[sdiy] Adapting exponential convertor for single supply

[Roman Sowa]

I wasn't following this thread closely, but when we talk about rough 
expo aproximation, diodes are the way to go.
I used zeners with different values of resistors added in parallel. This 
can be seen here in the control of CA3080 used as the heart of ADSR. 
It's used in polysynth so voices should have tight ctolerances on 
timing, and indeed it was good enough for -5..+5V control range:
http://sowa.synth.net/poly/adsr.gif

In VCF control I used similar aproach with 4 LEDs instead of zeners, and 
it was possible to get acceptable tuning over wide range in selfoscillation.

Roman

W dniu 2017-07-27 o 13:34, Paul Perry pisze:
> If it's just a matter of getting a rough expo/square function, you could
> possibly do
> something with a diode or two in series with the control input to the OTA.
> I've had some luck in the past making rough nonlinear conversions with
> resistor/diode
> networks.
>
> paul perry Melbourne Australia
>
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