A

Abbreviation for "ampere" a unit of electrical current.

Absorption

Loss or dissipation of energy as it travels through a medium, Example: radio waves lose some of their energy as they travel through the atmosphere.

AC

Alternating Current. In a time/voltage diagram, AC voltage represents a sine function (usually), or just any periodically alternating function. The mains voltage is AC voltage, for example.

AC coupling

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

AC generator

Device used to transform mechanical energy into AC electrical power.

AC load line

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

AC power supply

Power supply that delivers an AC voltage.

AC voltage

A voltage in which the polarity alternates.

AC/DC

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

Acceptor atoms

Trivalent atoms that accept free electrons from pentavalent atoms.

Active component

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

Active filter

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

Active high /
active low

Normally, signals are active high, which means a voltage level of 0V represents a logical 0 (LOW) and a voltage of above 5V represents a logical 1 (HIGH). If, for example, an IC pin is named "CS" (chip select), the chip is usually selected by pulling this line to HIGH (5V for TTL), and it gets deselected by pulling it to LOW (0V).

Active region

The region of BJT operation between saturation and cutoff used for linear amplification.

ADC

Abbreviation for "analog to digital converter"

Admittance

(symbol "Y") Measure of how easily AC will flow through a circuit. Admittance is the reciprocal of impedance and is measured in siemens.

AF

Abbreviation for "audio frequency".

AFC

Abbreviation for "automatic frequency control".

AGC

Abbreviation for "automatic gain control"

Alkaline cell

A primary cell that delivers more current than a carbon-zinc cell. Also known as an "alkaline manganese cell".

Alligator clip

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

Alpha

Ratio of collector current to emitter current in a bipolar junction transistor (BJT). Greek letter alpha "a" is the symbol used.

Alternating current

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

Alternator

Name for an AC generator.

AM

Abbreviation for "amplitude modulation"

Ammeter

Device for measuring electric current. Usually part of a multi meter.

Ampere

Unit of electrical current.

Amplifier

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

Amplitude:

Magnitude or size of a signal voltage or current.

Analog

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

AND

Logical function which is TRUE if all inputs are TRUE.

Examples:

  7408: 4 AND gates with 2 inputs each

  7409: 4 AND gates with 2 inputs each, open collector

  4081: 4 CMOS AND gates with 2 inputs each

Anode

The positive electrode or terminal of a device. The "P" material of a diode.

Antenna, receiving

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

Antenna, transmitting

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

Apparent power

Power attained in an AC circuit as a product of effective voltage and current which reach their peak at different times.

Arc

Discharge of electricity through a gas such as lightning discharging through the atmosphere.

Armature:

The rotating or moving component of a magnetic circuit.

Armstrong oscillator

An oscillator that uses an isolation transformer to achieve positive feedback from output to input.

Astable multivibrator

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

Atom

The smallest particle that an element can be broken down into and still maintain its unique identity.

Atomic number

The number of positive charges or protons in the nucleus of an atom.

Attenuate

To reduce the amplitude of an action or signal. The opposite of amplification.

Audio

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

Autotransformer

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

AVC

Abbreviation for "automatic volume control"

Average value

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

Avionics

Aviation electronics.

AWG

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

Balanced bridge

Condition that occurs when a bridge circuit is adjusted to produce a zero output.

Band-pass filter

A tuned circuit designed to pass a band of frequencies between a lower cut-off frequency (f₁) and a higher cut-off frequency (f₂). Frequencies above and below the pass band are heavily attenuated.

Band-stop filter

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

Bandwidth

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

Barrier potential

The natural difference of potential that exists across a forward biased pn junction.

Base

The region that lies between the emitter and collector of a bipolar junction transistor (BJT).

Base biasing

A method of biasing a BJT in which the bias voltage is supplied to the base by means of a resistor.

Battery

A DC voltage source containing two or more cells that convert chemical energy to electrical energy.

Baud

A unit of signaling speed equal to the number of signal events per second. Not necessarily the same as bits per second.

Beta

(b) The ratio of collector current to base current in a bipolar junction transistor (BJT).

BGA

Ball Grid Array. A type of chip package where the fixing method consists of a number of solder balls mounted under the chip and directly soldered onto a PCB.

Bias

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

Binary

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

Bipolar junction transistor

(BJT), A three terminal device in which emitter to collector current is controlled by base current.

Bistable multivibrator

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

Bleeder current

A current drawn continuously from a source. Bleeder current is used to stabilize the output voltage of a source.

Bode plot

A graph of gain versus frequency.

Branch current

The portion of total current flowing in one path of a parallel circuit.

Bread Board

Board made of pertinax or other insulating material for building prototype circuits. It contains a matrix of holes. There are also types with soldering pads around the holes, these cost more but are easier to work with.

Breakdown voltage

Voltage at which the breakdown of a dialectric or insulator occurs.

Breakover voltage

Minimum voltage required to cause a diac to break down and conduct.

Bridge rectifier

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

Buffer

An amplifier used to isolate a load from a source. Same as driver.

Bulk resistance

The natural resistance of a "P" type or "N" type semiconductor material.

Bus

The name for a set of lines/signals fulfilling a common function, e.g. the address bus and the data bus. Examples include the PCI bus, H.100 and H.110 buses

Butterworth filter

A type of active filter characterized by a constant gain (flat response) across the midband of the circuit and a 20 dB per decade roll-off rate for each pole contained in the circuit.

BW

Abbreviation for bandwidth.

Bypass capacitor

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

Byte

Group of eight binary digits or bits.

Cable

Group of two or more insulated wires.

CAD

Abbreviation for "computer aided design"

Calibration

To adjust the correct value of a reading by comparison to a standard.

Capacitance

Electrical entity which describes the amount of charge a capacitor can store. Unit: farad (F).

