[sdiy] VCO reset time

[Magnus Danielson]

From: "JH." <jhaible at debitel.net>
Subject: Re: [sdiy] VCO reset time
Date: Sat, 5 Jun 2004 13:30:01 +0200
Message-ID: <001201c44af0$9efbb900$cc71b9d9 at jhsilent>

> > The tri-to-saw conversion is not good in
> > that, in typical circuits, the wave is at double frequency to the
> > triangle wave.
> > > 
> > > Double frequency?  Heh-heh.
> > > 
> 
> OTOH, double frequency saw also has some benefits:
> If you switch from normal rate triange to double rate saw, the
> ramping time stais the same, where saw is "up-up-up-up-up",
> triangle is "up-down-up-down" and inverted saw is "down-down-down"

There is BTW a very interesting little way to transform a triangle core to a
sawtooth core momentarilly. By enabling a transistor between the squarewave
output and the CV input mixer, the discharge-part is done at basically full
speed as being basically current limited. This is how the Pearl Syncussion
does it. Lovely design by the way, full of curcuit-benders deligth! ;O)
The extra waveform cost 2 additional resistors and a transistor, which is fair.

> But I agree that same freuency is tho more useful version.
> It's not trivial to make it free of glitches, but the MOTM VCLFO
> does it as well, so it's certainly possible. (I got some inspiration
> from the CEM3340 for this design ...)

Which reminds me that I haven't dug deeply into the CEM and SSM chips...

Cheers,
Magnus