VCO's for homebuilt synths

Ric Miller rmiller at
Fri Aug 11 20:18:27 CEST 1995

> On Thu, 10 Aug 1995, SuperBAD MoFo wrote:
> > As the Chroma SM put it, the Charge Pump design 
> > is often found in instrumentation, but rarely in synths.  The only catch 
> > is, I don't know how available the charge pump chip...
> I've used this design for some of my VCOs, and it works very well.
> The 4151 V-to-F converter has been manufactured by at least Raytheon
> (RC4151) and Exar (XR4151). I've been able to get the XR4151 for around
> $2 in small quantities. There's also the RC4152, which has better
> linearity, but is also much more expensive. National has a second
> source for the latter (LM-something...).
> (Chop chop>
> The 4151 together with a temp controlled CA3046 should make for a very
> compact and easy-to-set-up VCO.
> -joachim

Ehhh?  The 4151 and 4152 V to F converters?  If there is a VCO schematic 
using these chips available somewhere, PLEASE let me have a copy of it! I 
can supply the chips!  We've got a PILE of of both of these at work, and 
they're CHEAP (They were 'written off' as a loss a few years ago, and are 
now available for pennies.  (Literally).
If these can be used for VCOs, I'll buy them all, and who ever wants can 
have some for the cost of postage!

Pending of course, building a 'Chroma' VCO from one, and having it work.

Don't want to count any chickens before they're hatched but .....  :)


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