Glossary of Industry Terms

This page explains some of the frequently used industry abbreviations you may encounter on our website, catalogues or technical information. Is there something missing from this page that you think should be included? Click here to email us

• A

• AC

  - Abbreviation for Alternating Current

• AC coupling

  - Circuit that passes an AC signal while blocking a DC voltage

• AC/DC

  - Equipment that will operate on either an AC or DC power source

• AC generator

  - Device used to transform mechanical energy into AC electrical power

• AC load line

  - A graph representing all possible combinations of AC output voltage and current for an amplifier

• AC power supply

  - Power supply that delivers an AC voltage

• Active component

  - A component that changes the amplitude of a signal between input and output

• Active filter

  - A filter that uses an amplifier in addition to reactive components to pass or reject selected frequencies

• AC voltage

  - A voltage in which the polarity alternates from positive to negative

• ADC

  - Abbreviation for analogue to digital converter

• AF

  - Abbreviation for audio frequency

• AFC

  - Abbreviation for automatic frequency control

• AGC

  - Abbreviation for automatic gain control

• Alkaline battery

  - A battery that delivers more current than a carbon-zinc cell

• Alligator clip

  - Spring clip on the end of a test lead used to make a temporary connection

• Alternating current

  - An electric current that rises to a maximum in one direction, falls back to zero and then rises to a maximum in the opposite direction and then repeats

• Alternator

  - Another name for an AC generator

• AM

  - Abbreviation for amplitude modulation

• Ammeter

  - A meter used to measure current

• Ampere

  - Unit of electrical current

• Amplifier

  - A circuit that increases the voltage, current, or power of a signal

• Amplitude

  - Magnitude or size of a signal voltage or current

• Analogue

  - Information represented as continuously varying voltage or current rather than in discrete levels as opposed to digital data varying between two discrete levels

• Anode

  - The positive electrode of a device. Often of a diode or LED

• Antenna, transmitting

  - A device that converts an electrical wave into an electromagnetic wave that radiates away from the antenna

• Antenna, receiving

  - A device that converts a radiated electromagnetic wave into an electrical wave

• Astable multivibrator

  - An oscillator that produces a square wave output from a DC voltage

• Attenuate

  - To reduce the amplitude of a signal. The opposite of amplification

• Audio

  - Relating to frequencies that can be heard by the human ear. Approximately 20 Hz. to 20 kHz

• Autotransformer

  - A single winding transformer where the output is taken from taps on the winding

• Average value

  - A value of voltage or current where the area of the wave above the value equals the area of the wave below the value

• AVC

  - Abbreviation for automatic volume control

• AWG

  - Abbreviation for American wire gauge. A gauge that assigns a number value to the diameter of a wire

• B

• Band-Pass Filter

  - A tuned circuit designed to pass a band of frequencies between a lower cut-off frequency and a higher cut-off frequency . Frequencies above and below the pass band are attenuated

• Band-Stop Filter

  - A tuned circuit designed to stop frequencies between a lower cut-off frequency (f1) and a higher cut-off frequency (f2) of the amplifier while passing all other frequencies

• Bandwidth

  - Width of the band of frequencies between the half power points

• Base

  - The Junction that lies between the emitter and collector of a transistor

• Battery

  - A DC voltage device that converts chemical energy into electrical energy

• Baud

  - A unit of signaling speed equal to the number of signal events per second

• Bias

  - A DC voltage applied to a device to control its operation

• Binary

  - A number system having only two symbols, 0 and 1. A base 2 number system

• Bipolar Transistor

  - A three terminal device in which emitter to collector current is controlled by base current

• Bistable Multivibrator

  - A multivibrator with two stable states. An external signal is required to change the output from one state to the other. Also called a latch

• Breakdown Voltage

  - Voltage at which the breakdown of a dielectric or insulator occurs

• Bridge Rectifier

  - A circuit using four diodes to provide full wave rectification. Converts an AC voltage into a DC voltage

• Buffer

  - An amplifier used to isolate a load from a source

• BW

  - Abbreviation for bandwidth

• Bypass Capacitor

  - A capacitor used to provide an AC ground at some point in a circuit

• Byte

  - Group of eight binary digits or bits

• C

• Cable

  - Two or more insulated wires within an outer sheath

• CAD

  - Abbreviation for computer aided design

• Calibration

  - To adjust the correct value of a reading by comparison to an exacting standard

• Capacitance

  - The amount of electrical energy a capacitor can store. Measured in Farads

• Capacitive reactance

  - The opposition to current flow provided by a capacitor. Capacitive reactance is measured in ohms and varies inversely with frequency

• Capacitor

  - An electronic component that stores electrical energy. Formerly known as a condensor

• Capacitor microphone

  - Microphone whose operation depends on variations in capacitance caused by varying air pressure on the movable plate of a capacitor

• Carbon-film resistor

  - A component made by depositing a thin carbon film on a ceramic form

• Carbon microphone

  - Microphone whose operation depends on pressure variation in carbon granules causing a change in resistance

• Carbon resistor

  - Resistor of fixed value made by mixing carbon granules with a binder which is moulded and then baked

• Cathode

  - The negative electrode of a device. Often of a diode or LED

• Cathode ray tube

  - (CRT) Vacuum tube used to display data in a visual form. Picture tube of a television or Oscilloscope

• Cell

  - Single unit used to convert chemical energy into a DC electrical voltage

• Center tap

  - Midway connection between the two ends of a winding quite often in a coil or transformer

• Center tapped rectifier

  - Circuit that make use of a center tapped transformer and two diodes to provide full wave rectification

• Center tapped transformer

  - A transformer with a connection at the electrical center of a winding

• Ceramic capacitor

  - Capacitor in which the dielectric is ceramic

• Charge

  - Quantity of electrical energy

• Charge current

  - Current that flows to charge a capacitor or battery when voltage is applied

• Choke

  - Inductor used to oppose the flow of an alternating current

• Circuit

  - Interconnection of components to provide an electrical path between two or more components

• Circuit breaker

  - A protective device used to open a circuit when the specified current is exceeded

• Clamper

  - A diode circuit used to change the DC level of a waveform without distorting the waveform

