A transducer is a device that converts one type of energy In physics, energy is a quantity that can be assigned to every particle, object, and system of objects as a consequence of the state of that particle, object or system of objects. Different forms of energy include kinetic, potential, thermal, gravitational, sound, elastic, light, and electromagnetic energy. The forms of energy are often named to another. The conversion can be to/from electrical Electricity is a general term that encompasses a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning and static electricity, but in addition, less familiar concepts, such as the electromagnetic field and electromagnetic induction, electro-mechanical, electromagnetic Electromagnetism is one of the four fundamental interactions of nature, along with strong interaction, weak interaction and gravitation. It is the force that causes the interaction between electrically charged particles; the areas in which this happens are called electromagnetic fields, also known as B fields in physics classes, photonic The science of photonics includes the generation, emission, transmission, modulation, signal processing, switching, amplification, detection and sensing of light. The term photonics thereby emphasizes that photons are neither particles nor waves — they are different in that they have both particle and wave nature. It basically covers all, photovoltaic A photovoltaic array is a linked collection of photovoltaic modules, which are in turn made of multiple interconnected solar cells. By their modularity, they are able to be configured to supply most loads, or any other form of energy. While the term transducer commonly implies use as a sensor/detector, any device which converts energy can be considered a transducer.
Types
Transducers may be categorized by application: Sensor A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass tube. A thermocouple converts temperature to an, actuator The efficiency of an actuator is a standard tool used to calculate or estimate the usefulness of any actuating mechanism. It is a dimensionless quantity which is generally lower than 1 expressing the energy conversion factor. For better explanation see Thermodynamic efficiency. Most of the wasted energy is thermally dissipated, or combination.
A sensor is used to detect a parameter in one form and report it in another form of energy (usually an electrical and/or digital signal). For example, a pressure sensor A pressure sensor measures pressure, typically of gases or liquids. Pressure is an expression of the force required to stop a fluid from expanding, and is usually stated in terms of force per unit area. A pressure sensor usually acts as a transducer; it generates a signal as a function of the pressure imposed. For the purposes of this article, might detect pressure Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure (a mechanical form of energy) and convert it to electricity for display at a remote gauge.
An actuator accepts energy and produces movement (action). The energy supplied to an actuator might be electrical or mechanical (pneumatic Pneumatic systems are extensively used in industry, where factories are commonly plumbed with compressed air or other compressed inert gases. This is because a centrally-located and electrically-powered compressor that powers cylinders and other pneumatic devices through solenoid valves is often able to provide motive power in a cheaper, safer,, hydraulic Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics is used for the generation, control, and transmission of power by the use of, etc.). An electric motor An electric motor uses electrical energy to produce mechanical energy, very typically through the interaction of magnetic fields and current-carrying conductors. The reverse process, producing electrical energy from mechanical energy, is accomplished by a generator or dynamo. Many types of electric motors can be run as generators, and vice versa and a loudspeaker A loudspeaker is an electroacoustic transducer that converts an electrical signal into sound. The speaker moves in accordance with the variations of an electrical signal and causes sound waves to propagate through a medium such as air or water are both transducers, 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.
Applications
- Electromagnetic:
- Antenna An antenna is a transducer designed to transmit or receive electromagnetic waves. In other words, antennas convert electromagnetic waves into electrical currents and vice versa. They are used with waves in the radio part of the electromagnetic spectrum, that is, radio waves, and are a necessary part of all radio equipment. Antennas are used in - converts electromagnetic waves into electric current and vice versa.
- Cathode ray tube The Cathode Ray Tube is a vacuum tube containing an electron gun (a source of electrons) and a fluorescent screen, with internal or external means to accelerate and deflect the electron beam, used to create images in the form of light emitted from the fluorescent screen. The image may represent electrical waveforms (oscilloscope), pictures ( (CRT) - converts electrical signals into visual form
- Fluorescent lamp A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful light more efficiently than an incandescent lamp, light bulb The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric light that works by incandescence . An electric current passes through a thin filament, heating it to a temperature that produces light. The enclosing glass bulb contains either a vacuum or an inert gas to prevent oxidation of the hot filament - converts electrical power into visible light
- Magnetic cartridge A magnetic cartridge is a transducer used for the playback of gramophone records on a turntable or phonograph. It converts mechanical vibrational energy from a stylus riding in a spiral record groove into an electrical signal that is subsequently amplified and then converted back to sound by a loudspeaker system - converts motion into electrical form
- Photodetector Photosensors or photodetectors are sensors of light or other electromagnetic energy. There are several varieties: or Photoresistor (LDR) - converts changes in light levels into resistance changes
- Tape head A tape head is a type of transducer used in tape recorders to convert electrical signals to magnetic fluctuations and vice versa - converts changing magnetic fields into electrical form
- Hall effect sensor A Hall effect sensor is a transducer that varies its output voltage in response to changes in magnetic field. Hall sensors are used for proximity switching, positioning, speed detection, and current sensing applications - converts a magnetic field level into electrical form only.
