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

ulfur hansson ulfurh at gmail.com
Sun Sep 16 07:19:33 CEST 2018

no, of course the output is a bipolar wave, what I am referring to is that
negative control voltages will yield mirrored results, i.e. same frequency
but reversed in phase compared to positive cv.

so a square wave alternating between -2v / +2v should not change the
oscillator frequency per se, just reverse the direction of where the
oscillator is heading. I may have used the term "sign" improperly here,
correct me if i'm wrong :)

lau., 15. sep. 2018 kl. 22:16 skrifaði <rsdio at audiobanshee.com>:

> What is the definition of a “through-zero” oscillator? My impression was
> always that it was an oscillator that could go down to 0 Hz and then into
> negative frequencies. I recall that this is important for FM, especially
> with high amplitude modulation.
> It seems that you’re using “through-zero” to refer to the bipolar voltage
> of your oscillator, as contrasted with common unipolar oscillators. Perhaps
> I misunderstand.
> Brian
> On Sep 15, 2018, at 3:26 PM, 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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