Electronics Topics

A
The abbreviation of Ampere, the SI unit of Electric current.
ab
A prefix indicating that an electrical unit is part of the CGS absolute electromagnetic system.
Absolute Delay
The time interval between the transmission of sequential signals.
AC Brownout
The condition that exists when the ac line voltage drops below some specified value.
AC coupling
Circuit that passes an AC signal while blocking a DC voltage.
AC Line
The set of conductors that route ac voltage from one point to another.
AC Line Filter
A circuit filter placed in the ac line to condition or smooth out variations that are higher in frequency than the line frequency.
AC Voltage
The AC voltage is normally given as the RMS value.
AC
An electric current whose direction changes direction with a frequency independent of circuit components.
Acausal
If a system is acausal it means the output begins before the input.
Accelerated Life Test
A component test over a shortened timescale that has been designed to represent complete life history.
Accelerating Electrode
An electrode in an electron tube which is maintained at a positive potential with respect to the cathode and any other electrodes situated between the cathode and the accelerating electrode, thus imparting acceleration to electrons in the direction away from the cathode.
Accelerating Grid
An accelerating electrode in the form of a grid.
Accelerometer
An instrument for measuring acceleration, as of aircraft or guided missiles.
Accumulator
A device by which energy or power can be stored.
ACK
In telecommunications, this is the acknowledge character in many data codes; used most commonly for an affirmative response of correct receipt.
Acorn Valve
An acorn valve is a form of thermionic valve used at ultra-high frequencies.
Acoustic Coupler
An acoustic coupler is means of connecting external devices to a telephone handset avoiding direct electrical connection.
Acoustic Delay Line
A device used in a communications link or a computer memory in which the signal is delayed by the propagation of a sound wave.
Active Device
A component that has gain or operates in a non-linear fashion to change the basic character of an electric signal by, for example, amplification or rectification.
Active High
The active, true, one, or asserted case of a binary signal is the high or most positive voltage level.
Active Leg
An electrical element within a transducer which changes its electrical characteristics as a function of the application of a stimulus.
Active Low
The active, true, one, or asserted case of a binary signal is the low or less positive voltage level.
Active Network
A circuit that produces gain.
Active Power
The real power supplied by a system to the electrical load.
Actuating System
A mechanical system that supplies and transmits energy for the operation of other mechanisms or systems.
ADC
Abbreviation of Analogue to Digital converter.
Adcock Aerial
An Adcock aerial is a radio aerial system consisting of two vertical open-spaced dipoles with screened horizontal connections.
Adjacent Signal
A signal whose fundamental frequency falls outside the 3 dB IF bandpass of a receiver, but whose spectral sidebands have the potential of being linearly transferred into the baseband of a receiver and causing interference.
Adjustable Resistor
A resistor whose value can be mechanically changed, usually by the use of a sliding contact.
Admittance
The ratio of current to voltage, the reciprocal of impedance.
Aerial
Another name for an antenna.
AGC
Abbreviation of Automatic Gain Control.
Air Blast Transformer
A transformer cooled by forcing a circulation of air around its windings.
Air Capacitor
A capacitor, which uses air as the dielectric between the plates.
Air Pressure Switch
A switch that operates at a pre-determined air pressure.
Air Temperature Switch
A switch that operates at a pre-determined air temperature.
Alternating Current
An electric current whose direction changes direction with a frequency independent of circuit components.
AM
Where audio signals increase and decrease the amplitude of the "carrier wave".
Ammeter
Instrument for measuring the current in amps, milliamps or microamps.
Ammeter Shunt
A low-resistance conductor, placed in parallel with an ammeter movement, so that most of the current flows through the shunt, and only a small portion flows through the ammeter.
Amorphous Semiconductor
A non-crystalline semiconductor material that has no long range order.
Amorphous Solar Cell
These cells are not as efficient as the monocrytalline cells but they do perform better in low light levels.
Amperage
The amount of current flow within a circuit, expressed in amps.
Ampere Hour Efficiency
The ratio of the output of a secondary cell or battery, measured in ampere-hours, to the input required to restore the initial state of charge, under specified conditions.
Ampere-Turn
The magnetomotive force developed by 1 ampere of current flowing through a coil of one turn.
Amplidyne
A special dc generator in which a small dc voltage applied to field windings controls a large output voltage from the generator. In effect, an amplidyne is a rotary amplifier that often times produces gain of approximately 10,000.
Amplification
Amplifiers are used to provide a number of functions.
Amplification Factor
The voltage gain of an amplifier with no load on the output.
Amplifier
A circuit or element that provides gain.
Amplitude Modulation
Where audio signals increase and decrease the amplitude of the "carrier wave".
Amplitude Stability
The ability of the oscillator to maintain a constant amplitude in the output waveform.
Analogue
Any representation of a physical quantity in terms of a continuous variation of a second physical quantity.
Analogue to Digital converter
A circuit that converts an analog signal, having a continuously varying amplitude, to a digitally quantized representation using binary output signals.
ANC
This is an electronic method of reducing or removing unwanted sound by the production of a pressure wave of equal amplitude but opposite sign to the nwanted sound.
AND Gate
Gate that produces a logic 1 when all of its inputs are 1. In all other cases the output is 0.
Angle Modulation
Modulation in which the angle of a sine-wave carrier is varied by a modulating wave.
Antenna
A length of wire or similar that radiates (such as a transmitting antenna) or absorbs (such as a radio antenna) radio waves.
Antenna Beam Width
Width of a radar beam measured between half-power points.
Antenna Coupler
A device used for impedance matching between an antenna and a transmitter or receiver.
Antistatic
Of or pertaining to the ability to either prevent the accumulation of or to enable the dissipation of static charge.
Antitransmit Receive Tube
A tube that isolates the transmitter from the antenna and receiver.
Aperture Delay
In an analog-to-digital converter, the delay in time from when the user requests the analog input to be sampled and the actual time when this occurs.
Aperture Jitter
The amount of variance in the aperture delay.
Apparent Power
That power apparently available for use in an ac circuit containing a reactive element. It is the product of effective voltage times effective current expressed in volt-amperes. It must be multiplied by the power factor to obtain true power available.
Application Specific Integrated Circuit
An integrated circuit designed for a custom requirement, frequently implemented in a gate array or field programmable array.
Aquadag
The colloidal graphite coating in cathode-ray or television tubes.
Armature
In a relay, the movable portion of the relay. The windings in which the output voltage is generated in a generator or in which input current creates a magnetic field that interacts with the main field in a motor.
Armature Losses
Copper losses, eddy current losses, and hysteresis losses that act to decrease the efficiency of armatures.
Armature Reaction
The effect in a dc generator of current in the armature creating a magnetic field that distorts the main field and causes a shift in the neutral plane.
Artificial Transmission Line
An LC network that is designed to simulate characteristics of a transmission line.
ASIC
An abbreviation of Application Specific Integrated Circuit.
Asserted High
The asserted, true, one, or active case of a binary signal is the high or most positive voltage level.
Asserted Low
The asserted, true, one, or active case of a binary signal is the low or less positive voltage level.
Astable
A circuit that has no stable state and thus oscillates at a frequency dependent on component values.
Astable Multivibrator
A multivibrator that has no stable state.
Asymmetric Capacitor
A capacitor where the two plates differ in surface area.
Asymmetrical Multivibrator
A multivibrator that generates rectangular waves.
Atmospheric Interference
The radiofrequency electromagnetic radiation originating, principally, in the irregular surges of charge in thunderstorm lightning discharges.
Attenuator
A two port circuit or device that reduces the amplitude of an input signal by a desired amount typically expressed in decibels.
Audio Amplifier
An amplifier designed specifically for amplifying audio signals in the frequency range 20Hz to 20kHz.
Autodyne
A system of heterodyne reception. The circuit combines the functions of an oscillator and detector.
Automatic Frequency Control
A circuit that keeps a receiver in tune with the wanted transmission.
Automatic Gain Control
A circuit that adjusts the gain of a stage so that the volume is constant even though the input signal may vary over a wide range.
Autotransformer
Both primary and secondary coils have turns in common.
Avalanche
A cumulative ionization process.
B
An abbreviation of bel, the logarithm of the ratio of two powers. The decibel is one tenth of a bel.
Back Bias
An external voltage applied to a diode or semiconductor junction to reduce the flow of electrons across the junction.
Balanced Circuit
A circuit having symmetrical sections above ground potential.
Ballast Tube
A current-controlling resistance device designed to maintain substantially constant current over a specified range of variation in applied voltage or resistance of a series circuit.
Balun
A transformer circuit that couples a balanced transmission line to an unbalanced transmission line.
Band Gap Energy
For semiconductors and insulators, the energies that lie between the valence and conduction bands.
Band Reject Frequencies
A tuned circuit that does not pass a specified band of frequencies.
Base Station
A focal point for data and communications.
Base Terminal
That electrode of a transistor which compares generally to the grid of a vacuum tube.
Batteries in Parallel
The connection of like terminals of cells or batteries to form a system of greater capacity, but with the same voltage.
Battery
A device for converting chemical energy into electrical energy.
Battery Abuse Testing
A series of tests to establish that the battery is not a danger to the user or to itself under any conceivable conditions of use or abuse.
Battery Charger
A device capable of supplying electrical energy to a battery.
Battery Conditioning
The initial application of charge-discharge cycling to establish full battery capacity.
Battery Cycle Life
How many charge/discharge cycles the battery can endure before it loses its ability to hold a useful charge.
Battery Discharge Rate
The maximum rate at which a battery may discharged and charged is normally expressed as a fraction or multiplier of the battery capacity.
Battery Efficiency
This the energy out of a battery during discharge divided by the energy in during charging.
Battery Holder
A component designed to mechanically hold batteries and provide electrical connections.
Battery Module
A battery unit manufactured as the basic component of a battery pack.
Battery Pack
A number of batteries connected together to provide the required power and energy for a given application.
Battery String
A number of batteries connected in series.
Battery Testing
The measurement of single or multiple battery cells under given test criteria to determine their operational parameters.
Bay
A subdivision of the interior space of a building.
Beam Power Tube
An electron tube in which the grids are aligned with the control grid.
Beat Frequency Oscillator
An oscillator whose output is intended to be mixed with another signal to produce a sum or difference beat frequency.
bel
The bel is the logarithm of the ratio of two powers, and the decibel is one tenth of a bel.
Beta
The current gain in a grounded-emitter transistor amplifier.
Beverage Antenna
A horizontal, long-wire antenna designed for reception and transmission of low-frequency, vertically polarized ground waves.
Bias
Used in recording signals on a magnetic media (tape). As the tape passes the recording head, the head generates a varying magnetic field corresponding to the analogue signal to be recorded.
Bias Current
Current that flows through the base-emitter junction of a transistor and is adjusted to set the operating point of the transistor.
Bidirectional Array
An array that radiates in opposite directions along the line of maximum radiation.
Bifilar Winding
Two conductors wound in parallel.
Biot-Savart Law
A law describing the magnetic flux density at a distance r away from an electrical conductor.
Bipolar
A signal that swings both above and below analog ground, thus having positive and negative values.
Bipolar Battery
Design in which the component cells are connected through plates which each, in turn, act as the current-collector for the positive electrode in one cell and for the negative in the adjacent cell.
Bipolar Lead Acid Battery
Design in which the cells are connected through the plates which each, in turn, act as the current-collector for the positive electrode in one cell and for the negative in the adjacent cell.
Bistable
Circuit that has two stable states.
Bistable Multivibrator
A multivibrator that has two stable states.
Bit
Binary Digit - the smallest unit of binary data.
Bit Clock
The synchronizing signal that indicates the rate of individual data bits over a digital audio interface.
Bit Mapped Display
A display in which each pixel's color and intensity data are stored in a separate memory location.
Bitrate
The rate at which the compressed bitstream is delivered from the storage medium to the input of a decoder.
Bitstream
An ordered series of bits that forms the coded representation of the data.
Bleeder Current
A current drawn continously from a souce.
Bleeder Resistor
A resistor that allows a small current drain on a power source to discharge filter capacitors or to stabilize an output.
Blocking
A condition in an amplifier, caused by overdriving one or more stages, in which the amplifier is insensitive to small signals immediately after reception of a large signal.
Blocking Diode
A diode connected in series with a solar cell or cells and a storage battery to keep the battery from discharging through the cell when there is no output, or low output, from the solar cell.
BNC Connector
A twist lock bayonet coaxial connector commonly used in applications involving small coaxial cables.
Bonding Wires
Fine wires connecting the bonding pads of the chip to the external leads of the package.
Boolean Algebra
A system of logic dealing with on-off circuit elements associated by such operators as the AND, OR, NAND, NOR, and NOT functions.
Bottoming
A transistor in the fully conducting state.
Boule
A sausage-shaped, synthetic single-crystal mass grown in a special furnace, pulled and turned at a rate necessary to maintain the single-crystal structure during growth.
Breadboard
An assembly of preliminary circuits.
Breakdown Voltage
Voltage at which the breakdown of a dialectric or insulator occurs.
Bridge Circuit
A circuit usually diagrammed as a square formation of components which gives a null indication on a sensing device when a balance is achieved.
Bridge Rectifier
A full-wave rectifier in which there are four arms - each containing a diode.
Broad Band Signal
A random signal containing a wide range of frequency components. Some types of electrical noise in a cable and acoustic noise from turbulent flow tend to be broad band.
Brushes
Sliding contacts, usually carbon, that make electrical connection to the rotating part of a motor or generator.
Buffer Amplifier
An amplifier that isolates one circuit from another.
Built in Test Equipment
A permanently mounted device that is used expressly for testing a sensor or system.
Buncher Cavity
The input resonant cavity in a conventional klystron oscillator.
Buncher Grid
In a velocity-modulated tube, the grid that concentrates the electrons in the electron beam into bunches.
Burn In
The operation of a newly fabricated device or system prior to application with the intent to stabilize the device, detect defects, and expose infant mortality.
Bus
Transmission medium for electrical or optical signals that perform a particular function, such as computer control.
Busbar
Copper bar or section used for carrying heavy currents, generally rigid when compared to cables.
Bypass Capacitor
A capacitor so wired in a circuit that it has low reactance for signal frequencies and, hence, effectively shunts them around another component.
By-Pass Capacitor
A capacitor that provides a path of low impedance - low resistance to AC signals.
Byte Aligned
A bit in a coded bitstream is byte-aligned if its position is a multiple of 8 bits from the first bit in the stream.
Cable
Either a stranded conductor or a combination of conductors insulated from one another.
