Thermistor
The thermistor is a semi-conductor device whose resistivity (r) varies as a function of temperature (T):
- R = Ro [1 + a (T-To)] where,
- R = resistance of temp. at T
- T = temp at the end of measurement
- Ro = resistance of temp. at To
- To = temp at the beginning of measurement
Temperature resistance coefficient is the parameter that determines if the resistivity variation is positive (as with the Positive Temperature Coefficient, or PTC sensors) or negative (as with the Negative Temperature Coefficient, or NTC thermistors). It is possible to determine the temperature by applying a potential difference and measuring the resistance.
Thermistor sensors are suitable for a temperature range of -50 to 150oC (-58 to 302oF). Higher temperatures may damage the semi-conductor sensor. Accurate temperature measurements are possible (tenths of degree) due to the high sensitivity of the sensor.
