Electronic – Very low wiper resistance Digital Pots – Anyone know of any

digital potentiometer

I am trying to find a 1k linear digital pot which has a very low (preferably 0) wiper resistance. Any interface would be ok (apart from just up/down).

I found this article: http://electronicdesign.com/components/active-cancellation-pots-wiper- resistance
which could be a way around the issue.

What I am trying to do, is substitute the 1k pot in the classic fuzz circuit


with a digitally controlled one, and it needs to pretty much go down to 0 Ohm to get the full fuzz effect. I am not sure if the above 'trick' may interfere the fuzz's simple circuit which is extremely sensitive.

Does anyone have any suggestions, feedback or alternative idea?


Best Answer

You will likely not find such a part because there will always be some kind of electrical switch in a digital potentiometer, and these always have some built-in resistance.

You can however compensate the resistance. You've already linked one article that shows it, but you can improve upon that.

A single OpAmp and three resistors can work as a negative resistor. If you tune the negative resistance to your wiper resistance you end up with near perfect compensation.

Wikipedia Article on Negative Impendance Converters

For your application there is even a article on the web that does exactly what you need:

Negative Resistance Nulls Potentiometer's Wiper Resistance