• Class A amplifier

  - A linear amplifier biased so the active device conducts through 360 degrees of the input waveform

• Class B amplifier

  - An amplifier with two active devices. The active components are biased so that each conducts for approximately 180 degrees of the input waveform cycle

• Class C amplifier

  - An amplifier in which the active device conducts for less than 180 degrees of the input waveform cycle

• Clipper

  - A diode circuit used to eliminate part of a waveform

• Clipping

  - Distortion caused by overdriving an amplifier

• Clock

  - A square waveform used for synchronizing and timing of several circuits

• Coaxial cable

  - Transmission line in which the signal carrying conductor is covered by a dialectric and another conductor. Normally 75 ohm for TV signals and 50 ohms for digital audio

• Collector

  - The semiconductor region in a transistor through which a flow of charge carriers leaves the base region

• Colour code

  - Set of colours used to indicate value of a component. Commonly resistors and some other components

• Common-anode display

  - A multi-segment light emitting diode (LED) with a single positive voltage input connection. Separate cathode connections are provided for each individual segment

• Common cathode display

  - A multi-segment light emitting diode (LED) with a single negative voltage input connection. Separate anode connections are provided for each individual segment

• Common gate amplifier

  - A FET circuit in which the gate connection is common to both input and output

• Common source amplifier

  - A FET circuit in which the source connection is common to both input and output

• Comparator

  - An op-amp circuit that compares two inputs and provides a DC output indicating the polarity relationship between the inputs

• Complementary transistors

  - Two transistors, one NPN and one PNP having near identical characteristics

• Constant current circuit

  - Circuit used to maintain constant current to a load having resistance that changes. Commonly used to drive LED circuits

• Contact

  - Current carrying part of a switch, relay or connector

• Continuity

  - An unbroken electrical path within a circuit,cable or connector

• Copper loss

  - Power lost in transformers, generators, connecting wires and other parts of a circuit due to current flow through the resistance of copper conductors

• Core

  - Magnetic material within a coil used to concentrate the magnetic field

• Coulomb

  - Unit of electric charge. A negative coulomb charge consists of 6.24 x 10¹⁸ electrons

• Counter electromotive force

  - (counter emf) Voltage induced into an inductor due to an alternating or pulsating current. Counter emf is always in polarity opposite to that of the applied voltage. Opposing a change of current

• Coupling

  - To electronically connect two circuits so that signal will pass from one to the other

• Crocodile clip

  - Sprung toothed device for creating a temporary connection that resembles a crocodile available in insulated or uninsulated versions

• Crossover distortion

  - Distortion caused by both devices in a class B amplifier being cut-off at the same time

• Crowbar

  - Circuit used to protect the output of a source from a short circuited load. Load current is limited to a value the source can deliver without damage

• CRT

  - Abbreviation for cathode ray tube

• Crystal

  - Natural or synthetic piezoelectric or semiconductor material with atoms arranged with some degree of geometric regularity

• Crystal-controlled oscillator

  - Oscillator that uses a quartz crystal in its feedback path to maintain a stable output frequency

• Current

  - Measured in amperes, it is the flow of electrons through a conductor. Also know as electron flow

• Current-limiting resistor

  - Resistor in the path of current flow to control the amount of current drawn by a device

• Cutoff frequency

  - Frequency at which the power gain of an amplifier falls below 50% of maximum

• Cycle

  - When a repeating wave rises from zero to a positive maximum then back to zero and on to a negative maximum and back to zero it is said to have completed one cycle

• D

• DAC

  - Abbreviation for digital to analogue converter

• Damping

  - Reduction in magnitude of oscillation due to energy being dissipated as heat

• Darlington pair

  - An amplifier consisting of two transistors with their collectors connected together and the emitter of one connected to the base of the other. Circuit has an extremely high current gain and input impedance

• DC

  - Abbreviation for direct current

• DC offset

  - The change in input voltage required to produce a zero output voltage when no signal is applied to an amplifier

• DC power supply

  - A source of DC power for electrical equipment. Normally derived from 230V AC to the necessary DC voltage and current capacity of the device to be powered

• Dead short

  - Short circuit having no resistance

• Decade

  - A frequency factor of ten

• Decibel

  - (dB) a logarithmic repreentation of gain or loss

• Delay time

  - The time for collector current to reach 10% of its maximum value in a transistor switching circuit

• Depletion layer

  - Is an insulating region within a conductive, doped semiconductor material where the mobile charge carriers have diffused away, or have been forced away by an electric field. Usefully creating a voltage drop across it of approximately 0.6-0.7V for a silicon device at room temperature

• Device

  - A component or part

• Diac

  - A two terminal bidirectional thyristor. Has a symmetrical switching mode

• Dielectric

  - Insulating material between two plates where an electrostatic field exists

• Dielectric constant

  - Property of a material that determines how much electrostatic energy can be stored per unit volume when unit voltage is applied

• Dielectric strength

  - The maximum voltage an insulating material can withstand without breaking down

• Differential amplifier

  - An amplifier in which the output is in proportion to the differences between voltages applied to its two inputs

• Differentiator

  - A circuit in which the output voltage is in proportion to the rate of change of the input voltage. A high pass RC circuit

• Digital

  - Relating to devices or circuits that have outputs of only two discrete levels. Examples: 0 or 1, high or low, on or off, true or false etc

• Diode

  - A two legged devicewith an anode and cathode that conducts in only one direction

• DIP

  - Abbreviation for dual in line package

• Direct coupling

  - Where the output of an amplifier is connected directly to the input of another amplifier or to a load. Also known as DC coupling because DC signals are not blocked

• Direct current

  - Current that flows in only one direction

• Discharge

  - Release of energy stored in either a battery or a capacitor

• Discrete component

  - Package containing only a single component as opposed to an integrated circuit containing many components in a single package

• Dissipation

  - Release of electrical energy in the form of heat

• Distortion

  - An undesired change in a waveform or signal

• Doping

  - The process of adding impurity atoms to intrinsic (pure) silicon or germanium to improve the conductivity of the semiconductor material

