What is a Transducer in Electronics? Transducer types with applications

(Last Updated On: July 29, 2020)



Transducer is a part of a measuring chain and they transform a physical quantity into an electrical signal. Transducers are important for detecting physical quantities. Normally, such quantities as temperature, pressure, air humidity, sound pressure or light, are transformed into normalized signals.

In this article, we will discuss

  • What is a transducer?
  • Basic concept of Transducer
  • Main component
    • Sensing parameter
    • Element of Transducer
  • Categorization of Transducers
    • Resistive Transducers
    • Capacitance Transducers
    • Inductance Transducers
    • Voltage and current Transducers
    • Self-Generating Transducers
    • Favorable circumstances of Electrical transducers
    • Factor to be thought of while choosing transducer:
    • Prerequisites of a decent transducers

Introduction to Transducers

A gadget that changes over a physical amount into the relative electrical signal is known as a transducer. The electrical signal delivered might be a voltage, flow or recurrence. A transducer utilizes numerous impacts to produce such change. The way toward changing signal from one structure to other is called transduction. A transducer is additionally rung pick. The transduction component changes the yield of the sensor to an electrical yield, as appeared in the Fig 1.

Fig 1: Basic concept of Transducer.

A transducer includes basically two main components, which are listed as follow:

  1. Sensing parameter

The physical amount or its pace of progress is detected and reacted to by this piece of the transistor.

  1. Element of Transducer

The yield of the detecting component is given to the transduction component. This component is dependable for changing over the non-electrical sign into its corresponding electrical sign. There might be situations when the transduction component plays out the activity of both transduction and detecting. The best case of such a transducer is a thermocouple. A thermocouple is utilized to create a voltage comparing to the warmth that is created at the intersection of two unique metals.

Categorization of Transducers

The Classification of Transducers is done from multiple points of view as declared in Fig 2. A portion of the standards for the grouping are in view of their zone of utilization, Method of vitality change, Nature of yield signal, According to Electrical standards included, Electrical boundary utilized, rule of activity, and Typical applications.

Fig 2: Classification of Transducer.

The transducers can be grouped extensively

  1. Based on transduction structure utilized
  2. As essential and auxiliary transducers
  3. As dynamic and uninvolved transducers
  4. As transducers and backwards transducers.

Extensively one such speculation is worried about vitality contemplations wherein they are delegated dynamic and passive transducers. A part whose yield vitality is provided completely by its info signal (physical amount under estimation) is ordinarily called a passive transducer‟. As it were the aloof transducers determine the force required for transduction from a helper source. Dynamic transducers are those which don’t require an assistant force source to create their yield. They are otherwise called self-creating type since they produce their own voltage or current yield. A portion of the inactive transducers (electrical transducers), their electrical boundary (obstruction, capacitance, and so on), guideline of activity and applications are recorded underneath.

Resistive Transducers

  1. Obstruction Strain Gauge – The adjustment in estimation of opposition of metal semi-conduit due to lengthening or pressure is known by the estimation of force, relocation or power.
  2. Opposition Thermometer – The adjustment in obstruction of metal wire because of the change in temperature known by the estimation of temperature.
  3. Opposition Hygrometer – The adjustment in the obstruction of conductive strip because of the difference in dampness content is known by the estimation of its relating mugginess.
  4. Hot Wire Meter – The adjustment in opposition of a warming component because of convection cooling of a stream of gas is known by its comparing gas stream or weight.
  5. Photoconductive Cell – The adjustment in obstruction of a cell because of a relating change in light motion is known by its comparing light force.
  6. Thermistor – The adjustment in obstruction of a semi-conductor that has a negative co-effective of obstruction is known by its relating proportion of temperature.
  7. Potentiometer Type – The adjustment in opposition of a potentiometer perusing because of the development of the slider as a piece of an outside power applied is known by its relating pressure or dislodging.
Fig 3: Resistive transducer internal structure

Capacitance Transducers

The capacitive transducer is utilized for estimating the dislodging, pressure and other physical amounts. It is a latent transducer that implies it requires outside force for activity. The capacitive transducer takes a shot at the guideline of variable capacitances. The capacitance of the capacitive transducer changes as a result of numerous reasons like covering of plates, change in separation between the plates and dielectric consistent. The capacitive transducer contains two equal metal plates. These plates are isolated by the dielectric medium which is either air, material, gas or fluid. In the typical capacitor the separation between the plates are fixed, however in capacitive transducer the separation between them are differed. The capacitive transducer utilizes the electrical amount of capacitance for changing over the mechanical development into an electrical sign. The information amount causes the difference in the capacitance which is legitimately estimated by the capacitive transducer.

The capacitors measure both the static and dynamic changes. The dislodging is likewise estimated straightforwardly by interfacing the quantifiable gadgets to the mobile plate of the capacitor. It chips away at with both the reaching and non-reaching modes.

