building a linear slide potentiometer?

If you really want to create your own track and it doesn't have to last too many cycles, maybe conductive plastic from static shielding bags could be cut to size and shape. The conductivity varies tremendously, though, from around 100 ohms/square up to maybe 10,000 ohms/square depending on type.

Personally I like the idea of the reverse radio tuning dial - string around a pulley on the pot shaft.

Nick o

I've seen it done (as a servo feedback sensor) with a single length of resistance wire, but of course it's nothing like even 100K; more like < 100 ohms.

Best regards, Spehro Pefhany

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I'll second this recommendation. Many years ago in an alternate universe far, far away I was an automotive engineer for GM, and we used string pots a lot for long-travel measurements. One application in particular was monitoring the motion of suspension parts during travel down various roads. String pots were more accurate than (say) tricks with multiple accelerometers (which we also used in abundance) when you wanted displacement.

As I recall, the stringpots were basically 10-turn rotary pots with a return-spring mechanism that tried to keep them at one end of the travel. A string around the shaft pulled against the spring to advance the pot. Stringpots with stronger springs handled higher accelerations.

Depending on your application, you might not need this return-spring at all... use an old-time radio dial arrangement that turns a pot instead of the tuning cap.

Best regards,

Bob Masta DAQARTA v3.50 Data AcQuisition And Real-Time Analysis

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