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Unread 17-01-2007, 22:42
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DonRotolo DonRotolo is offline
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Re: Crab drive without a pot

Don't be afraid of potentiometers. Do use the correct value (I think 2.5k is the best match for the RC - or is it 5k??). Linear taper, as eshteyn noted, is what you need.

Connect a pot to the RC - one end to red, the other end to black, and the center to white, hooked up to an analog input - and get a feel for what kind of information you can get from it. You will see values in the range of 0 to 1023, varying linearly (linear taper, remember?) with rotational position.

Pots are available with 360 degree rotation, but these often have a small dead zone, where no signal is available.

Absolute encoders are great, can get costly (Mouser 594-601-1045 is one example, $60, get the connector wire too), but feature true 360 rotation, no dead zone, reliability and precision.

Multi-turn post can be a good solution, but you can eventually run out of turns if you don't enforce some kind of discipline on which way the wheels turn.

Running without pots (or similar) will lead to astoundingly poor performance.

Don
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