What is a Thermistor?
Thermistor comes from “thermally sensitive resistor,” which was the original name of these devices. Thermistors are resistance thermometers and a type of semiconductor that have an electrical resistance that changes depending on the weather. They have a low resistance to insulation but a higher resistance to conduction. Thermistors are made of metallic oxides that are formed into a bead, cylinder, or disk and surrounded with glass or epoxy.
How Does a Thermistor Work?
There are two types of thermistors available: Positive Temperature Coefficient (PTC) or Negative Temperature Coefficient (NTC). With the NTC, the resistance decreases and the temperature increases, and as the temperature drops, the resistance rises. This is the most frequently used type of thermistor.
With the PTC thermistor, the temperature and resistance move in tandem. So, when the temperature rises, the resistance rises, and when the temperature decreases, the resistance decreases. These are most often fused in fuses.
Thermistors can be applied in a variety of electronics, and they’re most frequently used as temperature sensors. They can also be used in heating elements and as current protectors and current limiters.
Thermistor vs Thermocouple
While thermistors and thermocouples are both temperature sensors, a thermocouple is made of two different conductor metals connected at a point, which form a measuring junction and a reference junction. Then these junctions have different temperatures, hot and cold, they produce a thermo-electric voltage, which can be translated into a temperature, you can measure the resistance.
Pros and Cons of Thermistors
The benefits of a thermistor sensor include long-lasting durability and an affordable cost. They’re fairly small in size and highly sensitive, so they’re good for measuring single temperature points. That said, thermistors don’t provide a linear output because they don’t “measure” temperature, and they can have a slower response time.