General Properties of an NTC Thermistor

Thermistors are considered solid state temperature sensing tools that are electrical resistors, which are sensitive to temperature. The device is often used for producing an analog output voltage that has variations in ambient temperature. Thermistors are referred to as transducers because they create changes in electrical properties that are the result of a physical change in heat.


A thermistor is a two-terminal solid state and a thermally sensitive transducer that is constructed from a sensitive semiconductor (metal oxide). It also has connecting leads that are attached to a bead or ceramic disc. Thermistors indicate change of the resistive value directly in proportion to the changes in temperature. This means that as temperature changes, the resistance of the device will change in correlation with temperature.

In a standard resistor, changing resistance due to heat is typically a bad thing, but for thermistors, they thrive in those environments. Heat change is valuable in temperature detection circuits. Thermistors are used for measuring temperatures in ambient air and liquids.

Because thermistors are solid state devices, made from sensitive metal oxides, they can work at molecular levels. The outermost electrons become active, which produces a negative temperature coefficient.

Primarily, thermistors are used as resistive temperature sensors, but they are also used in series with components and devices that have currents flowing through them. Some engineers use these devices as a current-limiting tool. Typically, these heat-dependent resistors operate in two ways: decreasing or increasing of resistive values related to changes in temperature.


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