Polykit Octo VCO

That’s sweet! Sounds fat and the github is a nice touch.

Some question on your use of the NTC - firstly, they’re the 4k7 resistors in your BOM? What kind of temp coefficient do they have? I used PTCs in my VCO, but they’re in a negative feedback path - so I guess it has the same effect as an NTC? Any particular reason you did it that way?

If you’re working on VCAs, here’s an lm13700 linear VCA I recently built - two ICs and two transistors for two channels. It seems to more or less work:

lm13700 vca schematic

I’ve got a JFET variant that’s a single IC and two transistors I can share if you’re interested.

Cheers,
Jared

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