Capacitive reactance

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

Capacitor

A capacitor is an electrical element which is capable of storing small amounts of electrical energy, just like an accumulator. The five most common capacitor types are:

Since a simple capacitor only consists of two plates facing each other, you can imagine that even two wires lying in parallel have a certain capacitance. When you charge a capacitor by applying voltage to it, it first behaves like a shortcut, then its resistance increases until no current flows through it anymore. This shortcut period is also present in parallel wires (e.g. a cable), it drains lots of power from the chip the wires are connected to and the longer the cable, the higher its capacitance, the longer the shortcut period, the higher the current which the chip has to endure, and the shorter the chip's lifetime.

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.

Carbon resistor

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

Carbon-film resistor

Device made by depositing a thin carbon film on a ceramic form.

Cascade amplifier

A high frequency amplifier made up of a common-source amplifier with a common-gate amplifier in its drain network.

Cascaded amplifier

An amplifier with two or more stages arranged in a series configuration.

Cathode

The negative terminal electrode of a device. The "N" material in a junction diode.

Cathode ray tube

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

Cell

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

Center frequency

Frequency to which an amplifier is tuned. The frequency half way between the cut-off frequencies of a tuned circuit.

Center tap

Midway connection between the two ends of a winding.

Center tapped rectifier

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

Center tapped transformer

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

Ceramic capacitor

Capacitor in which the dielectric is ceramic.

Charge

Quantity of electrical energy.

Charge current

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

Chassis

Metal box or frame into which components are mounted.

Chassis ground

Connection to a chassis.

Chebyshev filter

A type of active filter characterized by high roll-off rates (40 dB per decade per pole) and midband gain that is not constant.

Chip

Generic Term. An IC in a housing or package. Package types may be Thru-Hole (THT), Surface Mount (SMT/SMD), Ball Grid Array (BGA) or Wafer-level Chip-scale Packaging (WLCSP).

Dimensions and sizes for chips are defined by JEDEC.

The following types are some examples:

Choke

Inductor used to oppose the flow of alternating current.

Circuit

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

Circuit breaker

A protective device used to open a circuit when current exceeds a maximum value. In effect a reusable fuse.

Clamper

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

Clapp oscillator

A variation of the Colpitts oscillator. An added capacitor is used to eliminate the effects of stray capacitance on the operation of the basic Colpitts oscillator.

Class A amplifier

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

Class B amplifier

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

Class C amplifier

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

Clipper

A diode circuit used to eliminate part of a waveform

Clipping

Distortion caused by overdriving an amplifier.

Clock

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

Closed circuit

Circuit having a complete path for current flow.

Closed-loop gain

Gain of an amplifier when a feedback path is present.

CMOS

Complementary Metal Oxide Semiconductor. TTL uses bipolar transistors, while CMOS chips use uni-polar transistors (FETs) which are connected complementarily (one p-mos, one n-mos), thus consuming virtually no power and staying much cooler than appropriate TTL chips. Alas, CMOS chips are not suitable for very high frequencies: when the input level changes, the supply voltage pin and GROUND get quickly short-circuited. The higher the switch frequency, the higher the shortcut time. If you run CMOS chips at high frequencies, most of the switching time there is a shortcut, resulting in high power consumption and heat generation.
The switching thresholds are less than 30% (LOW) and greater than 70% (HIGH) of the supply voltage.

As opposed to the TTL series (74xx), CMOS family chips are not bound to 5V supply voltage. V_cc ranges from 3 to 18V (for the 4000 family). There are also TTL compatible CMOS families available, e.g. the widely used 74HCxx series (voltage range 4-6V), where HC stands for High speed Cmos.

Coaxial cable

Transmission line in which the signal carrying conductor is covered by a dialectric and another conductor.

Coefficient of coupling

The degree of coupling between two circuits.

Coercive force

(H) Magnetizing force needed to reduce residual magnetism in a material to zero.

Collector

The semiconductor region in a bipolar junction transistor through which a flow of charge carriers leaves the base region.

Collector characteristic curve

A graph of collector voltage over collector current for a given base current.

Color code

Set of colors used to indicate value of a component.

Colpitts oscillator

An oscillator with a pair of tapped capacitors in the feedback network.

Common base amplifier

A BJT circuit in which the base connection is common to both input and output.

Common cathode display

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

Common collector amplifier

A BJT circuit in which the collector connection is common to both input and output.

Common drain amplifier

A FET circuit in which the drain connection is common to both input and output.

Common emitter amplifier

A BJT circuit in which the emitter connection is common to both input and output.

Common gate amplifier

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

Common source amplifier

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

Common-anode display

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

Common-mode rejection ratio

(CMRR) The ratio of op-amp differential gain to common-mode gain. A measure of an op-amp's ability to reject common-mode signals such as noise.

Common-mode signals

Signals that appear simultaneously at two inputs of an operational amplifier (op-amp). Common mode signals are always equal in amplitude and phase.

Comparator

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

Complementary symmetry amplifier

A class B amplifier using matched complementary transistors. Does not require a phase inverter for push-pull output.

Complementary transistors

Two transistors, one NPN and one PNP having near identical characteristics. N-channel and P-channel FETs can also be complementary.

Complex numbers

Numbers composed of a real number part and an imaginary number part.

Compliance

The maximum possible peak-to-peak output of an amplifier.

Composite video

Video signal which comprises of color and brightness information as well as horizontal and vertical synchronization information. Since the video chip's output signals are mixed into one signal (the composite video signal) and then must be split again in the monitor, losses occur and deteriorate the display quality, often resulting in color streaks. If possible, use the computer's Chroma/Luma output, which carries brightness and sync information on one line, but color information on another line, which eliminates the color streaking. The best result is achieved by using an RGB output.

Conductor

A material is called a conductor if electrons can move through it, in other words, if it allows flow of electrical current. How well current can flow through the conductor is determined by its resistance. If the resistance is very high, the material is called an insulator.

Connector

Many types of connectors are used the following list indicates some of the most common:

Constant current circuit

Circuit used to maintain constant current to a load having resistance that changes.

