Passive Transducers

These type of transducers requires an external power supply and therefore output is equal to the variation in a physical parameter such as pressure, temp etc.

Thermister

It is a negative temperature device means that its resistance decreases with increase with temperature and voice versa, It can handle temperature range from -100C° to +350C° and so sensitive to temperature change. It is made of copper, nickel and cobalt. Its resistance varies from 0.5Ω to 100µΩ due to the temperature change.

Uses of Thermister

Due to small in size and very sensitive to temperature therefore, it is used at large scale in small digital devices.

Resistance Temperature Transducer

The Resistance Temperature Transducer is positive temperature co-efficient, its resistance increases with increases in temperature and vice versa. It is also called resistance thermometer, it is made of platimiun, nickel and copper, it can handle temperature of -180° to 650C°. It means that the resistance temperature transducer is more sensitive and can handle high temperature as well.