Using a Potentiometer for Adjusting a Setpoint

A question came in today on how to set up a potentiometer for use as a setpoint adjustment knob. We had a 10k pot on hand and wired it directly to one of the inputs of the T3 controller.

First configure the input to use custom analog range β€˜50’ as shown.

This brings up the custom range dialog where you can fill in the range for the potentiometer. The T3 controller uses an excitation voltage of 3V which is connected through a 10k pullup resistor for reading thermistors and dry contacts. This means we should see the voltage on the input swing from 0V to 1.5V when the pot goes through its full range of motion from 0 ohms to 10k ohms. We fill in these expected voltages at Tab4 and the corresponding min/max setpoints we want at Tab8. We’re using a linear pot so we only need two data points in our custom table. Be sure to select thermistor/dry contact as the signal type at Tab1.

I had to tweak the max voltage value at Tab6, lowering it from the expected 1.5V down to 1.4V. As I did this I moved the pot to min and max position a few times till I got the value at Tab7 to properly reflect the desired min and max setpoints at tab8.

Final Notes: 10k ohm pots will give you the best response for a given rotation of the potentiomenter but you can use pots of other values, just adjust the voltage value at Tab6 accordingly. The downside to using larger or smaller pots is that the pot will be less sensitive to motion.

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