A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another.[1] Transducers are often employed at the boundaries of automation, measurement, and control systems, where electrical signals are converted to and from other physical quantities (energy, force, torque, light, motion, position, etc.). The process of converting one form of energy to another is known as transduction.[2]


Mechanical transducer

Sensors, actuators and transceivers

Transducers can be categorized by which direction information passes through them:

Active vs passive transducers

Passive transducers require an external power source to operate, which is called an excitation signal. The signal is modulated by the sensor to produce an output signal. For example, a thermistor does not generate any electrical signal, but by passing an electric current through it, its resistance can be measured by detecting variations in the current or voltage across the thermistor.[5][2]

Active transducers in contrast, generate electric current in response to an external stimulus which serves as the output signal without the need of an additional energy source. Such examples are a photodiode, and a piezoelectric sensor, photovoltic, thermocouple.[5]


Some specifications that are used to rate transducers:


Transducers are used in electronic communications systems to convert signals of various physical forms to electronic signals, and vice versa. In this example, the first transducer could be a microphone, and the second transducer could be a speaker.




Electromechanical input feeds meters and sensors, while electromechanical output devices are generically called actuators):



Also known as photoelectric:




See also


  1. ^ Agarwal, Anant; Lang, Jeffrey H. (2005). Foundations of analog and digital electronic circuits. Amsterdam: Elsevier. p. 43. ISBN 9780080506814.
  2. ^ a b c d e f g Winer, Ethan (2013). "Part 3". Plasma Speaker. New York and London: Focal Press. ISBN 978-0-240-82100-9.
  3. ^ Fraden J. (2016). Handbook of Modern Sensors: Physics, Designs, and Applications 5th ed. Springer. p.1
  4. ^ Kalantar-zadeh, K. (2013). Sensors: An Introductory Course 2013th Edition. Springer. p.1
  5. ^ a b Fraden J. (2016). Handbook of Modern Sensors: Physics, Designs, and Applications 5th ed. Springer. p.7