A digitally linearized thermistor thermometer referenced to IPTS-68.

We describe a digitally linearized thermistor thermometer that is accurate to +/- 0.01 degrees C from 0 to 60 degrees C at a wattage of 50 microW and a sampling time of 1 s. It is traceable to the International Practical Temperature Scale of 1968 (IPTS-68). Analog and digital outputs are provided, the latter as ASCII RS-232C. The thermistor is a 10-cm long immersible probe, 1.5 mm in diameter. Only 0.5 cm of the probe need be immersed, with proper heat sinking of at least 1 cm of the remaining 9.5 cm, for accurate readings. Error from self-heating of the thermistor is less than 5X 10(-3) degrees C at all power settings from 50 to 1 microW.