Phaseshift / Osc Sync idea

[Grant Richter]

I believe this is the idea in the Rivera "Phase Modulated Synch"
modification for the
Arp 2600. It is covered extensively in the Sept/Oct 1979 issue of Polyphony
magazine.
One of the later Aries oscillators also had this as a feature, designed, I
believe by Ron Rivera.

Electronotes had a short article on phase modulated synch. The method
described used
a comparator on an input followed by a monostable. The input is fed with a
triangle wave
from the master oscillator. The idea being to force the oscillator to reset
at a specific time
by injecting a very short pulse into the oscillator comparator. By varying
the threshold of the
input comparator, it is possible to modulate the phase of the slave
oscillator relative to the
master oscillator.

If the slave oscillator has this type of pulsed reset synch, and both
oscillator are tuned to the
same frequency, then a PWM square wave into the synch input should modulate
the phase
of the slave as the master PWM is changed.

----------
> From: Per Mattsson <per.mattsson at mkv.mh.se>
> To: synth-diy at mailhost.bpa.nl
> Subject: Phaseshift / Osc Sync idea
> Date: Saturday, February 20, 1999 7:28 AM
> 
> I got this idea on phaseshift by using osc sync which I simply has to
> bring up here.
> 
> In short: A slave osc syncs to the inverted output of the master osc's
> PWM-stage. What we get (if it works and I cannot see why it shouldn't) is
> two oscillators in sync where the slave is phase shifted as much as the
> master osc's PWM output is shifted.
> 
> OK, but why?
> By using CV on the PWM-stage we get CV-able phase shift between the
> oscillators. Since there's no delay line or filter involved to do the
> phase shift both oscillators should repond at the precisley the same time
> to freq modulation even at audiorange modulation. Route any non-square
> wave output from the oscillators to the CV-PWM input of the master osc
and
> you should get some sort of
> waveshaping thing.
> 
> I guess this is already used somewhere but is it possible to sync on a
> squarewave and not on a saw?
> 
> ---Per