Contact

Current carrying part of a switch, relay or connector.

Continuity

Occurs when a complete path for current exists.

Continuity

A cable (or other conducting material) has continuity when it has a low resistance, when it therefore constitutes a shortcut.

Continuity tester

Device for checking for continuity. It reacts to a resistance below ~100ohm, normally acoustically; some devices have a selectable threshold. Usually part of a multimeter.

Conventional current flow

Concept of current produced by the movement of positive charges towards the negative terminal of a source.

Copper loss

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

Core

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

Coulomb

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

Counter

Counters are elements counting the number of clock signals and outputting them as binary or decimal representation on the output pins.

Examples

4060: 14-step CMOS binary counter with internal oscillator circuit 7468: 2 asynchronous decimal counters

Counter electromotive force

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

Coupling

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

Covalent bond

The way some atoms complete their valence shells by sharing valence electrons with neighboring atoms.

Crossover distortion

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

Crowbar

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

CRT

Abbreviation for cathode ray tube.

Crystal

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

Crystal-controlled oscillator

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

Current

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

Current

Electrical entity which is defined by the amount of charge flow in Coulomb per second. Unit:=Ampere (A). 1 A = 1 C / 1 sec. Symbol:=I In electrical equations

Current amplifier

Amplifier to increase signal current.

Current divider

Parallel network designed to divide the total current of a circuit

Current feedback

Feedback configuration where a portion of the output current is fed back to the amplifier input.

Current mirror

Term used to describe the fact that DC current through the base circuit of a class B amplifier is approximately equal to the DC collector current.

Current-limiting resistor

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

Cutoff

Condition when an active device is biased such that output current is near zero or beyond zero.

Cutoff frequency

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

Cycle

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

DAC

Abbreviation for "digital to analog converter."

DAC

Digital-Analog Converter.

Damping

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

Darlington pair

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

DC

Abbreviation for "direct current".

DC

Direct current. DC voltage is linear and constant, and either positive or negative. The same applies to direct current. See also AC.

DC load line

A graph representing all possible combinations of voltage and current for a given load resistor in an amplifier.

DC offset

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

DC power supply

Any source of DC power for electrical equipment.

Dead short

Short circuit having zero resistance.

Decade

A frequency factor of ten.

Decibel

(dB) a logarithmic representation of gain or loss.

Degenerative feedback

Also called negative feedback. A portion of the output of an amplifier is inverted and connected back to the input. This controls the gain of the amplifier and reduces distortion and noise.

Delay time

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

Depletion mode

In a FET, an operating mode where reverse gate-source voltage is used to deplete the channel of free carriers. This reduces the size of the channel and increases its resistance.

Depletion region

The area surrounding a pn junction that is depleted of carriers.

Depletion-mode MOSFET

A MOSFET designed to operate in either depletion mode or enhancement mode.

Device

A component or part.

Diac

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

Dialectric constant

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

Dialectric strength

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

Dielectric

Insulating material between two plates where an electrostatic field exists.

Differential amplifier

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

Differentiator

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

Diffusion

Tendency of conduction band electrons to wander across a pn junction to combine with valence band holes.

Digital

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

Diode

A two terminal device that conducts in only one direction.

Diode

Semiconductor element which lets current flow in only one direction (forward direction). Current flows if a positive voltage greater than the forward voltage is applied to the anode of the diode (the other end is called cathode and is usually marked with a black ring on the case), otherwise, the diode has a very high resistance. If the applied voltage is below the avalanche / blocking voltage (which is always negative), the diode breaks down and constitutes a shortcut.
The rarely used germanium diodes have a forward voltage of 0.3V, while the standard silicon diode has a forward voltage of 0.6V. (Graphic symbol)

Schottky diode

Diode with a P-N junction consisting of metal and silicon [?]. It is used for applications requiring fast switching, for instance ecl circuits.

Zener diode [Z-Diode]

As opposed to all other diodes, the Z diode is used in reverse direction. It has a defined avalanche voltage and is often used for voltage stabilizing.
Z diodes often have a blue, yellow or red base color. Common series are BZXxx, ZPDxx, and BZYxx, where xx is the avalanche voltage, e.g. ZPD4.7 or BZY9.1.

Tunnel diode

Only for very high frequency applications. Its function is not based on the avalanche effect, but on the tunnel effect.

DIP

Abbreviation for "dual in line package."

Direct coupling

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

Direct current

Current that flows in only one direction.

Discharge

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

Discrete component

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

Dissipation

Release of electrical energy in the form of heat.

Distortion

An undesired change in a waveform or signal.

Distributed capacitance

Any capacitance other than that within a capacitor. For example, the capacitance between adjacent turns of wire in a coil.

Distributed inductance

Any inductance other than that within an inductor. Example inductance in any conductor.

Domain

A moveable magnetized area in a magnetized material. Also known as magnetic domain.

Donor atoms

Pentavalent atoms that give up electrons to the conduction band in an N type semiconductor material.

Doping

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

Dot convention

Standard used with transformer symbols to indicate whether the secondary voltage is in phase or out of phase with the primary voltage.

DRAM

Dynamic RAM. DRAM needs a continuous refresh (through the use of CAS and RAS signals), as the information in it is stored by very small capacitors.

Drift

A problem that can develop in tuned amplifiers when the frequency of the tuned circuit changes due to temperature or component aging.

Driver

Sometimes called a Buffer. A driver's output level follows the input level if it is a non-inverting type, and it implements a NOT function, if it is an inverting type. Drivers are employed for

• increasing the maximum output current of logical signals.
• signal shaping - turn a noisy signal into a clean signal
• protecting expensive chips

Examples:

  7404: hex inverter (6 inverters)

        7414: hex inverter with Schmitt trigger inputs

  7405: hex inverter with O.C. outputs

        7406: inverting driver with O.C. outputs (30V)

  7416: inverting driver with O.C. outputs (15V)

  7407: non-inverting driver with O.C. outputs (30V)

  4069: inverting CMOS driver

  4049: inverting CMOS driver, buffered

  4050: CMOS driver

Dropping resistor

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

Dry cell

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

Dual in-line package

Integrated circuit package having two rows of connecting pins.

