An electronic component is any basic discrete device or physical entity in an electronic system used to affect electrons or their associated fields. Electronic components are mostly industrial products, available in a singular form and are not to be confused with electrical elements, which are conceptual abstractions representing idealized electronic components.
Electronic components have a number of electrical terminals or leads. These leads connect to create an electronic circuit with a particular function (for example an amplifier, radio receiver, or oscillator). Basic electronic components may be packaged discretely, as arrays or networks of like components, or integrated inside of packages such as semiconductor integrated circuits, hybrid integrated circuits, or thick film devices. The following list of electronic components focuses on the discrete version of these components, treating such packages as components in their own right.
Components can be classified as passive, active, or electromechanic. The strict physics definition treats passive components as ones that cannot supply energy themselves, whereas a battery would be seen as an active component since it truly acts as a source of energy.
However, electronic engineers who perform circuit analysis use a more restrictive definition of passivity. When only concerned with the energy of signals, it is convenient to ignore the so-called DC circuit and pretend that the power supplying components such as transistors or integrated circuits is absent (as if each such component had its own battery built in), though it may in reality be supplied by the DC circuit. Then, the analysis only concerns the AC circuit, an abstraction that ignores DC voltages and currents (and the power associated with them) present in the real-life circuit. This fiction, for instance, lets us view an oscillator as "producing energy" even though in reality the oscillator consumes even more energy from a DC power supply, which we have chosen to ignore. Under that restriction, we define the terms as used in circuit analysis as:
Active components rely on a source of energy (usually from the DC circuit, which we have chosen to ignore) and usually can inject power into a circuit, though this is not part of the definition. Active components include amplifying components such as transistors, triode vacuum tubes (valves), and tunnel diodes.Passive components can't introduce net energy into the circuit. They also can't rely on a source of power, except for what is available from the (AC) circuit they are connected to. As a consequence they can't amplify (increase the power of a signal), although they may increase a voltage or current (such as is done by a transformer or resonant circuit). Passive components include two-terminal components such as resistors, capacitors, inductors, and transformers.Electromechanical components can carry out electrical operations by using moving parts or by using electrical connectionsMost passive components with more than two terminals can be described in terms of two-port parameters that satisfy the principle of reciprocity—though there are rare exceptions. In contrast, active components (with more than two terminals) generally lack that property.
Conduct electricity easily in one direction, among more specific behaviors.
Diode, Rectifier, Bridge rectifierSchottky diode, hot carrier diode – super fast diode with lower forward voltage dropZener diode – Passes current in reverse direction to provide a constant voltage referenceTransient voltage suppression diode (TVS), Unipolar or Bipolar – used to absorb high-voltage spikesVaractor, Tuning diode, Varicap, Variable capacitance diode – A diode whose AC capacitance varies according to the DC voltage applied.Light-emitting diode (LED) – A diode that emits lightPhotodiode – Passes current in proportion to incident lightAvalanche photodiode Photodiode with internal gainSolar Cell, photovoltaic cell, PV array or panel, produces power from lightDIAC (Diode for Alternating Current), Trigger Diode, SIDAC) – Often used to trigger an SCRConstant-current diodePeltier cooler – A semiconductor heat pumpTunnel diode - very fast diode based on quantum mechanical tunnelingTransistors were considered the invention of the twentieth century that changed electronic circuits forever. A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.
TransistorsBipolar junction transistor (BJT, or simply "transistor") – NPN or PNPPhoto transistor – Amplified photodetectorDarlington transistor – NPN or PNPPhoto Darlington – Amplified photodetectorSziklai pair (Compound transistor, complementary Darlington)Field-effect transistor (FET)JFET (Junction Field-Effect Transistor) – N-CHANNEL or P-CHANNELMOSFET (Metal Oxide Semiconductor FET) – N-CHANNEL or P-CHANNELMESFET (MEtal Semiconductor FET)HEMT (High electron mobility transistor)ThyristorsSilicon-controlled rectifier (SCR) – Passes current only after triggered by a sufficient control voltage on its gateTRIAC (TRIode for Alternating Current) – Bidirectional SCRUnijunction transistor (UJT)Programmable Unijunction transistor (PUT)SIT (Static induction transistor)SITh (Static induction thyristor)Composite transistorsIGBT (Insulated-gate bipolar transistor)DigitalAnalogHall effect sensor –senses a magnetic field.Current sensor – Senses a current through itOpto-electronicsOpto-Isolator, Opto-Coupler, Photo-Coupler – Photodiode, BJT, JFET, SCR, TRIAC, Zero-crossing TRIAC, Open collector IC, CMOS IC, Solid state relay (SSR)Opto switch, Opto interrupter, Optical switch, Optical interrupter, Photo switch, Photo interrupterLED display – Seven-segment display, Sixteen-segment display, Dot-matrix displayCurrent:
Filament lamp (indicator lamp)Vacuum fluorescent display (VFD) (preformed characters, 7 segment, starburst)Cathode ray tube (CRT) (dot matrix scan, radial scan (e.g. radar), arbitrary scan (e.g. oscilloscope)) (monochrome & colour)LCD (preformed characters, dot matrix) (passive, TFT) (monochrome, colour)Neon (individual, 7 segment display)LED (individual, 7 segment display, starburst display, dot matrix)Flap indicator (numeric, preprinted messages)Plasma display (dot matrix)Obsolete:
Incandescent filament 7 segment display (aka 'Numitron')Nixie TubeDekatron (aka glow transfer tube)Magic eye tube indicatorPenetron (a 2 colour see-through CRT)A vacuum tube is based on current conduction through a vacuum (see Vacuum tube).
