[sdiy] Adding "sync" to a Through-Zero Sinewave Oscillator design
David G Dixon
dixon at mail.ubc.ca
Sun Sep 16 08:45:06 CEST 2018
The Intellijel Rubicon 2 is a through-zero VCO which I designed, and it has
both kinds of sync. We call them "Hard" and "Flip" on the panel, but I
always think of them as "Reset" and "Reverse". The Resetting sync is
achieved in the normal way, with a JFET across the integrator capacitor.
The Reversing sync is achieved by syncing to the threshold input pin of the
comparator in the tri-square core.
> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On
> Behalf Of Donald Tillman
> Sent: Saturday, September 15, 2018 10:31 PM
> To: ulfur hansson
> Cc: synth-diy mailing list
> Subject: Re: [sdiy] Adding "sync" to a Through-Zero Sinewave
> Oscillator design
> > On Sep 15, 2018, at 3:26 PM, ulfur hansson <ulfurh at gmail.com> wrote:
> > 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?
> There are several way to sync a triangle wave.
> The technically correct way would be to force the oscillator
> to the start of the waveform. So if it's advertised as a
> sine wave, the sync pulse should bring it to 0V, ascending.
> I'll claim that reversing the direction of the wave is not
> actually a sync. The word "synchronize" means to bring an
> oscillator to the same frequency, and same phase, as another.
> I don't think that's remotely possible by flipping the
> direction of the triangle every cycle.
> I'd even call it "anti-sync".
> But if it's an expressive sound, it's probably worth coming
> up with a better name.
> -- Don
> Donald Tillman, Palo Alto, California
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