From keen@austin.ibm.com Sat Mar 8 13:14:39 1997 8 Mar 97 16:12:54 -0500 7 Mar 97 18:00:34 -0500 id XAA18349; Fri, 7 Mar 1997 23:01:12 GMT id XAA36007; Fri, 7 Mar 1997 23:01:09 GMT Subject: Re: pots In-reply-to: (Your message of Fri, 07 Mar 97 22:47:02 +0000.) <199703072247.WAA20456@irwell.zetnet.co.uk> Date: Fri, 07 Mar 97 17:01:12 -0600 From: "R.G. Keen" >>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 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 >dots.... ... 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.