Pozistor and thermistor, what is the difference?


Pozistor (PTC-thermistor)is an electronic component that has a positive drag coefficient and performs a dual function: a heater and a temperature sensor. When a high voltage or current is applied, the electronic component heats up. The higher the temperature becomes, the more its internal resistance increases, and therefore less current will flow through the element. Heating of the PTC component can occur under the influence of the external environment. In this case, it works as a temperature sensor. Pozistor has a box design in the form of round washers, filled with enamel, or in the form of ceramic elements, successively installed in a single case.
Posistor and thermistor what is the difference

In the diagram, the posistor has the following designation:

Posistor and thermistor, what is the difference

Application of posistor

Because the posistor is a fairly accurate component,its field of application in electronics is as follows:
  • protection of the primary circuits of the transformer winding;
  • effective motor current starter;
  • current limiter


  • u>Thermistor (NTC thermistor)is a sensitive electronic component with a negative resistance coefficient. When heated, its internal resistance begins to fall. The component can serve as a temperature sensor or a variable resistor (as protection against overheating in electrical circuits). The parameters of the thermistor are not linear, which means that with increasing temperature the resistance drops disproportionately and unevenly. The thermistor case is made of beads, covered with ceramic or glass, which differ in size.
    Posistor and thermistor what's the difference

    The diagram has the following notation:

    Pistor and thermistor what's the difference
One of the major drawbacks of a thermistor is the mismatch of characteristics in the manufacture of the same process technology.Components in the same conditions can produce different data, so when you replace one component with a similar one, re-calibration is required. With long-term operation in conditions of high temperature, NTC-thermistors begin to degrade over time and need to be replaced. Maximum sensor operating temperature is 300 degrees Celsius.

NTC thermistors application area:

  • temperature measurement of radio components of a computer and mobile equipment (processors and memory chips, hard disks, video cards, etc.);
  • in power supplies and lithium-ion (Li-ion) batteries as protection against overheating;
  • in office equipment (laser printers and fax machines);
  • in 3D printers (for extruders and heated tables).
In fact, both components are able to control the temperature, but the resistance RTS-t rmorezistora with heating tends to infinity, while the resistance NTC-thermistor at the same conditions tends to zero. To measure the temperature, you need a controller that will calculate the resistance data of the components.

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