Diode or rectifier tubeAmplifying tubes
TriodeTetrodePentodeHexodePentagridOctodeMicrowave tubesKlystronMagnetronTraveling-wave tubeOptical detectors or emitters
Phototube or Photodiode – tube equivalent of semiconductor photodiodePhotomultiplier tube – Phototube with internal gainCathode ray tube (CRT) or television picture tubeVacuum fluorescent display (VFD) – Modern non-raster sort of small CRT displayMagic eye tube – Small CRT display used as a tuning meter (obsolete)X-ray tube – Produces x-raysGas discharge tubeObsolete:
Mercury arc rectifierVoltage regulator tubeNixie tubeThyratronIgnitronSources of electrical power:
Battery – acid- or alkali-based power supplyFuel cell – an electrochemical generatorPower supply – usually a main hook-upPhoto voltaic device – generates electricity from lightThermo electric generator – generates electricity from temperature gradientsElectrical generator – an electromechanical power sourcePiezoelectric pressure - creates electricity from mechanical strainVan de Graaferator - Van de Graaff generator or essentially creating voltage from frictionComponents incapable of controlling current by means of another electrical signal are called passive devices. Resistors, capacitors, inductors, and transformers are all considered passive devices.
Pass current in proportion to voltage (Ohm's law) and oppose current.
Resistor – fixed valuePower resistor – larger to safely dissipate heat generatedSIP or DIP resistor network – array of resistors in one packageVariable resistorRheostat – two-terminal variable resistor (often for high power)Potentiometer – three-terminal variable resistor (variable voltage divider)Trim pot – Small potentiometer, usually for internal adjustmentsThermistor – thermally sensitive resistor whose prime function is to exhibit a large, predictable and precise change in electrical resistance when subjected to a corresponding change in body temperature.Humistor – humidity-varied resistorPhotoresistorMemristorVaristor, Voltage Dependent Resistor, MOV – Passes current when excessive voltage is presentResistance wire, Nichrome wire – wire of high-resistance material, often used as a heating elementHeater – heating elementCapacitors store and release electrical charge. They are used for filtering power supply lines, tuning resonant circuits, and for blocking DC voltages while passing AC signals, among numerous other uses.
CapacitorIntegrated capacitorsMIS capacitorTrench capacitorFixed capacitorsCeramic capacitorFilm capacitorElectrolytic capacitorAluminum electrolytic capacitorTantalum electrolytic capacitorNiobium electrolytic capacitorPolymer capacitor, OS-CONSupercapacitor (Electric double-layer capacitor)Nanoionic supercapacitorLithium-ion capacitorMica capacitorVacuum capacitorVariable capacitor – adjustable capacitanceTuning capacitor – variable capacitor for tuning a radio, oscillator, or tuned circuitTrim capacitor– small variable capacitor is usually for slight internal adjustments made with a small screw driver turned into the right position.Vacuum variable capacitorCapacitors for special applicationsPower capacitorSafety capacitorFilter capacitorLight-emitting capacitorMotor capacitorPhotoflash capacitorReservoir capacitorCapacitor network (array)Varicap diode – AC capacitance varies according to the DC voltage appliedElectrical components that use magnetism in the storage and release of electrical charge through current:
Inductor, coil, chokeVariable inductorSaturable InductorTransformerMagnetic amplifier (toroid)ferrite impedances, beadsMotor / GeneratorSolenoidLoudspeaker and microphoneElectrical components that pass charge in proportion to magnetism or magnetic flux, and have the ability to retain a previous resistive state, hence the name of Memory plus Resistor.