Dual trace oscilloscope

Oscilloscope that can simultaneously display two signals.

Dynamic

Relating to conditions that are changing or in motion

ECL

Emitter-Coupled-Logic. Very fast logic family and used in some processor designs such as the AMD2900 range.

E-core

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

Eddy currents

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

EEPROM

Electrically Erasable PROM. In contrast to EPROMs, EEPROMs don't need exposure to UV light to be erased, but can be erased electrically. A big advantage is that is accessed like an SRAM. Write accesses perform an automatic clear before write and thus make writing EEPROMs as easy as writing to SRAMs. Series designator: 28xx, where xx is the number of K bits stored.
Serial EEPROMs are labeled 24Cxx (8bit) or 93Cxx (16bit).
Low voltage eproms (PLCC): 3.3V are labeled 27Vxx.

Efficiency

The amount of power delivered to the load of an amplifier as a percentage of the power required from the power supply.

Electric charge

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

Electric field

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

Electric polarization

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

Electrical
Equations

Ohm's Law. Additional equations.

Electricity

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

Electro acoustic transducer

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

Electroluminescence

Conversion of electrical energy into light energy.

Electrolyte

Electrically conducting liquid (wet) or paste (dry)

Electrolytic capacitor

A capacitor having an electrolyte between the two plates. A thin layer of oxide is deposited on only the positive plate. The oxide acts as the dielectric for the capacitor. Electrolytic capacitors are polarized and so must be connected in correct polarity to prevent breakdown.

Electromagnet

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

Electromagnetic communication

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

Electromagnetic induction

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

Electromagnetic spectrum

List or diagram showing the range of electromagnetic radiation.

Electromagnetic wave

Wave that consists of both electric and magnetic variation.

Electromagnetism

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

Electromechanical transducer

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

Electromotive force

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

Electron

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

Electron

To be supplied.

Electron flow

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

Electrostatic

Related to static electric charge.

Electrostatic field

Force field produced by static electrical charges.

Emitter

The semiconductor region from which charge carriers are injected into the base of a bipolar junction transistor.

Emitter feedback

Coupling from the emitter output to the base input of a bipolar junction transistor.

Emitter follower

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

Energized

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

Energy

Capacity to do work.

Engineering notation

A floating point system in which numbers are expressed as products consisting of a number greater than one multiplied by an appropriate power of ten that is some multiple of three.

Enhancement-mode MOSFET

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

EPROM

Erasable PROM. EPROMs allow the contents to be erased by exposing its builtin window to UV light. After this process, all memory cells contain $ff and the EPROM can be written again.
Series designator: 27xx, where xx is the number of K bits stored.

Equivalent resistance

Total resistance of all the individual resistances in a circuit.

EXOR (XOR)

Exclusive OR. Logical function which is TRUE, if and only if, exactly one input is TRUE. Frequently called XOR.

Examples:

  7486 : 4 XOR gates with 2 inputs each

  74136: 4 XOR gates with 2 inputs each, open collector

  4070 : 4 CMOS XOR gates with 2 inputs each

Fall time

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

Farad

The basic unit of capacitance.

Feedback

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

Feedback amplifier

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

Ferrite

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

Ferrite bead

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

Ferrite-core inductor

An inductor wound on a ferrite core.

Ferrites

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

Ferrous

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

FET

Field Effect Transistor. As opposed to normal bipolar transistors, these uni-polar transistors have a negligible flow of current through their gate (bipolar: base), they consume virtually no power. NMOS-FETs and PMOS-FETs can be coupled to form CMOS circuits.

Fiber optics

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

Field effect transistor

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

Filament

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

Filter

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

FLASH

An EEPROM which can be written (and erased) in whole banks or sectors. Typically comes un Uniform Sectored or Bootstrap Sectored designs.
Series designator: 28Fxxx (12 V prg. voltage), 29Fxxx (5 V prg. voltage), and 29LVxxx/29SLxxx (3 V and below), where xxx is the memory capacity: 010 - 1 Mbit, 020 - 2 Mbit, etc. If the FLASH supports 16 bit organization, xxx is: 100 - 1 Mbit, 200 - 2 Mbit, etc. Early FLASH (before 1998) had a limit on the number of erase cycles (typically 100,000) but most modern FLASH has essentially no erase limits.

Flip flop

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

Flip-flop

This edge-triggered element has two stable states, which are toggled on different events, depending on the type:

Examples:

  7470 : JK flip-flop with 3 inputs each, preset and reset

  74L71: RS master slave flip-flop with 3 inputs each, preset and reset

  74171: 4 D flip-flops with clear input

Float

An electronic signal is said to 'float' when its value is not defined under all conditions. Floating is generally a 'bad thing' since random effects (e.g. induction) could easily change the value with unexpected or unpleasant results. Signals that would otherwise 'float' are typically 'pulled-up'(High) or 'pulled-down'(Low) with a weak resistor such that they can be easily changed when driven.

Floating ground

Common connection in a circuit that provides a return path for current but is not connected to an earth ground.

Flow soldering

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

Flux

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

Flux

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

Flux density

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

Flywheel effect

Sustaining effect of oscillation in an LC circuit.

Forward bias

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

Free electrons

Electrons that are not in any orbit around a nucleus.

Free running multivibrator

A multivibrator that produces a continuous output waveform without any signal input. A square wave generator used to produce a clock signal.

Frequency

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

Frequency meter

Meter used to measure frequency of periodic waves.

Frequency multiplier

A harmonic conversion circuit in which the frequency of the output signal is an exact multiple of the input frequency.

