On Sat, 6 Feb 2010, ivp wrote:

> > You may have already thought of using a rotary potentiometer with
> > a ~100mm diameter pulley on it, and use a string attached to the slide,
> > in the style of a dial cord in old radios.
> 
> If it's robust enough in the long term (got a bit of a downer on carbon pot
> tracks but you can get conductive plastic, at a price) that might be a goer
> 
> The client has indicated he'd like the slider moved by a brass crank. !!!!
> This probably means that the slider will be on a lead screw and several
> turns of the crank will move the pointer from one item to the next

in that case what about an IR distance measuring widget in parallel with 
the lead screw. IIRC these can measure distances upto about 20cm without 
problems

Regards
Sergio Masci
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist