Measure a resistance far away

[vortex3]

Hello guy,

I'm trying to read the position of a potentiometer from a long distance. My idea is to use a constant current passing throw the potentiometer and then using two instrumentation op-amp with a analog MUX and a 16bits ADC for reading the voltage drop on the hole potentiometer and on the cursor position. I will use two cables for the current path, one cable from the "bottom" of the potentiometer to both the negative inputs of the op-amps, one cable from the cursor to the positive input of one op-amp and one cable from the "top" of the potentiometer to the positive input of the second op-amp. At the end I can calculate the position of the potentiometer dividing the to voltage values.

Do you think this is a good idea? Any suggestion or comment will be welcome!

Thanks!

 

[schmitt trigger]

This is called 4-wire sensing, and yes it works.

I would also twist the wires, or better still, use shielding to prevent noise pickup. Also choose an integrated instrumentation op-amp like the INA series from Texas Instruments.
You may still find that software averaging may be required to obtain your full 16 bit resolution. But overall, your idea is perfectly feasible.