Friday, May 27, 2011

Pseudo-sine generator - part 1

Here is a new project I'm working on - a pseudo-sine wave generator.  It uses a 40106 CMOS to generate a square wave, using a B100K pot to control frequency. This is the clock-in to a 4017 decade counter.  Each output of the decade counter goes through a different resistor, which all connect together to the output.  There's an additional resistor between the output and ground -- this creates a voltage divider, between whichever of the 4017's outputs is active (which will be at 9V) and ground.

If I know what I'm doing, it should create a roughly sine waveform:

So, I designed a PCB and once I etch it and build, I'll be back with part 2...




Follow-up:

Doesn't seem to work quite right:(  It definitely produces a complex waveform, with multiple frequency components.  I haven't really tried much trouble-shooting, other than making sure the resistors aren't open or shorted.  Wish I had an oscilloscope!

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