[sdiy] EMS VCO expo

René Schmitz synth at schmitzbits.de
Tue Jul 11 16:56:32 CEST 2023


Am 11.07.2023 um 16:22 schrieb Tony Allgood via Synth-diy:
> Can anyone explain the function of Q61 and Q63 in the exponential 
> convertor of the EMS Synthi VCO?

Q63 acts as a Zener Diode. 9V ish.

Q61 is a very crude servo. The collector works into R182, stabilizing 
the current through Q59 and R161.

(Voltage across R161 will be the "Zener" Voltage + Vbe of Q61)

Mind this doesn't have to be perfect.


Best,

  René



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