[sdiy] High frequency VCO designs

[Tom Wiltshire]

On 23 Sep 2014, at 11:40, rburnett at richieburnett.co.uk wrote:

> I'd vote DDS all the way, but a VCO it isn't unfortunately.

Fair enough. So long as it lets me apply a vibrato to the master clock, I don't think I care. I'm thinking about how you'd clone a 70's combo organ. So either you go with a TOG+dividers, or (better) 12 oscillators with dividers. Each note osc and its associated divider is a single PIC - giving the frequencies of the classic TOG. If you use separate crystals for each PIC, you can have the TOG sound without the locked-together pitches. If you use a master clock, you do lock the pitches together, but you can throw vibrato on the whole lot. Wider pitch modulation would be nice, but if a few semitones is as far as it goes, that's probably ok too.

I'll look into clocking a PIC from a DDS. Might throw up all sorts of things.

Tom