Electronics Definitions

AC - Alternating Current. An electric current that reverses direction in a circuit at regular intervals.

Active - Requiring a source of power to operate. Includes transistors (all types), integrated circuits (all types), TRIACs, SCRs, LEDs, etc.

Algorithm - A programming and mathematical term. It is a procedure or formula for solving a problem. 

AM - Amplitude modulation. A technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent.

Ampere - the SI unit of electric current and is one of the seven SI base units. It is named after André-Marie Ampère, considered the father of electrodynamics. In practice, its name is often shortened to amp.

Amplify - To increase the strength of the signal. An amplifier can be used to pass a signal with either an increase or a decrease (attenuate) in amplitude.

Amplitude – the level of a signal. It can be measure as peak or RMS (Root-Mean Squared) and in linear or logarithmic units.

Analog/Analogue - Electronic communication sent as signals of varying frequency instead of ON or OFF like a digital data transmission. Analog allows equipment to handle information that continuously changes such as voltage, current, and wave.

Anode - An electron collector. An anode has a more positive voltage relative to a cathode.

Atom - The basic building block of matter composed of different types of particles. Major atom particles are the electron, proton, and neutron.

Attenuate - Decrease the strength of a signal.

Band Pass Filter - An analog filter that absorbs low and high frequencies but allows a band of frequencies in the middle to pass through.

Base - the part of a transistor that separates the emitter from the collector and controls the flow of current between them.

Battery - An electrical device consisting of one or more cells which converts chemical or solar energy into electrical energy. A battery provides a source of steady-state DC voltage.

Bipolar - Transistor or chip commonly used to amplify a signal.

BJT - Bipolar junction transistor. A transistor in which the resistance of the channel is controlled by a current at the gate. Can be thought of as a current-controlled resistor. FET is the other major type of transistor.

Capacitor - An electronics component that stores energy in the form of electric charge (Coulombs). It resists a sudden change in voltage.

Cathode - An electron emitter. A cathode has a more negative voltage relative to an anode.

Cell - A single unit of a battery that generates a DC voltage by converting chemical or solar energy into electrical energy.

Charge - A quantity of electricity determined by the product of an electric current and the time for which it flows, measured in coulombs.

Choke - Another name for an inductor, specifically referring to those used in power regulation.

Circuit - A combination of elements or components that are connected to provide paths for current flow to perform some useful function.

Coil - A helix of wire (the same shape as a spring). Its height, width, thickness, and material can all vary. Used as an inductor.

Collector – The part of a transistor that collects current. The direction of flow depends on the polarity of the transistor.

Complementary Metal Oxide Semiconductor - This is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits.

Component - An individual part or element of an electrical or electronic circuit which performs a designated function within that circuit. It may consist of a single part, a combination of parts, or assemblies.

Condenser - Another name for capacitor.

Conductance - The inverse of resistance. Measured in siemens (obsolete name mhos), which are the inverse of ohms.

Conductor - A material which contains movable electric charges.

Contact - A point of junction in an electrical circuit.

Coulomb - Unit of electric charge. The absolute coulomb is the amount of charge transferred in 1 second by a current of 1 ampere.

CMOS - Complementary Metal Oxide Semiconductor.

Current - A flow of electric charge. It is measured in amperes.

Cycles per second (cps) - A once-common unit of frequency which has been replaced by hertz, the standard SI unit. As the name implies, a measurement of frequency in full cycles of a wave per second. The unit cps (or kilocycles, megacycles, etc.) is more often seen in older documents.

dB - Decibel. A unit for expressing the ratio of two amounts of electric or acoustic signal power equal to 10 times the common logarithm of this ratio.

DC - Direct Current. The unidirectional flow of electric charge.

Digital - Pertains to the general class of devices or circuits in which the output varies in discrete steps.

DIAC - Diode for Alternating Current, a diode that conducts current only after its breakover voltage has been reached.

Diode - Two-terminal electronic device that permits current flow predominantly in only one direction. Most diodes are semiconductor devices. A diode has a low resistance to electric current in one direction and a high resistance to it in the reverse direction.

Drain – MOSFET equivalent to the collector in a BJT.

DTL - Diode–transistor logic. A class of digital circuits that is the direct ancestor of transistor–transistor logic.

EEPROM - Electrically Erasable Programmable ROM.

Electric Charge - A physical property of matter which causes it to experience a force when near other electrically charged matter.

