[sdiy] Adding "sync" to a Through-Zero Sinewave Oscillator design
David G Dixon
dixon at mail.ubc.ca
Mon Sep 17 01:49:03 CEST 2018
It brings it to 0V, but I'm not sure that it starts off in a certain
direction or not.
> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On
> Behalf Of Tom Bugs
> Sent: Saturday, September 15, 2018 11:55 PM
> To: synth-diy at synth-diy.org
> Subject: Re: [sdiy] Adding "sync" to a Through-Zero Sinewave
> Oscillator design
> David - does your hard sync do as Don suggests "
> the sync pulse should bring it to 0V, ascending.
> I've always used this hard sync approach but the waveform can
> rise or fall from this reset point.
> (sorry, straying off topic)
> On 16/09/2018 07:45, David G Dixon wrote:
> > 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 http://www.till.com
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