Frequency response

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

Frequency response curve

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

Frequency-division multiplex

(FDM) Transmission of two or more signals over a common path by using a different frequency band for each signal.

Frequency-domain analysis

A method of representing a waveform by plotting its amplitude against frequency.

Full scale deflection

(FDS) Deflection of a meter's pointer to the farthest position on the scale.

Full wave rectifier

Rectifier that makes use of the full AC wave in both the positive and negative half cycles.

Function generator

Signal generator that can produce sine, square, triangle and sawtooth output waveforms.

Fundamental frequency

Lowest frequency in a complex waveform.

Fuse

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

Fuse

A device designed to break a circuit when too much voltage or current is applied. The idea being that its cheaper to replace a fuse than a device.
Electronic fuses:
Domestic fuses: Historically little glass tubes with a wire of defined maximum voltage and current which melts when its capacity is exceeded. There are two common formats: 5 x 20mm (German) and 6 x 30mm (American). Modern wiring typically uses circuit-breakers which can be reset rather than replaced.

Gain

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

Gain bandwidth product

A device parameter that indicates the maximum possible product of gain and bandwidth. The gain bandwidth product of a device is equal to the unity gain frequency (f_unity) of the device.

Gamma rays

High frequency electromagnetic radiation from radio active particles.

Ganged

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

Gas

Any aeriform or completely elastic fluid which is not a solid or a liquid. Gasses are produced by heating a liquid beyond its boiling point.

Gate

A gate is a circuit on a chip, which implements a logical function. A 7406, for example, contains 6 gates (non-inverting drivers).

Geiger counter

Device used to detect nuclear particles.

Generator

Device used to convert mechanical energy to electrical energy.

Giga

Metric prefix for 1 billion (10⁹).

Ground

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

Gunn diode

A semiconductor diode that utilizes the Gunn effect to produce microwave frequency oscillation or to amplify a microwave frequency signal.

Half power point

A frequency at which the power is 50% of maximum. This corresponds to 70.7% of maximum current or voltage.

Half wave rectifier

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

Harmonic

Sine wave that is smaller in amplitude and some multiple of a fundamental frequency. Example: 880 Hz. is the second harmonic of 440 Hz., 880 Hz. is the third harmonic of 220 Hz.

Hartley oscillator

An oscillator that uses a tapped inductor in the feedback network.

Henry

The basic unit of inductance.

HERTZ

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

High fidelity

(Hi Fi)Sound reproduction equipment that reproduces sound as near to the original sound as possible

High tension

Lethal voltage in the kilovolt range and above.

High-pass filter

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

Hole

A gap left in the covalent bond when a valence electron gains sufficient energy to jump to the conduction band

Hologram

Three-dimensional picture created with a laser.

Holography

The science dealing with three-dimensional optical recording.

Horizontally polarized wave

Electromagnetic wave that has the electric field in the horizontal plane.

H-parameters

(hybrid parameters) Transistor specifications that describe the component operating limits under specific circumstances.

Hybrid circuit

Circuit that combines two technologies (passive and active or discrete and integrated components) onto one microelectronic circuit. Passive components are usual made by thin film techniques, while active components are made with semiconductor techniques.

Hysteresis

Amount that the magnetization of a material lags the magnetizing force due to molecular friction. In Schmitt Trigger circuits, the difference between the upper and lower trigger points.

IC

Abbreviation for "integrated circuit"

IC

Generic Term. Integrated Circuit. A set of gates etched on a silicon wafer. As ICs are very sensitive, they are enclosed or packaged in a plastic or ceramic case/carrier, with their inputs and outputs connected to metal pins or balls. An IC in a package is commonly referred to as a CHIP. Chips are also called ICs!

IC voltage regulator

Three terminal device used to hold the output voltage of a power supply constant over a wide range of load variations.

IGFET

Insulated gate field effect transistor. Another name for a "MOSFET."

Impedance

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

Impedance

Expressed in Ohms is the vector sum of all opposition to the flow of current in a (typically AC) circuit which includes resistance, capacitance and inductance.

Impedance coupling

Coupling of two signal amplifier circuits through the use of an impedance such as a inductor.

Impedance matching

Matching the output impedance of a source to the input impedance of a load to attain maximum power transfer.

In phase

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

Incandescence

State of a material when heated to the point where it emits light. (red hot or white hot).

Induced voltage

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

Inductance

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

Inductance

Measures in Henries. The ability of a component to store energy in the form of a magnetic field.

Inductive circuit

Circuit having greater inductive reactance than capacitive reactance.

Inductive reactance

Opposition to the flow of AC current produced by an inductor. Measured in Ohms and varies in direct proportion to frequency.

Inductor

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

Inductor

A passive device that stores electrical energy in the form of a magnetic field. Normally consists of a wire loop or coil. Inductors are typically used to smooth out voltage fluctuations in power supply circuits.

Infrared

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

Inhibit

To stop an action or block data from passing.

Input impedance

Opposition to the flow of signal current at the input of a circuit or load.

Insulated

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

Insulating material

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

Insulation resistance

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

Insulator

A material which doesn't conduct electrical current. The opposite is a conductor.

Integrated

When two or more components are combined into a circuit and then incorporated into a single package.

Integrator

A device that approximates and whose output is proportional to an integral of the input signal. A low pass filter.

Intermediate frequency amplifier

In a superheterodyne radio it amplifies a fixed frequency lower than the received radio frequency and higher than the audio frequency.

Intermittent

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

Internal resistance

Every source has some resistance in series with the output current. When current is drawn from the source some power is lost due to the voltage drop across the internal resistance. Usually called output impedance or output resistance.

Intrinsic material

A semiconductor material with electrical properties essentially characteristic of ideal pure crystal. Essentially silicon or germanium crystal with no measurable impurities.

Intrinsic stand-off ratio

A unijunction transistor (UJT) rating used to determine the firing potential of the device.

Inverter

Gate inverting a logical signal, thus implementing a NOT function. For examples, see drivers.

