Temperature Compensated VCO follow up

[patchell]

Ian Fritz wrote:

> Jim et al. --
>
> Out of curiosity, I wonder if you can say anything yet about the freq
> dependence of the drift. Remember that the expo converter gives a T
> dependence like exp[q(dVbe)/kT], where dVbe is the differential base-emitter
> voltage. If the compensation isn't perfect, then the drift in ppm/K is zero
> when dVbe=0 and increases -- in opposite directions -- on either side of
> zero.
>

    Good point.  I only checked the scale drift at one point.

>
> Did the change from 80 to 100mV affect the tracking accuracy? I always seem
> to find the best tracking around 60-70mV.
>

    I did not check for tracking this go around (tomorrow?maybe).  I was mostly
concerned with weather the temperature compensation would work at all.  Also, I
was trying to keep the number of variables down to a minimum.  My poor brain is
slowly becoming accustomed to doing Synth DIY again (it has taken me a year and
a half to get to this point).

>
> By an amazing coincidence, just today I finally got all the drift out of my
> differential-integrator tri osc. I've been fighting this one for a couple of
> months. I'll post that tale separately.
>

    Congrats.  I will be curious to see it.

>
>   Ian
>

    -Jim