Saturday, October 3, 2015

Project Signal Generator - ICL8038

The first chip I've had success in testing is the ICL8038 Precision Waveform Generator  (I have also tested the AD9850 DDS Synthesizer - but I'll post that separately).  This chip is fairly inexpensive off of eBay (just a couple of dollars a chip).  The ICL8030 only needs a few external components (resistors, potentiometer's and capacitors) to generate a sine, triangle or square wave.

Vary stable chip (I haven't accidentally fried even 1 of them).  I have not been able to test the frequency sweep function due to some issues with my bench PSU.  Using the test circuits presented in the datasheet I was able to produce sine, triangle and square waves.
Sine wave

Triangle Wave

Square wave

Datasheet Test Circuit

Formula for determining resistor and capacitor  values
Frequency range is ultimately determined by the capacitor value, so it would be necessary to be able to change  values for different ranges.  You are able to sweep through frequencies by varying input voltages across pins 7 and 8.

Current ranges at pins 4 and 5 are set by the resistor values Ra and Rb and need to fall within the range of 0.01mA to 1mA (so resistor values depend on supply voltage - I'm using 12v so my range is 2.6k to 260k).