Inverting amplifier

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

Inverting input

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

Ion

An atom with fewer electrons in orbit than the number of protons in the nucleus is a positive ion. An atom with a greater number of electrons in orbit than the number of protons in the nucleus is a negative ion.

Ionized

Atoms become ionized when they gain or lose a valence electron.

j 

A prefix used to indicate an imaginary number. (Operator j)

Jack

Socket or connector into which a plug may be inserted.

JFET

Abbreviation for "Junction field effect transistor".

Joule

The unit of work and energy.

Junction

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

Junction diode

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

Kilo

Metric prefix for 1000. (10³)

Kilovolt-ampere

1000 volts at 1 ampere.

Kilowatt-hour

1000 watts for 1 hour.

Kilowatt-hour meter

A meter used by electric utility companies to measure the amount of electric power used by a customer.

Kinetic energy

Energy associated with motion.

Kirchhoff"s current law

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

Kirchhoff"s voltage law

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

Knee voltage

The voltage at which a curve joins two relatively straight portions of a characteristic curve. For a PN junction diode, the point in the forward operating region of the characteristic curve where conduction starts to increase rapidly. For a zener diode, the term is often used in reference to the zener voltage rating.

Lag

Difference in time between two waveforms of the same frequency expressed in degrees. Example: One waveform lags another waveform by a certain number of degrees.

Laminated core

Core made up of sheets of magnetic material insulated from one another by an oxide or varnish.

Lamp

Device that produces light.

Laser

Device that produces a very narrow intense beam of light. The name is an acronym for "light amplification by stimulated emission of radiation.

Latch

A set of flip-flops with a common clock signal. In each cycle, they take the logical input signals over to their outputs. Usually used to form multiplex address busses. As opposed to flip-flops, latches are level-triggered.

Lead

The angle by which one alternating signal leads another in time. Opposite of lag. Also a wire that connects two points in a circuit.

Lead-acid cell

Cell made up of lead plates immersed in a sulfuric acid electrolyte. An automobile battery usually consists of six lead-acid cells.

Leakage

Small undesirable flow of current through an insulator or dielectric.

LED

Abbreviation for "light emitting diode."

LED

An LED (Light Emitting Diode) is a diode emitting light when operated in a forward direction. Since it is a diode, it has a nearly negligible resistance and MUST be operated with a series resistor.

The forward voltages depend on the type:

While normal LEDs consume about 20mA, high efficiency LEDs require only currents from 2-4mA (depending on type and color), which means that you can directly connect them to standard logical outputs (74LSxx or CMOS 4000 series) without the need for a driver. Nevertheless you still need an appropriate series resistor. Resistor calculation = voltage drop x current required in amps

Left-hand-rule

If fingers of the left hand are placed around a wire so that the thumb points in the direction of electron flow, the fingers will be pointing in the direction of the magnetic field being produced by the conductor.

Lenz's law

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

Level detector

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

Lie detector

Piece of electronic equipment also called a polygraph used to determine whether a person is telling the truth by looking for dramatic changes in blood pressure, body temperature, breathing rate, heart rate and skin moisture in response to questions.

Lifetime

The time from the creation of an electron hole pair until recombination occurs.

Light

Electromagnetic radiation in a band of frequencies that can be received by the human eye.

Light-emitting diode

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

Limiter

Circuit or device that prevents some portion of its input from reaching the output. A clipper.

Line regulation

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

Linear

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

Linear scale

A scale in which the divisions are uniformly spaced.

Live

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

Load

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

Load current

Current drawn from a source by a load.

Load impedance

Vector sum of reactance and resistance in a load.

Load regulation

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

Load resistance

Resistance of a load.

Loading effect

Large load impedance will draw a small load current and so loading of the source is small. (light load). A small load impedance will draw a large load current from the source. (heavy load).

Logic

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

Logic Tester/Probe

Detects and indicates logic TTL (and/or) CMOS voltage levels. It usually contains a pulse memory (comprising a flip-flop) that memorizes pulses too short to be noticed otherwise.

Loss

Term used to describe a decrease in power.

Low pass filter

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

Magnet

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

Magnetic circuit breaker

Circuit breaker that is tripped or activated by use of an electromagnet.

Magnetic coil

Spiral of a conductor which is called an electromagnet.

Magnetic core

Material that exists in the center of the magnetic coil to either physically support the windings (non-magnetic material) or to concentrate the magnetic flux (magnetic material).

Magnetic field

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

Magnetic flux

The magnetic lines of force produced by a magnet.

Magnetic leakage

The passage of magnetic flux outside the path along which it can do useful work.

Magnetic poles

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

Magnetism

Property of some materials to attract or repel others.

Magnetizing force

Also called magnetic field strength. It is the magnetomotive force per unit length at any given point in a magnetic circuit.

Magnetomotive force

Force that produces a magnetic field.

Mains voltage

The voltage at the wall outlet.

Majority carriers

The conduction band electrons in an n-type material and the valence band holes in a p-type material. Produced by pentavalent impurities in n-type material and trivalent impurities in p-type material.

Matched impedance

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

Matching

Connection of two components or circuits so that maximum power is transferred between the two.

Maximum power transfer

A theorem that states that maximum power will be transferred from source to load when input impedance of the load equals the output impedance of the source.

Maxwell

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

Mercury cell

Primary cell using a mercuric oxide cathode, a zinc anode and a potassium hydroxide electrolyte.

Metal film resistor

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

Metal oxide field effect transistor

(MOSFET) A field effect transistor in which the insulating layer between the gate electrode and the channel is a metal oxide layer.

Metal oxide resistor

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

Meter

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

Meter FSD current

Value of meter current needed to cause the needle to deflect to its maximum position (full scale deflection).

Meter resistance

DC resistance of the meter's armature coil.

Mica capacitor

Capacitor using mica as the dielectric.

Microphone

Electroacoustic transducer that converts sound energy into electric energy.