Cable Harness
A group of wires or ribbons of wiring used to interconnect electronic systems and subsystems.
Capacitance
The capacitance is defined as the total electric charge on a body divided by its potential.
Capacitative Coupling
The transfer of energy within an electrical network by means of the capacitance between circuit nodes. This coupling can be an intentional or accidental effect.
Capacitive Reactance
The opposition, expressed in ohms, offered to the flow of an alternating current by capacitance.
Capacitor
An electrical component that passes alternating currents but blocks direct currents.
Capacitor Microphone
Microphone whose operation depends on variations in capacitance caused by varying air pressure on the movable plate of a capacitor.
Carbon Microphone
Microphone whose operation depends on pressure variation in carbon granules causing a change in resistance.
Carrier Frequency
The frequency of an unmodulated transmitter output.
Carrier Suppression
The degree to which the carrier signal is reduced in amplitude in a modulator or mixer.
Catcher Grid
In a velocity-modulated tube, a grid on which the spaced electron groups induce a signal.
Cathode Bias
The method of biasing a vacuum tube in which the biasing resistor is placed in the common-cathode return circuit, thereby making the cathode more positive with respect to ground.
Cathode Keying
A system in which the cathode circuit is interrupted so that neither grid current nor plate current can flow.
Cathode Modulator
Voltage on the cathode is varied to produce the modulation envelope.
Cathode Ray Tube
An evacuated tube containing an anode and a cathode that generates cathode rays when operated at a high voltage.
Cathode Sputtering
A process of producing thin film components.
Cavity Resonator
A space totally enclosed by a metallic conductor and supplied with energy in such a way that it becomes a source of electromagnetic oscillations.
Cavity Wavemeter
An instrument used to measure microwave frequencies.
CCD
Abbreviation of Charge Coupled Device.
cdrom
Abbreviation that stands for Compact Disc Read Only Memory.
Cell Reversal
Inversion of the polarity of the electrodes of the weakest cells in a battery, usually as a result of overdischarge.
Central Processing Unit
The computer chip primarily responsible for executing instructions.
Centre Feed Method
Connecting the center of an antenna to a transmission line which is then connected to the output stage of the transmitter.
Centre Frequency
Frequency to which an amplifier is tuned. The frequency half way between the cut-off frequencies of a tuned circuit.
Centre Tap
Midway connection between the two ends of a winding.
Centrifugal Cutout Switch
A centrifugally operated automatic mechanism used in conjunction with split phase and other types of single-phase induction motors.
Ceramic Capacitor
Generally a single layer capacitor that is flat and has a brown coating, Also have the name monoblock or monolithic in which the capacitor is made even smaller by creating multy-layers and coated in orange or blue paint.
Channel
A frequency interval or frequency band assigned for communications.
Characteristic Impedance
The ratio of voltage and current at every point along a transmission line on which there are no standing waves.
Charge Acceptance
The ability of a battery to convert active material during charge into a form which can be subsequently discharged.
Charge Carrier
The particle carrying the electrical charge during the flow of electrical current.
Charge Coupled Device
A self-scanning semiconductor imaging device which uses metal-oxide-semiconductor, surface storage and information transfer technologies.
Charge Cycle
The period of time that a capacitor in an electrical circuit is storing a charge.
Chemical Vapour Deposition
A method of depositing thin semiconductor films.
Chip
A piece of semiconductor substrate on which active and/or passive circuit elements have been fabricated. Small piece of material removed from a workpiece by a cutting tool or grinding wheel.
Choke
An inductor designed to present a high impedance to alternating current.
Chrominance
The colour portion of the video signal that includes hue and saturation information but not brightness.
Circuit
Interconnection of components to provide an electrical path between two or more components.
Circular Mil
An area equal to that of a circle with a diameter of 0.001 inch.
Clamper
A circuit in which either the upper or lower extremity of a waveform is fixed at a desired value.
Class A Amplifier Operation
The type of operation in which the amplifier is biased so that variations in input signal polarities occur within the limits of cutoff and saturation.
Class AB Amplifier Operation
The type of operation in which the amplifier is biased so that collector current is cut off for a portion of the alternation of the input signal.
Class B Amplifier Operation
The type of operation in which the amplifier is biased so that collector current is cut off for one-half of the input signal.
Class C Amplifier Operation
The type of operation in which the amplifier is biased so that collector current is cut off for more than one-half of the input signal.
Class D Amplifier Operation
A switching amplifier or PWM amplifier, the switches are either fully on or fully off, significantly reducing the power losses in the output devices.
Clipper Circuit
A circuit that blocks or removes the portion of a voltage waveform above some threshold voltage.
Closed Loop
A system in which the output is used to control the input.
Closed-Circuit Voltage
The voltage of a battery when it is discharging ie under load.
Clutter
Confusing, unwanted echoes that interfere with the observation of desired signals on a radar indicator.
CMOS
Family of logic devices that uses p-type and n-type channel devices on the same IC.
Coaxial Cable
A round cable with a central conductor and screening around with a insulating medium between.
Coaxial Line
A type of transmission line that contains two concentric conductors.
Coil
An inductive device made by looping turns of wire around a core.
Cold Cathode Tube
A gas-filled electron tube that conducts without the use of filaments.
Cold Junction Compensation
The means to compensate for the ambient temperature in a thermocouple measurement circuit.
Colinear Array
An array with all the elements in a straight line. Maximum radiation is perpendicular to the axis of the elements.
Collector
One terminal of a transistor.
Collector Injection Modulator
The transistor equivalent of a plate modulator.
Combination Array
An array system that uses the characteristics of more than one array.
Combinational Logic
Logic circuits whose outputs depend only on the present logic inputs.
Common Base Connection
Same as ground base connection. A mode of operation of a transistor in which the base is common to both the input and output circuits and is usually earthed.
Common Collector Connection
A mode of operation of a transistor in which the collector is common to both the input and the output circuits and is usually connected to one of the power rails.
Common Emitter Connection
A mode of operation for a transistor in which the emitter is common to the input and output circuits. The base is the input terminal and the collector is the output terminal.
Common Return
return conductor common to two or more circuits.
Common-Mode Rejection Ratio
The ability of the differential amplifier to obtain the difference between the + and - inputs whilst rejecting the signal common to both.
Common-Mode Signal
A signal applied simultaneously to both inputs of a differential amplifier.
Commutator
An electrical switch that periodically reverses the current direction in an electric motor or electrical generator.
Compandor
A combination of a compressor at one point in a communication path for reducing the volume range of signals, followed by an expander at another point for restoring the original volume range.
Compensation Windings
Windings embedded in slots in pole pieces, connected in series with the armature, whose magnetic field opposes the armature field and cancels armature reaction.
Complementary Transistor
A PNP and NPN pair used in a push-pull circuit.
Completion Resistor
A resistor, typically a precision resistor, that completes a bridge measurement system and across which a voltage drop is measured.
Compliance Voltage
The output dc voltage of a constant current supply.
Complimentary Metal Oxide Semiconductor
Family of logic devices that uses p-type and n-type channel devices on the same IC. It has the advantage of offering medium speed and very low power requirements.
Component Video
A video system for colour television that stores separate channels of red, green and blue.
Composite Video
A video signal combining luminance, chrominance, and synchronization data on a single coax cable using RCA connectors and colour-coded yellow.
Condenser
An old fashioned name for a capacitor.
Conduction Band
Lowest empty or partially filled band in a semiconductor.
Conductive
Having the property or capability of conducting.
Conductivity
The ease with which a substance transmits electricity.
Conductor
A material that allows the passage of electric charge or the easy transfer of thermal energy.
Conduit
A tubular raceway, usually metal or plastic, for holding wires or cables.
Continuity
An uninterrupted, complete path for current flow.
Control Grid
The electrode of a vacuum tube, other than a diode, upon which a signal voltage is impressed to regulate the plate current.
Control Grid Modulator
Uses a variation of grid bias to vary the instantaneous plate voltage and current.
Control Loop
Feedback circuit used to control an output signal.
Control System
A group of components systematically organized to perform a specific control purpose.
Control Variable
The inputs and outputs which a control system manipulates and measures to keep proper control.
Controller
A device that controls the operation of part or all of a system.
Cookie Cutter Tuner
A mechanical magnetron tuning device that changes the frequency by changing the capacitance of the anode cavities.
Copper Loss
The power lost because of the resistance of the conductors.
Cordwood Module
A method of increasing the number of discrete components in a given space.
Corner Frequency
The frequency at which linear extrapolations of two contiguous sections of a device's or component′s transfer function drop by 3 decibels.
Corner Reflector Antenna
A half-wave antenna with a reflector consisting of two flat metal surfaces meeting at an angle behind the radiator.
Corona Extinction Voltage
The highest voltage at which continuous corona of specified pulse amplitude no longer occurs as the applied voltage is gradually decreased from above the corona inception value.
Corona Inception Voltage
The lowest voltage at which continuous corona of specified pulse amplitude occurs as the applied voltage is gradually increased.
Correlated Double Sampling
A circuit commonly used to process the output signal from a CCD image sensor in order to reduce low-frequency noise components.
Cosmic Noise
Interference caused by cosmic radio waves.
Counter
A circuit that counts input pulses.
Counter EMF
Another name for Back Electromotive Force.
CPU
Abbreviation of Central Processing Unit, the computer chip primarily responsible for executing instructions.
Cross Modulation
The modulating of a desired signal carrier by undesired signal modulation as the result of accidental mixing of the two signals in a non-linear device.
Cross Talk
Unwanted breakthrough of one channel into another.
Crossover
An electrical circuit consisting of a combination of high-pass, low-pass and bandpass filters used to divide the audio frequency spectrum (20Hz to 20kHz) into segments suitable for individual loudspeaker use.
Crossover Frequency
In a loudspeaker with multiple radiators, the crossover frequency is the 3dB point of the network dividing the signal energy.
Crowbar
Circuit used to protect the output of a source from a short circuited load.
Crown of Thorns Tuner
A mechanical tuning device for magnetron tubes that changes the frequency of the cavities by changing the inductance.
CRT
An evacuated tube containing an anode and a cathode that generates cathode rays when operated at a high voltage.
Crystal Controlled Oscillator
Oscillator that uses a quartz crystal in its feedback path to maintain a stable output frequency.
Crystal Oven
A closed oven maintained at a constant temperature in which a crystal and its holder are enclosed to reduce frequency drift.
Current
Current is often used to transmit signals in noisy environments because it is much less affected by environmental noise pick-up.
Current Density
Amperes per unit area.
Current Drain
The amount of current used by a device.
Current Rating
The safe current-carrying capacity of a wire or cable on a continuous basis.
Current Regulator
A circuit that provides a constant current output.
Current Shunt
A resistor that converts a current signal to a voltage signal.
Current Sink
This refers to a sensor output configuration which switches a voltage to the negative side of the power supply.
Current Source
This refers to a sensor output configuration which provides a source of current to the load.
Current Standing Wave Ratio
The ratio of maximum to minimum current along a transmission line.
Current Transformer
Used for measurement of electric currents where the current is too high to measure directly.
Cutoff
A transistor operating mode where very little current flows between the collector and emitter.
Cylindrical Parabolic Reflector
A parabolically shaped reflector that resembles part of a cylinder.
DAQ
Abbreviation of Data Acquisition.
daraf
A unit of electrical elastance, which is the ability of an electric potential to charge a capacitor.
Dark Current
Thermally induced current of a detector in the absence of an optical signal.
Darlington Pair
Two directly coupled transistors in which the emitter of the first drives the base of the second.
Datalogger
An electronic device that automatically records and stores signals from transducers for later analysis.
dBc
Decibels referenced to the carrier signal.
dBi
Decibels referenced to an isotropic radiator.
dBLi
Decibels referenced to a linear isotropic radiator.
dBm
Decibels referenced to 1 mW.
dBsm
Decibel referenced to one square meter.
dBv
Decibels referenced to one volt.
dBW
Decibels referenced to 1 watt.
DC
A current that does not change in direction.
DC Amplifier
An amplifier employing direct coupling.
DC DC Converter
A circuit or device that changes a dc input signal value to a different dc output signal value.
DC Restorer
A damper circuit which restores the DC level to a signal waveform.
Dead Short
A short circuit having minimum resistance.
Decibel
The human ear responds logarithmically and it is convenient to deal in logarithmic units in audio systems.
Decoder
Extracts intelligence from a coded signal.
Deflection Coils
In a cathode-ray tube, coils used to bend an electron beam a desired amount.
Deflection Plates
Two pairs of parallel electrodes, one pair set forward of the other and at right angles to each other, parallel to the axis of the electron stream within an electrostatic cathode-ray tube.
Degeneration
The process whereby a part of the output signal of an amplifying device is returned to its input circuit in such a manner that it tends to cancel part of the input.
Degenerative Feedback
Feedback in which the feedback signal is out of phase with the input signal.
Degradation
A decrease in the quality of a desired signal as the result of interference, noise or distortion.
Deionization Potential
The potential at which ionization of the gas within a gas-filled tube ceases and conduction stops.
Delay Line
A transmission line or circuit that imposes a desired amount of propagation delay on an incident signal.
Delta Connection
A three phase connection in which the start of each phase is connected to the end of the next phase, forming the triangle-shaped Greek letter Delta.
Delta-Sigma Modulating ADC
A high-accuracy circuit that samples at a higher rate and lower resolution than is needed and pushes the quantization noise above the frequency range of interest.
Demodulation
The process of recovering intelligence from a signal, some parameter of which was modified to carry the intelligence.
Dendrite
A crystal that has a tree-like branching pattern.
Depth of Discharge
The amount of energy that has been removed from a battery.
Deviation Ratio
Ratio of the maximum frequency deviation to the maximum modulating frequency of a frequency modulation system, under specified conditions.
Dielectric Hysteresis Loss
Power loss of a capacitor because of the changes in orientation of electron orbits in the dielectric; the changes in orientation are caused by rapid reversal in polarity of line voltage.
Dielectric Losses
Power losses due to the conductance of dielectric materials.
Differential Amplifier
One whose output is proportional to the difference between two inputs.
Differential Input
Often used to reduce noise picked up by the signal leads.
Differential Voltage
The difference in voltages at two points as measured with respect to a common reference.
Digital Circuit
A collection of logic gates used to process or generate digital signals.
Digital Signal Processing
The term used for calculations performed on digital signals.
Digital Visual Interface
A video interface standard designed to provide very high visual quality on digital displays.
Digital-to-Analogue Converter
Converts a digital number into a corresponding analogue voltage or current.
Diode
A semiconductor that allows current to flow in one direction only.
