[sdiy] Synthancon VC-Resonance

[Aaron Lanterman]

On Tue, 2 May 2006, John Luciani wrote:

> There is probably a way that is more clever but a voltage controlled 
> current-sink is a trivial circuit to make and should be able to replace 
> the pot. Requires an op-amp, a couple of resistors and an N-channel FET.
>
> If you look in the "Load Schematic" section of the document at
>
> http://www.luciani.org/geda/util/matrix.pdf
>
> you will see a schematic for a circuit called "Load Cell" which is the
> current sink.

Oh, interesting circuit - I've seem people play that game with JFETs, but 
not MOSFETs.

What worries me though is that the resistor it looks like they want to 
replace is a floating resistor. The circuit there looks like like it 
insists that one point of the "variable resistor" be tied to ground, but 
in Ken's Synthacon, the 1k/1kpot setup is tied from emitter of the 2n2222 
back to the BP input through a 1k resistor.

- Aaron

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