What are Transducer Types and Their Applications

There are various electrical and electronic components are used to build the circuits and projects for engineering students. The components are active and passive cacomponents, sensors, transducers, transmitters, receivers, modules (WiFi, Bluetooth, GSM, RFID, GPS), and so on. In general, the process of transduction involves the conversion of one form of energy into another form. This process mainly includes a sensing element to sense the input energy and then converting it into another form by a transduction element. Measurand tells the property, quantity, or state that the transducer looks to translate into an electrical output. Here, this article discusses what is a transducer,  transducer types, and applications of the transducer.

What is Transducer/Transducer Types?

A transducer is an electrical device that is used to convert one form of energy into another form. In general, these devices deal with different types of energies such as mechanical, electrical energy, light energy, chemical energy, thermal energy, acoustic energy, electromagnetic energy, and so on.

For instance, consider a mic we use in daily life in telephones, mobile phones, that converts the sound into electrical signals and then amplifies it into the preferred range.  Then, alters the electrical signals into audio signals at the o/p of the loudspeaker. Nowadays, fluorescent bulbs are used for lighting, change electrical energy into light energy.

The best transducer examples are loudspeakers, microphones, position, thermometers, antenna & pressure sensor. Likewise, there are different kinds of transducers used in electrical and electronic projects.

Conditions for Transducer Types

Some conditions that are mainly used to rate transducers are discussed below.

Dynamic Range

The dynamic range of the transducer is the ratio among the high amplitude signal as well as the least amplitude signal so that the transducer can efficiently translate. When the Transducers have a high dynamic range are more precise as well as sensitive.

Repeatability

Repeatability is the capability of the transducer for generating an equal output once it is stimulated through a similar input.

Noise

The output of the transducer adds some random noise. In electrical type transducers, the noise added by this can be electrical because of the thermal action of charges within circuits. The small signals can be corrupted by the noise more than large signals.

Hysteresis

In this property, the output of the transducer not only depends on its present input however it also depends on its past input. For instance, an actuator uses a gear train that has some reaction, when the direction of movement of the actuator overturns, then there will be a deceased zone before the actuator’s output overturns by play among the teeth of the gear.

Transducer Types and Its Applications

There are a variety of transducer types like pressure transducer, piezoelectric transducer, ultrasonic transducer, temperature transducer, and so on.  Let us discuss the use of different types of transducers in practical applications.

Some transducer types like active transducer and passive transducers are based on whether a power source is required or not.

Active transducer doesn’t require any power source for their operations. These transducers work on the principle of energy conversion. They generate an electrical signal that is proportional to the i/p. The best example of this transducer is a thermocouple. Whereas passive transducer requires an external power source for their operation. They generate an o/p in the form of capacitance, resistance. Then that has to be converted to an equivalent voltage or current signal. The best example of a passive transducer is a photocell.

Ultrasonic Transducer

The main function of the ultrasound transducer is to convert electrical signals to ultrasound waves. This transducer can also be called capacitive or piezoelectric transducers.

Application of Ultrasonic Transducer

This transducer can be used to measure the distance of the sound based on reflection. This measurement is based on a suitable method compared to the straight methods which use different measuring scales. The areas which are hard to find, such as pressure areas, very high temperature, using conventional methods the measurement of the distance is not a simple task. So, this transducer-based measuring system can be used in this kind of zone.

The proposed system uses 8051 microcontrollers, power supplies, an ultrasonic transducer module that includes transmitter and receiver, LCD display blocks are used which are shown in the above block diagram.

Here, if any obstacle or any object is found that is detected by ultrasonic transducer then it transmits the waves and gets reflected back from the object and these waves are received by the transducer. The time consumed by the transducer for transmitting & receiving the waves can be noted by considering the velocity of sound. Then, based on the sound velocity and a pre-programmed microcontroller is performed such that the distance is measured and displayed on an LCD display. Here, the display is interfaced with a microcontroller. The ultrasonic transducer produces 40kHz frequency waves.

Temperature Transducer

A temperature transducer is an electrical device that is used to convert the temperature of a device into another quantity like electrical energy or pressure or mechanical energy, then the quantity will be sent to the control device for controlling the temperature of the device.

Application of Temperature Transducer

A temperature transducer is used to measure the temperature of the air such that to control the temperature of several control systems like air-conditioning, heating, ventilation, and so on.

Let us consider a practical example of a temperature transducer that is used to control the temperature of any device based on the necessity for different industrial applications. An Arduino based automatic fan speed regulator controlling temperature and exhibiting a measure of temperature on an LCD display.

In the proposed system, IC LM35 is used as a temperature transducer. An Arduino board is used to control the various functions that include analog to digital conversion and an LCD display that is connected in the above fig.

