Specifications: Waveform Generation: 32-bit DDS, 10-bit DAC Distortion: <1% at 1kHz Frequency Range: 1Hz to 10MHz in 1Hz steps Frequency Display: "Sliding Window" 7 digit (EEPROM frequency retention) User Input: Three push buttons Sinewave Output: 0-5Vp-p adjustable, 50 Squarewave Output: CMOS/TTL compatible, 50% duty cycle Output Connections: RCA Power: 9VAC 100mA plugpack

The 20MHz Low Cost Function Generator I described in the August 96 issue of "Electronics Australia" has proven very popular, with thousands having been built. The low cost, simple construction and wide bandwidth made it a very attractive project.

However, there were two problems with that design – the lack of a frequency display and being able to set the frequency to exactly what you wanted. To overcome these, one kit supplier bundled the function generator with another frequency counter kit.

So it is not surprising that many people have asked for an updated design with a built-in frequency display. While a frequency display would be relatively easy to add, it would add significantly to the cost and complexity of the project. In addition, the analog nature of the original design meant that temperature drift would also be an issue.

This new design overcomes these problems by adding a frequency display and digital frequency selection, while still maintaining the low-cost approach.