  1. Variable capacitance pressure gage – Rule of activity: Distance between two equal plates is shifted by a remotely applied power Applications: Measurement of Displacement, pressure
  2. Capacitor mouthpiece Rule of activity: Sound weight shifts the capacitance between a fixed plate and a portable stomach. Applications: Speech, music, clamor
  3. Dielectric check Rule of activity: Variation in capacitance by changes in the dielectric. Applications: Liquid level, thickness
Fig 4: Capacitive Transducer

Inductance Transducers  

  1. Attractive circuit transducer Rule of activity: Self-inductance or shared inductance of air conditioning energized loop is shifted by changes in the attractive circuit. Applications: Pressure, dislodging
  2. Hesitance pickup Guideline of activity: Reluctance of the attractive circuit is fluctuated by changing the situation of the iron center of a curl. Applications: Pressure, uprooting, vibration, position
  3. Differential transformer Rule of activity: The differential voltage of two optional windings of a transformer is changed by situating the attractive center through a remotely applied power. Applications: Weight, power, removal, position
  4. Swirl current gage Rule of activity: Inductance of a loop is changed by the vicinity of a vortex current plate. Applications: Displacement, thickness
  5. Magnetostriction check Rule of activity: Magnetic properties are fluctuated by weight and stress. Applications: Force, pressure, sound
Quantity being
Input Device
Output Device
Light Level Light Dependent Resistor (LDR)
Solar Cell
Lights & Lamps
LED’s & Displays
Fiber Optics
Temperature Thermocouple
Resistive Temperature Detectors
Force/Pressure Strain Gauge
Pressure Switch
Load Cells
Lifts & Jacks
Position Potentiometer
Reflective/Slotted Opt-switch
Panel Meters
Speed Tacho-generator
Reflective/Slotted Opto-coupler
Doppler Effect Sensors
AC and DC Motors
Stepper Motor
Sound Carbon Microphone
Piezo-electric Crystal
Fig 5: Inductive transducer

Voltage and Current Transducers

  1. Corridor impact pickup Rule of activity: A potential contrast is produced over a semiconductor plate

(Germanium) when attractive motion connects with an applied current. Applications: Magnetic transition, current

  1. Ionization chamber Standard of activity: Electron stream instigated by ionization of gas because of radioactive radiation. Applications: Particle checking, radiation
  2. Photoemissive cell Standard of activity: Electron emanation because of occurrence radiation on photo emissive surface. Applications: Light and radiation
  3. Photomultiplier tube Rule of activity: Secondary electron outflow because of occurrence radiation on photosensitive cathode. Applications: Light and radiation, photograph touchy transfers Figure 7 presents schematic graph of the new structured current and voltage detecting circuit for DC estimation. The principle segments of the proposed estimation framework are CASR25 current transducer and MCP6002 direct operation amp. Different info signals, for example, direct current (DC), elective current (AC) and beat signals, can be detected by this current transducer. The CASR25 gives a galvanic confinement trademark among information and yield circuits. The utilized operation amp in the new plan is double organized and can be fueled by voltages from 1.8V to 6V because of its rail-to-rail structure. A positive 5V DC power flexibly is simply used to work the transducer and the operation amps in the structure. The new structured circuit can straightforwardly detect the line current and line voltage over the positive terminal. The Vdc+ mark appeared in the figure expresses the positive association of the DC line. There isn’t any physical association is made among the negative DC terminal what’s more, the ground of detecting gadget. Along these lines, the grounds of force and sign segment are separated. The sizes to be estimated are taken care of to the information terminals of the current transducer. The maximum furthest reaches of the estimation range might be changed by the association of the transducer. In the event that the associations between essential also, optional pins of the transducer are short-circuited among themselves, the transducer may detect flows as much as 25A. The yield of the CASR25 is applied to a differential speaker circuit to procure detected estimation of the current. The voltage estimation some portion of the proposed framework is appeared in the lower part of the outline. As can be seen from the schematic chart, sequential resistor squares are misused to detect estimation of the DC voltages. The detected DC voltage is acquired over the yield of the differential enhancer circuit. The acquired sign from the transducer yield what’s more, the negative terminal of DC input (Vcc-) are applied to the resistor systems (R3, R4, R5 and R6, R7, R8) so as to change current sign to the voltage signal. After this transformation procedure, the obtained voltage is taken care of to the differential speaker circuit. The transformation paces of the proposed detecting gadget are set to 7.24mV for 1V and 153mV for each 1A.
Fig 6: Voltage and current transducer.

Self-Generating Transducers

They don’t require an outer force, and produce a simple voltage or current when invigorated by some physical type of vitality.

