pl, explane .difference between thermister & thremostate?

Answer 1

thermostat : This is a device for regulating the temperature of a system so that the system's temperature is maintained near a desired setpoint temperature. The thermostat does this by controlling the flow of heat energy into or out of the system. That is, the thermostat switches heating or cooling devices on or off as needed to maintain the correct temperature.

The thermostat was invented in 1885 by Albert Butz and is the first known example of process control methodology. This invention was the genesis for what is now Honeywell corporation.

These may then control the heating or cooling apparatus using:

(1) Direct mechanical control,

(2) Electrical signals,

(3) Pneumatic signals.


thermistor : This is a type of resistor used to measure temperature changes, relying on the change in its resistance with changing temperature. Thermistor is a combination of the words thermal and resistor.

The Thermistor was invented by Samuel Ruben in 1930, and has U.S. Patent #2,021,491.

there are two types of thermistors :

a. negative (NTC),
b. positive (PTC).

TC-temperature coefficient.

(a) NTC: Manufactured from the oxides of the transition metals - manganese, cobalt, copper and nickel, NTC thermistors are temperature dependant semiconductor resistors. Operating over a range of -200°C to + 1000°C, they are supplied in glass bead, disc, chips and probe formats. NTCs should be chosen when a continuous change of resistance is required over a wide temperature range. They offer mechanical, thermal and electrical stability, together with a high degree of sensitivity.

(b) PTC thermistors are temperature dependent resistors manufactured from barium titanate and should be chosen when a drastic change in resistance is required at a specific temperature or current level. PTCs can operate in the following modes:

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Temperature sensing, switching at temperatures ranging from 60°C to 180°C, e.g. protection of windings in electric motors and transformers.

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Solid state fuse to protect against excess current levels, ranging from several mA to several A (25°C ambient) and continuous voltages up to 600V and higher, e.g. power supplies for a wide range of electrical equipment.

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Liquid level sensor.

Answer 2

I think you mean thermostat. A thermistor is a resistor which changes value with temperature. A thermostat is a control device that closes or opens a switch when a particular temperature is reached.