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 connections
Most 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 rectifier
Schottky diode, hot carrier diode – super fast diode with lower forward voltage drop
Zener diode – Passes current in reverse direction to provide a constant voltage reference
Transient voltage suppression diode (TVS), Unipolar or Bipolar – used to absorb high-voltage spikes
Varactor, 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 light
Photodiode – Passes current in proportion to incident light
Avalanche photodiode Photodiode with internal gain
Solar Cell, photovoltaic cell, PV array or panel, produces power from light
DIAC (Diode for Alternating Current), Trigger Diode, SIDAC) – Often used to trigger an SCR
Constant-current diode
Peltier cooler – A semiconductor heat pump
Tunnel diode - very fast diode based on quantum mechanical tunneling
Transistors 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.
Transistors
Bipolar junction transistor (BJT, or simply "transistor") – NPN or PNP
Photo transistor – Amplified photodetector
Darlington transistor – NPN or PNP
Photo Darlington – Amplified photodetector
Sziklai pair (Compound transistor, complementary Darlington)
Field-effect transistor (FET)
JFET (Junction Field-Effect Transistor) – N-CHANNEL or P-CHANNEL
MOSFET (Metal Oxide Semiconductor FET) – N-CHANNEL or P-CHANNEL
MESFET (MEtal Semiconductor FET)
HEMT (High electron mobility transistor)
Thyristors
Silicon-controlled rectifier (SCR) – Passes current only after triggered by a sufficient control voltage on its gate
TRIAC (TRIode for Alternating Current) – Bidirectional SCR
Unijunction transistor (UJT)
Programmable Unijunction transistor (PUT)
SIT (Static induction transistor)
SITh (Static induction thyristor)
Composite transistors
IGBT (Insulated-gate bipolar transistor)
Digital
Analog
Hall effect sensor –senses a magnetic field.
Current sensor – Senses a current through it
Opto-electronics
Opto-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 interrupter
LED display – Seven-segment display, Sixteen-segment display, Dot-matrix display
Current:
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 Tube
Dekatron (aka glow transfer tube)
Magic eye tube indicator
Penetron (a 2 colour see-through CRT)
A vacuum tube is based on current conduction through a vacuum (see Vacuum tube).
Diode or rectifier tube
Amplifying tubes
Triode
Tetrode
Pentode
Hexode
Pentagrid
Octode
Microwave tubes
Klystron
Magnetron
Traveling-wave tube
Optical detectors or emitters
Phototube or Photodiode – tube equivalent of semiconductor photodiode
Photomultiplier tube – Phototube with internal gain
Cathode ray tube (CRT) or television picture tube
Vacuum fluorescent display (VFD) – Modern non-raster sort of small CRT display
Magic eye tube – Small CRT display used as a tuning meter (obsolete)
X-ray tube – Produces x-rays
Gas discharge tube
Obsolete:
Mercury arc rectifier
Voltage regulator tube
Nixie tube
Thyratron
Ignitron
Sources of electrical power:
Battery – acid- or alkali-based power supply
Fuel cell – an electrochemical generator
Power supply – usually a main hook-up
Photo voltaic device – generates electricity from light
Thermo electric generator – generates electricity from temperature gradients
Electrical generator – an electromechanical power source
Piezoelectric pressure - creates electricity from mechanical strain
Van de Graaferator - Van de Graaff generator or essentially creating voltage from friction
Components 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 value
Power resistor – larger to safely dissipate heat generated
SIP or DIP resistor network – array of resistors in one package
Variable resistor
Rheostat – two-terminal variable resistor (often for high power)
Potentiometer – three-terminal variable resistor (variable voltage divider)
Trim pot – Small potentiometer, usually for internal adjustments
Thermistor – 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 resistor
Photoresistor
Memristor
Varistor, Voltage Dependent Resistor, MOV – Passes current when excessive voltage is present
Resistance wire, Nichrome wire – wire of high-resistance material, often used as a heating element
Heater – heating element
Capacitors 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.
Capacitor
Integrated capacitors
MIS capacitor
Trench capacitor
Fixed capacitors
Ceramic capacitor
Film capacitor
Electrolytic capacitor
Aluminum electrolytic capacitor
Tantalum electrolytic capacitor
Niobium electrolytic capacitor
Polymer capacitor, OS-CON
Supercapacitor (Electric double-layer capacitor)
Nanoionic supercapacitor
Lithium-ion capacitor
Mica capacitor
Vacuum capacitor
Variable capacitor – adjustable capacitance
Tuning capacitor – variable capacitor for tuning a radio, oscillator, or tuned circuit
Trim capacitor– small variable capacitor is usually for slight internal adjustments made with a small screw driver turned into the right position.