  1. Thermocouple and thermopile Guideline of activity: An emf is created over the intersection of two divergent metals or semiconductors when that intersection is warmed. Applications: Temperature, heat stream, radiation.
  2. Moving-curl generator Guideline of activity: Motion of a loop in an attractive field produces a voltage. Applications: Speed. Vibration
  3. Piezoelectric pickup: – An emf is produced when an outside power is applied to certain translucent materials, for example, quartz Sound, vibration. Speeding up, pressure changes
  4. Photovoltaic cell Standard of activity: A voltage is created in a semi-conductor intersection gadget when brilliant vitality invigorates the cell Applications: Light meter, sun oriented cell Essential Transducers and Secondary Transducers-Burden tube going about as an essential detector faculties the weight and changes over the weight into an uprooting of its free end. The dislodging of the free end moves the center of a straight factor differential transformer (LVDT) which creates a yield voltage. Simple Transducers-These transducers convert the info amount into a simple yield which is a nonstop capacity of time. Strain Gauge, LVDT, Thermocouple and Thermistor Computerized Transducers-These transducers convert the info amount into an electrical yield which is in the type of heartbeats. ◦ Glass Scale can be perused optically by methods for a light source, an optical framework and photocells Transducers and Inverse Transducers- – A Transducer can be comprehensively characterized as a gadget which changes over a non-electrical amount into an electrical amount. Ex:- Resistive, inductive and capacitive transducers – An converse transducer is characterized as a gadget which changes over an electrical amount into a non-electrical amount. Ex:- Piezoelectric precious stones.
Fig 7: Self generating transducer

Favorable circumstances of Electrical transducers

For the most part amounts to be estimated are non-electrical, for example, temperature, pressure, uprooting, mugginess, liquid stream, and speed and so forth. Yet these amounts can’t be estimated straightforwardly. Thus such amounts are required to be detected and changed into some other structure for simple estimation. Electrical amounts for example, current, voltage, obstruction, inductance and capacitance and so on can be advantageously estimated, moved and put away, and, in this manner, for estimation of the non-electrical amounts these are to be changed over into electrical amounts first and ten estimated. The capacity of changing over non-electrical amount into electrical one is cultivated by a gadget called the electrical transducer. Essentially an electrical transducer is a detecting gadget by which a physical, mechanical or optical amount to be estimated is changed legitimately, with an appropriate component, into an electrical sign (flow, voltage and recurrence). The creation of these signs depends on electrical impacts which might be resistive, inductive, and capacitive and so forth in nature. The info versus yield vitality relationship takes a distinct reproducible capacity. The yield to include and the yield to time conduct is unsurprising to a known level of exactness, affectability and reaction, inside the predetermined ecological conditions. Electrical transducers have various points of interest. Present day computerized PCs have utilized electrical transducers significant. Electrical transducers endure because of some disadvantages as well, for example, low unwavering quality in contrast with that of mechanical transducers because of the maturing and float of the dynamic parts and near significant expense of electrical transducers and related sign conditioners. At times the precision and goal achievable are not as high as in mechanical transducers. A portion of the preferences are:

  1. Electrical enhancement and weakening should be possible effectively and that to with a static gadget.
  2. The impact of rubbing is limited.
  3. The electric or electronic framework can be controlled with an exceptionally little electric force.
  4. The electric force can be effortlessly utilized, transmitted and process with the end goal of estimation.

Factor to be thought of while choosing a transducer:

It ought to have high information impedance and low yield impedance, to abstain from stacking impact.

It ought to have great goal over is whole chosen extend. It must be exceptionally touchy to wanted sign and coldhearted toward undesirable sign. Ideally little in size. It ought to have the option to work n destructive condition. It ought to have the option to withstand pressure, stuns, vibrations and so forth..

It must have serious extent of precision and repeatability. Chosen transducer must be liberated from blunders. The transducer circuit ought to have over-burden security so it will withstand over-burdens.

Prerequisites of a decent transducers

  • Smaller in size and weight.
  • High affectability.
  • Ability to withstand ecological conditions.
  • Low expense.

Applications of Transducer

The following are the application of the transducers.

  • It is used for detecting the movement of muscles which is called acceleromyograph.
  • The transducer is used in the speaker for converting the electrical signal into acoustic sound.
  • It converts the temperature of the devices into an electrical signal or mechanical work.
  • The transducer measures the load on the engines.
  • It is used in the antenna for converting the electromagnetic waves into an electrical signal.
  • It is used as a sensor for knowing the engine knock.
  • The transducers measure the pressure of the gas and liquid by converting it into an electrical signal.
  • The transducer is used in the ultrasound machine. It receives the sound waves of the patient by emitting their sound waves and pass the signal to the CPU.

The classifications of the transducers depend on the various factors like by transduction, the converting electrical signal from AC or DC, etc.

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My name is Shahzada Fahad and I am an Electrical Engineer. I have been doing Job in UAE as a site engineer in an Electrical Construction Company. Currently, I am running my own YouTube channel "Electronic Clinic", and managing this Website. My Hobbies are * Watching Movies * Music * Martial Arts * Photography * Travelling * Make Sketches and so on...

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