[sdiy] Cheapest, simplest but still reliable VCO & VCA for polyphonic project

[George Hearn]

Minimal JH, I like it.  Another option for a VCA is a single FET in the
linear mode Vds<(Vgs-Vt) as one half of a potential divider.  For a VCO it
is possible to make four exponential VCOs from a single SSM2164, I never
tried it so I don't know what they'd be like but if you have autotune on
your polyphonic synth the scale errors wouldn't matter too much.  George

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of JH.
Sent: 08 January 2009 19:07
To: elektrodwarf at yahoo.se; synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Cheapest, simplest but still reliable VCO & VCA for
polyphonic project

> Any suggestions on good, cheap and very low parts-count VCAs?

Yes - a single diode + one resistor.
Terrible CV feedthru, limited range, but good enough to control the filter 
resonance in a Korg PS3200.
For a slightly "better" VCA, a single NPN transitor + a resistor.

JH. 

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