A thermistor is a component
changes when its temperature changes.
A thermistor is a special type of resistor
resistance decreases as its temperature increases.
A plot of resistance against temperature for
a thermistor is shown above. The plot is unusual
because it shows that a bigger current will flow
at a higher temperature. For most components, the
increases as the temperature increases
and a smaller current
flows at a higher temperature.
What is a Thermistor used for?
A thermistor can be used in a circuit to detect a
temperature change. For example, a thermistor may
be used to keep a freezer at the right temperature.
A circuit with a thermistor in it can switch the freezer on if the temperature gets too high and switch the freezer
off again when the correct low temperature is reached.
A thermistor can also be used to trigger a fire alarm. Thermistor are used in all Temperature controlled device and Motors to cut off
circuit when temperature rises over a certain limit to cut off power or trigger another circuit.