I'm working with an R/C electric motor that has a 10K thermistor sensor built into it, which is connected to a speed control that has basic thermal protection. I would like to build a secondary sensor board that displays the temperature on a segment display, but I still want to pass it through to the speed control so that it still has thermal protection.
The issue I'm having is that the thermistor is only connected to ground on one end, no other reference potential, so I plan to read it with a voltage divider. This means I can't just pass the end of the thermistor back through to the speed control, which may have its own voltage divider. Is there a way I can replicate the resistance of the thermistor to two different read circuits expecting a variable resistance?
Best Answer
You could use an op-amp as a buffer/voltage follower, then put whatever scaling you need after the follower. The high input impedance of the buffer shouldn't appreciably load the thermistor circuit.
simulate this circuit – Schematic created using CircuitLab