• DPST

  - Double pole single throw switching configuration of a switch or relay

• DPDT

  - Double pole double throw switching configuration of a switch or relay

• Dropping resistor

  - Resistor whose value has been chosen to drop or develop a given voltage

• Dry cell

  - DC voltage generating chemical cell using a non liquid (paste) electrolyte

• Dual in-line package

  - Integrated circuit package having two rows of connecting pins

• Dual in-line socket

  - Socket for dual in-line integrated circuits for fast pacement or replacement

• Dual trace oscilloscope

  - Oscilloscope that can simultaneously display two signals

• Dynamic

  - Relating to conditions that are changing or in motion

• E

• E-core

  - Laminated form in the shape of the letter E, onto which inductors and transformers are wound

• Eddy currents

  - Currents induced into a conducting core due to the changing magnetic field. Eddy currnts produce heat which is a loss of power and lowers the efficiency of an inductor

• Electrical charge

  - Electric energy stored on the surface of a material. Also known as a static charge

• Electrical field

  - A field or force that exists in the space between two different potentials or voltages. Also known as an electrostatic field

• Electricity

  - Science states that certain particles possess a force field or charge. The charge possessed by an electron is negative while the charge possessed by a proton is positive. Electricity can be divided into two groups, static and dynamic. Static electricity deals with charges at rest and dynamic electricity deals with charges in motion

• Electric polarisation

  - A displacement of bound charges in a dielectric when placed in an electric field

• Electro acoustic transducer

  - Device that produces an energy transfer from electric to acoustic (sound) or from acoustic to electric. Examples include a microphone, earphones, loudspeakers and pick up cartridges

• Electroluminescence

  - Conversion of electrical energy into light energy

• Electrolyte

  - Electrically conducting liquid (wet) or paste (dry)

• Electrolytic capacitor

  - A capacitor having an electrolyte between the plates. A thin layer of oxide is deposited on just the positive plate. The oxide acts as the dielectric for the capacitor. Most electrolytic capacitors are polarised and must be connected in correct polarity to prevent damage, some electrolytic capacitors are non-polarised typically in loudspeaker crossovers

• Electromagnet

  - A coil of wire usually wound on a soft iron or steel core. When current is passed through the coil a magnetic field is generated. The core provides an easy path for the magnetic lines of force. This concentrates the field in the core

• Electromagnetic communication

  - Use of an electromagnetic wave to pass information between two points. Also called wireless communication

• Electromagnetic induction

  - Voltage produced in a coil due to relative motion between the coil and magnetic lines of force

• Electromagnetic wave

  - Wave that consists of both electric and magnetic variation

• Electromagnetism

  - Relates to the magnetic field generated around a conductor when current is passed through it

• Electromechanical transducer

  - Device that transforms electrical energy into mechanical energy (electric motor) or mechanical energy into electrical energy (generator)

• Electromotive force

  - (emf) Force that causes the motion of electrons due to potential difference between two points. (voltage)

• Electron

  - Smallest sub atomic particle of negative charge that orbits the nucleus of an atom

• Electron flow

  - Electrical current produced by the movement of free electrons towards a positive terminal

• Electrostatic

  - Related to static electric charge

• Electrostatic field

  - Force field produced by static electrical charges

• Emitter

  - The semiconductor region from which charge carriers are injected into the base of a transistor

• Emitter feedback

  - Coupling from the emitter output to the base input of a transistor

• Emitter follower

  - A common collector amplifier. Has a high current gain, high input impedance and low output impedance

• Energised

  - Being electrically connected to a voltage source so the device is activated

• Enhancement-mode MOSFET

  - A field effect transistor in which there are no charge carriers in the channel when the gate source voltage is zero

• Equivalent resistance

  - Total resistance of all the individual resistances in a circuit

• F

• Fall time

  - Time it takes the falling edge of a pulse to go from 90% of peak voltage to 10% of peak voltage

• Farad

  - The basic unit of capacitance. Although this is actually a high value most capacitors are shown as micro-farad (uf) 10-6 farad, nano-farad (nf) 10-9 farad and pico farad (pf) 10-12 farad. Nowadays capacitors are available in the farad range commonly known as super capacitor

• Feedback

  - A portion of the output signal of an amplifier which is connected back to the input of the same amplifier

• Feedback amplifier

  - An amplifier with an external signal path from its output back to its input

• Ferrite

  - A powdered, compressed and sintered magnetic material having high resistively. The high resistance creates eddy current losses low at high frequencies

• Ferrite bead

  - Ferrite composition in the form of a bead. Running a wire through the bead increases the inductance of the wire

• Ferrite-core inductor

  - An inductor wound on a ferrite core

• Ferrites

  - Compound composed of iron oxide, a metallic oxide and ceramic. The metal oxides include zinc, nickel, cobalt or iron

• Ferrous

  - Composed of and or containing iron. A ferrous metal exhibits magnetic characteristics as opposed to non-ferrous material

• Fiber optics

  - Laser's light output carries information that is conveyed between two points by thin glass optical fibers

• Field effect transistor

  - (FET) A voltage controlled transistor in which the source to drain conduction is controlled by gate to source voltage

• Filament

  - Thin thread of carbon or tungsten which produces heat or light with the passage of current

• Filter

  - Network consisting of capacitors, resistors and/or inductors used to pass certain frequencies and block others

• Flip flop

  - A bistable multivibrator. A circuit which has two output states and is switched from one to the other by means of an external signal (trigger)

• Flow soldering

  - Flow or wave soldering technique in large scale electronic assembly to solder all the connections on a printed circuit board by moving the board over a wave of molten solder

• Flux

  - Material used to remove oxide films from the surface of metals in preparation for soldering

• Flux

  - In magnetism, the magnetic field consisting of lines of force

• Flux density

  - The concentration of magnetic lines of force. Determines strength of the magnetic field

• Forward bias

  - A PN junction bias which allows current to flow through the junction. Forward bias decreases the resistance of the depletion layer

• Frequency

  - Rate of recurrence of a periodic wave. Measured in Hertz (cycles per second)

• Frequency meter

  - Meter used to measure frequency of periodic waves

• Frequency response

  - Indication of how well a circuit responds to different frequencies applied to it

• Frequency response curve

  - A graph of amplitude over frequency indicating a circuit response to different frequencies