Diode Drop
The forward voltage developed across a diode when it is operating.
Diode Transistor Logic
Logic gates implemented using particular configurations of diodes and bipolar junction transistors.
DIP
Abbreviation of Dual Inline Package.
Diplexer
A circuit or system that allows the ability to transmit and receive two distinct signals simultaneously.
Direct Coupled Amplifier
An amplifier in which the output of one stage is coupled to the input of the next without the use of a capacitor.
Direct Coupling
A coupling system which provides a direct path for DC or AC signals between one circuit and another, without intervening series inductors or capacitors, except when shunted by resistors.
Direct Current
A current that does not change in direction.
Direct Current Amplifier
A direct coupled amplifier that can provide gain for zero-frequency signals.
Direct Current Restorer
A damper circuit which restores the DC level to a signal waveform.
Direct Short
A short circuit.
Directional Antenna
An antenna that radiates most effectively in only one direction.
Discrete Components
Individual transistors, diodes, resistors, capacitors, and inductors.
Displacement Current
The current that appears to flow through a capacitor.
Distributed Capacitance
Capacitance that is not concentrated within a lumped capacitor, but spread over a circuit or group of components.
Distributed Constants
The constants of inductance, capacitance, and resistance in a transmission line.
Distributed Inductance
Inductance that is not concentrated within a lumped inductor, but spread over a circuit or group of components.
Distribution Circuit Breaker
A device used for overload and short current protection of loads connected to a main distribution device.
Dither
The noise added to a signal prior to quantization which reduces the distortion and noise modulation resulting from the quantization process.
Downconverter
A device which provides frequency conversion to a lower frequency.
DPDT Switch
Abbreviation of Double-Pole, Double-Throw switch.
DPST Switch
Abbreviation of Double-Pole, Single-Throw switch.
Drift
Motion of carriers caused by an electric field.
Driven Element
The element of an antenna connected directly to the transmission line.
Drum Type Armature
An efficient, popular type of armature designed so that the entire length of the winding is cutting the field at all times. Most wound armatures are of this type.
DSP
Abbreviation of Digital Signal Processing, the term used for calculations performed on digital signals.
D-Sub Connector
A connector whose male end has a D shaped raised shield that protects the connecting pins.
DTL
Logic gates implemented using particular configurations of diodes and bipolar junction transistors.
Dual Gate Mosfet
A two-gate MOSFET in which either gate can control the conductor independently, a fact which makes this MOSFET very versatile.
Dual Inline Package
IC package having two parallel rows of preformed leads.
Dummy Load
A dissipative but nonradiating device that has the impedance characteristics of an antenna or transmission line.
Duplexer
A device which uses the finite delay between the transmission of a pulse and the receipt of an echo to permit the use of the same antenna for both transmitting and receiving.
Duty Cycle
The ratio of operating to non-operating time for a device.
DVI
Abbreviation of Digital Visual Interface.
Dynamic Microphone
A device in which sound waves move a coil of fine wire that is mounted on the back of a diaphragm and located in the magnetic field of a permanent magnet.
Dynamic Range
The power range over which a component or system functions properly.
Dynamic Resistance
The first assumption with all circuit analysis is that the response of components is linear. Under certain dynamic conditions the resistance of a component or circuit may change and this is sometimes called Dynamic Resistance.
earth
Can mean a connection to the earth itself or the negative lead to the chassis or any point to zero voltage.
Echo Canceller
A filter that will remove reflected signals on a transmission line that are caused by impedance mismatches.
Eddy Currents
Circulating currents within inductor core material caused by magnetic lines of force cutting across the core in a direction which induces a voltage in the core material.
Effective Number of Bits
Figure of merit for an A/D converter describing how many bits of effective resolution, this is below the actual A/D word size.
Electric Current
Flow of electric charge through a medium, this charge is typically carried by moving electrons in a conductor such as wire.
Electric Motor Noise
There are numerous applications of electric motors and the type of noise produced by each may be very specific to the installation and type of motor.
Electrical Conductivity
The capacity of a material to conduct electric current.
Electrical Connector
An electro-mechanical device for joining electrical circuits as an interface using a mechanical assembly.
Electrical Impedance
Impedance of a linear circuit element with two terminals is the ratio of the complex sinusoidally varying voltage applied across the terminals to the complex current that flows in response.
Electrical Insulation
A material used to prevent the leakage of electricity from a conductor and to provide mechanical spacing or support as protection against accidental contact with the conductor.
Electrical Length
Physical length expressed in terms of the wavelength of a signal for the medium in which the component or structure is situated.
Electrical Resistance
The ability of a material to oppose the flow of an electric current, converting electrical energy into heat.
Electrical Screen
A metal shield which isolates a device from external fields.
Electrical Symbols
Graphic symbols used to illustrate the various electrical or electronic components of a circuit.
Electrolytic Capacitor
A type of capacitor that has a liquid or paste between the plates to increase its capacitance.
Electromagnetic Compatibility
The capability of different electrical systems to coexist in the electromagnetic environment without causing or being subjected to interference.
Electromagnetic Field
Electric and magnetic forces that exist in a physical volume.
Electromagnetic Radiation
The emanation of an electromagnetic field from a source through space.
Electromotive Force
The difference of potential produced by an electrical source to drive a current through an external electrical circuit.
Electron Flow
The direction in which electrons flow. This is from negative to positive - as electrons are negatively charged.
Electron Gun
An electrode of a CRT that is equivalent to the cathode and control grid of conventional tubes.
Electronic Filter
Any of various electric, electronic, acoustic, or optical devices used to reject signals, vibrations, or radiation of certain frequencies while passing others.
Electronic Frequency Counter
An instrument that counts the number of cycles occurring during a precise time interval.
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Electrostatic Sensitivity
The degree to which a component or device is susceptible to damage by electrostatic discharge.
Electrostatic Stress
An electrostatic field acting on an insulator, which produces polarization in the insulator and causes electrical breakdown if raised beyond a certain intensity.
EMC
Abbreviation of Electromagnetic Compatibility.
Emergency Power
Temporary source of limited electrical power used upon the loss of the normal power source.
EMI
Abbreviation of Electromagnetic Interference.
Emitter
One terminal of a transistor. Compares generally to the cathode of a tube.
Emitter Coupled Logic
Where transistors are held in the turned-on state to increase the speed of the gate.
Emitter Follower
A transistor circuit comparable to the cathode-follower tube circuit. (Also called grounded collector.)
Encoder
A device that converts linear or rotary displacement into digital or pulse signals.
End Fire Array
An array in which the direction of radiation is parallel to the axis of the array.
Engineering
A profession in which a knowledge of math and natural science is applied to develop ways to utilize the materials and forces of nature for the benefit of all human beings.
Equivalent Resistance
A resistance that represents the total ohmic values of a circuit component or group of circuit components.
Error Detector
The component in a servosystem that determines when the load has deviated from its ordered position, velocity, and so forth.
Error Signal
The signal whose amplitude and polarity or phase are used to correct the alignment between the controlling and the controlled elements.
E-Transformer
A special form of differential transformer employing an E-shaped core.
Excitation Voltage
The supply voltage required to activate a circuit.
Exclusive Or Gate
Logic element that features two inputs. The output will be 1 only when one or the other (but not both) is logic 1. In all other cases the output is 0.
Externally Excited Meter
A term used to describe meters that get their power from the circuit to which they are connected.
Externally Sychronized Radar
A radar system in which timing pulses are generated by a master oscillator external to the transmitter.
F
An abbreviation of farad, the SI unit of capacitance.
Far Field
The distribution of sound energy at a very much greater distance from a sources than the linear dimensions of the source and in which the sound waves can be considered to be plane waves.
Farad
The SI unit of capacitance.
Faraday Cage
An earthed metallic wire or gauze screen enclosing electrical equipment to shield it from the influence of external electric fields.
Faraday Screen
An earthed wire screen placed in an equipment so as to prevent electrostatic but not electromagnetic coupling between components.
Feedback
Occurs when some or all of the output of the device (such as an amplifier) is taken back to the input.
Feedback Control
Another name for Closed Loop control.
Feeder
A transmission line that carries energy to the antenna.
Feedhorn
A horn radiator used to feed a reflector.
Ferrite
A solid solution of one or more elements in body-centered cubic iron.
Ferrite Bead
A passive electric component used to suppress high frequency noise in electronic circuits, employing the mechanism of high dissipation of high frequency currents in a ferrite to give high frequency noise suppression.
Ferrite Rod Aerial
A coil of wire wound on a ferrite material to increase the inductance of the coil. It's signal capturing capability.
Ferromagnetic Material
A highly magnetic material, such as iron, cobalt, nickel, or their alloys.
Festoon Bulb
A light bulb in the form of a small glass tube with caps at each end providing the contacts.
Fetch-and-Deposit
A data transfer in which the data bytes are transferred from the source to the controller, and then from the controller to the target.
Fibre Washer
Used in many different applications for electrical or thermal insulation, to distribute the load or to add some complaince to the bolted structure.
Field Effect Transistor
A transistor that makes use of the field established in a p-type channel semiconductor material to control the flow of current through the channel.
Field Excitation
The creation of a steady magnetic field within the field windings by the application of a dc voltage either from the generator itself or from an external source.
Field-Programmable Gate Array
A programmable logic device which is larger and more versatile than traditional programmable devices such as PALs and PLAs.
Filament
That electrode within a tube which is heated for electron emission or which transfers its heat to a separate cathode for electron emission.
Filter
Any of various electric, electronic, acoustic, or optical devices used to reject signals, vibrations, or radiation of certain frequencies while passing others.
Filter Capacitor
A capacitor employed in power supplies for ripple reduction.
Filter Choke
An inductor used in power supplies for ripple reduction.
Finite Impulse Response Filter
A commonly used type of digital filter. Digitized samples of the audio signal serve as inputs, and each filtered output is computed from a weighted sum of a finite number of previous inputs.
FIR Filter
A commonly used type of digital filter. Digitized samples of the audio signal serve as inputs, and each filtered output is computed from a weighted sum of a finite number of previous inputs.
Fishpaper
An insulating paper, often fibre or oilcloth-like, used in the construction of transformers and coils.
Fixed Resistor
A resistor having a definite resistance value that cannot be adjusted.
Fleming Valve
An earlier name for a diode, or a two-electrode vacuum tube used as a detector.
Flexible Coaxial Cable
A line made with an inner conductor that consists of flexible wire insulated from the outer conductor by a solid, continuous insulating material.
Flip Chip
A monolithic IC packaging technique that eliminates the need for bonding wires.
Flip Flop
An astable multivibrator.
Float Voltage
The voltage at which the battery is floated, or just enough current is supplied to equal the self-discharge of the battery.
Fluorescent Tube
A gas-discharge lamp that uses electricity to excite mercury vapour.
Flywheel Battery
A battery in which the energy is stored in a flywheel, electrical energy is added or removed from the rotating flywheel using an electric motor.
Flywheel Effect
The continuous interchange of electric energy between the capacitor and inductor of a parallel resonant circuit wherein the energy level is diminished only by circuit resistance and radiated energy.
FM
An abbreviation of Frequency Modulation where the information signal is used to vary the carrier signal frequency.
Focusing Anode
An electrode of a CRT that is used to focus the electrons into a tight beam.
Folded Dipole
An ordinary half-wave antenna that has one or more additional conductors connected across the ends parallel to each other.
Foot Switch
A foot operated switch.
Footprint
The area occupied by a device or machine.
Forward Bias
The bias applied between the base and emitter of a transistor to coincide with the P and N zone polarities.
Forward Resistance
The smaller resistance value observed when you are checking the resistance of a semiconductor.
Foster Seeley Discriminator
A circuit that uses a double-tuned RF transformer to convert frequency variations in the received FM signal to amplitude variations.
Foucault Currents
Also known as Eddy Currents.
Four Element Array
An antenna array with three parasitic elements and one driven element.
FPGA
Abbreviation of Field-Programmable Gate Array.
Framing
The process of synchronizing a facsimile receiver to a transmitter allowing proper picture reproduction.
Frequency Compensation Network
Circuit modification used to improve or broaden the linearity of its frequency response.
Frequency Counter
Counts digital pulses over a defined gate time.
Frequency Cutoff
The frequency at which the filter circuit changes from an action of rejecting the unwanted frequencies to an action of passing the desired frequencies.
Frequency Deviation
The amount the frequency varies from the carrier frequency.
Frequency Distance Separation
The combined isolation effect resulting from tuning two or more electronic devices, one of which is an emitter, at different frequencies and separating them physically.
Frequency Diversity
Transmitting and receiving of radio waves on two different frequencies simultaneously.
Frequency Meter
A meter used to measure the frequency of an ac signal.
Frequency Modulation
The information signal is used to vary the carrier signal frequency.
Frequency Multipliers
Special RF power amplifiers that multiply the input frequency.
Frequency Shift Keying
The form of frequency modulation in which the modulating wave shifts the output frequency between predetermined values, and the output wave has no phase discontinuity.
Frequency Spectrum
The entire range of frequencies contained in a pulse or signal.
Frequency Stability
The ability of an oscillator to accurately maintain its operating frequency.
Frequency Synthesis
A process that uses hetrodyning and frequency selection to produce a signal.
Frequency Synthesizer
A frequency source of high accuracy.
Frequency Tolerance
The extent to which a characteristic frequency of an emission, for example, the carrier frequency itself or a particular frequency in the sideband, may be permitted to depart from a specified reference frequency within the assigned band.
Front to Back Ratio
The ratio of the energy radiated in the principal direction compared to the energy radiated in the opposite direction.
Fuel Cell
A device that converts the chemical energy obtained from a redox reaction directly into electrical energy.
Full Duplex
Operational mode of a communication circuit in which each end can simultaneously transmit and receive data.
Full Wave Voltage Doubler
Consists of two half-wave voltage rectifiers and is used to reduce the output ripple amplitude.
Fuse
A short length of wire that will easily burn out when excessive current flows.
Fusible Link
An electrical or mechanical link designed to break under high current or other mechanical input and so break a circuit.
Gain
The ratio of the output level of a circuit to the input. This will be positive for an amplifier and negative for an attenuator.
Gain Bandwidth Product
The number that results when the gain of a circuit is multiplied by the bandwidth of that circuit.
Galvanometer
An instrument for detecting and measuring a small electric current by movements of a magnetic needle or of a coil in a magnetic field.
Gamme Ring Armature
An inefficient type of armature winding in which many of the turns are shielded from the field by its own iron ring.
Ganged Tuning
The process used to tune two or more circuits with a single control.
