Presentation on DESIGN AND CONSTRUCTION OF FUNCTION GENERATOR TO GENERATE SQUARE, TRIANGULAR, SINE, PULSE TRAIN, FM AND AM WAVES
A function generator is a instruments that delivers a choice of different waveforms whose frequency are adjustable over a wide range. The most common output waveforms are sine, square, triangular, pulse-train wave’s .The frequency of the waveforms may be adjusted from a fraction of a 10Hz to several hundred kHz.
Objectives
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Design and construction of a square wave generator with minimum distortion.
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Design and construction of a triangle wave generator with minimum distortion.
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Design and construction of a sine wave generator with minimum distortion.
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Design and construction of a pulse train generator with minimum distortion.
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Design and construction of a complete function generator using IC with minimum distortion.
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Design and construction of AM modulator with minimum distortion.
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Design and construction of a FM modulator with minimum distortion.
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Performance and cost analysis.
Methodology
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Study about the different types of signal.
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Study about the different types of function generators.
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Study about the theory/operation of the different types of function generators.
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Design about the different types of function generators.
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Construction and performance test of a function generator.
DESIGN AND CONSTRUCTION OF DISCRETE FUNCTION GENERATOR
Block Diagram
Square wave generator
Circuit diagram
Output wave shape
Results
Calculated value
W=0.693(R1+R2) C =0.693(20k+1k) 0.1µF =1.455ms
T=0.693(R1+2R2) C =0.693(20k+2k) 0.1µF =1.5ms
f =1.44 / (R1+2R2) =655Hz.
Experimental Value
T = 1.4ms
f = 714Hz
Vm = 1.15v (p-p)
Triangular wave generator
Circuit diagram
Output wave shape
Results
Calculated value
P=PR/R=2.8
Frequency of oscillation is given by,
f=P/4RC=800Hz.
T=1.25ms
Experimental Value
T =1.3ms
f =769Hz
Vm = 0.5v (p-p)
Sine Wave Generator
Circuit diagram
Output wave shape
Results
Calculated value
The frequency of oscillation of RC Phase Shift Oscillator is given by ,
f =1/(2πRC*6^0.5)=628Hz.
T=1.59ms
Experimental Value
f=625Hz
T=1.6ms
Vm = 0.4v (p-p)
Pulse train wave generator
Circuit diagram
Output wave shape
Results
Calculated value
W=0.693R1C1 =69.3µs
T=W+0.693(R2+R3) C1 =1.12ms
f =1/T =890Hz.
Experimental Value
W=75µs.
T=1.2ms.
f=1/T=830Hz
Vm=1.2v (p-p).
DESIGN AND CONSTRUCTION OF MICROCONTROLLER BASED FUNCTION GENERATOR
Circuit diagram
Output wave shapes
Frequency range
1Hz-80kHz
1Hz-10kHz
1Hz-1kHz
1Hz-100Hz
DESIGN AND CONSTRUCTION OF MODULATORS
Frequency Modulator
Circuit diagram
Output wave shape
Result
Frequency of modulating signal, fm = 1kHz
Frequency of carrier signal, fc = 20kHz
Maximum modulated frequency, f(max) = 4.76kHz
Minimum modulated frequency, f(min) = 2.86kHz
The frequency deviation, ∆f = 1.90kHz
Modulation index, m = 1.90
Amplitude of the FM modulated wave, Vfm = 10v(p-p)
Average carrier Power, Pc = 1w
Total power of the modulated wave, Pt = Pc = 1w
AM modulator
Circuit diagram
Output wave shape
Results
Peak amplitude of the modulating waveform voltage, Vm =10v (p-p)
Peak amplitude of the carrier signal voltage, Vc = 10v (p-p)
Frequency of modulating signal, fm = 300Hz
Frequency of carrier signal, fc = 10 kHz
Modulating index, M = 1
Carrier power, Pc = 1w
Total power, Pt = 1.5w
CONCLUSION
To design, construct and performance test of function generator is the basic purpose of our project. Our project work is already completed. The constructed circuit is very nicely working. It can be used to test and align all types of transmitters and receivers, to measure frequency and to generate a signal, waveform or noise source. Signal generators can use AC energy, audio frequency (AF) and radio frequency (RF) to function. They are generally used in designing, testing, troubleshooting, and repairing electronic or electro acoustic devices. By studying books, searching internet, discussing with our teacher we got an idea about the work.
Submitted By Amirul Islam and Abdullah Al Mamun
