[sdiy] Adding "sync" to a Through-Zero Sinewave Oscillator design

[Tom Wiltshire]

I thought triangle oscillators didn’t change *sign*, but rather changed *direction*.

Changing sign would imply that a waveform at +2V would jump abruptly to -2V. Changing directions means only that a waveform that has been rising up to +2V would start falling instead.

> On 15 Sep 2018, at 23:26, ulfur hansson <ulfurh at gmail.com> wrote:
> 
> hello list!
> 
> i have been working on a prototype for a through zero quadrature sinecore oscillator over the past few weeks, and have been thinking of ways to add a novel type of "sync" to the circuit.
> 
> I love the way traditional triangle core oscillator sync sounds, and much prefer it to the harsher sawcore type sync.
> 
> with trianglecore sync (I hope I understand this correctly) the waveform changes sign at trigger points rather than doing a hard reset to 0v, right?
> 
> since my oscillator is through zero, my idea is to implement a switch that inverts the incoming v/8 CV everytime the "sync" input exceeds a certain threshold. 
> 
> this would (in my mind) effectively only change sign of the sine waveform, emulating the triangle core sync i mentioned before.
> 
> before I start gathering components and laying out a sync prototype board, i'd love to see if any of you think this is a ridiculous idea - and if there is any literature out there on various methods of sync, i would love to learn more about it beyond discharging integrator caps to ground :)
> 
> thanks so much for your insight!
> all the best,
> -úlfur
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