Gate
One of the terminals of a Field Effect Transistor (FET).
Gated Automatic Gain Control
Circuit that permits automatic gain control to function only during short time intervals.
Gating
The process of selecting those portions of a wave that exist during one or more selected time intervals or that have magnitudes between selected limits.
Getter
An alkali metal introduced into a vacuum tube during manufacture.
Gimbal
A mechanical frame, with two perpendicular intersecting axes of rotation, used to support and furnish a gyro wheel with the necessary freedom to tilt in any direction.
GND
Commonly used abbreviation for ground.
Greencap Capacitor
A type of polyester capacitor that the manufacturer dips in green paint to make it distinctive from all other capacitors.
Grid Bias
A constant fixed potential applied between the grid and the cathode of a vacuum tube to establish an operating point.
Grid Current
The current that flows in the grid-to-cathode circuit of a vacuum tube.
Grid Gap Tuning
A method of changing the centre frequency of a resonant cavity by physically changing the distance between the cavity grids.
Grid Leak Bias
A self-bias provided by a high resistance connected across the grid capacitor or between the grid and cathode.
Ground
To connect some point of an electrical circuit or some item of electrical equipment to earth or to the conducting medium used in lieu thereof.
Ground Clutter
Unwanted echoes, from surrounding land masses, that appear on a radar indicator.
Ground Plane
The earth or negative rail of a circuit. A large or significant mass that presents the effect of earth (ground) to a signal.
Ground Plane Antenna
A type of antenna that uses a ground plane as a simulated ground to produce low-angle radiation.
Ground Potential
Zero potential with respect to the ground or earth.
Ground Reflection Loss
The loss of RF energy each time a radio wave is reflected from the surface of the earth.
Ground Screen
A series of conductors buried below the surface of the earth and arranged in a radial pattern. Used to reduce losses in the ground.
Grounded Base
A transistor amplifier circuit comparable to the grounded-grid (signal ground) tube circuit.
Grounded Collector
A transistor circuit comparable to the cathode-follower tube circuit. (Also called emitter follower.)
Grounding
Establishing an electric connection to the Earth in order to neutralize an object.
Guard Band
A band of frequencies, adjacent to the frequency of a desired signal, left vacant to provide a safety margin against mutual interference.
Guard Time
The time gap between the end of the time slot for one channel and the beginning of the time slot for the next channel. Guard time prevents overlap between adjacent time slots.
Half Duplex
Describes a circuit capable of transmitting in either direction, but only one direction at a time.
Half Wave Dipole Antenna
An antenna, consisting of two rods in a single line, that radiates electromagnetic energy.
Half Wave Rectifier
A tube or solid-state diode which passes current in only one direction and thus converts ac to pulsating dc by rectification of one alternation of each cycle.
Hall Effect
The phenomenon whereby a force is brought to bear on a moving electron or hole by a magnetic field that is applied perpendicular to the direction of motion.
Hall Mobility
A measure of the flow of charged particles perpendicular to both a magnetic and an electric field.
Handshaking
The initial exchange between two communications systems prior to and during transmission to ensure proper data transfer.
Hay Bridge
A bridge circuit in which two opposite arms are resistors, the third arm C and B in series, and the fourth arm L and R in series.
HDMI
Abbreviation of High-Definition Multimedia Interface.
Headroom
A term related to dynamic range, used to express in dB, the level between the typical operating level and the maximum operating level above which the signal will be clipped.
Heat Pipe
A device that can transfer large amounts of heat with a small difference in temperature between the hot and cold interface.
Heat Shrink Tubing
A tubing that shrinks when heated.
Heat Shunt
A device used to absorb heat and protect heat-sensitive components during soldering.
Heat Sink
A structure that is mechanically attached to a device that generates heat.
Heaviside Oliver
An English electrical engineer who introduced Laplace transforms into electrical engineering.
Heptode
A high-vacuum thermionic valve having seven electrodes.
Hertz
The SI unit of frequency indicating the number of cycles per second (symbol Hz).
Hertz Antenna
A half-wave antenna that is installed some distance above ground and positioned either vertically or horizontally.
Hertzian Waves
Now generally called radio waves.
Heterodyning
The process of mixing the incoming signal with the local oscillator frequency. This produces the two fundamentals and the sum and difference frequencies.
High Power Effects
Interference effects that occur in the presence of strong signals.
High Tension
A comparative term used in electronics to denote high voltages.
High-Definition Multimedia Interface
A compact audio visual interface for transmitting uncompressed digital data.
Hits Per Scan
The number of times an RF beam strikes a target per antenna revolution.
Horizontal Deflection Plates
A pair of parallel electrodes that moves the electron beam from side to side in a CRT.
Horn Radiator
A tapered, tubular or rectangular microwave antenna that is widest at the open end.
Hot Carrier Diode
A semiconductor diode in which hot carriers are emitted from a semiconductor layer into the metal base.
Hot Spot
A region of high heat flow.
Hot Wire Meter Movement
A meter movement that uses the expansion of a heated wire to move the pointer of a meter; measures DC or AC.
Housing
An enclosure for electrical or mechanical parts.
Hybrid Circuit
A circuit made with a mixture of passive and active components.
Hybrid IC
Two or more integrated circuit types, or one or more integrated circuit types and discrete components on a single substrate.
I2R
Losses due to current flowing in a conductor caused by resistance.
IC
An abbreviation of Integrated Circuit, first proposed by G. W. A. Dunner in 1952.
Idler Frequency
In a parametric amplifier, the difference between the input signal and the pump signal frequency.
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IGBT
Abbreviation of Insulated Gate Bipolar Transistor.
IGFET
Any field-effect transistor that has an insulated gate.
Ignitron
A mercury-pool type of rectifier tube employing mercury-vapour ionization.
IIR
Abbreviation of Infinite Impulse Response filter, a commonly used type of digital filter.
Image Frequency
An undesired frequency capable of producing the desired frequency through heterodyning.
Image Rejection
The decrease in response of a superheterodyne receiver to the image frequency as compared with its response to the desired signal, usually expressed in decibels.
Impedance
Mechanical impedance is the ratio of a force-like quantity to a velocity like quantity when the arguments of the real (or imaginary) parts of the quantities increase linearly with time.
Impedance Matching
Maximum power is transferred from one circuit to another when the output impedance of the one is matched to the input impedance of the other.
Impulse
The product of the force and the time during which it acts.
In Circuit Meter
A meter permanently installed in a circuit; used to monitor circuit operation.
In Phase
Two periodic waves reaching peaks and going through zero at the same instant are said to be "in phase."
Indirectly-Heated Tube
A tube in which the filament heats the cathode to produce electron emission.
Induced Channel MOSFET
A MOSFET in which there is no actual channel between the source and the drain.
Induced Current
Current that flows as a result of an Induced EMF.
Induced Electromotive Force
Voltage induced in a conductor in a varying magnetic field.
Inductance
The property of an electric circuit to store magnetic energy when carrying a current.
Inductance Bridge
An AC bridge circuit used to measure an unknown value of inductance.
Induction Losses
The losses that occur when the electromagnetic field around a conductor cuts through nearby metallic objects and induces a current into that object.
Inductive Coupling
Coupling of two coils by means of magnetic lines of force.
Inductive Load
Load whose voltage and current are out-of-phase.
Inductive Reactance
The opposition to the flow of an alternating current caused by the inductance of a circuit, expressed in ohms.
Inductor
A magnetic device that stores energy in a magnetic field produced by flowing current.
Infinite Impulse Response Filter
A commonly used type of digital filter. This recursive structure accepts as inputs digitized samples of the audio signal, and then each output point is computed on the basis of a weighted sum of past output (feedback) terms, as well as past input values.
Infrared Reflow
Technique in which long wavelength light serves as the heat source to reflow solder and form solder joints.
Infrared Sensor
A device that can detect electromagnetic radiation with wavelengths that are greater than the visible radiation.
Input Bias Current
The current that flows into the inputs of a circuit.
Input Impedance
The measured resistance and capacitance between the input terminals of a circuit.
Input Offset Current
The difference in the input bias currents of the two inputs of an instrumentation amplifier.
Insertion Loss
This may be applied to a silencer or other sound-reducing element, in a specified frequency band, the decrease in sound power level, measured at the location of the receiver, when a sound insulator or a sound attenuator is inserted in the transmission path between the source and the receiver.
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Insulated Gate Bipolar Transistor
A three-terminal power semiconductor device, noted for high efficiency and fast switching.
Insulation Resistance
The resistance offered by an insulating material to current leakage.
Insulator
A material that does not allow the passage of electric charge or is a poor conductor of thermal energy.
Integrated Circuit
First proposed by G. W. A. Dunner in 1952.
Integrating ADC
An ADC whose output code represents the average value of the input voltage over a given time interval.
Integrator
A device for accomplishing a numeric approximation of the mathematical process of integration.
Interconnects
Connections between components.
Interelectrode Capacitance
The capacitance between the electrodes of an electron tube.
Interelectrode Capacity
The internal capacitances existing between the elements of a vacuum tube.
Interference
The combining of two or more signals results in an interaction called interference.
Interference to Noise Ratio
The ratio of the amount of interfering signal power at the input to the final detector of a receiver, to the amount of noise power produced by that receiver, usually expressed in decibels.
Intermediate Frequency
The fixed frequency to which all carrier waves are converted, resulting from the combination of the received signal and a local oscillator signal, in a superheterodyne receiver.
Internal Short-Circuit
A short circuit within a component.
Interpoles
Small auxiliary poles, placed between main field poles, whose magnetic field opposes the armature field and cancels armature reaction.
Intersection Law
States that if one input to an AND gate is already TRUE, then the output will depend upon the state of the other inputs only.
Intrinsic Carrier Density
The density of electrons and holes in an intrinsic semiconductor.
Inverter
A circuit in both analogue and digital systems that provides an output that is inverse to the input. Also a circuit that converts DC to AC.
Isolation
The prevention of unwanted interaction or leakage between components.
Isolation Voltage
The voltage that an isolated circuit can normally withstand, usually specified from input to input.
Isometric Diagram
A diagram showing the outline of a ship, aircraft, or equipment and the location of equipment and cable runs.
I Squared R Losses
Losses due to current flowing in a conductor caused by resistance.
ISWR
Abbreviation of Current Standing Wave Ratio.
JFET
A three-terminal transistor device where the output current flowing between the source and drain terminals is controlled by a variable electric field applied to the gate terminal. The gate design determines the type of FET: either JFET (junction FET) or MOSFET (metal-oxide semiconductor FET).
J-Type Thermocouple
Iron-constantan thermocouple with a temperature range of 0 to 750°C.
Junction
A connection between two or more parts.
Junction Box
A box with a cover that serves the purpose of joining different runs of wire or cable and provides space for the connection and branching of the enclosed conductors.
Junction Diode
A two-terminal device containing a single crystal of semiconducting material that ranges from P-type at one terminal to N-type at the other.
Junction Transistor
A bipolar transistor constructed from interacting PN junctions.
Key Clicks
Interference in the form of "clicks" or "thumps" caused by the sudden application or removal of power.
Klystron Power Amplifier
A multicavity microwave electron tube that uses velocity modulation.
K-Type Thermocouple
Chromel-Alumel thermocouple with a temperature range of -200 to 1200°C.
Laminated Core
A core built up from thin sheets of metal insulated from each other.
Lap Winding
An armature winding in which opposite ends of each coil are connected to adjoining segments of the commutator so that the windings overlap.
Large Scale Integration
An integrated circuit containing 1,000 to 2,000 logic gates or up to 64,000 bits of memory.
Laser Soldering
Method of soldering in which the heat required to reflow a solder interconnection is provided by a laser.
LC Capacitor Input Filter
Used in a power supply where output current is low and load current is relatively constant.
LC Choke Input Filter
Used in power supplies where voltage regulation is important and where the output current is relatively high and subject to varying load conditions.
LCD
Abbreviation of Liquid Crystal Display.
LDR
A layer of Cadmium Sulphide material that changes resistance according to the amount of light falling on it.
Lead Acid Battery
A battery with electrodes of lead oxide and metallic lead that are separated by an electrolyte of sulphuric acid.
Lead Inductance
Inductance of the lead wires connecting the components.
Lead Sheath
A continuous jacket of lead moulded around a single conductor or multiple conductor cable.
Lead
A wire or connection.
Leakage Current
The small amount of current that flows through the dielectric between the conductors of a transmission line.
Leakage Flux
Magnetic flux lines produced by the primary winding that do not link the turns of the secondary winding.
Leakage Resistance
The electrical resistance that opposes the flow of current through the dielectric of a capacitor.
LED
A diode that emits light when current is passed through it.
Lenzs Law
A basic law which states that an induced current set up by the relative motion of a conductor and a magnetic field always flows in such a direction as to form a magnetic field which opposes the motion.
Light Dependent Resistor
A layer of Cadmium Sulphide material that changes resistance according to the amount of light falling on it.
Light Emitting Diode
A diode that emits light when current is passed through it.
Lighthouse Tube
An electron tube shaped like a lighthouse that is designed to handle large amounts of power at uhf frequencies.
LiIon
Abbreviation of Lithium Ion Battery.
Limit Switch
A sensor used to determine the end of travel on a linear motion assembly.
Lin Log Amplifier
An amplifier in which the response is linear for weak signals and logarithmic for large signals.
Linear Impedance
An impedance in which a change in current through a device changes in direct proportion to the voltage applied to the device.
Linear Variable Differential Transformer
An inductance element that produces an electrical output proportional to the displacement of a separate movable core; used to measure position.
Liquid Crystal Display
A thin and flat display device made up of a number of colour or monochrome pixels arrayed in front of a light source or reflector.
Lissajou′s Figures
The pattern traced out when the displacements of two simple harmonic motions are traced in the x and y direction.
Lithium Ion Battery
Lithium ions are added to a carbon electrode instead of using metallic lithium as the anode.
Lithium Polymer Battery
The battery has a lithium anode that is separated from the cathode by a thin polymer electrolyte.
Load
The weight supported by a structure.
Load Isolator
A passive attenuator in which the loss in one direction is much greater than that in the opposite direction.
Loading Effect
The effect of a voltmeter upon the circuit being measured that results in an inaccurate measurement.
Lobe
An area of greater signal strength in the transmission pattern of an antenna.
Logarithmic Receiver
Receiver that uses a linear logarithmic amplifier instead of a normal linear amplifier.
Logic Circuit
The primary control information processor in digital equipment; made up of electronic gates and so named because their operation is described by simple equations of a specialized logic algebra.
