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Message

VCF controls

2009-02-03 by Gordon JC Pearce MM3YEQ

How does the VCF cutoff control voltage get generated?

Looking at the circuit, it seems that the control voltage is fed from
two outputs of IC8, through to half of IC7 forming a couple of
sample-and-holds, then into an odd-looking buffer arrangement.

Is it designed so that one output of IC8 provides fine tune and one
provides coarse tune?  I would have thought that 256 steps wouldn't be
enough for a smooth VCF envelope.

Gordon

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