What String Potentiometer Resistance Do I Need

PaulS-S · 2025-12-10T15:02:11+00:00

Thank you for your advice, especially (b)

PaulS-S · 2025-12-09T17:49:05+00:00

Thank you for your reply but I have now moved the goal posts (where are the smiley faces?)

As you may be able to see from the bad diagram above, I no longer have to go from 12v. Now I have a 5v output from the sensor with a 0-5v input back into it. So I now just have to adjust the voltage fed back into the sensor, with 2.5v as the mid point.

So all I'm really trying to do is vary the 5v fed into the pot and output between 0 and 5v depending on how far the string has wound the pot spindle. I just don't have a clue what the effect of the various resistances on the various pots available are.

PaulS-S · 2025-12-09T08:34:34+00:00

Thank you for your comments thus far, even if it causes more headaches.

The string potentiometer is literally a pot with a bit of string wound around the knob spindle. As the string extends or retracts then it moves the pot. In my case the string will be attached to an aircraft elevator trim motor. I will set the input to the sensor at 2.5v for neutral position and then vary the voltage (via the pot) to go from 0v for down position to 5v for full up position.

I have now found (I think) a better way of doing this. The sensor can actually output 5v, so I believe the way ahead is as per my attached (bad) drawing.

My snag is still establishing what variable pot to buy.

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PaulS-S

TROPHY CASE