- Electrochemical:
- pH probes A pH meter is an electronic instrument used to measure the pH of a liquid (though special probes are sometimes used to measure the pH of semi-solid substances). A typical pH meter consists of a special measuring probe (a glass electrode) connected to an electronic meter that measures and displays the pH reading
- Electro-galvanic fuel cell An electro-galvanic fuel cell is an electrical device used to measure the concentration of oxygen gas in scuba diving and medical equipment
- Hydrogen sensor A hydrogen sensor is a gas detector that detects the presence of hydrogen. They contain micro-fabricated point-contact hydrogen sensors and are used to locate leaks. They are considered low-cost, compact, durable, and easy to maintain as compared to conventional gas detecting instruments
- Electromechanical (electromechanical output devices are generically called actuators The efficiency of an actuator is a standard tool used to calculate or estimate the usefulness of any actuating mechanism. It is a dimensionless quantity which is generally lower than 1 expressing the energy conversion factor. For better explanation see Thermodynamic efficiency. Most of the wasted energy is thermally dissipated):
- Electroactive polymers Electroactive Polymers or EAPs are polymers whose shape is modified when a voltage is applied to them. They can be used as actuators or sensors. As actuators, they are characterized by being able to undergo a large amount of deformation while sustaining large forces. Due to the similarities with biological tissues in terms of achievable stress and
- Galvanometer A galvanometer is a type of ammeter: an instrument for detecting and measuring electric current. It is an analog electromechanical transducer that produces a rotary deflection of some type of pointer in response to electric current flowing through its coil. The term has expanded to include uses of the same mechanism in recording, positioning, and
- Microelectromechanical systems Microelectromechanical systems (also written as micro-electro-mechanical, MicroElectroMechanical or "microelectronic and microelectromechanical systems") is the technology of the very small, and merges at the nano-scale into nanoelectromechanical systems (NEMS) and nanotechnology. MEMS are also referred to as micromachines (in Japan), or
- Rotary motor An electric motor uses electrical energy to produce mechanical energy, very typically through the interaction of magnetic fields and current-carrying conductors. The reverse process, producing electrical energy from mechanical energy, is accomplished by a generator or dynamo. Many types of electric motors can be run as generators, and vice versa, linear motor A linear motor or linear induction motor is an alternating current electric motor that has had its stator "unrolled" so that instead of producing a torque (rotation) it produces a linear force along its length. The most common mode of operation is as a Lorentz-type actuator, in which the applied force is linearly proportional to the
- Vibration powered generator
- Potentiometer A potentiometer is a three-terminal resistor with a sliding contact that forms an adjustable voltage divider. If only two terminals are used (one side and the wiper), it acts as a variable resistor or rheostat. Potentiometers are commonly used to control electrical devices such as volume controls on audio equipment. Potentiometers operated by a when used for measuring position
- Load cell A load cell is an electronic device that is used to convert a force into an electrical signal. This conversion is indirect and happens in two stages. Through a mechanical arrangement, the force being sensed deforms a strain gauge. The strain gauge converts the deformation (strain) to electrical signals. A load cell usually consists of four strain converts force to mV/V electrical signal using strain gauge A strain gauge is a device used to measure the strain of an object. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern. The gauge is attached to the object by a suitable adhesive, such as cyanoacrylate. As the object is
- Accelerometer Single- and multi-axis models are available to detect magnitude and direction of the acceleration as a vector quantity, and can be used to sense orientation, acceleration, vibration shock, and falling. Micromachined accelerometers are increasingly present in portable electronic devices and video game controllers, to detect the position of the
- Strain gauge A strain gauge is a device used to measure the strain of an object. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern. The gauge is attached to the object by a suitable adhesive, such as cyanoacrylate. As the object is
- String Potentiometer
- Air flow sensor A mass air flow sensor responds to the amount of a fluid (usually a gas) flowing through a chamber containing the sensor. It is intended to be insensitive to the density of the fluid
- Tactile sensor
- Electroacoustic:
- Loudspeaker A loudspeaker is an electroacoustic transducer that converts an electrical signal into sound. The speaker moves in accordance with the variations of an electrical signal and causes sound waves to propagate through a medium such as air or water, earphone Headphones are a pair of small loudspeakers, or less commonly a single speaker, with a way of holding them close to a user's ears and a means of connecting them to a signal source such as an audio amplifier, radio or CD player. They are also known as stereophones, headsets or, colloquially cans. The in-ear versions are known as earphones or - converts electrical signals into sound (amplified Generally, an amplifier or simply amp, is any device that changes, usually increases, the amplitude of a signal. The relationship of the input to the output of an amplifier—usually expressed as a function of the input frequency—is called the transfer function of the amplifier, and the magnitude of the transfer function is termed the gain signal → magnetic field Magnetic fields surround magnetic materials and electric currents and are detected by the force they exert on other magnetic materials and moving electric charges. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field → motion In physics, motion is change of location or position of an object with respect to time. Change in motion is the result of an applied force. Motion is typically described in terms of velocity also seen as speed, acceleration, displacement, and time. An object's velocity cannot change unless it is acted upon by a force, as described by Newton's → air pressure)
- Ear The ear is the organ that detects sound. The vertebrate ear shows a common biology from fish to humans, with variations in structure according to order and species. It not only acts as a receiver for sound, but also plays a major role in the sense of balance and body position. The ear is part of the auditory system - converts sound into electrical signals (air pressure → Eardrum The tympanic membrane, or eardrum, is a thin membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air to the ossicles inside the middle ear. The malleus bone bridges the gap between the eardrum and the other ossicles. Rupture or perforation of the eardrum can lead to conductive hearing loss motion → Basilar membrane The basilar membrane within the cochlea of the inner ear is a stiff structural element that separates two liquid-filled tubes that run along the coil of the cochlea, the scala media and the scala tympani/Stereocilia Stereocilia are mechanosensing organelles of hair cells, which respond to fluid motion or fluid pressure changes in numerous types of animals for various functions, primarily hearing. They are about 5 micrometers in length and share some similar features of microvilli. The hair cells turn the fluid pressure and other mechanical stimuli into electricity(Action potential An action potential is a short-lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a stereotyped trajectory. Action potentials occur in several types of excitable cells, including neurons, muscle cells, and endocrine cells. In neurons, they play a central role in cell-to-cell communication. In))
- Microphone A microphone (colloquially called a mic or mike is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1876, Emile Berliner invented the first microphone used as a telephone voice transmitter. Microphones are used in many applications such as telephones, tape recorders, karaoke systems, hearing aids, - converts sound into an electrical signal (air pressure → motion In physics, motion is change of location or position of an object with respect to time. Change in motion is the result of an applied force. Motion is typically described in terms of velocity also seen as speed, acceleration, displacement, and time. An object's velocity cannot change unless it is acted upon by a force, as described by Newton's of conductor/coil → magnetic field Magnetic fields surround magnetic materials and electric currents and are detected by the force they exert on other magnetic materials and moving electric charges. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field → signal)
- Pick up (music technology) A pickup device acts as a transducer that captures mechanical vibrations, usually from suitably-equipped stringed instruments such as the electric guitar, electric bass guitar or electric violin, and converts them to an electrical signal which can then be amplified, recorded and broadcast - converts motion of metal strings into an electrical signal (magnetism → electricity (signal))
- Tactile transducer - converts solid-state vibrations into electrical signal (vibration → ? → signal)
- Piezoelectric crystal - converts solid-state electrical moduluations into an electrical signal (vibration → ? → signal)
- Geophone - convert a ground movement (displacement) into voltage - (vibrations → motion of conductor/coil → magnetic field → signal)
- Gramophone pick-up - (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 - convert electrical power into forms of light
- Photodiode, photoresistor, phototransistor, photomultiplier tube - converts changing light levels into electrical form
- Electrostatic:
- Thermoelectric:
- RTD Resistance Temperature Detector
- Thermocouple
- Peltier cooler
- Thermistor (includes PTC resistor and NTC resistor)
- Radioacoustic:
- Geiger-Müller tube used for measuring radioactivity.
- Receiver (radio)
See also
Categories: Transducers
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