Electrically Erasable Programmable ROM - A rewritable memory chip that holds its content without power. EEPROMs are bit or byte addressable at the write level, which means either the bit or byte must be erased before it can be re-written.

Electrodes - Conductive metallic strips normally inserted into an electrolyte to provide the chemical action needed to convert chemical energy into electrical energy.

Electron - The negatively charged particle in an atom orbiting the atom's nucleus.

Electromotive Force - Difference in electric potential, or voltage, between the terminals of a source of electricity, e.g., a battery from which no current is being drawn. When current is drawn, the potential difference drops below the emf value. Electromotive force is usually measured in volts.

Electronics - The branch of science that deals with the study of flow and control of electrons (electricity) and the study of their behaviour and effects in vacuums, gases, and semiconductors, and with devices using such electrons. This control of electrons is accomplished by devices that resist, carry, select, steer, switch, store, manipulate, and exploit the electron.

EMF - Electromotive Force.

Emitter – the part of a transistor that emits current. The direction of flow depends on the transistor polarity.

Engineering Humour - Humour that is particularly appealing to engineers or related technical professionals.

Ethernet - a family of frame-based computer networking technologies for local area networks (LAN). It defines a number of wiring and signaling standards for the physical layer of the standard networking model as well as a common addressing format and a variety of medium access control procedures at the lower part of the data link layer.

Farad - The SI unit for capacitance. A capacitor is one farad if it has a coulomb of charge on it with a voltage separation of a volt.

FET - Field Effect Transistor. This can be thought of as an Electric Field Transistor. A transistor in which the voltage at the gate controls the resistance of the channel. (i.e. a FET has voltage-controlled resistance.) BJT is the other major type of transistor.

FLASH -  An EEPROM which can be written (and erased) in whole banks or sectors.

Flip-Flop - An electronic circuit that alternates between two states.

FM - Frequency Modulation. Changing the frequency of a carrier signal to represent the amplitude of the original signal.

Forward Bias - A bias voltage that is applied to a pn-junction in the direction that causes a large current flow; used in some semiconductor diode circuits.

Frequency - The number of revolutions (cycles) per unit time. Usually expressed in either radians per second or cycles per second.

Fuse - A short strip of metal having extremely low resistance and functioning as a protective device in a circuit. A fuse will melt when its rated current is exceeded, thereby opening the circuit

Gain - A multiplier of voltage or current.

Generator - Rotating electric machine that converts mechanical energy into electrical energy.

Gate – the part of the JFET or MOSFET that controls current flow. Equivalent to the base in a BJT.

Grid - An electrode that has an open structure, such as a mesh or a plate with a hole in it, thus allowing an electron beam to pass through it.

Ground - The point in the circuit which is at zero voltage. Voltage is relative, and is the same throughout a conductor, so any point in the circuit can be defined as ground, and all other voltages are referenced to it. Usually it is defined as the most negative point in the circuit for convenience. Sometimes it is defined in the middle of two bipolar rails, for balanced circuits. In many cases this circuit point is connected to the Earth (Ground) by some buried conductor.

Henry- The SI unit for inductance.

Hertz - The SI unit for frequency. One hertz (Hz) is one cycle per second.

High-Pass Filter - An analog filter that absorbs low frequencies but allows high frequencies to pass.

Horsepower - A unit of measurement of mechanical power equal to 746 watts. It indicates the ability of a device or mechanism to do a specific amount of work over a period of time.

Integrated Circuit - Integrated circuit (also known as chip, or microchip). A circuit constructed on one chip of semiconductor, rather than as discrete components.

Impedance - A more generalised form of resistance. The impedance of a device varies with the frequency of the electricity applied. A perfect resistor will have a constant impedance for all frequencies. Capacitors and inductors have varying impedances at different frequencies. Measured in ohms.

Inductance - Inherent property of an electric circuit that opposes a change in current. Property of a circuit whereby energy may be stored in a magnetic field. Unit of measurement is the Henry.

Inductor - An inductor is a device that stores energy in a magnetic field. It opposes a sudden change in the flow of current. A solenoid is usually shaped like a spring. The unit of measure is the Henry.

Infrared - Method of transferring data without the use of wires. A common example of an infrared device is a TV remote. 

JFET – Junction Field Effect Transistor. A field effect transistor in which the conducting channel lies between pn junctions in the silicon material. A pn junction acts as a diode, so it becomes conductive if the gate voltage gets reversed.

Joule - The work required to exert a force of a newton for a metre.

Junction - An electrical connection.

Junction Diode - A diode having a pn junction.

