R.G. Keen keen at austin.ibm.com
Sat Mar 8 00:01:12 CET 1997

>>Anyone know of a source for 2M2 rev log pots (Radiohm)?
>Take a LINEAR 2M2 pot and put a 220K resistor in parallel across the 
>centre tap and the <HIGH> side.  This get's you a really clean rev-log 
>curve. If you strap the resistor from centre to low side you get a log 
>pot, generally with a better curve than a cheap log pot too. If you 
>don't believe me, run the plots for ten positions and join the 

... as long as the pot is being used as a voltage divider
potentiometer (three terminal), not as a variable resistor 
(two terminal). The tapering resistor does not yield a good
approximation to a reverse log (or ordinary log) pot when used
as a two terminal device. 

I had a desperate need for two terminal reverse log devices for 
the speed control of an RC oscillator, and the tapering resistor 
won't do it well. 

More information about the Synth-diy mailing list