[sdiy] How DCOs work

[David G Dixon]

> There was(is) a mono synth that actually did this - Fredrik 
> Carlqvist's Minod Vorga:
> 
> http://www.minod.com/products/minodvorga/vorga.html
> 
> There may be others, I don't know. If I was building a DCO 
> synth, I'd certainly include it.
> 
> It's very simple to do, and I once experimented with the idea 
> on the breadboard. You can set the ramp core up with a 
> comparator that resets the integrator like normal, and also 
> feed in a reset pulse form the counter. Setting the control 
> current correctly gives you the normal ramp wave, reset by 
> the counter reset pulse. Pushing the control current higher 
> forces additional resets from the comparator and gives you 
> sync sounds.

Right, so if I understand you correctly: You basically build a bog-standard
sawcore VCO, but you have a digitally controlled reset pulse as well which
ensures "perfect" tracking.  Presumably, if the tracking is poor, the
digital reset pulse will occur slightly before the comparator pulse (which
is late because the tracking is off).  However, if you increase the
integrator current, the integrator will still reset "normally" perhaps
several times before the next digital pulse comes through.

What if the comparator and digital reset pulses come at exactly the same
time?  I guess it wouldn't really matter, except that you may be a slightly
longer-than-normal interval at 0V.

By this philosophy, any VCO could be made into a DCO without too much fuss,
no?