• Full wave rectifier

  - Rectifier that makes use of the full AC wave in both the positive and negative half cycles to produce a DC waveform

• Function generator

  - Signal generator that can produce sine, square, triangle and saw tooth output waveforms

• Fundamental frequency

  - Lowest frequency in a complex waveform

• Fuse

  - A protective device in the current path that melts or breaks when current exceeds a predetermined maximum value

• G

• Gain

  - Increase in voltage, current and/or power. Gain is expressed as a ratio of amplifier output value to the corresponding amplifier input value

• Ganged

  - Mechanical coupling of two or more capacitors, switches, potentiometers, or any other adjustable components so that adjusting one control will operate all

• Generator

  - Device used to convert mechanical energy to electrical energy

• Giga

  - Metric prefix for 1 billion (10⁹)

• Ground

  - An intentional or accidental conducting path between an electrical system or circuit and the earth or some conducting body acting in place of the earth. A ground is often used as the common wiring point or reference in a circuit

• H

• Half wave rectifier

  - A diode rectifier that converts AC to pulsating DC by eliminating either the negative or the positive alternation of each input AC cycle

• Henry

  - The basic unit of inductance

• HERTZ

  - (Hz.) Unit of frequency. One hertz is equal to one cycle per second

• High-pass filter

  - A tuned circuit designed to pass all frequencies above a designated cut-off frequency. Frequencies below the cut-off frequency are rejected or attenuated

• I

• I.C

  - Short for "integrated circuit"

• Impedance

  - (Z) Measured in ohms it is the total opposition to the flow of current offered by a circuit. Impedance consists of the vector sum of resistance and reactance

• Induced voltage

  - Voltage generated in a conductor when subjected to a moving magnetic field

• Inductance

  - Property of a circuit to oppose a change in current. The moving magnetic field produced by a change in current causes an induced voltage to oppose the original change

• Inductive circuit

  - Circuit having greater inductive reactance than capacitive reactance

• Inductor

  - Length of conductor used to introduce inductance into a circuit. The conductor is usually wound into a coil to concentrae the magnetic lines of force and maximise the inductance. While any conductor has inductance, in normal usage the term inductor usually refers to a coil

• Infrared

  - Electromagnetic heat radiation whose frequencies are above the microwave frequency band and below red in the visible band

• In phase

  - When two or more waves of the same frequency have their positive and negative peaks occurring at the same time

• Insulated

  - When a non conducting material is used to isolate conducting materials from one another

• Insulating material

  - Material that will prevent the flow of current due to its chemical composition

• Insulation resistance

  - Resistance of insulating material. The greater the insulation resistance, the better the insulation

• Intermittent

  - A fault occurring at random intervals of time. Intermittent problems are often difficult to locate because of the random nature. They often don't occur when the technician is present

• Inverting amplifier

  - An amplifier that has a 180° phase shift from input to output

• Inverting input

  - In an operational amplifier (op amp) the input that is marked with a minus sign. A signal applied at the inverting input will be given 180° phase shift between input and output

• J

• Jack

  - Socket or connector into which a plug may be inserted

• Joule

  - The unit of work and energy

• Junction

  - Contact or connection between two or more wires or cables. The area where the p-type material and n-type material meet in a semiconductor

• Junction diode

  - diode. A semiconductor diode in which the rectifying characteristics occur at a junction between the n-type and p-type semiconductor materials

• K

• Kilowatt-hour

  - 1000 watts for 1 hour

• Kinetic energy

  - Energy associated with motion

• Kirchhoff's current law

  - The sum of the currents flowing into a point in a circuit is equal to the sum of the currents flowing out of that same point

• Kirchhoff's voltage law

  - The algebraic sum of the voltage drops in a closed path circuit is equal to the algebraic sum of the source voltages applied

• L

• Lamp

  - Device that produces light

• Laser

  - Device that produces a very narrow intense beam of light

• Lead-acid cell

  - Cell made up of lead plates immersed in a sulphuric acid electrolyte. An SLA battery usually consists of lead-acid cells

• Leakage

  - Small undesirable flow of current through an insulator or dielectric

• LED

  - Abbreviation for "light emitting diode"

• Lenz's law

  - The current induced in a circuit due to a change in the magnetic field is so directed as to oppose the flux, or to exert a mechanical force to oppose the motion

• Level detector

  - An op-amp circuit that compares two inputs and provides a DC output indicating the polarity relationship between the inputs. A comparator

• Light-emitting diode

  - A semiconductor diode that converts electric energy into electromagnetic radiation at a visible and near infrared frequencies when its pn junction is forward biased

• Linear

  - Relationship between input and output in which the output varies in direct proportion to the input

• Line regulation

  - The ability of a voltage regulator to maintain a constant voltage when the regulator input voltage varies

• Live

  - Term used to describe a circuit or piece of equipment that is on and has current flow within it

• Load

  - A source drives a load. Whatever component or piece of equipment is connected to a source and draws current from a source is a load on that source

• Load current

  - Current drawn from a source by a load

• Load impedance

  - Vector sum of reactance and resistance in a load

• Load regulation

  - The ability of a voltage regulator to maintain a constant output voltage under varying load currents

• Load resistance

  - Resistance of a load

• Logic

  - Science of dealing with the principle and applications of gates, relays and switches

• Loss

  - Term used to describe a decrease in power

• Low pass filter

  - A tuned circuit designed to pass all frequencies below a designated cut-off frequency

• M

• Magnet

  - Body that can be used to attract or repel magnetic materials

• Magnetic coil

  - Spiral of a conductor which is called an electromagnet

• Magnetic field

  - Magnetic lines of force traveling from the north pole to the south pole of a magnet

• Magnetic flux

  - The magnetic lines of force produced by a magnet

• Magnetic poles

  - Points of a magnet from which magnetic lines of force leave (north pole) and arrive (south pole)

• Magnetism

  - Property of some materials to attract or repel others

• Matched impedance

  - Condition that occurs when the output impedance of a source is equal to the input impedance of a load

• Maxwell

  - Unit of magnetic flux. One maxwell equals one magnetic line of force

• Metal film resistor

  - A resistor in which a film of metal oxide or alloy is deposited on an insulating substrate

