Transducers classification

1. Directorate of Technical
Education,
Tamilnadu.
Thanthai Periyar Government
Institute of Technology,
Vellore–632002
Department of ECE

2. Transducers
Unit 5
Presented by.
Mrs. M.P.Sasirekha

3. Contents
• Definition – Sensor , Transducer
• Block diagram
• Classification 1 , 2
• Factor for selecting Transducer
• Reference
• Thank you
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4. Sensor
• A Sensor is defined as a device which
measures a physical quality (light, sound,
space) and converts them into an easily
readable format.
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5. Transducer
• Transducer is a device which converts one
form of energy into another form i.e,. the
given non-electrical energy is converted into
an electrical energy.
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6. Transducer Block diagram
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7. Classification of Transducers
1. Based on the physical phenomenon
• Primary transducer
• Secondary transducer
2. Based on the power type Classification
• Active transducer
• Passive transducer
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8. Classification of Transducers
3. Based on the type of output the classification of
transducers are made
• Analog transducer
• Digital transducer
4. Based on the electrical phenomenon is a best
Classification of Transducer
• Resistive transducer
• Capacitive transducer
• Inductive transducer
• Photoelectric transducer
• Photovoltaic transducer
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9. Classification of Transducers
5. Based on the transduction phenomenon
• Transducer
• Inverse transducer.
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10. Factor to be considered while
Selecting Transducer
• It should have high input impedance and low output
impedance, to avoid loading effect.
• It should have good resolution over is entire selected
range.
• It must be highly sensitive to desired signal and
insensitive to unwanted signal.
• Preferably small in size.
• It should be able to work in corrosive environment.
• It should be able to withstand pressure, shocks,
vibrations etc..
• It must have high degree of accuracy and repeatability.
• Selected transducer must be free from errors.
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11. classification
1. Physical phenomenon
2. Power type
3. Type of output
4. Transduction phenomenon
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12. Based on the physical phenomenon
• Primary Transducer – The transducer consists the
mechanical as well as the electrical devices. The
mechanical devices of the transducer change the
physical input quantities into a mechanical signal.
This mechanical device is known as the primary
transducers.
• Secondary Transducer – The secondary
transducer converts the mechanical signal into an
electrical signal. The magnitude of the output
signal depends on the input mechanical signal.
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13. Example - Bourdon’s Tube
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14. Primary and secondary transducer
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15. • If pressure is applied to the tube it will try to
straighten causing the free end to move up and
to the right. This motion is converted to a circular
motion for a pointer with a quadrant and pinion
linkage. A Bourdon tube inherently measures
gauge pressure.
• Bourdon tubes are usable up to about 50 MPa,
(about 10000 psi). Where an electrical output is
required the tube can be coupled to a
potentiometer or LVDT.
• The Bourdon’s Tube is the primary transducer,
and the L.V.D.T is called the secondary
transducer. NEXT

16. Power type
• Passive Transducer – The transducer which
requires the power from an external supply
source is known as the passive transducer. They
are also known as the external power transducer.
The capacitive, resistive and inductive
transducers are the example of the passive
transducer.
• Example : strain gauges, resistance temperature
detectors (RTDs), and thermistors.
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17. Active Transducer
• Active Transducer – The transducer which
does not require the external power source is
known as the active transducer. Such type of
transducer develops theirs owns voltage or
current, hence known as a self-generating
transducer. The output signal is obtained from
the physical input quantity.
• Examples : Thermocouples and piezoelectric
accelerometers.
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18. Active transducers
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19. Active transducers
• Photoelectric
• Thermoelectric
• Piezoelectric

20. Photoelectric transducers
• Photo transistor
• Photo diode
• Photo resistor
• Photovoltaic cell or solar cell
• Light energy is converted into electrical
energy. (current or voltage)
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21. Photo transistor
• The phototransistor is a device that converts the
light energy into electric energy. It produces both
the current and voltage.
• The photovoltaic cell is a bipolar device which is
made of semiconductor material.
• The semiconductor material is enclosed in an
opaque container in which the light easily
reaches to the photosensitive element.
• The element absorbs light, and the current starts
flowing from base to emitter of the device. This
current is converted into the voltages. NEXT

22. Photo transistor
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23. Photo diode
• The photodiode is a semiconductor material
which converts the light into the current. The
electrons of the semiconductor material start
moving when the photodiode absorbs the
light energy.
• The response time of the photodiode is very
less. It is designed for working in reverse bias.
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24. Photo diode
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25. Photoresistor
• Photoresistor is the combination of words
“photon” (meaning light particles) and “resistor”.
True to its name, a photo-resistor is a device or
we can say a resistor dependent on the light
intensity. For this reason, they are also known as
light dependent a.k.a. LDRs.
Photoresistor is a variable resistor whose
resistance varies inversely with the intensity of
light”
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26. Photoresistor
• Photoresistors work based on the principle of
photoconductivity. Photoconductivity is an
optical phenomenon in which the material’s
conductivity is increased when light is
absorbed by the material.
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27. Photoresistor
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28. Photovoltaic (PV) cell
• A photovoltaic (PV) cell, also known as a solar
cell, is an electronic component that
generates electricity when exposed to
photons, or particles of light. This conversion
is called the photovoltaic effect,
• A photovoltaic cell is made of semiconductor
materials that absorb the photons emitted by
the sun and generate a flow of electrons.
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29. Photovoltaic (PV) cell
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30. Thermoelectric
• Resistance temperature detectors (RTD)
• Thermocouples
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31. NEXT

32. • 1) Seebeck effect: The Seebeck effect states
that when two different or unlike metals are
joined together at two junctions, an
electromotive force (emf) is generated at the
two junctions. The amount of emf generated
is different for different combinations of the
metals.
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33. RTD
• Resistance thermometers, also called
resistance temperature detectors (RTDs), are
sensors used to measure temperature.
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34. Piezoelectric transducer • The Piezoelectric
transducer is an
electroacoustic
transducer use for
conversion of
pressure or
mechanical stress into
an alternating
electrical force. It is
used for measuring
the physical quantity
like force, pressure,
stress, etc., which is
directly not possible
to measure.
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35. Analog and Digital Transducer
• Analog and Digital Transducer
• The transducer can also be classified by their output
signals. The output signal of the transducer may be
continuous or discrete.
• Analog Transducer – The Analog transducer changes
the input quantity into a continuous function. The
strain gauge, L.V.D.T, thermocouple, thermistor are the
examples of the analogue transducer.
• Digital Transducer – These transducers convert an
input quantity into a digital signal or in the form of the
pulse. The digital signals work on high or low power.
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36. Analog transducer Digital trasnsducer
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37. Transducer and Inverse Transducer
• Transducer – The device which converts the
non-electrical quantity into an electric
quantity is known as the transducer.
• Inverse Transducer – The transducer which
converts the electric quantity into a physical
quantity, such type of transducers is known as
the inverse transducer. The transducer has
high electrical input and low non-electrical
output.
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38. Inverse transducer
PIEZOELECTRIC
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39. Reference
• https://instrumentationtools.com/what-is-a-
transducer/
• https://www.sciencedirect.com/topics/engineering/bo
urdon-tube
• http://www.instrumentationtoday.com/transducers/20
11/07/
• https://circuitglobe.com/capacitive-transducer.html
• https://instrumentationtools.com/capacitive-pressure-
sensor/
• https://circuitglobe.com/piezo-electric-transducer.html
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40. Thankyou