circuit for four-wire measurnment of a 100k 1% Tolerance Thermistor

Hi everyone.

I was wondering if anyone had any suggestions of a way to use an arduino to accurately measure the temperature of a Thermistor attached to a 3d printing extruder head?
(Extruder:MBE SINGLE 1.75mm Extruder)

I'm assuming i would have to pass a constant current through the thermistor then measure the v drop across it. however its the only one i have and I'm hoping not to make too many mistakes.

Building a test circuit with a 100k pot instead of the actual thermistor would be the first goal but i was hoping someone on here might have done something similar and may be willing to share some experience, schematics or sketches :slight_smile:

thanks!!

You can build a circuit called a "wheatstone bridge", which will produce voltage you can measure with the analog input. This requires three accurately known resistors, and a variable resistor ( in this case, your thermistor ). It also requires a nice constant voltage supply.

The outcome of the calculation would be the resistance of the variable resistor, at a particular point in time. You would then need to convert this to a temperature based on some presumed or calibrated relationship between the resistance and temperature of the thermistor.

Given all the unknowns in this process which will require precise calibration, it is questionable whether it is worthwhile. It is probably easier to get a "one wire" DS18B20 sensor and use that directly.