• Metal oxide resistor

  - A metal film resistor in which an oxide of metal (such as tin) is deposited as a film onto the substrate

• Meter

  - Any electrical or electronic measuring device. In the metric system, it is the unit of length equal to 39.37 inches

• Meter resistance

  - DC resistance of the meter's armature coil

• Mica capacitor

  - Capacitor using mica as the dielectric

• Microphone

  - Electro acoustic transducer that converts sound energy into electric energy

• Microwave

  - Band of very short wavelength radio waves within the UHF, SHF and EHF bands

• Mid-band gain

  - Gain of an amplifier operating within its bandwidth

• Modulation

  - Process by which an information signal (audio for example) is used to modify some characteristic of a higher frequency wave known as a carrier (radio for example)

• Monostable multivibrator

  - A multivibrator with one stable output state. When triggered, the circuit output will switch to the unstable state for a predetermined period of time and then return to the stable state. A timer

• MOSFET

  - Abbreviation for ""metal oxide field effect transistor"" also known as an ""insulated gate field effect transistor). A field effect transistor in which the insulating layer between the gate electrode and the channel is a metal oxide layer

• Moving coil microphone

  - Microphone that uses a moving coil within a fixed magnetic field. Dynamic microphone

• Moving coil loudspeaker

  - Loudspeaker that uses a moving ""voice coil"" placed within a fixed magnetic field. Audio frequency current in the voice coil causes movement which is mechanically transferred to the speaker cone. Also known as a dynamic loudspeaker

• Multimeter

  - Electronic test equipment that can perform multiple tasks. Typically one capable of measuring voltage, current and resistance. More sophisticated modern digital multimeters also measure capacitance, inductance, current gain of transistors and/or anything else that can be measured electronically

• Multivibrator

  - A class of circuits designed to produce square waves or pulses. Astable multivibrators produce continuous pulses without an external stimulus or trigger. Monostable multivibrators produce a single pulse for some predetermined period of time only when triggered. Bistable multivibrators produce a DC output which is stable in either one of two states. Either high or low. An external stimulus or trigger is required for the bistable circuit to change states, either high to low or low to high

• N

• Negative

  - Terminal that has an excess of electrons

• Negative charge

  - A charge that has more electrons than protons

• Negative feedback

  - A feedback signal 180° out of phase with an amplifier input signal. Used to increase amplifier stability, bandwidth and input impedance. Also reduces distortion

• Negative ground

  - A system where the negative terminal of the source is connected to the system's metal chassis

• Negative temperature coefficient

  - A term used to describe a component whose resistance or capacitance decreases when temperature increases. Normally called a thermistor

• Neon bulb

  - Glass envelope filled with neon gas which when ionised by an applied voltage will glow red

• Network

  - Combination of interconnected components, circuits or systems

• Neutral

  - A terminal, point or object with balanced charges. Neither positive or negative

• Neutron

  - Subatomic particle in the nucleus of an atom and having no electrical charge

• Noise

  - Unwanted electromagnetic radiation within an electrical or mechanical system

• Non-inverting input

  - The terminal on an operational amplifier that is identified by a plus sign

• Normal closed

  - Designation which states that the contacts of a switch or relay are closed or connected when at rest. When activated the contacts are opened or separated

• Normally open

  - Designation which states that the contacts of a switch or relay are normally open or not connected. When activated the contacts are closed or become connected

• Npn transistor

  - A transistor in which a p-type base element is sandwiched between an n-type emitter and an n-type collector

• O

• Octave

  - Interval between two sounds whose fundamental frequencies differ by a ratio of 2 to 1. 440 Hz. is one octave above 220 Hz

• Offset null

  - An op amp control pin used to eliminate the effects of internal component voltages on the output of the device

• Ohm

  - Unit of resistance symbolized by the Greek capital letter omega (W)

• Ohmmeter

  - Device used to measure electrical resistance

• Ohm's law

  - Relationship between voltage, current and resistance. Ohm's law states that current in a resistance varies in direct proportion to voltage applied and inversely proportional to resistance

• Ohms per volt

  - Refers to a value of ohms per volt of full scale defection for a moving coil meter movement. The number of ohms per volt is the reciprocal of the amount of current required to produce full scale deflection of the needle. A meter requiring 50 microamps for full scale deflection has an internal resistance of 20 kW per volt. The higher the ohms per volt rating, the more sensitive the meter

• Operational amplifier

  - A high gain DC amplifier that has a high input impedance and a low output impedance. Op-amps are the most basic type of linear integrated circuits

• Oscillator

  - An electronic circuit that produces a continuous output waveform with only DC applied

• Oscilloscope

  - An instrument used to display a signal graphically. Shows signal amplitude, period and wave shape in addition to any DC voltage present. A multiple trace oscilloscope can show two or more waveforms at the same time for phase comparison and timing measurements

• Out of phase

  - When the maximum and minimum points of two or more waveshapes do not occur at the same time

• Output

  - Terminal at which a component, circuit or piece of equipment delivers current, voltage or power

• Output impedance

  - Impedance measured across the output terminals of a device without a load connected

• Output power

  - Amount of power a component, circuit or system can deliver to a load

• Overload protection

  - Protective device such as a fuse or circuit breaker that automatically disconnects a load when current exceeds a predetermined value

• P

• Paper capacitor

  - Fixed capacitor using oiled or waxed paper as a dielectric

• Parallel

  - Circuit having two or more paths for current flow. Also called shunt

• Pass band

  - The range of frequencies that will be passed and amplified by a tuned amplifier. Also the range of frequencies passed by a band pass filter

• Passive component

  - Component that does not amplify a signal. Resistors and capacitors are examples

• Passive filter

  - A filter that contains only passive or non amplifying components

• Passive system

  - System that emits no energy. It only receives. It does not transmit or reveal its position

• Peak

  - Maximum or highest amplitude level

• Peak inverse voltage

  - (PIV) The maximum rated value of a AC voltage acting in the direction opposite to that in which a device is designed to pass current

• Peak to peak

  - Difference between the maximum positive and maximum negative values of an AC waveform

