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

[Tim Ressel]

Yo Part 2,

Of course, keeping he crcuit as isothermal as possible
will have an effect on how well any temperature
compensation scheme works.

--TR

--- John Blacet <blacet at blacet.com> wrote:
> The whole "how stable should it be" regarding VCOs
> is an interesting
> discussion. On the one hand, you don't want absolute
> lock-step digital
> stability in an analog oscillator, as being just a
> bit drifty makes them
> sonically much more interesting to use. But, you
> don't want to be
> reaching for the Fine Tune knob more than a few
> times a session; that
> gets annoying.
> 
> The whole technology limitations of analog guarantee
> that absolute
> stability is really unobtainable, but you can get
> close enough to make
> nice analog VCOs. The best commercial VCOs go a bit
> beyond the customary
> temp comp resistor approach with techniques to "mop
> up" residual drift.
> Some synths of old, for example seem to auto tune
> via uP on a periodic
> basis.
> 
> 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".
> 
> Regards,
> -----------------------------
> John Blacet
> Blacet Research
> http://www.blacet.com
> 
> 


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