Transducer

Definition: The device which converts the one form of energy into another is known as the transducer. The process of conversion is known as transduction. The conversion is done by sensing and transducing the physical quantities like temperature, pressure, sound, etc.

The electrical transducer converts the mechanical energy into an electric signal. The electrical signal may be voltage, current and frequency. The production of the signal depends on the resistive inductive and capacitive effects of the physical input.

Needs of Transducer

It is quite difficult to determine the exact magnitude of the physical forces like temperature, pressure, etc. But if the physical force is converted into an electrical signal, then their value is easily measured with the help of the meter. The transducers convert the physical forces into an electrical signal which can easily be handled and transmitted for measurement. 

The following are the advantages of converting the physical quantity into an electrical signal.

1. The attenuation and amplification of the electrical signals are very easy.
2. The electrical signal produces less friction error.
3. The small power is required for controlling the electrical systems.
4. The electrical signals are easily transmitted and processed for measurement.
5. The component used for measuring the electrical signal is very compact and accurate.
6. The electrical signals are used in telemetry.

Parts of Transducer

The transducer consists two important parts.

1. Sensing Element
2. Transduction Element

The transducer has many other parts like amplifiers, signal processing equipment, power supplies calibrating and reference sources, etc.

1. Sensing or Detector Element  – It is the part of the transducers which give the response to the physical sensation. The response of the sensing element depends on the physical phenomenon.
2. Transduction Element  – The transduction element converts the output of the sensing element into an electrical signal. This element is also called the secondary transducer.

Factors Influencing the Choice of Transducer

The choice of the transducers used for measuring the physical quantity depends on the following factors.

1. Operating Principle – The transducers are selected by their operating principles. The operating principle may be resistive, inductive, capacitive, optoelectronic, piezoelectric, etc.
2. Sensitivity – The sensitivity of the transducer is enough for inducing the detectable output.
3. Operating Range – The transducer must have wide operating ranges so that it does not break during the working.
4. Accuracy  – The transducers gives accuracy after calibration. It has a small value for repeatability which is essentials for the industrial applications.
5. Cross Sensitivity – The transducers gives variable measured value for the different planes because of the sensitivity. Hence, for the accurate measurement, the cross sensitivity is essential.
6. Errors  – The errors are avoided by taking the input output relations which is obtained by the transfer function.
7. Loading Effect – The transducers have high input impedance and low output impedance for avoiding the errors.
8. Environmental Compatibility – The transducers should be able to work in any specified environments like in a corrosive environment. It should be able to work under high pressure and shocks.
9. Insensitivity to Unwanted Signals – The transducer should be sensitive enough for ignoring the unwanted and high sensitive signals.
10. Usage and Ruggedness  – The durability, size and weight of the transducer must be known before selecting it.
11. Stability and Reliability – The stability of the transducers should be high enough for the operation. And their reliability should be good in case of failure of the transducer.
12. Static characteristic – The transducer should have a high linearity and resolution, but it has low hysteresis. The transducer is always free from the load and temperature.

Applications of Transducer

The following are the application of the transducers.

1. It is used for detecting the movement of muscles which is called acceleromyograph.
2. The transducer measures the load on the engines.
3. It is used as a sensor for knowing the engine knock.
4. The transducers measure the pressure of the gas and liquid by converting it into an electrical signal.
5. It converts the temperature of the devices into an electrical signal or mechanical work.
6. 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.
7. The transducer is used in the speaker for converting the electrical signal into acoustic sound.
8. It is used in the antenna for converting the electromagnetic waves into an electrical signal.

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