Deluxe Function Generate

This simple project has many uses.

by David Gripe KC3ZQ

A function generator is one piece of equipment found in the Jab of nearly every electronics technician and engineer. In conjunction with an oscilloscope, a function generator can be used to test or trou-blesboot most gear found in the hamshackn Unfortunately, commercial funaion generators are priced well out of the range of most hams, and good used ones don't often appear at hamfesis, Consequently, I decided to design my own! I :iis simple, low-cost function generator features TTU square-wavcT

triangle, and sine-wave outputs, and portable battery operation.


I started out by defining the features I wanted. This project had to be low-cost, using commonly available parts, it had to be portable, operating from batteries, El needed to have a 7TL output for testing logic circuits, as well as variable-amplitude square, triangle, and sine-wave outputs. The sine wave output must be relatively pure, with the amplitude of the harmonics less than of the fundamental frequency. The frequency range of the function generator had to cover 100 hertz to 10 ktlohertz, which would include most of the audio range. After a few hours of breadboard ing 1 arrived at a circuit which met all of these requirements.

Sec Figure 1. This is a fairly simple design using only three ICs. All of the parts arc available at your neighborhood Radio Shack, or from any weII-stocked junk box.

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