[sdiy] Newbie needs help with VCO

[Tony Clark]

> P.S I had a look at my EXPO circuit. I am pretty sure it is working,
> as I get an exponential rise in voltage across R10, the 10K resistor
> on the emitters. I also removed (temporarily) the LM311 and the FET
> used for sync - She still refuses to oscillate though :(

   That would be because it requires the FET and LM311 in order to 
oscillate.  :)  The exponential converter charges the capacitor across 
the CA3140 in one direction only.  So that when powered up, the voltage 
will rise from 0 to V+ and stay there.  The FET and LM311 are there to 
discharge the capacitor upon reaching 5 volts.  Once discharged, the 
voltage can then begin rising back to V+.
  
   Cheers,

   Tony

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