[sdiy] Expo converter tempco placement

[Justin Owen]

From: René Schmitz [uzs159 at uni-bonn.de]

Hi René,
 
> I'd like too add, that if you start to design your scaling summer with a 
100k input resistance, then using a 1k in the feedback doesn't leave you 
with enough drive for the ~18mV per octave required at the base of the 
expo pair.

(At the risk of embarrassing myself...) Can I ask how (or why...) this '~18mV per octave' is a standard that's quoted so often?

Wouldn't the current output requirement potentially vary depending on the VCO circuit that the current source was driving? 

Thanks,

- Justin