Difference between Sensor and Transducer?

We have often heard the words such as Sensor and Transducer as a person related to electrical and instrument maintenance services. Many of us know that what is sensor and transducer?

But there are some peoples who really want to know about the difference between sensor and transducer. This blog is for those people.

Overview about Sensor and Transducer

What is Sensor?

sensor and transducer

A sensor is a device that is used to measure the physical changes in the nearby environment and gives output in an easy-to-read format for the user.

The following is a list of different types of sensors.

  • Temperature Sensor
  • Pressure Sensor
  • Vibration Sensor
  • Level Sensor
  • Proximity Sensor
  • IR Sensor
  • Ultrasonic Sensor
  • Photo Sensor
  • Humidity Sensor
  • Touch Sensor
  • Tilt Sensor

All these sensors are used to detect the changes in one of the physical properties such as Resistance, Capacitance, Conduction, Light, Heat Transfer, etc.

The most common example of a temperature sensor is RTD, it has a positive temperature co-efficient. As the temperature increases the resistance of the RTD increases. Another example is the mercury thermometer, the user can see the physical changes in the mercury as it expands with the rise in temperature.


What is Transducer?

sensor and transducer

A transducer is a device that converts one form of energy into another form. Basically, it converts the signal from one form to another form, which means the input and output signals of the transducer are not the same.

A transducer is often related to the electrical, instrumentation, and automation field. Where it converts the electrical signal to and from the other physical quantities such as torque, motion, force, light, heat, pressure, etc. This conversion is known as transduction.


A transducer converts a non-electrical signal into an electrical signal and vice versa. The transducer can be an input transducer or an output transducer.

An input transducer has mainly two parts:

Sensor or Sensing element

This part of the transducer responds to the physical changes in the nearby environment. The response of the sensing element depends on the physical phenomenon.

Transduction element

The transduction element of the transducer converts the output from the sensing element into an appropriate electrical signal.

The most common examples of input transducers are LDR, thermistors, RTD, thermocouple, diaphragm, etc.


An output transducer converts the electrical signal into another form of energy. It has an actuator instead of a sensor.


An actuator is a device that controls the mechanism or a system by a signal from a control system.

The most common examples of output transducers are LED, Bulb, Relay, Buzzer, Siren, Motor, Valves, etc.


Types of transducer based on the power source:

⇒ Active Transducer

An active transducer doesn’t require a power source to function. This transducer works on the energy conversion principle where they produce an output based on the input signal.

A common example of an active transducer is a thermocouple.

⇒ Passive Transducer

A passive transducer requires an external power source in order to function. They produce the output signal in the form of some variation in resistance, capacitance, inductance, etc., and then it is converted into an electrical signal.

Common examples are loadcell, LDR, RTD, etc.

Difference between Sensor and Transducer

Sensor Transducer
A device that detects the physical changes in the nearby environment. A device that converts the energy from one form to another.
A sensor has no other components with itself. A transducer contains a sensor and signal conditioning circuit.
All the sensors may not be transducers. All transducers contain a sensor.
A sensor detects the physical changes only and can’t give feedback to the control system on its own. A transducer is generally used to provide feedback to the control system.


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