What is the Difference Between Sensor and Transducer?

The physical devices, sensor and transducers are might used by some people interchangeably. These devices are used in numerous electrical and electronic gadgets and appliances. But, people fail to make a difference between sensor and transducer. Because, transducers are sometimes found in sensors.The main difference between sensor and transducer is, the sensor is a physical device, that senses a physical quantity and then converts it into signals which can be read by an instrument or the user. The transducer is also a physical device, that converts one form of energy into an another form. The best example of a transducer is an antenna. Because, it converts electricity to electromagnetic waves. A sensor also converts one form of energy to another, means it senses a physical quantity and converts it into an electrical signal.

What is a Sensor and Transducer?

The sensor is a device, that senses a physical quantity and converts it into an analogue quantity which can be measured electrically such as voltage, capacitance, inductance and ohmic resistance. The output needs to be operated, interfaced & regulated by the system designer.

There are different kinds of sensors are available, that are used in various applications. The motion sensor is a one type of sensor, that is used in numerous systems like home security lights, automatic door fixtures normally send out some kind of energy like ultrasonic waves, microwaves or light beams and sense when the energy flow is interrupted by something entering its lane.

The transducer is a device that is connected to sensor to convert the measured quantity into a standard electrical signal such as 0-10V DC, -10 to +10V DC, 4 to 20mA, 0 to 20mA, 0-25mA etc. The o/p of the transducer can be directly used by the system designer.

Transducers are used in electronic communication systems to convert signals of different physical forms to electronic signals.In the below figure, two transducers are used where the microphone is used as the first transducer and as a second transducer speaker is used.

There are various types of sensors and transducers are available to choose from like analog, digital, input and output. The type of i/p or o/p transducer being used, really depends upon the kind of signal sensed or controlled. But, a sensor and transducer can be defined as they converts one physical quantity to another.

A device which performs an i/p function is called sensor because they sense a physical change in some characteristic that changes in response to some excitation.Transducer is also a device, that converts the energy from one form to another.Examples for the transducer is microphone, loudspeaker etc.

Common Sensors and Transducers

What is The Main Difference between Sensor and Transducer

People get confused with both terms sensor and transducer, they do not understand why transducers are used in sensors. In a multi-operational device, a transducer converts one form of energy to another, and this converted energy is measured to the user for other measurements using sensors. It is mystifying to see contact transducers are being used in sensors for detecting energy levels and then converts them into electrical energy so as to be shown on a screen.

About 20years before, the application of the transducer is used in tape heads of cassette players to transfer the magnetic information by direct contact with the magnetic tape. Then, this data was converted into electrical signals. These signals were sent to the load speakers and then converted to sound format to hear.

Coming to another type of transducers like immersion and paintbrush transducers. Immersion transducers were used to measure energy in the form of sound, pressure so on. Paintbrush transducers operate in the air and these transducers are also similar to the immersion transducers.

The main purpose to use a senor is to convert an energy into a one form which is noticeable by the user. To make this happen, a sensor may contain a transducer as they are capable of converting from one form to another. The simplest example of the transducer is an LED (Light Emitting Diode) converts light energy into electrical energy. The best example of a sensor is the sensors used in cars and bikes which can detect the touch and activates the sirens. There are also cases when both the physical devices are the same. For instance, a bi-metallic spring is used to measure the temperature change, and if a pointer is attached to the bi-metallic spring, and may well be the entire sensor.

Applications of Sensors and Transducers

Applications of sensors and transducers mainly involve in various electronics and electrical projects.

Programmable Digital Temperature Controller

This project is an electronic project based on embedded systems. The main intention of this project is to control the temperature of any device used in industrial applications. This project mainly uses a temperature sensor.

The LCD display is interfaced to the microcontroller for displaying the readings of the temperature readings. The digital temperature sensor provides 9-bit temperature readings to the 8051 microcontroller. The EEPROM non-volatile memory is used to store user defined temperature settings through a set of switches to the microcontroller. A relay is connected to the microcontroller which can be driven using the transistor driver. The load can be driven using this relay

Touch Controlled Load Switch

Touch controlled load switch is designed to control the load, and in this project a piezoelectric plate is used as a transducer. This project consists of a power supply, touch sensor plate, 555 timer, touch plate, relay and load.

This project uses a 555 timer in monostable mode, that is used to make a relay for switching ON a load in the duration of fixed time.555 timer includes a triggered pin which is connected to the touch plate. When 555 timer is activated by touch it delivers logic high for a fixed time duration. This time interval can be varied by changing the RC time constant connected to the timer. Thus, the o/p of the timer drives the load through the relay. The load automatically turns OFF after a fixed time duration.

Thus, this is all about the main difference between sensor and transducer with their practical examples.We believe that you have got a better understanding of this concept.Furthermore, any queries regarding this concept or electronics projects please give your feedback by commenting in the comment section below.Do you know few more differences between sensor and transducer?