The temperature can be fixed by using settings like INC and DEC for increasing and decreasing. Based on the temperature measured a pulse width modulation o/p will be generated by the program of an Arduino board. The output of this is used to control the DC fan through the motor driver IC.

Piezoelectric Transducer

A piezoelectric transducer is a special kind of sensor, and the main function of this transducer is to convert mechanical energy into electrical energy. In the same way, electrical energy can be transformed into mechanical energy.

Piezoelectric Transducer Applications

• This transducer is mainly used to detect the stick drummer’s impact on electronic drum pads. And also used to detect the movement of the muscle, which can be named acceleromyography.
• The load of the engine can be determined by calculating diverse absolute pressure, which can be done by using these transducers as the MAP sensor in fuel injection systems.
• This sensor can be used as a knock sensor in automotive engine management systems for noticing the knock of the engine.

Pressure Transducer

A pressure transducer is a special kind of sensor that alters the pressure forced into electrical signals. These transducers are also called pressure indicators, manometers, piezometers, transmitters, and pressure sensors.

Application of Pressure Transducer

The pressure transducer is used to measure the pressure of a specific quantity like gas or liquid by changing the pressure into electrical energy. The different kinds of these transducers like an amplified voltage transducer, strain-gage base pressure transducer, millivolt (mv) pressure transducer, 4-20mA pressure transducer, and pressure transducer.

The applications of pressure transducer mainly involve altitude sensing, pressure sensing, level or depth sensing, flow sensing, and leak testing. These transducers can be used for generating electrical power under the speed breakers on the highways or roads where the force of the vehicles can be converted into electrical energy.

Classification of Transducer Types

There are different methods to classify the transducers that comprise but not restricted toward the function of the transducer, structure otherwise the occurrence of their working. It is extremely simple to categorize transducers like Input & Output Transducers, but they are treated like simple signal converters. The main function of the input transducer is to gauge quantities from non-electrical to electrical.

On the other hand, o/p transducers work is quite opposite because their electrical are input signals whereas nonelectrical are output signals like displacement, force, pressure, torque, etc.
Transducers are classified into three types based on their operation principle like electrical, thermal, and mechanical. The following three methods are used to classify the transducers.

• Physical Effect
• Physical Quantity
• Source of Energy
• Principle of Transduction
• Primary & Secondary Transducer
• Analog & Digital Transducer
• Transducer & Inverse Transducer

Physical Effect

The first classification of the transducer can be done based on physical effect. This is the first classification of the transducer which depends on physical effect, used to change the quantity from physical to electrical. For instance, copper elements change within resistance will be in proportion with the temperature change. Here are the physical effects which are used for change in resistance, in inductance, in capacitance, Hall Effect & piezoelectric effect

Physical Quantity

The second classification of the transducer can be done based on physical quantity changed that is, the end-use of the transducer behind the conversion. For example, a Pressure Transducer is a transducer that converts pressure into an electrical signal. The classification of transducer-based on physical quantity includes the following.

• Flow transducer like flow Meter
• Acceleration transducer like accelerometer
• Temperature transducer like thermocouple
• Level transducer like torque Tube
• Pressure transducer like Bourdon Gauge
• Displacement transducer like Linear Variable Differential Transformer (LVDT)
• Force Transducer like dynamometer

Source of Energy

The classification of transducer-based on the source of energy can be done through two types which include the following.

• Active Transducers
• Passive Transducers

Active Transducers

In this type of transducers, the input energy can be used as a control signal while transmitting energy using a power supply toward the proportional output.

For instance, in an active transducer like a strain gauge, the strain can be changed into resistance. However, as the energy of the strained element is less, then the energy for the output can be given through an external power supply.

Passive Transducers

In this transducer, the input energy can be converted directly into the output. For instance, a passive transducer like Thermocouple, wherever the heat energy can be absorbed from the input can be changed into voltage or electrical signals.

Principle of Transduction

The classification of a transducer can be done based on the medium of transduction. Here the medium may be capacitive, resistive, or inductive based on the conversion method that how the input transducer changes the input signal into resistance, inductance & capacitance respectively.

Primary & Secondary Transducer

The primary transducer includes electrical & mechanical devices. The mechanical devices is also called the primary transducers, which are used to change the physical i/p quantity to a mechanical signal. The main function of a second transducer is used to change the signal from mechanical to electrical. The o/p signal’s magnitude mainly depends on the i/p mechanical signal.

Example

The best example of the primary and secondary transducer is Bourdon’s Tube because thus tube works like a primary transducer to notice the force as well as changes it into a dislocation from its open end. The dislocation of the open ends moves the center of the LVDT. The center movement can induce the output voltage which is relative directly to the dislocation of the tube open end.

