Definition of Transducer
What is a transducer?
Transducer is a device that converts energy form one form to other, to make it readable for measurement. Thus it converts energy to a readable form e.g. thermometer that converts heat energy into height of mercury column. In transducer output is controlled by the input.
Role of transducer
They play a vital role in field of measurements. As we discuss earlier transducer covert physical quantity into electrical signal. So without transducer, it would be very difficult to measure the continues physical quantity e.g. light intensity,speed,flow,temperature,radiation,electric flux etc.The quantities are first converted into electrical signal ,then they are monitored by dedicated equipments. Some one could not imagine the measurement of these continuous physical quantities without transducers.
Types of transducers
They are broadly divided into two categories;
- Active transducer
- Passive transducer
Active transducer: Such type of transducers required external source of energy to operate. Energy is supplied through a separate voltage source. An example is potentiometer, which senses the resistance by flow of a minute current through itself. Most of the transducers now a day are active.
Passive transducer: They convert one form of energy to other form without any use of energy. Passive transducers convert physical quantities like;temperature,pressure,speed etc.
Transducers are further subdivided as;
- Resistive transducer
- Inductive changing transducer
- Capacitive changing transducer
- Displacement transducers
- Velocity transducers
- Pressure transducers
These transducers operate on the principle of, variation in resistance. Resistance is changed by several ways including;
- sliding viper along a rheostat,
- applying physical stress,
- Light variation on photosensitive element
- temperature variation.
RTD abbreviated as Resistance temperature detector. The resistance of RTD changes with the variation in temperature and this change in resistance in monitored in term of variation in current/voltage. Normally RTD are constructed from materials like Platinum. Ni and Germanium are used for manufacturing of RTDs for special applications. When it comes to performance Platinum RTD (PRDS) are best. RTDs are used in thermometer, having range between B.P of O2 to milting point of Antimony.
- Widely used to measure high temperature.