One of the most frequently used temperature transducers is the thermocouple. Thermocouples are very rugged and inexpensive and can operate over a wide temperature range.
A thermocouple is created whenever two dissimilar metals touch and the contact point produces a small open-circuit voltage as a function of temperature.
This thermoelectric voltage is known as the Seebeck voltage, named after Thomas Seebeck, who discovered it in 1821. The voltage is nonlinear with respect to temperature.
Thermocouple Tutorial.pdf (932.6 KB)