[sdiy] Temperature stable lin-exp converter with a CA3086 or CA3046

[The Old Crow]

On Tue, 28 May 2002, John Blacet wrote:

> I wonder about a PIC based processor in a correction loop? Say, just a
> nudge now and agian to make the CV to freq ratio stay "close". You could
> even program in bits of subtle "misbehaviour".

  With that last statement, you've just described nearly exactly what the
PIC on my 'P6VCO2' board does.  P6VCO2 is a 2nd set of VCOs for the Korg
Polysix.  I use a PIC to store a few paramter settings such that when
patches are saved and recalled from the front panel, the P6VCO2 keeps with
the program.

  One of the controlled parameters is 'linear detune', (detunes VCO2 plus 
or minus a small amount).  I added an extra mode to the PICcode that, sort 
of in yamaha GS1 'random detune' fashion, randomly adjusts the linear 
detune CV between a couple of hard-coded endpoints (not the entire 
digitized knob's range).  Worked out quite well.

Crow
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