[sdiy] expo accuracy? or integrator accuracy?, or both?

[Grant Richter]

With all due respect to Ian, Magnus, Rene et al.
> 
> While I agree with you, I just want you to remember that one of the things we
> where discussing was an alternative to TEMPCO resistors and alternative
> solutions to that. That is one of the things which I think is fashinating and
> the experiments that Tim and Scott have done is encouraging to say the least.
> But onces you've got an oscillator which allows itself to be built from not so
> rare components and doesn't need constant tuning to be reasnoble, then looking
> at means of modulation, timbral aspects, etc. all come in, I agree, but that

As my understanding goes, each component is specified with a tempco, but
then there is a tolerance on the tempco. For example polycarbonate caps with
a +150 ppm +/-50 ppm or between 100 and 200 ppm.

Now someone pointed out that the silicon will have a tempco tolerance and is
only centered on 3300 ppm.

So each unique collection of components will have a unique composite ppm
drift.

So if you develop a stable but temperature variable multiplier for the 1
volt to ~18mv conversion, wouldn't you still have to do a zero and span
calibration using an actual temperature chamber to calibrate it? Mucho work!

I have also noticed that the 1 watt copper wirewound tempcos (KRL) exhibit a
better short term stability, than the same circuit with an 1/8 watt film
tempco (because the 1 watt has a much larger thermal mass?). I don't think
you WANT to change the scale factor very fast. I get the impression that
adds instability from air movement.

It seems these exquisite design enhancements may have reached the law of
decreasing returns.