[sdiy] Saw vs Triangle Sync

[Magnus Danielson]

David G. Dixon wrote:
> I've been playing with my 2164 Expo VCO, and I've realized that I've got it
> arranged so that the sync master signal must have a falling edge to work.
> Hence, the typical saw with a rising edge won't sync without inversion, but
> a pulse will.  It would have been fairly inconvenient to organize it any
> other way, but I see that the Oakley VCO syncs on a rising edge.

While it is convenient to have the same polarity of sync as mostly 
supported by the oscillators in the rest of the modular, you are free to 
choose whatever you like.

> Is it generally accepted that VCOs must sync on rising edges, or can it be
> either way?  My sync circuit is so simple (and, dare I say, elegant) that
> I'm loathe to change it.

Is it too much to ask for an inverter?

You could fairly easy have a sync polarity switch for the trigger on 
rising (inverted), falling (non-inverted) and both (inverted through a 
capacitor together with the non-inverted through a capacitor).

Cheers,
Magnus