• Period

  - Time to complete one full cycle of a periodic or repeating waveform

• Permanent magnet

  - Magnet normally made of hardened steel that retains its magnetism indefinitely

• Phase

  - Angular relationship between two waves

• Phase splitter

  - Circuit that takes a single input signal and produces two output signals that are 180° apart in phase

• Photoconductive cell

  - Material whose resistance decreases or conductance increases when exposed to light

• Photo detector

  - Component used to detect or sense light

• Photodiode

  - A semiconductor diode that changes its electrical characteristics in response to illumination

• Photoresistor

  - Also known as a photoconductive cell or light dependent resistor. (LDR) A device whose resistance decreases with exposure to light

• Photovoltaic cell

  - Component commonly called a solar cell used to convert light energy into electrical energy

• Piezoelectric crystal

  - Crystal material that will generate a voltage when mechanical pressure is applied and conversely will undergo mechanical stress when subjected to a voltage

• Plastic film capacitor

  - Capacitor in which alternate layers of aluminum foil are separated by thin films of plastic dielectric

• Plate

  - Conductive electrode in either a capacitor or battery. In vacuum tube technology, it is the name given to the anode

• Plug

  - Movable connector that is normally connected into a socket or jack

• Pnp transistor

  - A transistor with an n-type base and p-type emitter and collector

• Pole

  - In an active filter, a single RC circuit. A one pole filter has one capacitor and one resistor. A two pole filter has two RC circuits and so on

• Polarity

  - Term used to describe positive and negative charges

• Polarised

  - A component which must be connected in correct polarity to function and/or d/or prevent destruction. Example: Electrolytic capacitor

• Positive

  - Polarity of point that attracts electrons as opposed to negative which supplies electrons

• Positive charge

  - A charge that exists in a body that has fewer electrons than protons

• Positive feedback

  - A feedback signal that is in phase with an amplifier input signal. Positive feedback is necessary for oscillation to occur

• Positive ground

  - A system whereby the positive terminal of the source is connected to the system's conducting chassis

• Potential difference

  - Voltage difference between two points which will cause current to flow in a closed circuit

• Potentiometer

  - A variable resistor with three terminals. Mechanical turning of a shaft can be used to produce variable resistance and potential either linear or logarithmic in action. Example: A volume control is usually a potentiometer

• Power

  - Amount of energy converted by a circuit or component in a unit of time, normally seconds. Measured in units of watts. (joules/second)

• Power amplifier

  - An amplifier designed to deliver maximum power output to a load. Example: In an audio system, it is the power amplifier that drives the loudspeaker

• Power dissipation

  - Amount of heat energy generated by a device in one second when current flows through it

• Power factor

  - Ratio of actual power to apparent power

• Power loss

  - Ratio of power absorbed to power delivered

• Power supply

  - Electrical equipment used to deliver either AC or DC voltage

• Primary

  - First winding of a transformer. Winding that is connected to the source as opposed to secondary which is a winding connected to a load

• Primary cell

  - Cell that produces electrical energy through an internal electrochemical action. Once discharged a primary cell cannot be reused

• Printed circuit board

  - Insulating board containing conductive tracks for circuit connections

• Protoboard

  - Board with provision for attaching components without solder. Also called a breadboard. Primarily used for constructing experimental circuits

• Pulse

  - Rise and fall of some quantity (usually voltage) for a period of time

• Pulse width

  - Time interval between the leading edge and trailing edge of a pulse at a point where the amplitude is 50% of the peak value

• Push-pull amplifier

  - Amplifier using two active devices operating 180° apart

• Q

• Quiescent

  - At rest. For an amplifier the term is used to describe a condition with no active input signal

• Quiescent current

  - The current which continues to be drawn from the battery when the application it powers is in standby or hibernation mode

• R

• Radio communication

  - Term used to describe the transfer of information between two or more points by use of radio or electromagnetic waves

• Radio-frequency probe

  - Probe used in conjunction with an AC meter to measure radio-frequency signals

• RC

  - Abbreviation for ""resistance capacitance"" also abbreviation for "radio controlled" as in "RC model airplanes."

• Reactance

  - Symbol ""X"". Opposition to current flow without the dissipation of energy. Example: The opposition provided by inductance or capacitance to AC current

• Receiver

  - Unit or piece of equipment used to receive information

• Rectification

  - Process that converts alternating current to direct current

• Rectifier

  - Diode circuit that converts alternating current into pulsating direct current

• Reed relay

  - Relay consisting of two thin magnetic strips within a glass envelope. When a coil around the envelope is energized, the relay's contacts snap together making a connection between leads attached to the reed strips

• Regulated power supply

  - Power supply that maintains a constant output voltage under changing load conditions

• Regulator

  - Device or circuit that maintains a desired output under changing conditions

• Relay

  - Electromechanical device that opens or closes contacts when a current is passed through a coil

• Resistance

  - Symbolised ""R"" and measured in ohms. Opposition to current flow and dissipation of energy in the form of heat

• Resistive power

  - Amount of power dissipated as heat in a circuit containing resistive and reactive components. True power as opposed to reactive power

• Resistor

  - Component made of material that opposes flow of current and therefore has some value of resistance

• Resistor colour code

  - Coding system of coloured stripes on a resistor to indicate the resistor's value and tolerance

• Resonance

  - Circuit condition that occurs at the frequency where inductive reactance (XL) equals capacitive reactance (XC)

• Reverse bias

  - Bias on a PN junction that allows only leakage current (minority carriers) to flow. Positive polarity on the n-type material and negative polarity to the p-type material

• Reverse breakdown voltage

  - Amount of reverse bias that will cause a PN junction to break down and conduct in the reverse direction

• Reverse current

  - Current through a diode when reverse biased. An extremely small current also referred to as leakage

• RF

  - Abbreviation for "radio frequency."

