[sdiy] Buffering 0V when using a pot as a voltage divider?

Neil Johnson neil.johnson97 at ntlworld.com
Wed Jun 29 21:31:24 CEST 2011


Hi,

> When using a pot as a voltage divider e.g. from 0-xV it's considered
> good practice to provide xV from a 'stout' buffered source.

Only if your pot's track resistance is low enough that it would load the 
source to a significant degree.

What's more important is the resistance seen by wiper.  Ideally this 
should be at least 10x the track resistance to minimise loading effects. 
  E.g., if you have a 100k pot, the wiper should be connected to a 1Meg 
resistance.  If not you end up distorting the pot curve, which is 
sometimes desirable:

http://sound.westhost.com/project01.htm

> Is there any advantage (or even any use?) to providing a buffered GND
> source for the 0V end of the voltage divider?

Only if you have a poor ground, or a virtual ground.

Cheers,
Neil
-- 
Synth DIY 2011 -- www.diy.synth.net/uk
Homepage -- www.njohnson.co.uk



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