Introduction to a Thermistor.

Here I will provide you a brief insight on what is a thermistor and how it works.

A thermistor is available in various shapes and colours but for starters we will use a green coloured one that looks something like this. :-


What is it? And what does it do?

Thermistors are temperature-sensing elements made of semiconductor material that has been sintered in order to display large changes in resistance in proportion to small changes in temperature.This resistance can be measured by using a small and measured direct current, or dc, passed through the thermistor in order to measure the voltage drop produced.

These solid state temperature sensors actually act like electrical resistors that are temperature sensitive. That is where the name, a clear combination of the words thermal and resistor, comes from. Ametherm specializes in NTC, or negative temperature coefficient, thermistors.


Thermistors are an incredibly accurate category of temperature sensors


In general, thermistors are composed of sintered ceramics consisting of highly sensitive material with consistently reproducible properties of resistance versus temperature.

There are two types of thermistors.

  • PTC

Positive Temperature Coefficient (PTC) thermistors exhibit increasing electrical resistance with increases in environmental temperature and decreasing electrical resistance with decreasing temperature.  Correspondingly, PTC thermistors exhibit a linear, decreasing electrical resistance with decreasing environmental temperature. These thermistors linear and proportional change in Resistance / Temperature (R/T) offers simplified and reliable thermal management.

  • NTC

NTC stands for “Negative Temperature Coefficient”. NTC thermistors are resistors with a negative temperature coefficient, which means that the resistance decreases with increasing temperature. They are primarily used as resistive temperature sensors and current-limiting devices. The temperature sensitivity coefficient is about five times greater than that of silicon temperature sensors (silistors) and about ten times greater than those of resistance temperature detectors (RTDs). NTC sensors are typically used in a range from −55°C to 200°C.

This is sufficient knowledge you require to get on with your next project that involves arduino and temperature sensing using a thermistor.


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