For precision temperature sensing, nothing beats a Platinum RTD. Resistance temperature detectors (RTDs) are temperature sensors that contain a resistor that changes resistance value as its temperature changes, basically a kind of thermistor. In this sensor, the resistor is actually a small strip of Platinum with a resistance of 100 ohms at 0°C, thus the name PT100. Compared to most NTC/PTC thermistors, the PT type of RTD is much most stable and precise (but also more expensive) PT100’s have been used for many years to measure temperature in laboratory and industrial processes, and have developed a reputation for accuracy (better than thermocouples), repeatability, and stability.

This MAX31865 amplifier breakout board handles all of your RTD needs, and can even compensate 3 or 4 wire RTDs for better accuracy. Connect to it with any microcontroller over SPI and read out the resistance ratio from the internal ADC. The board has a 430Ω 0.1% resistor as a reference resistor on the breakout. As always, Adafruit has provided example code that will calculate the temperature based on the resistance for you.

The amplifier breakout is 5V compliant, with a 3.3V regulator and level shifting, so you can use it with any Arduino or microcontroller. Some soldering is required to solder the headers and terminal blocks to the breakout, but it’s an easy task with soldering tools.

Please Note: A PT100 RTD is not included, but are available separately here.