Microwave

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

Midband gain

Gain of an amplifier operating within its bandwidth.

Mid-point bias

An amplifier biased at the center of its DC load line.

Mil

One thousandth of an inch (0.001 in.)

Miller's theorem

A theorem that allows you to represent a feedback capacitor as equivalent input and output shunt capacitors.

Minority carriers

The conduction band holes in n-type material and valence band electrons in p-type material. Most minority carriers are produced by temperature rather than by doping with impurities.

Mismatch

Term used to describe a difference between the output impedance of a source and the input impedance of a load. A mismatch prevents the maximum transfer of power from source to load.

Modulation

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

Molecule

Smallest particle of a compound that still retains its characteristics.

Monoflop

Also known as one-shot multivibrator. Flip-flop with only one stable state. It remains in the unstable state for a certain time determined by capacitors.

Examples:

74121: Monoflop with Schmitt trigger input 74221: 2 monoflops with Schmitt trigger input and reset 74122: Retriggerable monoflop with reset 74123: 2 retriggerable monoflops with reset

Monostable multivibrator

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

MOS

Metal Oxide Semiconductor.

MOSFET

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

Moving coil loudspeaker

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

Moving coil microphone

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

Moving coil pick-up

Dynamic phonograph pick-up in which the stylus causes a coil to move within a fixed magnetic field.

Multi emitter

Multimeter

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

Multi-meter

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

Multiplexing

Multiplier resistor

Resistor connected in series with a moving coil meter movement to extend the voltage ranges.

Multisegmant display

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

Multivibrator

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

Mutual inductance

Ability of one inductor's lines of force to link with another inductor.

NAND  

Logical function which is TRUE if and only if not all of the inputs are TRUE.

Examples:

  7400: 4 NAND gates with 2 inputs each

  7401: 4 NAND gates with 2 inputs each, open collector

  4012: 2 CMOS NAND gates with 4 inputs each

  4093: 4 CMOS NAND gates with 2 inputs each and Schmitt trigger

Negative

Terminal that has an excess of electrons.

Negative charge

A charge that has more electrons than protons

Negative feedback

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

Negative ground

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

Negative ion

An atom having a greater number of electrons in orbit than there are protons in the nucleus.

Negative logic

Negative logic means that the signals are active low.

Negative resistance

A resistance such that when the current through it increases the voltage drop across the resistance decreases.

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.

Network

Combination of interconnected components, circuits or systems.

Neutral

A terminal, point or object with balanced charges. Neither positive nor negative.

Neutral atom

An atom in which the number of negative charges (electrons in orbit) is equal to the number of positive charges (protons in the nucleus).

Neutral wire

The conductor of a polyphase circuit or a single-phase three wire circuit that is intended to have a ground potential. The potential difference between the neutral and each of the other conductors are approximately equal in magnitude and equally spaced in phase.

Neutron

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

Nickel-cadmium cell

A secondary cell that uses a nickel oxide positive electrode and a cadmium negative electrode.

NMOS

N-doped MOS.

Node

Junction or branch point in a circuit.

Noise

Unwanted electromagnetic radiation within an electrical or mechanical system. An operational amplifier circuit having no phase inversion between the input and output.

Non-inverting input

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

Non-linear scale

A scale in which the divisions are not equally spaced.

NOR

Logical function which is TRUE if and only if all inputs are FALSE.

Examples:

  7402: 4 NOR gates with 2 inputs each

  7423: 2 NOR gates with 4 inputs each and strobe

  4001: 4 CMOS NOR gates with 2 inputs each

  4002: 2 CMOS NOR gates with 4 inputs each

Normal closed

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

Normally open

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

North pole

Pole of a magnet out of which magnetic lines of force are assumed to originate.

Norton's theorem

Any network of voltage sources and resistors can be replace by a single current source in parallel with a single resistor.

NOT

Logical function which is TRUE if the input is FALSE.

Inverters implement this function.

Notch filter

A filter which blocks a narrow band of frequencies and passes all frequencies above and below the band.

Npn transistor

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

NTSC

National Television Standard Code. Video encoding standard in the United States and in Japan. NTSC has 60 pictures/sec and 526 lines vertical resolution.

n-type semiconductor

A semiconductor compound formed by doping an intrinsic semiconductor with a pentavalent element. An n-type material contains an excess of conduction band electrons.

Nucleus

Core of an atom. The nucleus contains both positive (protons) and neutral (neutrons) subatomic particles.

Octave

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

Offset null

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

Ohm

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

Ohmmeter

Device used to measure electrical resistance.

Ohmmeter

Device for measuring resistance. Usually part of a multi-meter.

Ohm's law

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

Ohm's Law

Defines the relationship between voltage (E) current (I) and Resistance (R) in a circuit. For DC circuits Ohms law is:

Additional equations.

Ohms per volt

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

One-shot

Monostable multivibrator.

Op-amp

Abbreviation for operational amplifier.

Open collector

A possible output connection of a TTL circuit. The output is formed by a single transistor, which is not connected to the supply voltage, therefore an external connection to the supply voltage (via a pull-up resistor) is required. Multiple open collector outputs can be connected together, the outputs carrying a 0 signal will override all other outputs.

Open loop gain

Gain of an amplifier when no feedback is present.

Open loop mode

An amplifier circuit having no means of comparing the output with the input. (No feedback.)

Operational amplifier

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

OR

Logical function which is TRUE if at least one input is TRUE.

Examples:

  7432 : 4 OR gates with 2 inputs each

  74832: 6 OR drivers with 2 inputs each

  4071 : 4 CMOS OR gates with 2 inputs each

  4072 : 2 CMOS OR gates with 4 inputs each

Oscillate

To produce a continuous output waveform without an input signal present.

Oscillator

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

Oscilloscope

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

Oscilloscope

A test device which displays voltage curves graphically.