• Rheostat

  - Two terminal variable resistor used to control current

• Ripple frequency

  - Frequency of the ripple present in the output of a DC source

• Rms

  - Abbreviation for "root mean square"

• Rms value

  - RMS value of an AC sine wave is 0.707 times the peak value. This is the effective value of an AC sine wave. The rms value of a sine wave is the value of a DC voltage that would produce the same amount of heat in a heating element

• Rotary switch

  - Electromechanical device that has a rotating shaft connected to one or more terminals capable of making or breaking a connection to one or more other terminals. Normally available in either make to break or break to make versions

• S

• Sawtooth wave

  - Repeating waveform that rises from zero to maximum value linearly drops back to zero and repeats. A ramp waveform

• Scale

  - Set of markings used for measurement

• Schematic diagram

  - Illustration of an electrical or electronic circuit with the components represented by their symbols

• Schmitt trigger

  - Circuit to convert a given waveform to a square wave output

• Schottky diode

  - High speed diode that has very little junction capacitance. Also known as a "hot-carrier diode" or a "surface-barrier diode."

• Secondary

  - Output winding of a transformer. Winding that is connected to a load

• Secondary cell

  - Electrolytic cell used to store electricity. Once discharged may be restored by recharging by putting current through the cell in the direction opposite to that of discharge current

• Selectivity

  - Characteristic of a circuit to discriminate between wanted and unwanted signals

• Semiconductor

  - An element which is neither a good conductor or a good insulator, but rather lies somewhere between the two

• Seven segment display

  - Device made of several light emitting diodes arranged in a numeric or alphanumeric pattern. By lighting selected segments numeric or alphabet characters can be displaye

• Shield

  - Metal grounded cover used to protect a wire, component or piece of equipment from stray magnetic and/or electric fields

• Short circuit

  - Also called a short. Low resistance connection between two points in a circuit typically causing excessive current

• Shunt resistor

  - Resistor connected in parallel or in shunt with another component or circuit

• Signal

  - Electrical quantity that contains information

• Signal to noise ratio

  - Ratio of the magnitude of the signal to the magnitude of noise usually expressed in decibels

• Silicon

  - (Si) Non metallic element used in pure form as a semiconductor

• Silicon-controlled rectifier

  - (SCR) Three terminal active device that acts as a gated diode. The gate terminal is used to turn the device on allowing current to pass from cathode to anode

• Silver mica capacitor

  - Mica capacitor with silver deposited directly onto the mica sheets instead of using conductive metal foil

• Silver solder

  - Solder composed of silver, copper and zinc. Has a melting point lower than pure silver, but higher than lead-tin solder

• Sine wave

  - Wave whose amplitude is the sine of a linear function of time. It is plotted on a graph that plots amplitude against time or radial degrees relative to the angular rotation of an alternator

• Single pole double throw

  - (SPDT) Three terminal switch in which one terminal can be connected to either one of the other terminals

• Single pole single throw

  - (SPST) Two terminal switch or relay that can open or close one circuit

• Single throw switch

  - Switch containing only one set of contacts which can be either opened or closed

• Sinusoidal

  - Varying in proportion to the sine of an angle or time function. AC voltage in which the instantaneous value is equal to the sine of the phase angle times the peak value

• SIP or SIL

  - Abbreviation for "single in-line package."

• Slew rate

  - The maximum rate at which the output voltage of an op-amp can change

• Slide switch

  - Switch having a sliding button, bar or knob

• Slow-blow fuse

  - Fuse that can withstand a heavy current (up to ten times its rated value) for a small period of time before it opens

• SMD

  - Short for surface mounted device like I.C's, resistors and most components normally supplied on a reel for pick and place PCB population. Available in different package sizes like 0402, 0603, 0805 and so on

• Software

  - Program of instructions that directs the operation of a computer

• Solar cell

  - Photovoltaic cell that converts light into electric energy. Especially useful as a power source for space vehicles

• Solder

  - Used to join two metal surfaces together. Now available in either leaded or unleaded versions

• Soldering

  - Process of joining two metallic surfaces to make an electrical contact by melting solder across them

• Soldering iron

  - Tool with an internal heating element used to heat surfaces being soldered to the point where the solder melts

• Solenoid

  - An air core coil. Equipped with a movable iron core the solenoid will produce motion. As a result of current through the coil the iron core is pulled into the center of the winding. When the coil is deenergised, a spring pulls the movable core away from the center of the winding. Mechanical devices connected to the movable core are made to move as a result of current through the coil

• Solid conductor

  - Conductor having a single solid wire instead of strands of fine wire twisted together

• Solid state

  - Pertaining to circuits where signals pass through solid semiconductor materials

• Sonic

  - Relating to sound

• Source

  - Device that provides signal power or energy to a load

• South pole

  - Pole of a magnet into which magnetic lines of force are assumed to enter. Also reportedly where Santa Claus gets his little helpers (Elfs) to make all the childrens christmas presents

• SPDT

  - Single pole double throw

• Speaker

  - Also called "loudspeaker". Transducer that converts electrical energy into mechanical energy at audio frequencies

• SPST

  - Abbreviation for "single pole single throw."

• Square wave

  - Wave that alternates between two fixed values for an equal amount of time

• Static

  - Crackling noise heard on AM radio receivers. Caused by electric storms or electric devices

• Static electricity

  - Stationary electric charges

• Stator

  - Stationary part of some rotary device such as a variable capacitor

• Step-down transformer

  - Transformer in which the output AC voltage is less than the input AC voltage

• Step-up transformer

  - Transformer in which the output AC voltage is greater than the input AC voltage

• Stranded conductor

  - Conductor composed of a group of strands of wire twisted together

• Stray capacitance

  - Undesirable capacitance that exists between two conductors such as two leads or one lead and a metal chassis

• Superconductor

  - Metal such as lead or niobium that, when cooled to within a few degrees of absolute zero, can conduct current with no resistance

• Super heterodyne receiver

  - Radio receiver that converts all radio frequencies to a fixed intermediate frequency to maximise gain and bandwidth before demodulation

• Supply voltage

  - Voltage provided by a power source

• Surface-barrier diode

  - (Schottky diode) High speed diode that has very little junction capacitance

• Sweep generator

  - Test instrument designed to produce a voltage that continuously varies in frequency over a band of frequencies. Used as a source to display frequency response of a circuit on an oscilloscope

• Switch

  - Electrical device having two states, on (closed) or off (open)

• Switching transistor

  - transistor designed to change rapidly between saturation and cut-off

• System

  - Combination of several pieces of equipment to perform in a particular manner

• T

• Tantalum capacitor

  - Electrolytic capacitor having a tantalum foil anode. Able to have a large capacity in a small package

