Hi,
I need to sense the position of a steel wire in a cable (similar to the cab=
les of
bicicles' brakes). It can be moved forth and back by 36mm. Endpoints not ac=
cessible,
but I could eventually cut the cable and put something inbetween, as long a=
s it's
thin and linear, not bulky like a rotary pot system (i.e. has to go into a =
20mm pipe).
I thought about using one of those slider audio pots, and anchoring the cab=
le on it,
but the ones I found last only 50000 cycles maximum (I need one million at =
least).

This is "almost" perfect, but extends for only 12mm, not 36mm, and I have n=
o way to
put a leverage in my application to extend it mechanically:
http://www.bitechnologies.com/pdfs/404.pdf

I'm in hope of any of you signaling me any device I missed in my long resea=
rch.

I also thought about going magnetic (with a Honeywell sensor), but this can=
not
be done due to magnetic interference nearby. So the only options are either
resistive (not carbon, of course) or, even better, linear encoder. Must be =
cheap,
i.e. in the $10-$20 range maximum. Space constraints (not entirely defined,=
 i.e.
the smaller, the better, because more space remains for electronics) anyway=
 not
bigger than 20mm make things more difficult.

Thank you in advance for any useful advice.

With kind regards,
Mario

--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.