Logic Diagram
Representing the logical elements and their interconnections without necessarily expressing construction or engineering details.
Logic Instruction
Any instruction that executes a logic operation that is defined in symbolic logic, such as AND, OR, NAND, or NOR.
Logic Operation
A nonarithmetical operation in a computer, such as comparing, selecting, making references, matching, sorting, and merging, where the logical YES or NO quantities are involved.
Logic Switch
A diode matrix or other switching arrangement that is capable of directing an input signal to one of several outputs.
Logic Symbol
A symbol used to represent a logic element graphically.
Long Wire Antenna
An antenna that is a wavelength or more long at its operating frequency.
Loose Coupling
Inefficient coupling of energy from one circuit to another that is desirable in some applications.
Loudspeaker
An electroacoustical transducer that changes electrical energy to acoustical energy.
Low Voltage
AC system operating voltages from 120 to 600 VAC.
Lower Frequency Cutoff
The lowest frequency a circuit will pass.
Lower Sideband
All difference frequencies below that of the carrier.
LSB
Abbreviation of Least Significant Bit, the bit within a digital word that represents the smallest possible coded value.
LSI
Abbreviation of Large Scale Integration.
LVDT
An inductance element that produces an electrical output proportional to the displacement of a separate movable core; used to measure position.
Machine
Any mechanical or electrical device that performs a task for people.
Magnet Wire
Wire coated with an enamel insulation and used in coils, relays, transformers and motor windings.
Magnetic Trip Element
A circuit breaker trip element that uses the increasing magnetic attraction of a coil with increased current to open the circuit.
Mains Noise
Unwanted noise in electrical signals related to mains signals.
Majority Carriers
The term used in transistor design to indicate the primary current-movement process.
Marconi Antenna
A quarter-wave antenna that is operated with one end grounded and is positioned perpendicular to the earth.
Mark
An interval during which a signal is present.
Mask
A device used to deposit materials on a substrate in the desired pattern.
Mayer Method
A method of evaluating the propagation delay of a transmission line.
Meaconing
A system for receiving beacon signals and rebroadcasting them on the same frequency to confuse navigation.
Mechatronics
The introduction of electronic controls into mechanical components.
Medium Voltage
AC system operating voltages from 601 to 15000 VAC.
Megohm
One million ohms.
Memory
In a computer system memory is used to store data temporarily or permanently. The capacity of the memory is normally measured in bytes.
MEMS
Abbreviation of Micro Electro Mechanical Systems.
Metal-Oxide-Silicon-Field-Effect-Transistor
In a MOSFET device the gate is insulated from the channel by a very thin (typically less than the wavelength of light) layer of glass (silicon dioxide) and the gate is either metal or doped silicon (polysilicon), hence the acronym metal-oxide semiconductor.
Meter
A device used to measure a specific quantity, such as current, voltage, or frequency.
Meter Movement
The part of the meter that moves to indicate some value.
Meter Shunt
A resistor placed in parallel with the meter terminals; used to provide increased range capability.
Mho
The unit of conductance, transconductance, or admittance; it is the word ohm spelled backwards.
Micro Electro Mechanical Systems
A technology dealing with building mechanical structures on silicon wafers using integrated circuit processing techniques.
Microcircuit
A small circuit having high equivalent-circuit-element density.
Microelectronics
The solid-state concept of electronics in which compact semiconductor materials are designed to function as an entire circuit or subassembly rather than as circuit components.
milliamp
One thousandth of an amp.
millivolt
A unit of electrical potential equal to one thousandth of a volt.
Miniature Electronics
Modules, packages, pcbs, and so forth, composed exclusively of discrete components.
Minimum Discernible Signal
The weakest input signal that produces a usable signal at the output of a receiver.
Minority Carriers
The conduction band holes in n-type material and valence band electrons in p-type material.
Mismatch Loss
The loss of power delivered into a load as a result of the interconnection of devices having unequal impedances.
Modem
A device whose name combines the term modulate with demodulate which refers to its ability to transmit and receive data superimposed on a carrier frequency.
Modulation
The process, or the result of the process, by which a characteristic of one wave is varied according to some characteristic of another wave.
Modulation Factor
The ratio of the peak variation of the envelope from its reference value, to the reference value.
Modulation Index
In frequency modulation with a sinusoidal modulating wave, the ratio of the frequency deviation of the modulated wave to the frequency of the modulating function.
Modulator
A device that produces modulation.
Monocrystalline Solar Cell
More expenive to make as the crystals are grown under carefully controlled conditions.
Monolithic Circuit
A circuit where all elements associated with the circuit are fabricated inseparably within a continuous piece of material.
Monostable
Circuit with two states. Only one state is stable.
Moore′s Law
This states that the number of devices on a silicon chip could double each year.
MOSFET
In a MOSFET device the gate is insulated from the channel by a very thin (typically less than the wavelength of light) layer of glass (silicon dioxide) and the gate is either metal or doped silicon (polysilicon), hence the acronym metal-oxide semiconductor.
Most Significant Bit (MSB)
The bit within a digital word that represents the biggest possible single-bit coded value.
Moving Vane Meter Movement
A meter movement that uses the magnetic repulsion of the like poles created in two iron vanes by current through a coil of wire.
MSB
Abbreviation of Most Significant Bit, the bit within a digital word that represents the biggest possible single-bit coded value.
MTBF
The average time between failures for a continuously operating system.
MTTF
The measured operating time of a system or component divided by the number of failures that occurred during that time.
MU
Symbol for Amplification Factor.
Multi Element Array
An array that consists of one or more arrays and is classified as to directivity.
Multi Element Parasitic Array
An array that contains two or more parasitic elements and a driven element.
Multi Unit Tube
An electron tube containing two or more units within the same envelope.
Multiconductor
More than one conductor, as in a cable.
Multicouplers
Couplers that patch receivers or transmitters to antennas.
Multiloop Servosystem
A servosystem that contains more than one servo loop.
Multimeter
Electronic meter that displays voltage, current and resistance.
Multiplexer
A mechanical or electrical device for time sharing or a circuit.
Multiplexing
A method for simultaneous transmission of two or more signals over a common carrier wave.
Multivibrator
A building block in which the output is either High or Low. There are three foms of multivibrator: Monostable, bi-stable and astable. The monostable has only one stable state, the bi-stable has two stable states and the astable is free-running (no stable states).
Mutual Conductance
The ratio of the current at the output port and the voltage at the input ports.
Mutual Flux
The total flux in the core of a transformer that is common to both the primary and secondary windings.
Mutual Inductance
A circuit property existing when the relative position of two inductors causes the magnetic lines of force from one to link with the turns of the other.
Mutual Interference
The condition resulting when electronic systems degrade each other on a reciprocal basis.
mV
An abbreviation of millivolt, a unit of electrical potential equal to one thousandth of a volt.
Nand Gate
Gate whose output is 0 when both input are 1 and 1 in all other cases.
National Electrical Code
The most commonly referenced general electrical standard in the United States.
NdFeB
Abbreviation of Neodymium Iron Boron.
Negative Alternation
That part of a sine wave that is below the reference level.
Negative Electrode
A terminal or electrode having more electrons than normal.
Negative Feedback
Feedback from the output of an analogue circuit that tends to oppose the input.
Negative Ground
A system where the negative terminal of the source is connected to the system′s metal chassis.
Negative Logic
The form of logic in which the more positive voltage level represents a logic 0, FALSE, or LOW and the more negative voltage represents a logic 1, TRUE, or HIGH.
Negative Resistance
A device having negative voltage-current characteristics.
Negative Temperature Coefficient
A term used to describe a component whose resistance or capacitance decreases when temperature increases.
Neon Bulb
Glass envelope filled with neon gas which when ionized by an applied voltage will glow red.
Nicad
Abbreviation of Nickel Cadmium Battery.
Nickel Cadmium Battery
The battery has a nickel-hydroxide cathode, a cadmium anode, and aqueous potassium hydroxide electrolyte.
Nickel Metal Hydride Battery
The battery has a nickel-hydroxide cathode, a metal hydride anode, and aqueous potassium hydroxide electrolyte.
NiMH
A common abbreviation for Nickel Metal Hydride Battery.
N-JFET
A three-terminal transistor device where the output current flowing between the source and drain terminals is controlled by a variable electric field applied to the gate terminal. The gate design determines the type of FET: either JFET (junction FET) or MOSFET (metal-oxide semiconductor FET).
N-MOSFET
In a MOSFET device the gate is insulated from the channel by a very thin (typically less than the wavelength of light) layer of glass (silicon dioxide) and the gate is either metal or doped silicon (polysilicon), hence the acronym metal-oxide semiconductor.
Noise
Noise is any undesired signal.
Noise Figure
The ratio of the noise power in the output of an amplifier to that part of the output noise power that is due solely to the noise in the input signal.
Noise Floor
Normally the lowest threshold of useful signal level.
Nondegenerative Parametric Amplifier
A parametric amplifier that uses a pump signal frequency that is higher than twice the frequency of the input signal.
Nonlinear Device
A device in which the output does not rise and fall in direct proportion to the input.
Nonlinear Impedance
An impedance in which the resulting current through the device is not proportional to the applied voltage.
Nor Gate
Gate whose output is 0 if any of its inputs is a 1.
Not Gate
Logic element that acts as an inverter.
Notch Filter
An electronic network which passes signals having frequencies above and below the band-elimination frequency span.
NPN Transistor
Type of bipolar transistor using n-type p-type n-type material in its manufacture.
N-Type Thermocouple
Nicrosil-Nisil thermocouple with a temperature range of -200 to 1200°C.
Nutating
Moving an antenna feed point in a conical pattern so that the polarization of the beam does not change.
Nyquist Frequency
Half the sampling frequency. Any analog frequency component above the Nyquist frequency will, after sampling, be converted (aliased) to a frequency below the Nyquist frequency.
OCV
Abbreviation of Open Circuit Voltage.
Off Frequency Rejection
The amount of attenuation to a signal at a frequency other than the tuned frequency as a result of the selectivity characteristic of the receiver and the power-versus-frequency characteristic of the signal.
Off Line Test Equipment
Equipment that tests and isolates faults in modules or assemblies removed from systems.
Offset Error
If you get a reading other than zero for a zero condition then you have an offset error.
Ohm Metre
A unit of resistivity, measuring the extent to which a substance offers resistance to passage of an electric current.
Ohmmeter
Device used to measure electrical resistance.
Ohms per Square
The resistance of any square area of thin film resistive material as measured between two parallel sides.
OLED
Abbreviation of Organic Light Emitting Diode.
Omnidirectional Antenna
An antenna that radiates and receives equally in all directions.
On Line Test Equipment
Continuously monitors the performance of electronic systems.
Op Amp
Abbreviation of Operational Amplifier.
Open Circuit
A circuit that does not provide a complete path for the flow of current.
Open Circuit Voltage
The voltage between the terminals of a battery or power source when no current is flowing.
Open Loop
A system operating without feedback.
Open Loop Gain
Gain of an amplifier when no feedback is present.
Operating Point
That point in the characteristics of a tube or transistor around which the signal voltages vary.
Operational Amplifier
One of the basic building blocks of analogue circuits.
Optical Coupler
A coupler composed of an LED and a photodiode and contained in a lightconducting medium.
Optical Encoder
A linear or angular position feedback device using light fringes to develop position information.
Optimum Working Frequency
The most practical operating frequency that can be used with the least amount of problems.
Opto-Coupler
Any device that functions as an electrical-to-optical or optical-to-electrical transducer.
Opto-Isolated
System or circuit that transmits signal with no direct electrical connections, using photoelectric coupling between elements.
Or Gate
Logic gate whose output will be a 1 if any of it imputs is at 1.
Organic Light Emitting Diode
A type of LED display made from organic polymers that provides a wide viewing angle, low power and does not require a backlight as do LCD screens.
Oscillator
A regenerative circuit which has signal-generating characteristics.
Oscilloscope
An instrument using a cathode-ray tube for visual display of electric signals.
Out of Phase
The offset in time of two related signals.
Output Impedance
The impedance that is presented to the load by the transmission line and its source.
Overcharge
Discharge past the point where the full capacity of the cell has been obtained.
Overcoupling
The degree of coupling beyond the critical point in resonant circuits which produces a dip at the resonant-frequency point on the response curve.
Overdriven
When the input signal amplitude is increased to the point that the transistor goes into saturation and cutoff.
Overload Rating
The load in excess of the nominal rating the device can carry for a specified length of time without being damaged.
Overmodulation
A condition that exists when the peaks of the modulating signal are limited.
PAM
Abbreviation of Pulse Amplitude Modulation
Parabolic Reflector
An antenna reflector in the shape of a parabola.
Parallel Circuit
Two or more electrical devices connected to the same pair of terminals so separate currents flow through each.
Parallel Limiter
A resistor and diode, connected in series with the input signal, in which the output is taken across the diode.
Parallel Negative Limiter
A resistor and diode, connected in series with the input signal, in which the output is taken across the diode and the negative alternation is eliminated.
Parallel Positive Limiter
A resistor and diode connected in series with the input signal, in which the output is taken across the diode and the positive alternation is eliminated.
Parallel Resonant Circuit
A resonant circuit in which the source voltage is connected across a parallel circuit to furnish a high impedance to the frequency at which the circuit is resonant.
Parametric Amplifier
A low-noise amplifier that uses a nonlinear variable reactance as the active element instead of a variable resistance.
Parametric Device
A device whose operation depends essentially upon the time variation of a characteristic parameter, usually reactance.
Parasitic Array
An antenna array containing one or more elements not connected to the transmission line.
Parasitic Element
The passive element of an antenna array that is connected to neither the transmission line nor the driven element.
Paschen Law
Theoretical relationship for the direct-current breakdown voltage of parallel-plane electrodes immersed in a gas as a function of the gas pressure and electrode separation.
Patch Panel
A panel used to tie electronics components together.
PCB
Abbreviation of Printed Circuit Board.
PCM
Coding where the input signal is represented by a given number of fixed-width samples per second.
PDM
Abbreviation of Pulse Duration Modulation.
Peak Current
The maximum current that flows during a complete cycle.
Peak to Peak Value
The over-all amplitude of a signal measured from its lowest peak to its most highest peak.
Peak Value
The instantaneous maximum value of a waveform.
Peak Voltage
The maximum value present in a varying or alternating voltage.
Peaking Coil
An inductor used in an amplifier to provide high-frequency compensation, which extends the high-frequency response of the amplifier.
Pentagrid Converter
A five-element tube employed as a mixer-oscillator in superheterodyne receivers.
