Results: Temperature compensated VCO

[Rene Schmitz]

As mentioned few weeks back I was working on a temp stable VCO without
tempco resistor.
(Before you read further check out http://www.uni-bonn.de/vco.html to see
what I'm talking about)
I got the thing working a few weeks back and have now made several tests.
I could not confirm the temperature stability in the circuit, since I'm lacking
the proper test equipment (ie freq counter and precise thermometer), but
after makeing the
"thumb heat" test, I am convinced that it is suitable. (theory and
simulations show the same)
The expected phase jitter from the noise in the diffamp is low. I think that
is due to the 
cap in the exp. converter (1nF) which I initially ommitted, it shorts the
ac/noise (?).
(This cap is in most converters out there anyway. You may have to tweak
anyway in existing VCOs)
I had some trouble with oscillations of the amp. thats why I placed a 1nF
cap on the second opamp.

Any suggestions/questions welcome

Bye 

  Rene