A transducer is a device which senses a non-electrical quantity and converts it into a proportionate electrical quantity for measurement.

Advantageous of Electrical Transducers

  1. The electrical signal can be easily amplified and filtered.
  2. The electrical signal can be converted into any desired format.
  3. The electrical signals can be transmitted through a long distance by electromagnetic waves.

Classification of Transducers

Transducers may be classified in different ways viz according to their application, method of energy conversion, the nature of the output signal and soon. On the basis of power utilized by them for operation, they may be classified as active transducers and passive transducers.

Active Transducers

The transducers which generate their own power for their operation are known as active transducers. In these transducers, a voltage or current are produced proportional to the measurand.

Examples of active transducers

  • Thermocouple
  • Thermopile
  • Piezoelectric crystals
  • Photovoltaic cell

Passive Transducers

The transducers which need an external source of power for their operation are known as passive transducers. In these transducers, a variation in some electrical parameter is produced, which in turn can be measured as a voltage or current.

Examples of passive transducers

  • Resistance strain gauge
  • Potentiometer
  • Hygrometer
  • Capacitive transducers
  • Inductive transducers
  • Resistance transducers