08-08-2015, 10:28 AM
(08-08-2015, 09:51 AM)Yorkie Wrote: I’d previously mentioned problems that I’d had in trying to create an antilog pot with an added resistor, in a thread entitled ‘Anti-log Pot Track Puzzler’ in connection with restoration of a Portadyne 'Princess' back in 2012:
As pointed out at the time, your measurement method was flawed.
You were measuring only the unmodified (lower) part of the track but completely ignoring the upper part which is where the non-linear change in resistance occurs.
A simple way to prove this is to pass a small current through the pot and measure the voltage between the slider and the earthy end at differing degrees of rotation.
As for tapped pots, I'm sure that, in another forum, Mike (Crackle) described how he had successfully added a tap to a pot but can't finf it at the moment.
Perhaps Mike can put in a repeat performance?
