A transducer is a device that converts a signal in one form of energy to another form of energy.
Energy types include electrical, mechanical, electromagnetic, chemical, acoustic and thermal
energy. While the term transducer commonly implies the use of a sensor/detector, any
device which converts energy can be considered a transducer. Transducers are widely used
in measuring instruments. A sensor is used to detect a parameter in
one form and report it in another form of energy, often an electrical signal. For example,
a pressure sensor might detect pressure and convert it to electrical signal for display
at a remote gauge. An actuator accepts energy and produces movement.
The energy supplied to an actuator might be electrical or mechanical. An electric motor
and a loudspeaker are both actuators, converting electrical energy into motion for different
purposes. Combination transducers have both functions;
they both detect and create action. For example, a typical ultrasonic transducer switches back
and forth many times a second between acting as an actuator to produce ultrasonic waves,
and acting as a sensor to detect ultrasonic waves. Rotating a DC electric motor's rotor
will produce electricity and voice-coil speakers can also act as microphones.
Applications
Electromagnetic: Antenna – converts propagating electromagnetic
waves to and from conducted electrical signals Magnetic cartridge – converts relative physical
motion to and from electrical signals Tape head, Disk read-and-write head – converts
magnetic fields on a magnetic medium to and from electrical signals
Hall effect sensor – converts a magnetic field level into an electrical signal
Electrochemical: pH probes
Electro-galvanic fuel cell Hydrogen sensor
Electromechanical: Electroactive polymers
Galvanometer Microelectromechanical systems
Rotary motor, linear motor Vibration powered generator
Potentiometer when used for measuring position Linear variable differential transformer or
Rotary variable differential transformer Load cell – converts force to mV/V electrical
signal using strain gauge Accelerometer
Strain gauge String potentiometer
Air flow sensor Tactile sensor
Electroacoustic: Loudspeaker, earphone – converts electrical
signals into sound Microphone – converts sound into an electrical
signal Pickup – converts motion of metal strings
into an electrical signal Tactile transducer – converts electrical
signal into vibration Piezoelectric crystal – converts deformations
of solid-state crystals to and from electrical signals
Geophone – converts a ground movement into voltage
Gramophone pickup – Hydrophone – converts changes in water pressure
into an electrical signal Sonar transponder
Ultrasonic transceiver, transmitting ultrasound as well as receiving it after sound reflection
from target objects, availing for imaging of those objects.
Electro-optical: Fluorescent lamp – converts electrical power
into incoherent light Incandescent lamp – converts electrical
power into incoherent light Light-emitting diode – converts electrical
power into incoherent light Laser Diode – converts electrical power
into coherent light Photodiode, photoresistor, phototransistor,
photomultiplier – converts changing light levels into electrical signals
Photodetector or photoresistor or light dependent resistor – converts changes in light levels
into changes in electrical resistance Cathode ray tube – converts electrical signals
into visual signals
Electrostatic: Electrometer
Thermoelectric: Resistance temperature detector – converts
temperature into an electrical resistance signal
Thermocouple – converts relative temperatures of metallic junctions to electrical voltage
Peltier cooler Thermistor
Radioacoustic: Geiger–Müller tube – converts incident
ionizing radiation to an electrical impulse signal
Receiver transmitter-propagates electromagnetic transmissions
to sound
Gravinertia Woodward effect – A hypothetical effect
that would convert electrical energy to "gravinertial" energy
See also Tactile sensor
Horn analyzer References
Agarwal, Anant. Foundations of Analog and Digital Electronic Circuits.Department of
Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 2005,
p. 43.
External links Introduction to Closed Loop Hall Effect Current
Transducers Federal Standard 1037C, August 7, 1996: transducer