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**

- Design and construction of a square wave generator with minimum distortion.
- Design and construction of a triangle wave generator with minimum distortion.
- Design and construction of a sine wave generator with minimum distortion.
- Design and construction of a pulse train generator with minimum distortion.
- Design and construction of a complete function generator using IC with minimum distortion.
- Design and construction of AM modulator with minimum distortion.
- Design and construction of a FM modulator with minimum distortion.
- Performance and cost analysis.

**Methodology**

- Study about the different types of signal.
- Study about the different types of function generators.
- Study about the theory/operation of the different types of function generators.
- Design about the different types of function generators.
- 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 =1.455msT=0.693(R1+2R2) C =0.693(20k+2k) 0.1µF =1.5msf =1.44 / (R1+2R2) =655Hz.

Experimental Value

T = 1.4msf = 714HzVm = 1.15v (p-p)

**Triangular wave generator**

Circuit diagram

Output wave shape

**Results**

Calculated value

P=PR/R=2.8Frequency of oscillation is given by,f=P/4RC=800Hz.T=1.25ms

Experimental Value

T =1.3msf =769HzVm = 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=625HzT=1.6msVm = 0.4v (p-p)

**Pulse train wave generator**
Circuit diagram

Output wave shape

**Results**

**Calculated value**

W=0.693R1C1 =69.3µsT=W+0.693(R2+R3) C1 =1.12msf =1/T =890Hz.

**Experimental Value**

W=75µs.T=1.2ms.f=1/T=830HzVm=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**