>> Thanks.   I am only looking for 5 bit accuracy.
>>
> That might be asking a bit much - not from the PIC, that's easy
> enough - from the person.
> 5 bits =3D 32 position values. Typical pot has about 270 degrees
> of travel. 270 / 32 =3D ~8.4 degrees.

My nephew has a guitar effects box, and one of the selectors
looks rather like that on a DMM, but is actually a pot with 10
detent positions between fully CCW and fully CW, giving 12
distinct settings altogether. The knob is spring-loaded against
a ring of bumps in the case plastic

Maybe you can make something with a slotted disc and a ball
bearing and a spring or other bits and pieces. 32 values is going
to be tricky though.

10-turn pot ? With vernier ?

Analogue TVs had slide pots with a screw thread for tuning

Two thumbwheel or BCD switches, 10s and 1s ?

How about an optical encoder, bought or made. You could
print a scale on a transparency. Perhaps 5 rings to represent
5 bits in a simple binary code, or 1 ring of stripes to generate
pulses to count

There are many variations of digital calipers, protractors and
rulers you could take apart for a very fine position sensor

Pehaps hack an optical mouse. Draw a circle on the screen
now with it. Can you potentiometerise that ?

All options have drawbacks - accuracy, precision, consumption,
reset on power-down, cost, fiddliness etc

Joe


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