Kirchhoff's Current Law - At any junction of conductors in a circuit, the algebraic sum of currents is zero.

Kirchhoff's Voltage Law - The algebraic sum of voltages around a circuit is zero.

LASCR - Light activated silicon controlled rectifier. A light activated SCR.

LDR - Light dependent resistor. As light intensity increases, its resistance decreases.

LED - Light Emitting Diode. A semiconductor light source. LEDs are used as indicator lamps in many devices.

Length - Distance is measured in metres (m).

Load - A device, component, appliance, system, or machine to which an electrical force (voltage) is applied. Resistance is inherent in the structure of a load and is an integral part of an electrical or electronic circuit.

Low Pass Filter - An analog filter that absorbs high frequencies (f) but allows low frequencies to pass.

Magnetic Flux - a measure of the amount of magnetic field passing through a given surface (such as a conducting coil). The SI unit of magnetic flux is the weber.

Magnetron - A special form of vacuum tube, typically used as the microwave emitter in a microwave oven, or in radar systems.

Metre - The SI unit for distance. The distance light travels in 1/299,792,458 second.

MOSFET - Metal-oxide-semiconductor field effect transistor. A FET that uses a thin layer of oxide (usually silicon) to insulate the gate terminal from the underlying channel.

Motor - Rotating electric machine that converts electrical energy to mechanical energy.

Multi-meter - An all-in-one measuring device. It combines a volt-meter, an amp-meter and an ohm-meter which usually also can act as continuity tester. It usually contains a transistor tester and measures capacities and inductivities (in a small range). There are both analog and digital types.

Neutron - Electrically neutral particle contained in the nucleus of an atom.

Newton - The SI unit of force, equal to the force that produces an acceleration of one meter per second per second on a mass of one kilogram. It is named after Isaac Newton in recognition of his work on classical mechanics, specifically Newton's second law of motion.

Ohm (Ω) - The basic unit of resistance. The amount of electrical resistance limiting the current to one ampere with one volt applied.

Ohm's Law - Mathematical relationship between current, voltage and resistance stating that when a voltage is applied to a metal conductor, the current moving through the conductor is proportional to the applied voltage. Discovered by Georg Simon Ohm.

Op-amp - Short for operational amplifier. An op-amp amplifies the voltage between its two inputs.

Oscilloscope - A test device which displays voltage curves graphically.

Oxidation - A reaction where something loses electrons. Given that oxygen will strip electrons from most elements, this has historically meant a reaction involving oxygen. A cathode is constantly oxidised as it loses electrons.

Parallel - Said of two or more circuit elements so connected that the total current flow is divided between them. Also called a shunt.

Parallel Circuit - Circuit that contains two or more paths for electron flow supplied by a common voltage source.

Passive - Capable of operating without an external power source. Typical passive components are resistors, capacitors, inductors and diodes.

PCB - Printed Circuit Board.

Period - The time between cycles of a periodic wave.

Periodic Wave - A wave whose displacement has a periodic variation with time or distance, or both.

Photovoltaic Effect - The generation of an electrical current in a circuit containing a photosensitive device when the device is illuminated by visible or nonvisible light.

PM¹ - Phase modulation. Sending information by modifying relative phases.

PM² - Pulse modulation. Sending information in binary pulses.

PN Junction - the interface within diodes, transistors, and other semiconductor devices between two different types of materials called p-type and n-type semiconductors.

Power - Voltage times current. The rate at which work is done and measured in watts.

Printed Circuit Board - This is a piece of plastic or fiberglass with copper attached. The copper is typically chemically etched away to leave traces for the electricity to be conducted through. Other electrical components are soldered to the traces.

Proton - A positively charged subatomic particle forming part of the nucleus of an atom.

Quality Factor - measure of the relationship between stored energy and rate of dissipation in certain electric elements, structures, or materials. In an inductor or capacitor, the ratio of reactance to effective series resistance at a given frequency. A measure of the sharpness of resonance or frequency selectivity of a mechanical or electrical system. Also called Q-factor.

Radio Frequency Identification - A data collection technology that uses electronic tags for storing data.

Reactance - Opposition to AC as a result of inductance or capacitance.

Rectify - Convert AC current to DC current.

Redox - A reversible chemical reaction in which one reaction is an oxidation and the reverse is a reduction. A cathode is oxidised (loses electron). The electron travels and is absorbed by an anode that is reduced (gains electron).

Reduction - A reaction where something gains electrons. In gaining electrons its charge value is reduced. An anode is constantly reduced as it gains electrons.

