Transducer & sensors

Have you read the name of section? 😒 Yes, you are right I am posting it in mechanical section. Do you know why? see the tutorial & you can get why it is important in mechanical

Introduction.

Transducers are the basic elements that converts or transforms one from of energy to another form. Let us change the world ‘energy’ to ‘signal’ which is more convenient to use. A transducer converts one form of signal to the another form without scarifying the principle of law of conservation of energy.
Transducer usually coverts first form of signal to electrical signal.
Transducers are mainly used to quantify the physical, electrical, fluidic, &mechanical variables or parameters such as temperature, pressure, magnetic field, voltage, flow, vibrations etc. such variables or parameters can commonly be called as measurands.

Various measurands

Vibrations
Speed
Rotations
Pressure
Motion
Intensity of light
Gas concentration & pH
Flow
Color
Amplitude
Voltage
Velocity
Stress & strain
Resistance
Frequency
Density
Acceleration
Vacuum
Temperature
Sound
Radiation
Length
Humidity level
Force & load
Current
Angle
Acoustic field
Medical imaging
Position
Audio field & noise
Image
Level
Magnetic field
Phase

To measure different measurent a variety of transducers are fabricated.

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ShrinkDWorld
- Difference between transducer & sensor.
Actually transducer is part of sensor.
A sensor is merely a sophisticated transducer in the sense that it contains some signal conditioning circuits capable of amplifying the weak & raw signal that is available at the output of transducer.
Amplifiers, filters, analog to digital converter (ADC) etc. are the some commonly used signal conditioning circuits. The input signal is called as measurent & output signal called as equivalence. The output signal is mostly in electrical signal which is mostly used in automation.
Fig
ShrinkDWorld

· Transducer types

The transducer are broadly classified as a passive equivalence & active equivalence
Passive equivalence are resistance, inductance & capacitance. In passive equivalence transducer the material used such that the change in measurent will affect the resistance/ Inductance / capacitance of that material.
While in active equivalence transducer directly provide electrical signals like voltage, current.
ShrinkDWorld

· Transducer material
ShrinkDWorld

· The principal of transducer may be derived form following affects.
ü Photoemissive
ü Photo resistive inductance
ü Bimetallic strips
ü Piezoelectric
ü Photoconductive
ü Pyro electric
ü Photovoltaic
ü Thermoelectric
ü Hall
ü Optical encoding
ü Capacitance
ü Ionization
ü Stain gauge
ü Optical fiber

ü Burden tube
ü Mechanical watch.
ShrinkDWorld

· Photoelectric transducer

For photo sensitive material electric properties changes when light falls upon it. These materials are Cadmium Sulphides, Cadmium Sulphoselenide, Lead, Telluride, & semiconductors.
The principle is based on fact that often light strike on such substance the entire photonic energy is converted into kinetic energy of the electron. This phenomenon is defined as photoelectric effect.
This phenomenon observed in effects known as Photoemissive, photoconductive, & photovoltaic effect.
ShrinkDWorld

· Photoemissive transducer

The schematic diagram of Photoemissive transducer is shown in fig.
Fig

It is a vacuum chamber containing Photoemissive cathode, an anode, & a photomultiplier consists of many dynodes. The light sensitive cathode emits electron by virtue of photoelectric effect. Electron thus ejected from photo sensitive cathode are attracted toward & strike the first positive electrode (dynode - 1) of the photo multiplier, liberating secondary electron. The photoelectron thus generated from the first dynode are again accelerated toward second dynode. Since it is kept at higher potential compared to first dynode. The secondary electron bombard on second dynode generates more secondary electrons & so on. Until a desirable current signal is produced through several stages. Finally a shower of electron is produced & collected at the anode current which is proportional to the intensity of light.
ShrinkDWorld

· Photoconductive transducer
ShrinkDWorld

Termistors (reserved)
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photovoltic transducer
ShrinkDWorld

This space has been reserved to write about thermo devices. As and when I get time for this I will write a detailed explanation about it.
ShrinkDWorld

thermo couple (reserved)
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inductive transducer (reserved)
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capacitive transducer (reserved)
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pyro electric transducer (reserved)
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piezoeletric transducer (reserved)
ShrinkDWorld

Hall effect transducer (reserved)
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ionisation transducer (reserved)
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light emitting diode (reserved)
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optical encoder
a) incremental encoder (reserved)
ShrinkDWorld

This space has been reserved to write about Absolute encoders. As and when I get time for this I will write a detailed explanation about it.
ShrinkDWorld

bimetallic strips
ShrinkDWorld

bourdon tube (reserved)
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load cell (reserved)
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strain gauge (reserved)
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diaphragm (reserved)

You are reading an archived discussion.

Transducer & sensors

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