What is a transducer, its types and its application (Updated)

April 2, 2020 by Electric Sparks

Table of Contents

• What is Transducer?
• Electric and Non-Electric:
• Active and Passive :
• Analog and Digital :
• Primary and Secondary :
• Different Types of Transducers.
• Thermocouple Transducer :
• Resistance Temperature Detector Transducer:
• Thermistor Transducer:
• Piezoelectric Transducer :
• Difference Between Sensor and Transducer:
• Transducer Working Principle
• Static Characteristics of Sensors and Transducers.
• Application of Transducer:
• Frequently Asked Questions on Transducer
• What’s the distinction between sensors and transducers?
• Why is a transducer so important?
• Transducer examples.
• Are thermometers sensors, or is it a transducer?
• Where can a transducer be used?
• The thermocouple is which type of transducer?

What is Transducer?

The Transducer is defined as a device that senses non-electrical variation signals and shows it in an electrical form.
It can also be defined as
The Transducer converts physical Quantity to Analog Normalized signal.

The function of the transducer is to convert the energy into sounds (source) or converts the sound energy (receiver) into the form of an electric signal.

Classification of Transducer.

It can also be defined as a device that converts one form of energy into another form of energy.
For Example, the speed meter of a car which shows digits on screen is an example of the it and also the length which measures and displays it on a screen, the change in temperature or change in Resistance.

Based on its working, it are classified into the following parts.

Classification of Transducer

Based on its working they are classified into the following;

1. Electric and Non-Electric Transducers
2. Active and Passive Transducers
3. Primary and Secondary Transducers
4. Analog and Digital Transducers

Electric and Non-Electric:

They are that type of transducers that convert one form of energy to an electrical structure of energy, for Example, microphone.

In a microphone, the voice is converted to electrical signals through IC’s.

Non-Electric Transducers are the type in which electrical energy is converted to other forms of energy for Example speaker.

In the speaker, the electrical signal is converted into sound waves, which is Non-electric.

Active and Passive :

The Active Transducer is that type which converts one form of energy into another way without the use of any auxiliary source.

It is also known as a self-generating Transducer.

For Example, solar cells, photovoltaic cells.

In the solar cell, the solar energy is converted to electrical power without using any source.

The passive Transducer is that type which converts one form of energy into another way with the use of any auxiliary source.

For Example potentiometer, bridges. To balance the bridges, some voltage is applied to the source to maintain its balance. The same is the case with a potentiometer when something is measured external power source is given to it.

Analog and Digital :

Analog transducer is the type that converts input quantity into an analog, and output is a continuous function of time for Example strain gauge.

Digital transducer converts input quantity into an electrical supply in the form of a pulse. Examples of digital sensors are half-wave and full-wave rectifiers.

Primary and Secondary :

The primary Transducer as the name implies, it is the first element that is directly coupled to the system . For Example, the bourdon tube.

The secondary Transducer is that type when the primary Transducer is connected in cascade to a transducer , which transforms the output of a sensor into an electrical output.

For Example, LVDT.

Different Types of Transducers.

You must be thinking of how many types of transducers are there?

The answer to your question is here:

Different kind of transducers are available which is as under,

1. Ultrasonic Transducer
2. Temperature Transducer
3. Piezoelectric Transducer
4. Pressure Transducer

Ultrasonic :

Ultrasonic transducers are divided into three broad categories.

1. Transmitters
2. Receivers
3. Transceivers

Transmitters convert electrical signals to ultrasounds.
Receivers transform ultrasound waves toward electrical signals.

The transceiver can do both send and receive ultrasound.

In a similar way, radar, ultrasonic sonar system is used which interpret the target by reflecting signals by measuring the time between sending and receiving signals and then measuring the distance.

It has a wide range of applications. For Example, ultrasound is used in the medical field, and it can also be used for wireless charging.

They are also usually used to track an object.

Temperature :

A temperature transducer is defined as a device that converts thermal energy to electrical energy.

Temperature transducers are further divided into the following categories.

1. Thermocouple
2. Resistance Temperature Detector
3. Thermistor

Temperature Transducer

Thermocouple Transducer :

The Thermocouple is defined as two similar methods joined together, as shown in the figure below.

Thermocouple

And there is a difference in temperature between the two ends, and hence the two terms create a small current, so this is called the See-back effect, and this phenomenon was discovered by Thomas see-back in 1821.