Resistance - Properties of a circuit that impede the flow of electrons. Resistance converts electrical energy into photons that are given off as waste heat. Resistance is measured in ohms.

Resistor - An electrical component designed to introduce a known value of resistance into a circuit.

Reverse Bias - A bias voltage applied to a diode or a semiconductor junction with polarity such that little or no current flows.

RFID - Radio Frequency IDentification.

Root-Mean Squared - The effective DC value for an AC value. Abbreviated to RMS.

SCR - Silicon-controlled rectifier. A four-layer solid state device that controls current.

Second - The SI unit for time.

Semiconductor - A solid substance that has a conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects. Devices made of semiconductors, notably silicon, are essential components of most electronic circuits.

Series Circuit - A circuit that contains only one possible path for electron flow supplied by a common voltage source.

Shunt -a low-resistance conductor connected in parallel across a device, circuit, or part of a circuit to provide an alternative path for a known fraction of the current. See parallel.

SI - The standard system of units.

Siemens - The SI unit of conductance, equal to one reciprocal ohm.

SMD - Surface Mount Device. An individual SMT component.

SMT - Surface Mount Technology. This is a circuit built on a PCB with the components soldered directly to pads on the surface, without going through the board. The components and boards are usually much more compact than through hole boards.

Solid State – Using transistors and not vacuum tubes

Source – the MOSFET equivalent of the emitter in a BJT

Speed of Light - Varies depending on the medium it is traveling through. Maximum speed c of 299,792,458 m/s in a perfect vacuum. Light has been slowed down to less than 17 m/s (~60 kph) in special mediums.

Terminal - the end of a line where signals are either transmitted or received, or a point along the length of a line where the signals are made available to apparatus.

Tesla - Unit of magnetic flux density.

Thermistor - Temperature based resistor. As temperature increases resistance decreases.

Through Hole - This means the circuit is built on a PCB with holes drilled in it for the component leads to go through. The leads are soldered on the other side of the board.

Thyristor - A type of electronic switch. It has two states which are triggered by another voltage or current. SCRs and switching transistors are examples of thyristors.

Time - The symbol for time in seconds (s).

Transformer - A static device that transfers electric energy from one circuit to another by magnetic coupling.

Transistor - A solid-state semiconductor device, with three terminals, which can be used for amplification, switching, voltage stabilisation, signal modulation, and many other functions.

Transistor-Transistor Logic - A digital circuit composed of bipolar junction transistors (BJTs).

Turns Ratio - Ratio of the number of turns of a primary winding to the number of turns of a secondary winding.

TRIAC - Triode for Alternating Current, is a generalised name for an electronic component which can conduct current in either direction when it is triggered (turned on), and is formally called a bidirectional triode thyristor or bilateral triode thyristor.

Triode - an electronic amplification device having three active electrodes. The term most commonly applies to a vacuum tube or valve with three elements: the cathode, the grid, and the anode.

TTL - Transistor-Transistor Logic.

Ultra High Frequency - Frequency band from 300 MHz - 3000 MHz.

Variac - A type of transformer with a movable tap to provide a variable output voltage.

Very High Frequency - Frequency band from 30 MHz - 300 Mhz.

Volt - Unit of measure of electric potential and potential difference, where 1 Volt equals 1 Joule per Coulomb. It is named in honour of the Italian physicist, Alessandro Volta (1745–1827), who invented the voltaic pile, possibly the first chemical battery.

Volt-amperes - a measurement of power in a direct current (DC) electrical circuit. In a DC circuit, 1 VA is the equivalent of one watt. The power (in watts) in a DC circuit is equal to the product of the voltage (in volts) and the current (in amperes):

Voltage - An electric field between two charges. Similar to gravity this acts as an electric potential. Measured in volts.

Voltage-amperes reactive - Reactive voltage.

V_CC - Common-collector voltage source. This is an alternate label for the power supply in electronic diagrams for BJT-based circuits such as common-collector amplifiers.

Watt - The unit of measurement for electrical power, named after James Watt, an 18th century Scottish engineer.

Wavelength - The length in space occupied by one cycle of a periodic wave.

Weber - Unit of magnetic flux.

Zener Diode - A pn junction diode that makes use of the breakdown properties of a pn junction. The diode is designed to conduct in the reverse direction when its value of breakdown voltage is reached. Beyond this point, the diode will maintain a relatively constant voltage despite variations in current. Widely used for voltage regulation in electronic products.

Electronics Abbreviations