MemristorComponents that use more than one type of passive component:
RC network – forms an RC circuit, used in snubbersLC Network – forms an LC circuit, used in tunable transformers and RFI filters.- Transducers generate physical effects when driven by an electrical signal, or vice versa.
- Sensors (detectors) are transducers that react to environmental conditions by changing their electrical properties or generating an electrical signal.
- The transducers listed here are single electronic components (as opposed to complete assemblies), and are passive (see Semiconductors and Tubes for active ones). Only the most common ones are listed here.
AudioLoudspeaker – Electromagnetic or piezoelectric device to generate full audioBuzzer – Electromagnetic or piezoelectric sounder to generate tonesPosition, motionLinear variable differential transformer (LVDT) – Magnetic – detects linear positionRotary encoder, Shaft Encoder – Optical, magnetic, resistive or switches – detects absolute or relative angle or rotational speedInclinometer – Capacitive – detects angle with respect to gravityMotion sensor, Vibration sensorFlow meter – detects flow in liquid or gasForce, torqueStrain gauge – Piezoelectric or resistive – detects squeezing, stretching, twistingAccelerometer – Piezoelectric – detects acceleration, gravityThermalThermocouple, thermopile – Wires that generate a voltage proportional to delta temperatureThermistor – Resistor whose resistance changes with temperature, up PTC or down NTCResistance Temperature Detector (RTD) – Wire whose resistance changes with temperatureBolometer – Device for measuring the power of incident electromagnetic radiationThermal cutoff – Switch that is opened or closed when a set temperature is exceededMagnetic field (see also Hall Effect in semiconductors)Magnetometer, Gauss meterHumidityHygrometerElectromagnetic, lightPhoto resistor – Light dependent resistor (LDR)Antennas transmit or receive radio waves
Elemental dipoleYagiPhased arrayLoop antennaParabolic dishLog-periodic dipole arrayBiconicalFeedhornMultiple electronic components assembled in a device that is in itself used as a component
OscillatorDisplay devicesLiquid crystal display (LCD)Digital voltmetersFilterWire-wrapBreadboardPassive components that use piezoelectric effect:
Components that use the effect to generate or filter high frequenciesCrystal – a ceramic crystal used to generate precise frequencies (See the Modules class below for complete oscillators)Ceramic resonator – Is a ceramic crystal used to generate semi-precise frequenciesCeramic filter – Is a ceramic crystal used to filter a band of frequencies such as in radio receiverssurface acoustic wave (SAW) filtersComponents that use the effect as mechanical transducers.Ultrasonic motor – Electric motor that uses the piezoelectric effectsFor piezo buzzers and microphones, see the Transducer class belowTerminals and connectors
Devices to make electrical connection
TerminalConnectorSocketScrew terminal, Terminal BlocksPin headerCables with connectors or terminals at their ends
Power cordPatch cordTest leadComponents that can pass current ("closed") or break the flow of current ("open"):
Switch – Manually operated switch.Electrical description: SPST, SPDT, DPST, DPDT, NPNT (general)Technology: slide switches, toggle switches, rocker switches, rotary switches, pushbutton switchesKeypad – Array of pushbutton switchesDIP switch – Small array of switches for internal configuration settingsFootswitch – Foot-operated switchKnife switch – Switch with unenclosed conductorsMicro switch – Mechanically activated switch with snap actionLimit switch – Mechanically activated switch to sense limit of motionMercury switch – Switch sensing tiltCentrifugal switch – Switch sensing centrifugal force due to rate of rotationRelay – Electrically operated switch (mechanical, also see Solid State Relay above)Reed switch – Magnetically activated switchThermostat – Thermally activated switchHumidistat – Humidity activated switchCircuit breaker – Switch opened in response to excessive current: a resettable fusePassive components that protect circuits from excessive currents or voltages:
Fuse – over-current protection, one time useCircuit breaker – resettable fuse in the form of a mechanical switchResettable fuse or PolySwitch – circuit breaker action using solid state deviceGround-fault protection or residual-current device – circuit breaker sensitive to mains currents passing to groundMetal oxide varistor (MOV), surge absorber, TVS – Over-voltage protection.Inrush current limiter – protection against initial Inrush currentGas discharge tube – protection against high voltage surgesSpark gap – electrodes with a gap to arc over at a high voltageLightning arrester – spark gap used to protect against lightning strikesEnclosure (electrical)Heat sinkFanPrinted circuit boardsLampWaveguideMemristorCarbon amplifier (see Carbon microphones used as amplifiers)Carbon arc (negative resistance device)Dynamo (historic rf generator)CohererStandard symbols
On a circuit diagram, electronic devices are represented by conventional symbols. Reference designators are applied to the symbols to identify the component.
