tempco

[Paul Maddox]

David,

>
> How would i go about adding Tempcos to a vco. Is it just a simple 
>matter of keeping the expo transistor pair at a constant temp???
>
>dave
>


  Hmm, ok deffintitions first....
  tempco= Temperature compensation, not the same as keeping the 
transistor pair "oven'd" at a contsant temperature... if you want to 
use temperature compensation, you need a thermister (resistor that 
varies with tremperature) and a way of feeding this signal back into 
the tranny pair... 
   two things make this fun (hard)... Firstly you must get the correct 
resistor, one that vaires at the right rate, if it changes to quick or 
to slow it'll be worse than not haveing any temp compensation at all.
secondly you then have to feed this into the equation somehow and at 
the right scale...

   If you really want a temperature compensated logconvertor, pinch 
one from a VCO, the ASM-1 is good, there are also a few other good 
ones around..

   Paul


 
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