         |
The response graph of the thermistor is different from the thermocouple and the RTD in that it's not linear. Fig. 1 shows the typical response for thermocouples, RTDs, and thermistors. Since the thermistor response is a curve, it's important to locate linear portions of the curve to provide the best accuracy and repeatability. In some cases a table should be consulted to determine the exact amount of resistance the thermistor should provide for any given temperature. Also notice from the graph that the resistance decreases as the temperature increases, and at some point the temperature will increase sufficiently to make the resistance equal zero and the thermistor is no longer useful as a temperature sensor.
Above: Fig. 1: Response curves for thermistor, RTD, and thermocouple.
