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Unread 12-09-2009, 17:37
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kmcclary kmcclary is offline
Founder 830/1015;Mentor 66/470/1502
FRC #0470 (Alpha Omega Robotics)
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Re: CHEAP or EASY String Pots (source, or fabbed)

Now that we're all back, I'm reviving this thread from last December. We are still looking for a way to get our hands on (or make) some cheap string pots!

Quote:
Originally Posted by JesseK View Post
Last year our team brought up using an extending lanyard ($3) with a multi-turn pot ($3) for this purpose on our elevator. We tried it with a lanyard and with a $2 tape measure.
Interesting.

The spring system doesn't seem to be the biggest problem here. IF the pot has low enough friction, it looks as if keychain retrievers or autoclosing tape measures should be sufficient to keep it under tension.

The big problem seems to be fabbing a lanyard and drum rig that prevents string overlap. If an overlap occurs, you've completely lost data integrity and linearity.

How did you handle the overlap problem with your rig?

I've looked at creating a reel guide geared to the drum, but that's no longer a hardware store solution. (We're back to machining parts.)

I'd much rather find a Hardware Store Solution, if at all possible.

Any other suggestions, on how to make a String Pot with hardware store items, that will drive a standard 1/4" shaft multi-turn potentiometer? (OR, does anyone have a COTS source for CHEAP [say ~$20] 25" long string pots???)

- Keith
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Keith McClary - Organizer/Mentor/Sponsor - Ann Arbor MI area FIRST teams
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Last edited by kmcclary : 12-09-2009 at 17:42. Reason: added request for a cheap COTS source