Pentode Tube
A five-electrode electron tube containing a plate, a cathode, a control grid, and two grids.
Permanent Magnet Speaker
A speaker with a permanent magnet mounted on soft iron pole pieces.
pF
Abbreviation of picofarad, the farad is the SI unit of capacitance.
PFM
Abbreviation of Pulse Frequency Modulation.
Phantastron
A monostable pentode circuit used to generate sharp pulses at an adjustable and accurately timed interval after receipt of a triggering signal.
Phantom Power
The standardized scheme of providing power supply voltage to certain microphones using the same two lines as the balanced audio path.
Phase
Phase identifies the position at any instant which a periodic wave occupies in its cycle. A portion of a material system whose properties and composition are homogeneous and which is physically distinct from other parts of the system.
Phase Angle
The number of electrical degrees of lead or lag between the voltage and current waveforms in an ac circuit.
Phase Locked Loop
An electronic circuit with a voltage- or current-driven oscillator that is constantly adjusted to match in phase the frequency of an input signal.
Phase Shifter
A device used to change the phase relationship between two ac signals.
Photo Etching
Chemical process of removing unwanted material in producing printed circuit boards.
Photocell
A light-controlled variable resistor which has a light-to-dark resistance ratio of 1:1000.
Photodiode
A light-controlled PN junction. Current flow increases when the PN junction is exposed to an external light source.
Photoelectric Effect
The ejection of electrons from metallic surfaces by illuminating light.
Photoelectric Sensor
An electrical device that responds to a change in the intensity of the light falling upon it.
Photoelectric Voltage
A voltage produced by light.
Photoelectrochemical Cell
A type of photovoltaic device in which the electricity induced in the cell is used immediately within the cell to produce a chemical, such as hydrogen, which can then be withdrawn for use.
Phototransistor
A transistor with a window on the top face to allow light to fall on the active surface.
Photovoltaic Cell
A unit which generates a voltage related to the light intensity impinging on it.
Photovoltaic Cell Efficiency
Alternative name for Solar Cell Efficiency.
Picaxe
The name of a UK-sourced microcontroller system based on a range of Microchip PICs.
Piezo Sounder
Small crystal element that can emit very high sound levels while requiring low current.
Piezoelectric
Any material which provides a conversion between mechanical and electrical energy.
PIN Diode
A diode with a wide, lightly doped near intrinsic semiconductor region between a p-type semiconductor and an n-type semiconductor region.
Pixel
Single picture element of a detection device.
P-JFET
A three-terminal transistor device where the output current flowing between the source and drain terminals is controlled by a variable electric field applied to the gate terminal. The gate design determines the type of FET: either JFET (junction FET) or MOSFET (metal-oxide semiconductor FET).
PLA
Abbreviation of Programmable Logic Array.
Planar Tube
An electron tube, constructed with parallel electrodes and a ceramic envelope, that is used at uhf frequencies.
Plate
One of the electrodes in a storage battery or A planar body whose thickness is small compared with its other dimensions.
Plate Modulator
An electron-tube modulator in which the modulating voltage is applied to the plate circuit of the tube.
Plate Resistance
The plate voltage change divided by the resultant plate current change in a vacuum tube, all other conditions being fixed.
PLD
Abbreviation for Programmable Logic Device.
P-MOSFET
In a MOSFET device the gate is insulated from the channel by a very thin (typically less than the wavelength of light) layer of glass (silicon dioxide) and the gate is either metal or doped silicon (polysilicon), hence the acronym metal-oxide semiconductor.
PNP Transistor
Type of bipolar transistor using p-type, n-type, n-type semiconductor material.
Point Contact Diode
A diode in which the end of a fine wire is pressed against a semiconductor.
Point to Point Wiring
Individual wires run from terminal to terminal to complete a circuit.
Pole Piece
The shaped magnetic material upon which the stator windings of motors and generators are mounted or wound.
Polycrystalline Solar Cell
Cheap to make as the conditions required to produce the silicon wafers do not need to be so tightly controlled.
Polyphase AC
An electrical current which is generated in two or more phases each having exactly the same the same frequency.
Position Sensor
A component in a servosystem that measures position and converts the measurement into a form convenient for transmission as a feedback signal.
Position Servosystem
A servosystem whose end function is to control the position of the load it is driving.
Positive Clamper
A circuit that clamps the lower extremity of the output waveshape to a dc potential of 0 volts.
Positive Feedback
Feedback in which the feedback signal is in phase with the input signal.
Positive Logic
The form of logic in which the more positive logic level represents 1 and the more negative level represents 0.
Positive Temperature Coefficient
The characteristic of a conductor in which the resistance increases as temperature increases.
Potential Transformer
The voltage supplied to a primary coil induces a voltage in a secondary coil according, to the ratio of the wire windings in each of the coils.
Potentiometer
A variable resistor with three terminals-one on each end of the resistor and one "wiper" which contacts the resistor midpoint to indicate a variable position.
Potting Compound
An insulating material for encapsulating one or more circuit elements.
Power Amplifier
An amplifier in which the output-signal power is greater than the input-signal power.
Power Factor
The cosine of the phase angle between voltage and current.
Power Gain
In an antenna, the ratio of its radiated power to that of a reference.
Power Loss
The electrical power, supplied to a circuit, that does no work and is usually dissipated as heat.
Power Pentode
A special purpose tube used to provide high-current gain or power amplification.
Power Standing Wave Ratio
The ratio of the square of the maximum and minimum values of a wave.
Power Supply
A unit that supplies electrical power to another unit.
Powerline Carrier System
A method of sending information over an electrical power distribution system.
PPM
Abbreviation of Pulse Position Modulation.
Preamplifier
An amplifier that raises the output of a low-level source for further processing without appreciable degradation of the signal-to-noise ratio.
Pressure Switch
An electric switch operated by fluid pressure.
Primary Cell
A cell or battery which is not intended to be recharged and is discarded when the cell or battery has delivered all its electrical energy.
Primary Winding
The winding of a transformer connected to the electrical source.
Printed Circuit Board
A flat, insulating surface upon which printed wiring and miniaturized components are connected in a predetermined design and attached to a common base.
Programmable Logic Array
A programmable logic device in which both the AND & OR arrays are programmable.
Programmable Logic Device
Generic name for an integrated circuit offering a vast array of logic function building blocks that the circuit designer programs to interconnect for specific applications.
Protective Devices
Devices, such as fuses, diodes and current limiters which interrupt the current flow, block the current flow in one direction or limit the current flow in an electrical circuit.
Protective Relay
A relay, the principal function of which is to protect service from interruption, or to prevent or limit damage to apparatus.
Protocol
The set of conventions that govern the treatment and formatting of data in an electronic communications system.
PSWR
Abbreviation of Power Standing Wave Ratio.
PTM
Abbreviation of Pulse Time Modulation.
Pulse Amplitude Modulation
Pulse modulation in which the amplitude of the pulses is varied by the modulating signal.
Pulse Code Modulation
Coding where the input signal is represented by a given number of fixed-width samples per second.
Pulse Duration
The period of time during which a pulse is present.
Pulse Duration Modulation
Pulse modulation in which the time duration of the pulses is changed by the modulating signal.
Pulse Forming Network
An LC network that alternately stores and releases energy in an approximately rectangular wave.
Pulse Frequency Modulation
Pulse modulation in which the modulating voltage varies the repetition rate of a pulse train.
Pulse Modulation
A form of modulation in which one of the characteristics of a pulse train is varied.
Pulse Oscillator
A sine-wave oscillator that is turned on and off at specific times.
Pulse Position Modulation
Pulse modulation in which the position of the pulses is varied by the modulating voltage.
Pulse Time Modulation
Pulse modulation that varies one of the time characteristics of a pulse train.
Pulse Width
Duration of time between the leading and trailing edges of a pulse.
Pulse Width Modulation
Pulse modulation in which the duration of the pulses is varied by the modulating voltage.
Pump
Electrical source of the energy required to vary the capacitance of a parametric amplifier.
Push Pull Amplifier
An amplifier that uses two transistors whose output signals are in phase opposition.
PV Cell
Abbreviation of Photovoltaic Cell.
PWM
Abbreviation of Pulse Width Modulation.
Q
The quality factor defines the sharpness of resonance.
Q-Factor
Abbreviation of Quality Factor. The quality factor defines the sharpness of resonance.
Quadrature Circuit
A circuit designed to provide a 90° signal phase displacement.
Quality Factor
The quality factor defines the sharpness of resonance.
Quantization Error
When a continuous time signal is digitized, because there isn′t an infinite number of discrete digital levels, the difference between the actual analog value and the digital representation of that value is defined as the quantization error.
Quarter Wave Antenna
A quarter-wave antenna that is operated with one end grounded and is positioned perpendicular to the earth.
Quiescence
The operating conditions that exist in a circuit when no input signal is applied to the circuit.
Quiescent Current
The standing current that flows in a circuit when the signal is not applied. The quiescent current is usually very low or lower than when processing a signal.
Quiescent Operating Point
The zero-signal voltage and current values in a circuit or amplifier.
Quiescent State
The period during which a transistor, tube, or other circuit element is not performing an active function in the circuit.
Radar Altimeter
Airborne radar that measures the distance of the aircraft above the ground.
Radar Beam
The space in front of a radar antenna where a target can be effectively detected or tracked.
Radar Detector
A detector that, in its simplest form, only needs to be capable of producing an output when RF energy is present at its input.
Radar Mile
Time interval, 12.36 microseconds, for RF energy to travel out from a radar to a target and back to the radar.
Radiation Field
The electromagnetic field that radiates from an antenna and travels through space.
Radiation Losses
The losses that occur when magnetic lines of force about a conductor are projected into space as radiation and are not returned to the conductor as the cycle alternates.
Radiation Pattern
A plot of the radiated energy from an antenna.
Radiation Resistance
The resistance that if inserted in place of the antenna would consume the same amount of power as that radiated by the antenna.
Radio
Communication by electromagnetic waves, without a connecting wire.
Radio Frequency
Any frequency of electromagnetic energy capable of propagation into space.
Radio Frequency Amplifier
An amplifier designed to increase RF signal amplitudes.
Radio Frequency Choke
A choke coil with a high impedance at radio frequencies.
Radio Frequency Interference
This is unwanted Electromagnetic Emissions in the radio reception bands.
Radio Horizon
The boundary beyond the natural horizon in which radio waves cannot be propagated over the earth′s surface.
Radio Interference
The interference with radio reception caused by a system.
Radio Interference Suppression
The methods employed to minimize radio interference.
Radio Waves
Electromagnetic radiation in the region of the spectrum smaller than about 3 x 108Hz and wavelengths greater than about 1 m.
RAM
Abbreviation of Random Access Memory, a data storage device for which the order of access to different locations does not affect the speed of access, except for bursts.
Ramp Voltage
A steadily rising voltage.
Random Access Memory
A data storage device for which the order of access to different locations does not affect the speed of access, except for bursts.
Random Wound Stator
The stator windings are wound onto a bobbin without a defined structure to the windings.
Range
The maximum and minimum allowable full-scale signal.
Rate Gyroscope
A gyroscope used to detect and measure angular rates of change.
Ratio Detector
A detector that uses a double-tuned transformer to convert the instantaneous frequency variations of the FM input signal to instantaneous amplitude variations.
RC Constant
Time constant of a resistor-capacitor circuit.
RC Differentiator
An RC circuit in which the output is taken from the resistor.
RC Filter
A filter used in applications where load current is low and constant, and voltage regulation is not necessary.
RC Integrator
An RC circuit in which the output is taken from the capacitor.
RC Network
A circuit containing resistance and capacitance arranged in a particular manner to perform a specific function.
RC Oscillator
An oscillator in which the frequency is determined by resistive and capacitive elements.
Reactance
The opposition to the flow of electricity posed by capacitors and inductors.
Reactance Amplifier
A low-noise amplifier that uses a nonlinear variable reactance as the active element instead of a variable resistance.
Reactance Tube
A tube connected in parallel with the tank circuit of an oscillator.
Reactance Tube Modulator
An FM modulator that uses a reactance tube in parallel with the oscillator tank circuit.
Reactive Power
Power that flows back and forth between the inductive windings of the generator and the inductive windings of motors, transformers, which are part of the electrical load.
Receiver
Equipment that converts electromagnetic energy into an electrical signal that can be further processed.
Receiver Antenna
The device used to pick up the RF signal from space.
Receiver Noise Figure
A measure of signal-to-noise ratio degradation as the signal passes through the receiver.
Receiver Sensitivity
The degree to which a receiver can usefully detect a weak signal.
Reciprocity
If in a space filled with air which is partly bounded by finitely extended fixed bodies and is partly unbounded, sound waves being excited at any point A, the resulting velocity-potential at a second point B is the same both in magnitude and phase, as it would have been at A, had B been the source of the sound.
Recursive Filter
A filter in which there is no need to store past measurements for the purpose of calculating current estimates.
Reflex Klystron
A klystron with a reflector electrode in the place of a second resonant cavity used to redirect the velocity-modulated electrons back through the cavity that produced the modulation.
Reflow Soldering
Process of joining metallic surfaces through the mass heating of solder or solder paste to form solder fillets at metallized areas.
Regenerative Detector
A detector circuit that produces its own oscillations, heterodynes them with an incoming signal, and deflects them.
Regenerative Feedback
Feedback in which the feedback signal is in phase with the input signal.
Regulator
The section in a basic power supply that maintains the output of the power supply at a constant level in spite of large changes in load current or input line voltage.
Relaxation Oscillator
An oscillator circuit which generates a signal by periodic conduction-nonconduction periods. A nonsinusoidal waveform is produced and, generally, no resonant circuits are employed.
Relay
Electromechanical device containing a coil and set of contacts. The contacts close when the coil is activated.
Remote Cutoff Tube
An electron tube in which the control grid wires are farther apart at the centres than at the ends.
REN
Abbreviation of Ringer Equivalence Number.
Repeller
An electrode in a reflex klystron with the primary purpose of reversing the direction of the electron beam.
Resistance
The electrical resistance of a conductor.
Resistive Load
An electrical load where the time phase sequence of the current and the voltage is such that the current and the voltage are in phase with each other.
Resistivity
The resistance measured in ohms of a unit volume of a substance to the flow of electric current.
Resistor
Passive component with a known resistance. The value of resistance is usually shown by a set of coloured bands on the body of the component.
Resolver
A rotary, electromechanical device used to perform trigonometric computations by varying the magnetic couplings between its primary and secondary windings.
Resonant Circuit
A circuit that contains both inductance and capacitance and is resonant at one frequency.
