7.1 INTRODUCTION

The first classification of Transducers is based on the physical effect engaged to convert the physical quantity to electrical quantity. An example, is the change in resistance (physical quantity) of a copper element in proportion to the change in temperature.

The following physical effects are generally used:

• Variation in Resistance

• Variation in Inductance

• Variation in Capacitance

• Hall Effect

• Piezoelectric Effect

The second classification of Transducers is based on the physical quantity converted i.e. the end use of the transducer after the conversion. For example, a Pressure Transducer is a transducer that converts pressure into electrical signal.

Following is small list of transducers classified based on the physical quantity and corresponding examples

• Temperature Transducer – Thermocouple

• Pressure Transducer – Bourdon Gauge

• Displacement Transducer – LVDT (Linear Variable Differential Transformer)

• Level Transducer – Torque Tube

• Flow Transducer – Flow Meter

• Force Transducer – Dynamometer

• Acceleration Transducer – accelerometer

Transducers are also classified based on the source of energy. Under this category, there usually two types of transducers:

• Active Transducers

• Passive Transducers