Working Of Transducer and Classification of Transducer
Definition
A transducer is a device which converts the energy from one form to another.
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| Working Of Transducer and Classification of Transducer |
Most of the transducers either convert electrical energy into mechanical displacement or convert some non-electrical physical quantity such that force, sound, temperature etc. to an electrical signal.
A transducer performs the following functions in an electronic instrumentation system:
✓Detects or senses the presence,magnitude and changes in physical quantity being measured.
✓Provides a proportional electrical output signal.
Classification Of Transducer
Transducers are mainly classified into two groups as shown below:
(1)Active transducers
They are also known as self-generating type transducers.
These transducers develop their own voltage or current.
The energy required for production of an output signal is obtained from the physical phenomenon being measured.
Examples: Thermocouple and thermopiles, piezoelectric pickup, photo voltaic cell.
(2)Passive transducers
They are known as externally-powered transducers.
These transducers derive the power required for energy conuersion from an external power souce.
However, they may absorb some energy from the physical phenomenon under study.
Examples: Resistance thermometers and thermistors, potentiometeric devices, differential transformer, photoemission cell etc.
Classification based on the type of output
(1)Analogue transducers
These transducers convert the input physical phenomenon into an analogous output which is a continuous function of time.
Examples: Strain gauge,a thermocouple,a thermistor or an LVDT(linear voltage differential transformer.
(2)Digital transducers
These transducers convert the input physical phenomenon into an electrical output which may be in form of pulses.
Classification based on electrical principle involved:
1.Variable-resistance type
(1)Strain and pressure gauges
(2)Thermistors, resistance thermometers
(3)Photo conductive cell etc.
2.Variable-inductance type
(1)Linear variable differential transformer(LVDT)
(2)Reluctance pick-up
(3)Eddy current gauge
3.Variable-capacitance type
(1)Capacitor microphone
(2)Pressure gauge
(3)Dielectric gauge
4.Voltage-generating type
(1)Thermocouple
(2)Photovoltaic cell
(3)Rotational motion tachometer
(4)Piezoelectric pick-up
5.Voltage-divider type
(1)Potentiometer position sensor
(2)Pressure-actuated voltage divider
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