[sdiy] Variable waveform LFO

[Tom Wiltshire]

On 12 Jan 2007, at 20:26, Tim Parkhurst wrote:

> If you want a variable waveform under
> voltage control, then you've got your work cut out for you.

This is something I'm currently working on for my PIC-based VCLFO, as 
some of you know from our email discussions.

There isn't a lot of scope for heavy modification given the cheap 
processor I used (read 'slow') but it looks like it might be possible 
to squeeze this kind of variable "duty-cycle" (what do you call it if 
you're not talking about square waves?) out of it.
I've done some of the maths and the errors are worst at the lowest 
frequencies (where the NCO increments are smallest) but this is also 
where they will be least detectable by human perception, so I think it 
is worth a shot.

Tom