Resistance Temperature Detector Transducer:

RTD is a sensor whose resistance changes with the temperature.

Resistance Temperature Detector

As in the bride, the Rx shows the RTD the Ratio becomes R1/R3=R2/RX.

The change in the Resistance of the Rx changes the ratio of the bride, and thus we get the current in the in-circuit.

Thermistor Transducer:

Thermistors are different from RTD, the material used in thermistor is ceramic/polymer. However, RTD uses Pure metals.

Thermistors are made up of semiconductors materials; thus, with the increase in temperature, Resistance decreases.

We can calculate the Resistance with the help of the Steinhart-hart equation, as shown below.

​

Thermistor Formula

The thermistor has a wide range of applications.

It is used as a current limiting device and also temperature-controlled equipment, like Toasters and Coffee maker devices.

Piezoelectric Transducer :

What is Piezoelectric Transducer?

It is that type which converts external mechanical force into electric potential.

The construction of the piezoelectric is straightforward, shown below.

​

Piezoelectric Transducer

When external pressure is applied, as shown in the figure, the force summing factor collects the external force than through the anode. It is transmitted to the crystal, which produces electric potential and obtains the output region and represents it as VO shown in the figure.

The crystal used in the piezoelectric Transducer is quard crystal.

The electromotive force produced in the output (Vo) is directly proportional to the amount of pressure applied.

Pressure :

The pressure transducer is sometimes called a pressure transmitter, it converts pressure into an analog electrical signal.

Pressure Transducer

The most common type is the strain gauge transducer, as shown below.

Strain Gauge Transducer

The regeneration of pressure into an electrical signal is easily getting through the physical deformation of the strain gauge, which is attached to the diaphragm of the pressure transducer. The strain will produce an electrical resistance variation proportional to the pressure.

Construction

They are generally available in three different types to discuss below;

1. Millivolt output
2. Voltage output
3. 4–20mA output

Millivolt output transducer is economical, but because of their low output signal, they should not be located in electrical noise and required regulated power supply for the input power.

Voltage output transducer includes integral signal conditioning and has a high output level, so they are less susceptible to electrical noise and can be used for unregulated power supply.

4–20mA output is least affected by electrical noise and Resistance in signal wires and hence making it a best suitable for long-lasting transmission.

Difference Between Sensor and Transducer:

The sensor is defined as a device that can detect the physical quantity and convert the data into an electrical signal.

&

The Transducer converts physical Quantity to Analog Normalized signal.

Sensor and Transducer

It should be noted that sensors are a type of Transducer. The sensor is a device that detects physical quantity, i.e. (heat, sound, light, etc.) and converts it to an easily readable signal, i.e., voltage or current signals.

The key differences are shown below;

The sensor converts one physical quantity into electrical quantity.

The Transducer converts one form of energy into another form of energy.

Sensors just sense the physical quantity. It does not convert it to any form.

The Transducer is sensor + transduction converts one form of energy to another.

The sensor can respond to change in physical parameters and produce a change in the physical parameter that can be sensed.

It converts turn in the physical setting into some useful form of energy.

Sensor output is always an electric output.

Transducer output will not always be electric.

Sensors detect and communicate with a particular event.

The Transducer only is a detector of the event.

Sensors are proximity sensors, magnetic sensors, barometer are the Example of the sensors.

Transducer thermistor and Thermocouple are the Examples of it.

Transducer Working Principle

A transducer, a combination of transduction and detecting elements, must transform one type of energy into another. The sensor responds to the physical change and creates its output. For instance, the output could take forms of displacement, angle displacement strain, or strain. This output from the sensor then gets connected to the transduction component. The transduction element can react to the sensing element’s response and create an equivalent output in the form of an electrical signal.

Static Characteristics of Sensors and Transducers.

1:RANGE ;

Range of a Sensor/ Transducers indicates the limits between which the input can vary.

For Example.

•The Thermocouple may have a range of 25°C — 250°C.

2: SPAN ;

It is the difference between maximum and minimum values. For Example,

Thermocouple values are given above, so span is subtracting minimum from maximum like,

250°C — 25 °C = 225 °C

3:ACCURACY;

Accuracy indicates the nearest value to the actual cost of the quantity being measured by using a sensor or Transducer.