Resonant Line
A transmission line that has standing waves of current and voltage.
Rest Frequency
The carrier frequency during the constant-amplitude portions of a phase modulation signal.
Reverse Bias
An external voltage applied to a diode or semiconductor junction to reduce the flow of electrons across the junction.
RF
Abbreviation of Radio Frequency.
RF Amplifier
An amplifier designed to amplify signals with frequencies between 10 kilohertz and 100000 megahertz.
RF Choke
A choke coil with a high impedance at radio frequencies.
Rf Transformer
A transformer specially designed for use with radio frequencies.
RFI
Abbreviation of Radio Frequency Interference.
Rheostat
A device to regulate the flow of electric current by transforming part or all of it into heat.
Rhombic Antenna
A diamond-shaped antenna used widely for long-distance, high-frequency transmission and reception.
Ribbon Cable
Any cable constructed as a ribbon with parallel elements.
Rigid Coaxial Line
A coaxial line consisting of a central insulated wire mounted inside of a tubular outer conductor.
Ringer Equivalence Number
Denotes the electrical load that a telephone has on the line, the maximum REN for the UK is 4.
Ringing Oscillator
A sine-wave oscillator that is turned on and off at specific times.
Ripple Frequency
The frequency of the ripple current.
Ripple Voltage
The alternating component of unidirectional voltage.
Rise Time
The time required for the output of a transducer to rise from 10% to 90% of its final value, as it responds to a step change in the measurand.
Risers
Rectangular copper or aluminum bars that connect circuit breakers, fusible switches, and transfer switches with the main system bus.
RL Differentiator
An RL circuit in which the output is taken from the inductor.
RL Integrator
An RL circuit in which the output is taken from the resistor.
RLC Circuit
An electrical circuit that has the properties of resistance, inductance, and capacitance.
Rotary Switch
A multicontact switch with contacts arranged in a circular or semicircular manner.
Rotating Field
The magnetic field in a multiphase ac motor that is the result of field windings being energized by out-of-phase currents.
Rotor
A rotating part.
RS232
Serial communications system.
Saturable Core Reactor
A coil in which the reactance is controlled by changing the permeability of the core.
Saturation
An overwhelming concentration.
Saturation Velocity
Maximum velocity which can be obtained in a specific semiconductor.
SCART Connector
French-originated standard and associated 21-pin connector for connecting audio-visual equipment together.
Schottky Diode
A diode using an aluminium-silicon junction in which carrier storage is negligible, leading to very fast on and off states and thus very fast switching speeds. The foward voltages is 0.3v.
SCR
Abbreviation of Silicon Controlled Rectifier.
SDRAM
Abbreviation for Synchronous Dynamic Random Access Memory, SDRAM delivers bursts of data at high speeds using a synchronous interface.
Sea Clutter
Unwanted echoes, from surrounding sea, that appear on a radar indicator.
Secondary Cell
A galvanic battery which, after discharge, may be restored to the fully charged state by the passage of an electric current though the cell in the opposite direction to that of discharge.
Secondary Coil
The output coil of a transformer
Secondary Emission
Electron emission from a non-heated electrode when struck by a high-velocity electron beam.
Selectivity
The ability of a receiver to select the desired signal and reject unwanted signals.
Self Bias
In a vacuum tube circuit, the voltage developed by the flow of current through a resistor in the grid or cathode leads.
Self Discharge
The loss of useful capacity of a cell or battery due to internal chemical action.
Self Excited Meter
A term used to describe meters that operate from their own power sources.
Self Induction
The production of a counter electromotive force in a conductor when its own magnetic field collapses or expands with a change in current in the conductor.
Semiconductor
An element, such as silicon, that is intermediate in electrical conductivity between conductors and insulators, through which conduction takes place by means of holes and electrons.
Sensitivity Time Control
A circuit that varies the gain of a receiver as a function of time.
Series Circuit
An arrangement where electrical devices are connected so that the total current must flow through all the devices; electrons have one path to travel from the negative terminal to the positive terminal.
Series Diode Detector
The semiconductor diode in series with the input voltage and the load impedance.
Series Fed Oscillator
An oscillator in which dc power is supplied to the amplifier through the tank circuit or a portion of the tank circuit.
Series Limiter
A diode connected in series with the output, in which the output is taken across the resistor.
Series Parallel Circuit
A circuit that consists of both series and parallel networks.
Series Peaking
A technique used to improve high-frequency response in which a peaking coil is placed in series with the output signal path.
Series Resonant Circuit
A resonant circuit in which the source voltage is connected in series with a capacitor and an inductor to furnish a low impedance at the frequency at which the circuit is resonant.
Series Voltage Regulator
A regulator with a regulating device that is in series with the load resistance.
Servo Amplifier
Either ac or dc amplifiers used in servosystems to build up signal strength.
Servo Motor
An ac or dc motor used in servo systems to move a load to a desired position or at a desired speed.
Servo System
An automatic feedback control system that compares a required condition with an actual condition and uses the difference to drive a control device to achieve the required condition.
Set Point
Value of a controlled variable, departure from which causes a controller to operate to reduce the error and restore the intended steady state.
Settling Time
When a change in a signal occurs, this is the time taken for it to settle to its new value.
Shake Table Test
A laboratory test for vibration tolerance, in which the device to be tested is placed on a vibrator.
Shaping Circuit
A circuit that alters the shapes of input waveforms.
Sharp Cutoff Tube
An electron tube that has evenly spaced grid wires.
Shielded Pair
A line consisting of parallel conductors separated from each other and surrounded by a solid dielectric.
Shielding
Technique designed to minimize internal and external interference.
Short Circuited Line
A transmission line that has a terminating impedance equal to 0.
Short-Circuit
An un-intended path that conducts electricity.
Shunt Diode Detector
A diode detector in which the diode is in parallel with the input voltage and the load impedance.
Shunt Fed Oscillator
An oscillator that receives its dc power for the transistor or tube through a path both separate from and parallel to the tank circuit.
Shunt Peaking
A technique used to improve high frequency response in which a peaking coil is placed in parallel with the output signal path.
Shunt Resistor
A resistor in parallel. In an ammeter, shunt resistors are used to provide multiple ranges.
Shunt Voltage Regulator
A regulator whose regulating device is in parallel with the load resistance.
Signal Generator
A circuit that produces a variable and controllable signal.
Signal Ground
The common return or reference point for analog signals.
Signed Binary Coding
A coding scheme in which the Most Significant Bit represents the sign of a binary number.
Silicon Controlled Rectifier
A semiconductor device that functions as an electrically controlled switch.
Single Line Diagram
A diagram which shows, by means of single lines and graphic symbols, the course of an electric circuit or system of circuits and the component devices or parts used therein.
Single Pole Switch
A switch in which only one circuit is controlled.
Single-Ended Input
An analogue input measured with respect to a common ground.
Skin Effect
In the case of high frequency signals, electrons are only conducted on the outer surface, or skin, of a conductor.
Skip Distance
The distance from a transmitter to the point where the sky wave is first returned to earth.
Skip Zone
A zone of silence between the point where the ground wave becomes too weak for reception and the sky wave is first returned to earth.
Sky Waves
Radio waves reflected back to earth from the ionosphere.
Slip
The difference between rotor speed and synchronous speed in an ac induction motor.
Slip Rings
Devices for making electric connections between stationary and rotating contacts.
SNR
Abbreviation of Signal to Noise Ratio. The ratio between a recorded signal and spurious background noise.
SoC
Abbreviation of State of Charge.
Sodium Nickel Chloride Battery
This consists of a negative liquid sodium electrode and a solid positive electrode containing nickel chloride and nickel.
Solar Cell
A cell that produces current under sunlight.
Solar Cell Efficiency
The ratio of the electric power produced by a photovoltaic device to the power of the sunlight incident on the device.
Solder
A low melting point alloy that can wet copper, conduct current, and mechanically join conductors.
Solder Balls
Small spheres of solder adhering to the laminate, mask, or conductor surfaces usually after wave or reflow soldering.
Solder Bridging
When solder paste or solder on two or more adjacent pads come into contact to form a conductive path or bridge.
Solder Mask
A dielectric material used to cover the entire surface, except where the joints are to be formed, of a PCB primarily to protect the circuitry from environmental damage.
Soldering
Process of joining metallic surfaces with solder without melting the base material.
Solenoid
An electromagnetic device that changes electrical energy into mechanical motion.
Solid State Device
An electronic device that operates by the movement of electrons within a solid piece of semiconductor material.
Sonic Delay Line
A device used in a communications link or a computer memory in which the signal is delayed by the propagation of a sound wave. Also known as an Acoustic Delay Line.
Source
The object that produces the wave or disturbance.
Space Diversity
Reception of radio waves by two or more antennas spaced some distance apart.
Spark Gap Modulator
A modulator that consists of a circuit for storing energy, a circuit for rapidly discharging the storage circuit, a pulse transformer, and a power source.
SPDT Switch
Abbreviation of Single-Pole, Double-Throw switch.
Specific Resistance
The resistance measured in ohms of a unit volume of a substance to the flow of electric current.
Spectrum Signature
The power versus frequency distribution of the energy in a transmitted signal, or the response characteristic of a receiver.
Spiral Wound Lead Acid Battery
Instead of having the electrodes as flat plates, the electrodes are rolled up in a spiral.
Split Spectrum Solar Cell
A compound photovoltaic device in which sunlight is first divided into spectral regions by optical means.
Spread Spectrum Modulation
Digital modulation scheme that spreads the system bandwidth far greater than the minimum required bandwidth.
Sprocket Tuner
A mechanical tuning device for magnetron tubes that changes the frequency of the cavities by changing the inductance.
SPST Switch
Abbreviation of Single-Pole, Single-Throw switch.
Spurious Response
Any response of an electronic receiver or device to signals at frequencies other than the frequency to which it is tuned.
Sputtering
A process used to apply semiconductor material to a substrate by a physical vapour deposition process where high-energy ions are used to bombard elemental sources of semiconductor material, which eject vapours of atoms that are then deposited in thin layers on a substrate.
Squelch
A circuit that cuts off the output of a receiver when there is no input.
Squirrel Cage Windings
A type of rotor winding in which heavy conductors are embedded in the rotor body.
SRAM
An integrated circuit similar to a DRAM with the exception that the memory does not need to be refreshed.
Stable
In nuclear physics if something is stable it means it does not decay.
Stagger Tuning
A method of klystron tuning in which the resonant cavities are tuned to slightly different frequencies to increase the bandwidth of the amplifier.
Standing Wave Ratio
The ratio of the maximum to the minimum points of a wave.
State of Charge
The amount of electrical charge in the battery, expressed as a percentage of the difference between the fully-charged and fully-discharged states.
Statfarad
The unit of capacitance in the obsolete electrostatic system of units.
Stathenry
The unit of inductance in the obsolete electrostatic system of units.
Static Interference
Any radio interference detectable as noise in the audio stage of a receiver.
Static Random Access Memory
An integrated circuit similar to a DRAM (dynamic random access memory) with the exception that the memory does not need to be refreshed.
Stator
The stationary part of a rotating electrical machine.
Statvolt
The unit of electromotive force in the obsolete electrostatic system of units.
Step by Step Counter
A counter that provides an output for each cycle of the input in one-step increments.
Step Down Transformer
A transformer so constructed that the number of turns in the secondary winding is less than the number of turns in the primary winding.
Step Response
The response of a system to an instantaneous jump in the input signal.
Step Up Transformer
A transformer so constructed that the number of turns in the secondary winding is more than the number of turns in the primary winding.
Stepper Motors
Stepper motors are a special case of Brushless DC Motors.
Stickoff Voltage
A low voltage used in multispeed synchrosystems to prevent false synchronizations.
Stranded Conductor
A conductor composed of a group of wires.
Subatomic Erosion
A process in which structures on an integrated circuit′s substrate are eroded by the flow of electrons in much the same way as land is eroded by a river.
Subcarrier
A separate analog or digital signal carried on a main radio transmission, which may carry extra information such as voice or data.
Subharmonic
Sinusoidal quantity of a frequency that is an integral submultiple of a fundamental frequency.
Successive Approximation Register
Uses a digital-to-analog converter to determine the output word successively, bit by bit.
Summing Network
A combination of two or more parallel resistors used in servosystems as an error detector.
Super High Frequency
Radio Frequencies between 3 GHz and 30 GHz.
Superconductivity
The phenomena by which, at sufficiently low temperatures, a conductor can conduct charge with zero resistance.
Superheterodyne Receiver
A type of receiver that uses a mixer to convert the RF echo to an IF signal for amplification.
Supply Voltage
The voltage obtained from the power supply to operate a circuit.
Suppression
Elimination or reduction of any component of an emission, as a particular frequency or group of frequencies, in an audio or radio-frequency signal.
Surface Insulation Resistance
The electrical resistance of an insulating material between a pair of contacts or conductors.
Surface Mount Technology
The technology used when components are mounted to the surface of circuit boards.
Surface Plasmon
A collective motion of electrons in the surface of a metal conductor, excited by the impact of light of appropriate wavelength at a particular angle.
Surge Protector
A device for protecting electronic equipment from damaging voltage levels sometimes occurring in electrical transients.
Swamping Resistor
A resistor used to increase or broaden the bandwidth of a circuit.
Swinging Choke
A filter inductor employed for voltage-regulation purposes in power supplies.
Switch
Mechanical switches are used to permit or interrupt the flow of current in a circuit.
Switching Time
The time required for the output of a switch to attain 90 percent of its steady-state level referenced to the 50 percent level of the command signal.
SWR
Abbreviation of Standing Wave Ratio.
Symmetrical Multivibrator
A circuit that generates square waves.
Symptom Elaboration
Using built-in indicating instruments or other aids to define equipment malfunction.
Symptom Recognition
Recognition of a situation in equipment operation that is not normal.
Synchro
A small motorlike analog device that operates like a variable transformer and is used primarily for the rapid and accurate transmission of data among equipments and stations.
Synchro Capacitor
A unit containing three delta-connected capacitors.
Synchronous Dynamic Random Access Memory
SDRAM delivers bursts of data at high speeds using a synchronous interface.
Synchronous Speed
The speed at which the rotating field in an ac motor revolves.
Synchronous Tuning
In a klystron amplifier, a method of tuning that tunes all the resonant cavities to the same frequency.
Tank Circuit
A tuned circuit used to temporarily store energy.
Taper Charge
A charge regime delivering moderately high rate charging current when the battery is at a low state of charge and tapering the charging current to lower rates as the battery is charged.
