Audio Sine and Square Wave Signal Generator using a Wavetable

Not my first publication, but my first one with some challenging engineering. I did this in my late teens and it was published in a hobby electronics magazine, "Electronics Australia".

I discovered by accident that some folk from Greece published the same ideas in a professional technical journal in 1989 (attached). If you are a scholar of such things it is interesting to compare and contrast the modes of articulation in my vernacular engineering approach with those of the academic paper.

As I review this design from the 1970's I am struck by the exotic mixture of TTL/CMOS logic/CMOS switches, transistors and opamps that were required to pull it off. Although it might seem that such techniques are obsolete, I have seen plenty of recent Arduino designs using resistor networks that have faced the same challenge of creating a function with positive and negative values from binary sources.

Q: How would I do it differently today? A: I would replace the 555 timer and TTL parts for an Arduino and use a rail to rail inverting opamp.

Interestingly the parts required are all still available and the Arduino solution would cost about the same. The main cost difference would probably be from the the two-pole multiway switches which are expensive these days.

GreekPaperdigitalsinewavegeneration.pdf655.47 KB


flip flop to drive the

flip flop to drive the switches that decide whether to use the inverted or positive half cycle of the sine wave