[sdiy] Old unique VCO - T?==?windows-1256?Q?une drifting problem - adapting a servo c?==?windows-1256?Q?onversion‏

[David G Dixon]

>  So you guys think the solution is an oven with a simple 
> conversion with one transistor...
> Is it possible/usefull to add a servo conversion to that? 
> could it improve stability? tracking?

I wouldn't do it that way!  I'd simply use a matched pair, and put one of
them in the feedback loop of an opamp current servo.  Check out the Thomas
Henry VCO-1 schematic on Scott Stites's "Birth of a Synth" site for details.
It would help if the voltage reference for this servo came from a
temperature-stable voltage reference (like a bandgap reference) rather than
directly from the rail.