[sdiy] Resolution of analogue potentiometers?

Bob Weigel sounddoctorin at imt.net
Tue Feb 12 10:50:09 CET 2013

On 2/11/2013 11:51 PM, Ove Ridé wrote:
> Consider a wirewound potentiometer:
> http://upload.wikimedia.org/wikipedia/commons/c/c3/Pot1.jpg
> By its nature it has a ribbed surface and the wiper will tend to be
> attracted to discrete values. Obviously you don't use those in audio,
> but if smaller potentiometers of some type has a similar composition
> that might give a similar effect.
> However, it's more likely that precision means the minimum distance
> you can move the wiper due to surface retention inside the pot.
> On 12 February 2013 03:10, Paul Anderson<wackyvorlon at me.com>  wrote:
>> I'm not sure I understand your question? They're analog, so the change is continuous.
>> --------
>> Paul Anderson -- VE3HOP
>> On 2013-02-11, at 9:06 PM, Michael Zacherl<sdiy-mz01 at blauwurf.info>  wrote:
>>> Hi, I thought this already has been discussed but couldn't find the thread:
>>> How's the actual resolution of the resistive track of an analogue potentiometer
>>> specified? On some data sheets I read "<  0.1°" for a rotative pot.
>>> for instance,
>>> in terms of pitch control over a very wide range, using a multiturn pot or trimmer,
>>> where are the limits for the resistive tracks and pots at all?
>>> Technically speaking, leaving practical aspects aside for a moment.
>>> Thanks, Michael.
Actually wirewound resistors can be used in certain audio applications 
fine.  I wouldn't recommend for a pitch control but for volume they're 
often fine.  They're a make before break switch in essence with however 
many steps there are in the number of winds.  Volume pedals etc. they 
will leave no discernable difference probably.  They may last longer 
than carbon trace units also.

But anyway the resolution of other pot types has more to do with how 
incrementally they can be moved.  There is always a certain amount of 
friction in the mechanical aspects of the units.  So you have to put a 
certain torque on the shaft to get it to move.  And this creates a 
momentum that will cause it to turn some minimal angle of course.

Otherwise the resolution limits would fall into the realm of the 
molecular/atomic structure and how it interfaces with the wiper :-).  
Which is for all intensive purposes infinite resolution in any 
application known to man probably ...

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