more analogue additive (fwd)

[Ingo Debus]

David MOYLAN wrote:
> It helps to draw out the waves, but I'm not that good at ascii
> graphics so.  If the wave is centered about 0 volts and it is
> full wave rectified you do get a wave of twice the frequency
> f*2.  f*3 is a bit more difficult to explain but can be done with
> rectification.  It's kind of like a folding of the waveform.
> This was discussed a couple months back.  I think it was in
> relation to a Serge waveshaper module.  You can check the archive.
> Anyone else want to get a bit more detailed?

Add a dc offset to the triangle so that the positive peaks are twice as
high as the negative peaks. Then full-wave-rectify. Add a dc offset to
the result so that positive and negative peaks are of the same height
(this is not achieved by ac-coupling). Full-wave-rectify again, and you
get a triangle of 3* input frequency.

Ingo