Vacuum variable capacitor
Capacitors for special applications
Power capacitor
Safety capacitor
Filter capacitor
Light-emitting capacitor
Motor capacitor
Photoflash capacitor
Reservoir capacitor
Capacitor network (array)
Varicap diode – AC capacitance varies according to the DC voltage applied
Electrical components that use magnetism in the storage and release of electrical charge through current:
Inductor, coil, choke
Variable inductor
Saturable Inductor
Transformer
Magnetic amplifier (toroid)
ferrite impedances, beads
Motor / Generator
Solenoid
Loudspeaker and microphone
Electrical 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.
Memristor
Components that use more than one type of passive component:
RC network – forms an RC circuit, used in snubbers
LC 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.
Audio
Loudspeaker – Electromagnetic or piezoelectric device to generate full audio
Buzzer – Electromagnetic or piezoelectric sounder to generate tones
Position, motion
Linear variable differential transformer (LVDT) – Magnetic – detects linear position
Rotary encoder, Shaft Encoder – Optical, magnetic, resistive or switches – detects absolute or relative angle or rotational speed
Inclinometer – Capacitive – detects angle with respect to gravity
Motion sensor, Vibration sensor
Flow meter – detects flow in liquid or gas
Force, torque
Strain gauge – Piezoelectric or resistive – detects squeezing, stretching, twisting
Accelerometer – Piezoelectric – detects acceleration, gravity
Thermal
Thermocouple, thermopile – Wires that generate a voltage proportional to delta temperature
Thermistor – Resistor whose resistance changes with temperature, up PTC or down NTC
Resistance Temperature Detector (RTD) – Wire whose resistance changes with temperature
Bolometer – Device for measuring the power of incident electromagnetic radiation
Thermal cutoff – Switch that is opened or closed when a set temperature is exceeded
Magnetic field (see also Hall Effect in semiconductors)
Magnetometer, Gauss meter
Humidity
Hygrometer
Electromagnetic, light
Photo resistor – Light dependent resistor (LDR)
Antennas transmit or receive radio waves
Elemental dipole
Yagi
Phased array
Loop antenna
Parabolic dish
Log-periodic dipole array
Biconical
Feedhorn
Multiple electronic components assembled in a device that is in itself used as a component
Oscillator
Display devices
Liquid crystal display (LCD)
Digital voltmeters
Filter
Wire-wrap
Breadboard
Passive components that use piezoelectric effect:
Components that use the effect to generate or filter high frequencies
Crystal – 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 frequencies
Ceramic filter – Is a ceramic crystal used to filter a band of frequencies such as in radio receivers
surface acoustic wave (SAW) filters
Components that use the effect as mechanical transducers.
Ultrasonic motor – Electric motor that uses the piezoelectric effects
For piezo buzzers and microphones, see the Transducer class below
Terminals and connectors
Devices to make electrical connection
Terminal
Connector
Socket
Screw terminal, Terminal Blocks
Pin header
Cables with connectors or terminals at their ends
Power cord
Patch cord
Test lead
Components 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 switches
Keypad – Array of pushbutton switches
DIP switch – Small array of switches for internal configuration settings
Footswitch – Foot-operated switch
Knife switch – Switch with unenclosed conductors
Micro switch – Mechanically activated switch with snap action
Limit switch – Mechanically activated switch to sense limit of motion
Mercury switch – Switch sensing tilt
Centrifugal switch – Switch sensing centrifugal force due to rate of rotation
Relay – Electrically operated switch (mechanical, also see Solid State Relay above)
Reed switch – Magnetically activated switch
Thermostat – Thermally activated switch
Humidistat – Humidity activated switch
Circuit breaker – Switch opened in response to excessive current: a resettable fuse
Passive components that protect circuits from excessive currents or voltages:
Fuse – over-current protection, one time use
Circuit breaker – resettable fuse in the form of a mechanical switch
Resettable fuse or PolySwitch – circuit breaker action using solid state device
Ground-fault protection or residual-current device – circuit breaker sensitive to mains currents passing to ground
Metal oxide varistor (MOV), surge absorber, TVS – Over-voltage protection.
Inrush current limiter – protection against initial Inrush current
Gas discharge tube – protection against high voltage surges
Spark gap – electrodes with a gap to arc over at a high voltage
Lightning arrester – spark gap used to protect against lightning strikes
Enclosure (electrical)
Heat sink
Fan
Printed circuit boards
Lamp
Waveguide
Memristor
Carbon amplifier (see Carbon microphones used as amplifiers)
Carbon arc (negative resistance device)
Dynamo (historic rf generator)
Coherer
Standard symbols
On a circuit diagram, electronic devices are represented by conventional symbols. Reference designators are applied to the symbols to identify the component.