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These sensors use a solid-state technique to determine the temperature. That is to say, they don't use mercury (like old thermometers), [http://en.wikipedia.org/wiki/Bimetallic_strip bimetalic strips] (like in some home thermometers or stoves), nor do they use [http://en.wikipedia.org/wiki/Thermistor thermistors] (temperature sensitive resistors). Instead, they use the fact as temperature increases, the voltage across a diode increases at a known rate. (Technically, this is actually the voltage drop between the base and emitter - the Vbe - of a transistor.) By precisely amplifying the voltage change, it is easy to generate an analog signal that is directly proportional to temperature. There have been some improvements on the technique but, essentially that is how temperature is measured.
These sensors use a solid-state technique to determine the temperature. That is to say, they don't use mercury (like old thermometers), [http://en.wikipedia.org/wiki/Bimetallic_strip bimetalic strips] (like in some home thermometers or stoves), nor do they use [http://en.wikipedia.org/wiki/Thermistor thermistors] (temperature sensitive resistors). Instead, they use the fact as temperature increases, the voltage across a diode increases at a known rate. (Technically, this is actually the voltage drop between the base and emitter - the Vbe - of a transistor.) By precisely amplifying the voltage change, it is easy to generate an analog signal that is directly proportional to temperature. There have been some improvements on the technique but, essentially that is how temperature is measured.
[[Fichier:TMP36-pinout.jpg]]
[[Fichier:TMP36-pinout.jpg|250px]]
Because these sensors have no moving parts, they are precise, never wear out, don't need calibration, work under many environmental conditions, and are consistant between sensors and readings. Moreover they are very inexpensive and quite easy to use.
Because these sensors have no moving parts, they are precise, never wear out, don't need calibration, work under many environmental conditions, and are consistant between sensors and readings. Moreover they are very inexpensive and quite easy to use.