For Example,

Piezoelectric Transducers can detect 0.7 Kilo Pascal (KPA) to 70 mega Pascal (MPA) if accuracy is specified as[ +(-1%)] of the full-scale calculation reading expected by the Transducer.

In this, we have to tell the accuracy using Transducer by putting the given values in the following equation { x/70MPA} ×100.

SOLUTION = 0.7 KPa to 70 MPa

Formula = X/ 70MPa × 100

X = 0.7 MPa

The above value of X is the expected accuracy, the value of the Transducer is 0.7 MPa.

4: STABILITY;

The system can maintain the standard of the system over a while.

It means when we get the same output value as the input value.

5: ZERO STABILITY;

The instrument can restore the zero reading after the input quantity has been brought to zero.

FORMULA = Error r % = (Xm — Xl / Xt ) × 100 t= true value

m= measured value

The real value is usually given, and the measured value is measured so that error of zero stability can be found.

6: SENSITIVITY ;

It is defined as the ratio of change in the output value of a sensor to the per unit change in input value that causes the output change.

7: RESOLUTION;

Resolution is the smallest detectable incremental change of input parameter that can be detected in the output signal.

Resolution can be expressed instead as a proposition of the full-scale reading or in absolute terms.

8: REPEAT ABILITY;

It is expressed through a formula.

Maximum value — minimum value / full-scale range × 100.

9: THRESHOLD;

At the zero value condition of the measuring end, the smallest input change that produces a detectable output is called the threshold.

In a digital readout- system, the threshold is that input quantity, which is an increase to cause a change in one significant digit of the output signal.

10: DEAD BOND;

A deed bond or a dead space of a Transducer is the range of input value, for which there is no output.

11: HYSTERESIS ;

It is determined as the maximum difference in output at any measurement value within the sensors specified range. while approaching this point at first with increasing and then decreasing the input parameters to get accurate results.

Application of Transducer:

Transducers have a wide application in industry. Indeed control and automation would not be possible without the transducer. Some of the most significant uses of transducers are :

• It is employed in many home appliances , such as air conditioners to monitor temperature and regulate it.
• In a microphone, the sound wave is converted by a transducer the electrical signals. Similar to speakers, electrical signals are converted to sound wave.
• Thermocouples or RTDs are utilized in industry to monitor and regulate the temperature of systems.
• In the medical industry, acceleromyograph is utilized to monitor muscles’ movement following nerve stimulation.
• In the industrial sector, different kinds of transducers such as. Frequency, Active Power Voltage, Reactive Power Ampere Power Factor Transducers are employed together with CT and/or PT to show the values of these meters.
• Oil for transformers as well as winding temperatures are measured with OTI as well as WTI as well.
• It senses the pressure of the process fluid (gas or liquid) and convert it into electrical signals.
• In the communication system electromagnetic waves are converted to electrical signal by using the transducer inside Antenna.
• In the digital thermometer, body temperature is converted into an electrical signals.
• The photovoltaic cells is an example of a transducer that converts sunlight light into an electrical signals.
• The circumference of the chest are determined using the help of a pneumograph with an ionizer that functions as transducer.
• Utilized for Robotics and Automation to convert movements into electrical signals.
• Nuclear Radiation can be measured by using a transducer that transforms radiation energy into electrical signals through the Direct Reading Dosimeter (DRD).

These are just a few examples of transducers. Actually, it is used in a variety of ways and it’s impossible to include all of them in the same time.

Frequently Asked Questions on Transducer

What’s the distinction between sensors and transducers?

Sensors and transducers both sense changes in the environment they are in. The difference is in the output of each. The output is in the same format as input in an electronic sensor, but the input is transformed into an electrical signal by the transducer.

Why is a transducer so important?

Transducers transform physical information into an electric signal. Transducers are crucial for detecting and quantifying these signals (pressure or temperature, the humidity of the air, etc.)

Transducer examples.

Any device that transforms energy into another is called a transducer. A loudspeaker is just one of the most common examples of transducers. A speaker converts electrical signals into sound waves.

Are thermometers sensors, or is it a transducer?

A thermometer can be described as an instrument for transducing and a sensor.

Where can a transducer be used?

Transducers are often employed in situations that require measurement and automation. In

These electric signals will be converted into as well as from other physical quantities.

Thermocouple is which type of transducer?

A thermocouple is an instance of an the active transducer. Transducer that is active produces output in form of electric and voltage powered signals.

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