Taper Charging
A charging regime delivering moderately high rate of current when the battery is at a low state of charge and tapering the charging current to lower rates as the battery is charged.
Tapped Resistor
A wire-wound, fixed resistor having one or more additional terminals along its length, generally for voltage-divider applications.
Target Resolution
The ability of a radar to distinguish between two or more targets that are close to each other
Telecommunications
The transmission, emission, or reception of signs, signals, writings, images, or sounds.
Television
Telecommunication medium for transmitting and receiving moving images and sound.
Temperature Range
The minimum to maximum temperature over which a piece of equipment will operate.
Terminal
A point at which electrical connections can easily be made or broken.
Terminal Board
An insulating base or slab equipped with terminals for connecting wiring.
Terminal Diagram
A diagram of a switch, relay, terminal board, or other component showing the connections to the equipment.
Terminal Lug
A device attached to a conductor to permit connection to a terminal.
Terminal Voltage
The voltage at the battery or electrical power source terminals.
Tertiary Logic
An experimental technology in which logic gates are based on three distinct voltage levels.
Tetrode Tube
A four-electrode electron tube containing a plate, a cathode, a control grid, and a screen grid.
Thermal Magnetic Trip Element
A single circuit breaker trip element that combines the action of a thermal and a magnetic trip element.
Thermal Noise
Random noise associated with the thermodynamic interchange of energy necessary to maintain thermal equilibruim between the circuit and its surroundings.
Thermal Relay
A switching relay in which a small heater warms a bimetal element which bends to provide the switching force.
Thermal Resistance
The property of a material, device or system that impedes the flow of heat.
Thermal Runaway
A conduction that exists when heat causes more electron-hole pairs to be generated, which, in turn, causes more heat and which may eventually cause diode destruction.
Thermal Trip Element
A circuit breaker trip element that uses the increased bending of a bimetallic strip caused by increased current to open a circuit.
Thermion
A thermion is an electrically charged particle emitted from a heated body.
Thermocouple Meter Movement
A meter movement that uses the current induced in a thermocouple by the heating of a resistive element to measure the current in a circuit; used to measure ac or dc.
Thermoelectric Device
Most use the Seebeck effect devices similar to Peltier devices, but applying hot and cold sources to the surfaces.
Thevenin′s Theorem
Theorem that replaces any complex network with a single voltage source in series with a single resistance.
Thick Film Components
Passive circuit components having a thickness of 0.00001m
Thin Film Components
Passive circuit elements deposited on a substrate to a thickness of 0.000001m
Three Dimensional Radar
A radar set that measures the range, bearing and altitudes of a target.
Three Element Array
An array with two parasitic elements and a driven element.
Three Phase Electricity
Multiple phase power supply or load that uses at least three wires where a different voltage phase from a common generator is carried between each pair of wires.
Thyratron
A gas-tube rectifier with a grid electrode that has the ability to initiate current flow when the anode is positive.
Tickler Coil
A small coil connected in series with the collector or plate circuit of a transistor or tube and inductively coupled to the base or grid-circuit coil to establish feedback.
Time Constant
Time required for an exponential quantity to change by an amount equal to 63.2 percent of the total change that can occur.
Time Lag
The delay between the application of the input signal and the response.
Tin Whiskers
Electrically conductive, crystalline structures of tin that sometimes grow from surfaces where tin is used as a final finish.
Tinning
The process of applying a thin coat of solder to materials prior to their being soldered.
Toggle
A word meaning to reverse or complement the state of something.
Tone Terminal Set
Equipment that converts TTY dc pulses into audio tones for modulation of a transmitter in audio-frequency-tone shift transmissions.
Top Hat Antenna
An antenna that is centre-fed and capacitively loaded.
Torque Differential Receiver
A type of differential synchro that takes two electrical inputs, one to the rotor and one to the stator, and produces a mechanical output.
Total Harmonic Distortion
The RMS value of the distortion appearing at multiples of the input frequency to the RMS value of the input sine wave.
Track Radar
Radar that provides continuous range, bearing, and elevation data by keeping the RF beam on the target.
Tracking Filter
A low-pass or band-pass filter which automatically tracks the input signal.
Traction Battery
A battery designed to be used to provide the power to move a vehicle.
Transceiver
A device that both transmits and receives data.
Transconductance
The ratio of the current at the output port and the voltage at the input ports.
Transformer
A transformer is a device used for converting an alternating electric current from one voltage to another.
Transformer Core
The centre part of a transformer around which wire is wound.
Transformer Efficiency
The ratio of output power to input power, generally expressed as a percentage.
Transistor
A three leaded device (Collector, Base, Emitter) used for amplifying or switching.
Transistor-Transistor Logic (TTL)
Referring to logic circuits consisting of two or more directly interconnected transistors, to provide conditional switching capability.
Transmission Line
A structure that guides electromagnetic energy.
Transmit Receive Tube
A gas-filled Radio Frequency switch that is used as a duplexer.
Transmitter
Equipment that generates and amplifies an Radio Frequency carrier, modulates the Radio Frequency carrier with intelligence, and radiates the signal into space.
Transmitter Frequency
The frequency of an unmodulated transmitter output.
Transmitting Antenna
The device used to send the transmitted signal energy into space.
Triatic
A special type of monopole antenna array.
Trickle Charge
A charge at a low rate.
Trigger
A short pulse, either positive or negative, that can be used to cause an electronic function to take place.
Trimmer Capacitor
A small variable capacitor used in parallel across a larger capacitor to adjust the total capacitance a small amount.
Triode
An electronic amplifying valve with three main electrodes.
Trip Element
The part of a circuit breaker that senses any overload condition and causes the circuit breaker to open the circuit.
Trivalent Impurity
Acceptor impurities containing only three valence electrons.
Tropospheric Scatter
The propagation of radio waves in the troposphere by means of scatter.
Trouble Tables
Tables of trouble symptoms and probable causes, furnished by many manufacturers to help technicians isolate problems.
True Power
The power dissipated in the resistance of the circuit, or the power actually used in the circuit.
Tuned Circuit
A circuit consisting of inductance and capacitance that can be adjusted for resonance at a desired frequency.
Tuned Line
A transmission line that has standing waves of current and voltage.
Tuning
Optimizing loop gains to achieve the desired response from a stage or mechanism from an input command.
Tunnel Diode
Heavily doped junction diode that has negative resistance in the forward direction of its operating range.
Turn
One complete loop of a conductor about a core.
Turns Ratio
The ratio of the number of turns in the primary winding to the number of turns in the secondary winding of a transformer.
Turnstile Antenna
A type of antenna used in VHF communications that is omnidirectional and consists of two horizontal half-wave antennas mounted at right angles to each other in the horizontal plane.
Twisted Pair
Cable that consists of individual wires wrapped around each other for carrying telephone or computer data.
Two Wire Open Line
A parallel line consisting of two wires that are generally spaced from 50 to 150mm apart by insulating spacers.
Two Wire Ribbon
A parallel two-wire line in which uniform spacing is assured by two wires imbedded in a low-loss dielectric.
UHF
Radio frequencies that are between 300 to 3000 MHz.
ULSI
Abbreviation of Ultra Large Scale Integration.
Ultra High Frequency
Radio frequencies that are between 300 to 3000 MHz.
Ultra Large Scale Integration
A chip with over 1,000,000 components.
Unbalanced Crystal Mixer
A circuit consisting of a section of coaxial transmission line one-half wavelength long that is tuned to the difference frequency between the local oscillator and RF echo signals.
Unbalanced Line
Cable that consists of one conductor and a shield. Here the shield is also carrying the other half of the signal.
Unijunction Transistor
A trigger device that has an emitter lead (e) and two bases B1 and B2.
Unit
A standard for comparison in measurements. For example, the metre is a standard length which may be compared to any object to describe its length.
Unity Gain
A gain setting of one, or a device having a gain of one.
Universal Output Transformer
An audio output transformer having a number of taps on the secondary winding which provide a variety of impedances for matching the speaker impedance to that of the recommended load resistance.
Upper Frequency Cutoff
The highest frequency a circuit can pass.
Upper Sideband
All of the sum frequencies above the carrier.
UPS
A type of power supply designed to support the load for specified periods when the line varies outside specified limits.
Utility Transformer
Primary and secondary coils of wire which reduce the utility supply volt age for use within a facility.
VAC
Abbreviation of Voltage Alernating Current, normally given as the RMS value.
Valence Band
Highest filled or almost filled band in a semiconductor.
Valve
In electronics, a valve is a device consisting of two or more metal plates enclosed in an evacuated glass bulb.
V Antenna
A bidirectional antenna, shaped like a V, which is widely used for communications.
VAr
Abbreviation of Volt Amperes Reactive.
Varactor
A p-n junction diode that is designed to act as a voltage controlled capacitance when it is operated under reverse bias.
Varactor Modulator
An FM modulator that uses a voltage-variable capacitor.
Variable Attenuator
An attenuator for reducing the strength of an AC signal either continuously or in steps, without causing signal distortion.
Variable Mu Tube
An electron tube in which the control grid wires are farther apart at the centres than at the ends.
Variable Resistor
A wire-wound or composition resistor, the value of which may be changed over a designed range.
Varistor
A two-electrode semiconductor device having a voltage- dependent nonlinear resistance.
Varnished Cambric
Cotton cloth coated with insulation varnish.
V-Band
the frequency band from 46,000 to 56,000Mhz employed in radar.
Veitch Diagram
A diagram consisting of joined squares, which is used to give a graphic representation of basic logic relations.
Velocity Servosystem
A servosystem which controls the speed of the load it is driving.
Vertical Deflection Plates
A pair of parallel electrodes in a CRT that moves the electron beam up and down.
Very High Frequency
Radio frequencies that are between 30 to 300 MHz.
Very Large Scale Integration
An integrated crcuit with 100,000 to 1,000,000 components.
Very Low Frequency
Radio Frequencies from 3 kHz to 30 kHz.
Vestigial Sideband
The transmitted portion of the sideband which has been largely suppressed by a transducer.
VHF
Radio frequencies that are between 30 to 300 MHz.
Video
The technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.
Video Amplifier
An amplifier designed to amplify the entire band of frequencies from 10Hz to 6MHz.
Vidicon
A television pickup tube utilizing a photoconductor as the sensing element.
Virtual Ground
A point in a circuit that is at ground potential but is not connected to ground.
VLF
Radio Frequencies from 3 kHz to 30 kHz.
VLSI
Abbreviation of Very Large Scale Integration, an integrated crcuit with 100,000 to 1,000,000 components.
VOCODER
Abbreviation of Voice Coder.
Voice Coder
A device which converts speech input into coded form (usually digital) for secure transmission.
Voice Coil
Coil attached to the diaphragm of a moving coil loudspeaker.
Volt
The volt is the SI unit of electromotive force.
Volt Amperes Reactive
Unit used to measure reactive power in an AC electric power system.
Voltage
A potential difference causes current to flow in a circuit, no voltage no current.
Voltage Amplifier
An amplifier in which the output-signal voltage is greater than the input-signal voltage.
Voltage Controlled Crystal Oscillator
A crystal-based oscillator whose center frequency can be varied with an applied voltage.
Voltage Diode Detector
The semiconductor diode in series with the input voltage and the load impedance.
Voltage Divider
A precision resistor network that reduces the output voltage of a device.
Voltage Doubler
A power-supply circuit so designed that the rectified voltage amplitude is doubled at the output.
Voltage Drop
Voltage or difference in potential developed across a component due to current flow.
Voltage Gain
Ratio of amplifier output voltage to input voltage usually expressed in decibels.
Voltage Multiplier
Rectifier circuit using diodes and capacitors to produce a DC output voltage that is some multiple of the peak value of AC input voltage.
Voltage Regulation
A measure of the ability of a generator or power supply to maintain a constant output voltage from no-load to full-load operation.
Voltage to Frequency Converter
A device that converts an analogue input voltage into a sequence of digital pulses with a frequency that is proportional to the input voltage.
Voltaic Cell
Or more commonly known as a battery.
Voltaic Efficiency
The battery discharge voltage divided by the charge voltage.
Voltmeter
A device for measuring voltage across a component in a circuit.
VSB
The transmitted portion of the sideband which has been largely suppressed by a transducer.
Wafer
A slice of semiconductor material upon which monolithic ICs are produced.
Wafer Switch
A rotary switch in which the contacts are arranged on levels.
Warning Lamp
A small lamp that will light up if there is a problem.
Wattage Rating
A rating expressing the maximum power that a device can safely handle.
Watt-hour Efficiency
This the energy out of a battery during discharge divided by the energy in during charging.
Wattmeter
A meter used to measure electrical power.
Wave Antenna
Same as a Beverage Antenna.
Wave Winding
An armature winding in which the two ends of each coil are connected to commutator segments separated by the distance between poles.
Waveform
The shape of a time domain signal as seen on an oscilloscope screen.
Waveform Analysis
Observation displays of voltage and current variations with respect to time or by harmonic analysis of complex signals.
Wavemeter
An instrument for measuring the wavelength of an RF wave.
Wheatstone Bridge
Four arm bridge circuit used to measure resistance, inductance or capacitance.
White Room
A clean and dust-free room used for assembly and repair of precision equipment.
Wideband Amplifier
An amplifier designed to pass an extremely wide band of frequencies, such as a video amplifier.
Wire
A metal strand, normally pliable.
Wireless
A communications, monitoring, or control system in which a signal is carried through atmospheric space rather than along a wire.
Wiring Diagram
A diagram that shows the connections of an equipment or its component devices or parts.
Woofer
Large loudspeaker designed primarily to reproduce low frequency audio signals.
Word Clock
The synchronizing signal that indicates the sampling frequency or rate of sample words over a digital audio interface.
Working Voltage
The maximum voltage that a capacitor may operate at without the risk of damage.
Wye Connections
The same as a star connection, a method of interconnecting the phases of a three-phase system to form a configuration resembling the letter Y.
XLR Connector
A three pin connector widely used in the audio industry.
Yagi Antenna
A directional antenna consisting of a rod pointed in the direction of the transmission/reception and several cross bars.
Zener Diode
A diode that has been specially designed to break down at a particular voltage.
Zener Voltage
reverse voltage at which breakdown occurs in a zener diode.
Zero Insertion Force Socket
A standard IC-socket design requiring the user to move a lever to insert or remove the chip.
Zeroing
The process of adjusting a synchro to its electrical zero position.
Zinc Air Battery
Uses a zinc anode, a porous carbon cathode which absorbs oxygen from the air and a base electrolyte.
Zobel Network
A type of filter section based on the image impedance design principle.

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Subjects: Physics