DESIGN AND IMPLEMENTATION OF LOW COST DIGITAL FUNCTION GENERATOR

Presentation on DESIGN AND IMPLEMENTATION OF LOW COST DIGITAL FUNCTION GENERATOR

Objective

Designing a high performance function generator.

Automatic control of frequency range.

Low cost function generator.

Construction of designed function generator using the resources and lab of EEE department.

Why use Function Generator?

Measurements of AC gain at different frequencies.

Examination of the transient response.

Assessment of the overload margin of an amplifier.

Low levels distortion measurements.

Why use digital Function Generator?

Digital measurement of frequencies is possible.

Less harmonic distortion.

Automatic control of range selection.

Higher frequency range is possible.

No deviation between generated frequency & measured frequency.

Circuit diagram of generating wave

Functional diagram of ICL8038

The symmetry of the waveforms adjusted with the external resistor R512 & R511.

Frequency = 1/{ R512×C/0.66 (1 + R511/ (2R512-R511)}.

If R512=R511=R then 50% duty cycle is achieved.

Frequency of the waveform is a direct function of the DC voltage at pin 8.

Automatic control of range selection by a summing amplifier.

Circuit arrangement of summing amplifier

Interfacing keypad with microcontroller

Programming the microcontroller

Wave observation

Frequency response for different waves

Cost analysis

Range of frequencies vs. Price

Limitation

1. Can not generate wave well at high frequency (above 65KHz).
2. Below 10Hz triangular wave get distorted.
3. Above 50 KHz small tilt produce in square wave.
4. Bandwidth limitation.
5. Unavailability of components.

Conclusion

While constructing the device we face lots of problem. But we tried to give our best. We believe that our designed function generator will be useful for laboratory work.

Submitted by Surajit Das Barman and Riman Das