VCO using ICL8038

Paul Maddox Paul.Maddox at
Thu Nov 11 16:15:28 CET 1999


  I went down this route... never got anywhere, but recently
I found an article about the Minisonic synth (old eti or pr 
synth in a box thing), showing a mod that would replace the 
onboard opamp/cap/fet with a 8038 and this give you log
scaleing, though the minisonic used 0.6v/oct it would be 
simple enough to scale it to 1v/oct.. I reckon the heat from
the 8038 would be enough to "oven" the transistor it uses
for a log convertor.. Like I say, never got around to building
one though. It runs too hot for a modular synth, in my views.
but for a standalone it might be ok.


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-----Original Message-----
From:	Andy Main [SMTP:mainas at]
Sent:	Thursday, November 11, 1999 11:40 AM
To:	Synth DIY
Subject:	VCO using ICL8038

Hi all,

Has anyone tried making a VCO using the Harris chip ICL8038 (see
This is a precision waveform generator, allow PWM of sine, triangle
(allows adjustment of slope for previous discussions), and square.
Obviously it'll need other circuitry to change it to be 1V/Oct CV but it
is temperature stable (altiough it does run hot), ie no need to
dismantle any cruise missiles to get the temcos !!! Or find matched
pairs etc etc.

Appreciate any responses, and I've ordered one for testing for my
modular design.


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