Therefore, the two types of transduction take place within the tube. First, the force can be changed into a dislocation & after that, it is changed into the voltage using LVDT. The Bourdon’s Tube is the main transducer whereas the LVDT is the secondary transducer.

Analog & Digital Transducer

The classification of a transducer can be done based on their output signals which is continuous otherwise discrete.

The main function of the Analog transducer is to change the quantity of input to a constant function. The best examples of the analog transducer are LVDT, thermocouple, strain gauge & thermistor. Digital transducers are used to change the quantity of an input to a digital signal that works on low or high power.

A digital transducer is used to measure physical quantities to transmit the data like coded digital signals rather than like continuously changing voltages or currents. The digital transducer types are Shaft Encoders, Digital Resolvers, Digital Tachometers, Hall Effect Sensors & Limit Switches

Transducer & Inverse Transducers

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.

Strain Gauge Transducer

The main function of the strain gauge transducer is to convert physical quantities electrically. They function through changing physical quantities into mechanical pressure within a component known as a sensing element & after that convert the stress electrically using a strain gauge.

The structure of the sensing element, as well as the strain gauge, is designed optimally to give handling & superior accuracy products. These transducers are classified generally based on their application to construction/civil engineering types or general types. Some of the general-type transducers are utilized in the construction or civil engineering field. The types of strain gauge transducers are Wire Strain Gauge, Foil Strain Gauge & Semiconductor Strain Gauge.

Inductive Transducer

The inductive transducer works on the inductance change principle because of an appreciable transform within the amount to be measured. For instance, LVDT is a type inductive transducer, used to measures displacement like voltage disparity among its two secondary voltages. These voltages are the outcome of induction because of the change of flux within the secondary coil by the dislocation of the iron bar. The types of the inductive transducer are Simple Inductance and Two-Coil Mutual Inductance.

Transducer Types Characteristics

The characteristics of a transducer are given below that are determined by examining the o/p response of a transducer to a variety of i/p signals. Test conditions create definite operating conditions as closely as possible. The methods of computational and standard statistical can be applied to the test data.

The characteristics of the transducer play a key role while selecting the appropriate transducer, especially for a specific design. So knowing its characteristics is essential for suitable selection. So transducer characteristics are categorized into two types like static and dynamic.

• Precision
• Resolution
• Sensitivity
• Drift
• Linearity
• Conformance
• Span
• Hysteresis
• Distortion
• Noise
• Linearity
• Sensitivity
• Resolution
• Threshold
• Span & Range
• Accuracy
• Stability
• Drift
• Repeatability
• Responsiveness
• Threshold
• Input & O/P Impedances

Static Characteristics

The transducer’s static characteristics are a set of act criteria that are recognized throughout static calibration which means the explanation of the value of measurement through fundamentally maintaining the calculated quantities because constant values change very slowly.

For instruments, the set of criteria can be defined to calculate the quantities which are gradually changing with time otherwise mostly constant that does not differ through time is known as static characteristics. The characteristics include the following.

Dynamic Characteristics

The transducer’s dynamic characteristics relay toward its performance once the measured capacity is a function of time which changes quickly with respect to time. Once these characteristics rely on the transducer’s performance, then the measured quantity is basically stable.

So these characteristics rely on dynamic inputs because they are reliant on their own parameters & the character of the input signal. The dynamic characteristics of the transducer include the following.

• Fidelity
• Speed of Response
•  Bandwidth
• Dynamic Error

In general, both the characteristics of a transducer like static & dynamic will verify its performance & specify how efficiently it can recognize preferred input signals as well as refuse unnecessary inputs.

Transducer Types Applications

The applications of transducer types are discussed below.

• The transducer types are used in electromagnetic applications like antennas, magnetic cartridges, hall-effect sensors, disk read & writes heads.
• The transducer types are used in electromechanical applications like accelerometers, LVDT, galvanometers, pressure sensors, load cells, MEMS, potentiometers, airflow sensors, linear & rotary motors.
• The transducer types are used in electrochemical applications like oxygen sensors, hydrogen sensors, pH meters,
• The transducer types are used in electroacoustic applications like speakers, piezoelectric crystals, microphones, ultrasonic transceivers, sonar, etc
• The transducer types are used in photoelectric applications like LED, photodiodes, laser diodes, photoelectric cells, LDRs, fluorescent, incandescent lamps, and phototransistor
• The transducer types are used in thermoelectric applications like thermistors, thermocouples, Resistance Temperature Detectors (RTD)
• The transducer types are used in radio acoustic applications like Geiger-Muller Tube, radio transmitters & receivers

Thus, this is all about different types of transducers used in several electrical and electronics projects. Are you fascinated by implementing projects by using transducers? Then, please give your suggestions by commenting in the comment section below. Here is a question for you, what is the main function of the transducer?