[sdiy] Upper frequency limit for VCO

[Magnus Danielson]

From: Peter Grenader <peter at buzzclick-music.com>
Subject: Re: [sdiy] Upper frequency limit for VCO
Date: Tue, 02 Aug 2005 12:23:54 -0700
Message-ID: <BF15165A.254C6%peter at buzzclick-music.com>

Peter,

> What about tracking across the entire band?  Freq doublers I've found have
> limited response.

Really? ;O)

http://rubidium.dyndns.org/~magnus/synths/schematics/
http://rubidium.dyndns.org/~magnus/synths/schematics/freqdoubler.pdf

The limit is really in resetslope-speed and speed of op-amps. Those are
parameters which can be adjusted by choise of components and PCB layout.

> Getting one to maintain tracking, and at very least
> waveshape purity across the entire spectrum is dicey, no?

Depends what you start with and what you build with.

I actually think that a triangle core should work much better than a sawtooth
core when you try to reach higher frequencies.

Cheers,
Magnus

> Scott Gravenhorst wrote:
> 
> > 
> > If the idea is to replicate the original VCO waveform in all of the divided
> > outputs, wouldn't it be easier to use frequency doubling waveshapers and
> > start at the bottom instead of starting at the high end and using dividers?
> > I've seen frequency doubling circuits for tri and saw inputs.  AFAIK,
> > divider outputs are rectangular which doesn't lend well to waveshaping back
> > to saw or tri.  However, if you _want_ rectangular, that's easy to divide
> > and you could also investigate Walsh functions.
> > 
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