• Terminal

  - Point at which electrical connections are made

• Thermistor

  - A resistor whose resistance varies as a function of temperature. Thermistors are used in electrical devices such as thermometers and thermostats that measure, monitor, or regulate temperature. resistance decreases

• Thermocouple

  - Temperature transducer consisting of two dissimilar metals welded together at one end to form a junction that when heated will generate a voltage

• Thermostat

  - Device that opens or closes a circuit in response to changes in temperature

• Thick-film capacitor

  - Capacitor consisting of two thick-film layers of conductive film separated by a deposited thick-layer dielectric film

• Thick film resistor

  - Fixed value resistor consisting of thick-film resistive element made from metal particles and glass powder

• Thin film capacitor

  - Capacitor in which both the electrodes and the dielectric are deposited in layers on a substrate

• Three phase supply

  - AC supply that consists of three AC voltages 120° out of phase with each other

• Thyristor

  - A term used to classify all four layer semiconductor devices. SCRs and triacs are examples of thyristors

• Toggle switch

  - Spring loaded switch that is put in one of two positions either on or off

• Tolerance

  - Permissible deviation from a specified value normally expressed as a percentage

• TO package

  - Cylindrical, metal can type of package of some semiconductor components

• Toroidal coil

  - Coil wound on a doughnut shaped core

• Transducer

  - Device that converts energy from one form to another

• Transformer

  - Inductor with two or more windings. Through mutual inductance, current in one winding called a primary will induce current into the other windings called secondaries

• Transistor

  - Term derived from "transfer resistor."quot; Semiconductor device that can be used as an amplifier or as an electronic switch

• Transmission

  - Sending of information

• Transmitter

  - Equipment used to achieve transmission

• Triac

  - Bidirectional gate controlled thyristor similar to an SCR, but capable of conducting in both directions. Provides full wave control of AC power

• Triangular wave

  - A repeating wave that has equal positive going and negative going ramps. The ramps have linear rates of change with time

• Trimmer

  - Small value variable capacitor, resistor or inductor used to fine tune a larger value

• Tuned circuit

  - Circuit that can have its component values adjusted so that it responds to one selected frequency and rejects all others

• Tunnel diode

  - Heavily doped junction diode that has negative resistance in the forward direction of its operating range

• Turns ratio

  - Ratio of the number of turns in the secondary winding of a transformer to the number of turns in the primary winding

• Tweeter

  - Speaker that reproduces high frequencies

• Two phase

  - Two repeating waveforms having a phase difference of 90°

• U

• UHF

  - Abbreviation for ultra high frequency."

• Ultrasonic

  - Signals that are just above the frequency range of human hearing normally components are tuned at 38-40 kHz

• Unijunction transistor

  - Three terminal device that acts as a diode with its own internal voltage divider biasing circuit

• V

• Varactor diode

  - PN junction diode with a high junction capacitance when reverse biased. Most often used as a voltage controlled capacitor. The varactor is also called: varicap, tuning diode and epicap

• Variable capacitor

  - Capacitor whose capacitance can be change by varying the effective area of the plates or the distance between the plates

• Variable resistor

  - Resistor whose resistance can be changed by turning a shaft. See also "potentiometer and rheostat."

• Very high frequency

  - (VHF) Electromagnetic frequency band from 30 MHz to 300 MHz

• Video amplifier

  - Amplifier having one or mare stages designed to amplify video signals

• Virtual ground

  - Point in a circuit that is always at approximately ground potential. Often a ground for voltage, but not for current

• Voice coil

  - Coil attached to the diaphragm of a moving coil loudspeaker. The coil is moved through an air gap between magnetic pole pieces

• Volt

  - Unit of potential difference or electromotive force. One volt is the potential difference needed to produce one ampere of current through a resistance of one ohm

• Voltage

  - (V) Term used to designate electrical pressure or force that causes current to flow

• Voltage controlled oscillator

  - Oscillator whose output frequency depends on an input control voltage

• Voltage drop

  - Voltage or difference in potential developed across a component due to current flow

• Voltage gain

  - Also called voltage amplification. Ratio of amplifier output voltage to input voltage usually expressed in decibels

• Voltage rating

  - Maximum voltage a component can withstand without breaking down

• Voltage regulator

  - Device or circuit that maintains constant output voltage (within certain limits) in spite of changing line voltage and/or load current

• Voltaic cell

  - Primary cell having two unlike electrodes immersed in a solution that chemically interacts to produce a voltage

• Volt-ampere

  - Unit of apparent power in an AC circuit containing capacitive or inductive reactance. Apparent power is the product of source voltage and current

• Voltmeter

  - Instrument used to measure difference in potential between two points

• W

• Watt

  - Unit of electrical power required to do work at the rate of one joule per second. One att of power is expended when one ampere of direct current flows through a resistance of one ohm. In an AC circuit, true power is the product of effective volts and effective amperes, multiplied by the power factor

• Wattage rating

  - Maximum power a device can safely handle continuously

• Watt-hour

  - Unit of electrical work, equal to a power of one watt being absorbed for one hour

• Waveform

  - Shape of a wave

• Wavelength

  - (l) Distance between two points of corresponding phase and is equal to waveform velocity divided by frequency

• Wetting

  - Term used in soldering to describe the condition that occurs when the metals being soldered are hot enough to melt the solder so it flows over the surface

• Wheatstone bridge

  - Four arm bridge circuit used to measure resistance, inductance or capacitance

• Winding

  - One or more turns of a conductor wound in the form of a coil

• Wire

  - Single solid or stranded group of conductors having a low resistance to current flow. Used to make connections between circuits or points in a circuit

• Wire gauge

  - American wire gauge (AWG) is a system of numerical designations of wire diameters

• Wireless

  - Term describing radio communication commonly known as wi-fi

• Wire wound resistor

  - Resistor in which the resistive element is a length of high resistance wire or ribbon usually nichrome wound onto an insulating form

• Woofer

  - Large loudspeaker designed primarily to reproduce low frequency audio signals

• X

• X

  - Symbol for reactance

• Z

• Z

  - Symbol for inductance