A transducer is a device that converts one form of energy to another. Energy types include (but are not limited to) electrical, mechanical, electromagnetic (including light), chemical, acoustic or 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.

  Applications

  Transducers are used in electronic communications systems to convert signals of various physical forms to electronic signals, and vice versa.

• Electromagnetic:
  • Antenna – converts electromagnetic waves into electric current and vice versa
  • Cathode ray tube (CRT) – converts electrical signals into visual form
  • Fluorescent lamp, light bulb – converts electrical power into visible light
  • Magnetic cartridge – converts motion into electrical form
  • Photodetector or photoresistor or light dependent resistor (LDR) – converts changes in light levels into resistance changes
  • Tape head – converts changing magnetic fields into electrical form
  • Hall effect sensor – converts a magnetic field level into electrical form only
  • Disk read-and-write head - converts electrical digital signal into magnetic fields .

• Electrochemical:
  • pH probes
  • Electro-galvanic fuel cell
  • Hydrogen sensor
• Electromechanical (electromechanical output devices are generically called actuators):
  • Electroactive polymers
  • Galvanometer
  • Microelectromechanical systems
  • Rotary motor, linear motor
  • Vibration powered generator
  • Potentiometer when used for measuring position
  • 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 (amplified signal → magnetic field → motion → air pressure)
  • Microphone – converts sound into an electrical signal (air pressure → motion of conductor/coil → magnetic field → signal)
  • Pickup (music technology) – converts motion of metal strings into an electrical signal (magnetism → electricity (signal))
  • Tactile transducer – converts electrical signal into vibration ( signal → vibration)
  • Piezoelectric crystal – converts solid-state electrical modulations into an electrical signal (vibration → electrical current → signal)
  • Geophone – converts a ground movement (displacement) into voltage (vibrations → motion of conductor/coil → magnetic field → signal)
  • Gramophone pickup – (air pressure → motion → magnetic field → signal)
  • Hydrophone – converts changes in water pressure into an electrical form
  • Sonar transponder (water pressure → motion of conductor/coil → magnetic field → signal)

• Photoelectric:
  • Laser diode, light-emitting diode – converts electrical power into forms of light
  • Photodiode, photoresistor, phototransistor, photomultiplier tube – converts changing light levels into electrical form

• Electrostatic:
  • Electrometer

• Thermoelectric:
  • Resistance temperature detector (RTD)
  • Thermocouple
  • Peltier cooler
  • Thermistor (includes PTC resistor and NTC resistor)

• Radioacoustic:
  • Geiger–Müller tube – used for measuring radioactivity
  • Receiver (radio)

  See also

• Tactile sensor
• Horn analyzer

  External links

• Federal Standard 1037C, August 7, 1996: transducer
• Transducer