: Consider including selected
capacitors in reducing the power supply noise)
(10 Marks)
e) Implement the circuit on a Vero Board
(20 Marks)
f) Test the circuit using an audio source and a low power speaker
(10 Marks)
Report
A formal report should be submitted individually. The report should contain the
following.
All design steps
a)
b)
Full circuit schematic
c)
Test results such as the screenshots of the oscilloscope
d)
A discussion containing a reflection of your work.