Out of phase

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

Output

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

Output impedance

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

Output power

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

Overload

Condition that occurs when the load is greater than the system was designed to handle. (Load resistance too small, load current too high.) Overload results in waveform distortion and/or overheating.

Overload protection

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

PAL

This acronym has two meanings:

1.     Phase-Alternation Lines. Video encoding standard used in European countries. PAL has 50 pictures/sec interlaced and a resolution of 625 lines [?].

2.     Programmable Array Logic. A chip which implements a sum-of-products logic equation. A PAL can be programmed only once. Type designator: xxyzz, where xx is the number of inputs, y is either L for active low outputs or H for active high outputs, and zz is the number of outputs; example: 16L8. A derivate [?] is the PLA.

Paper capacitor

Fixed capacitor using oiled or waxed paper as a dielectric.

Parallel

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

Parallel resonant circuit

Circuit having an inductor and a capacitor in parallel with one another. Circuit offers a high impedance at resonant frequency. Sometimes called a "tank circuit."

Pass band

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

Passive component

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

Passive filter

A filter that contains only passive or non amplifying components.

Passive system

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

PCB

Printed Circuit Board. The circuit tracks or traces are etched photographically onto a media. PCBs may be single-sided (tracks on one side only), double-sided (both top and bottom surfaces are used) or multi-layer where tracks are placed on a number of separate layers which are then bonded together. Tracks are connected on multi-layer boards using VIAs (small holes). Holes are drilled in the board for thru-hole technology or solder pads provided for SMT or BGA devices. Components may be placed on the top or increasing on both the top and bottom of a PCB.

Peak

Maximum or highest amplitude level.

Peak inverse voltage

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

Peak to peak

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

Pentavalent element

Element whose atoms have five valence electrons. Used in doping intrinsic silicon or germanium to produce n-type semiconductor material. Most commonly used pentavalent materials are arsenic and phosphorus.

Percent of regulation

The change in output voltage that occurs between no-load and full-load in a DC voltage source. Dividing this change by the full-load value and multiplying the result by 100 gives percent regulation.

Percent of ripple

The ratio of the effective rms value of ripple voltage to the average value of the total voltage. Expressed as a percentage.

Period

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

Permanence

Magnetic equivalent of magnetic inductance and consequently equal to the reciprocal of reluctance, just as conductance is equal to the reciprocal of resistance.

Permanent magnet

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

Permeability

Measure of how m how much better a material is as a path for magnetic lines of force with respect to air which has a permeability of one. Symbolized by the Greek lower case letter mu (m).

Phase

Angular relationship between two waves.

Phase angle

Phase difference between two or more waves, normally expressed in degrees.

Phase shift

Change in phase of a wave form between two points, expressed as degrees of lead or lag.

Phase shift oscillator

An oscillator that uses three RC networks in its feedback path to produce the 180° phase shift required for oscillation.

Phase splitter

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

Phonograph

Piece of equipment used to reproduce sound stored on a disk called a phonograph record.

Phosphor

Luminescent material applied to the inner face of a cathode ray tube that when bombarded with electrons will emit light of various colors.<OLORS.< p>

Photo diode

Diode which is controlled by light.

Photo transistor

Transistor which is controlled by light.

Photoconduction

A process by which the conductance of a material is change by incident electromagnetic radiation in the visible light spectrum.

Photoconductive cell

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

Photodetector

Component used to detect or sense light.

Photodiode

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

Photometer

Meter used to measure light intensity.

Photon

Discrete portion of electromagnetic energy. A small packet of light.

Photoresistor

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

Photovoltaic cell

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

Pi

Value representing the ratio between the circumference and diameter of a circle and equal to approximately 3.142.

Pierce oscillator

A variation of the colpitts oscillator. This oscillator uses a quartz crystal in place of the inductor found in the colpitts oscillator feedback network. The crystal maintains a highly stable output frequency.

Piezoelectric crystal

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

Piezoelectric effect

The production of a voltage between opposite sides of a piezoelectric crystal as a result of pressure or twisting. Also the reverse effect which the application of a voltage to opposite sides causes a deformation to occur at the frequency of the applied voltage. (Converts mechanical energy into electrical energy and electrical energy into mechanical energy.)

Pinch-off region

A region on the characteristic curve of a FET in which the gate bias causes the depletion region to extend completely across the channel.

PLA

Programmable Logic Array. The same as a PAL, but with a programmable OR matrix

Plastic film capacitor

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

Plate

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

Plug

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

PMOS

P-doped MOS.

P-n junction

Pnp transistor

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

Polar coordinates

Either of two numbers that locate a point in a plane by its distance from a fixed point and the angle this line makes with a fixed line.

Polarity

Term used to describe positive and negative charges.

Polarized

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

Pole

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

Positive

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

Positive charge

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

Positive feedback

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

Positive ground

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

Positive ion

Atom that has lost one or more valence electrons resulting in a net positive charge.

Positive logic

Positive logic means that the signals are active HIGH. Negative logic means that signals are active LOW (most commonly in RS232 circuits).

Potential difference

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

Potential energy

Energy that has potential to do work because of its position relative to others.

Potentiometer

A variable resistor with three terhree terminals. Mechanical turning of a shaft can be used to produce variable resistance and potential. Example: A volume control is usually a potentiometer.

Potentiometer

A variable resistor the value of which is determined by the position of a slider or a knob.

Power

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

Power amplifier

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

Power derating factor

A transistor rating that tells how much the maximum allowable value of P_D decreased for each 1°C rise in ambient temperature.

Power dissipation

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

Power factor

Ratio of actual power to apparent power.

Power loss

Ratio of power absorbed to power delivered.

Power supply

Electrical equipment used to deliver either AC or DC voltage.

Power supply rejection ratio

A measure of an op-amps ability to maintain a constant output when the supply voltage varies.

Primary

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

Primary cell

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

Printed circuit board

Insulating board containing conductive tracks for circuit connections.

Programmable UJT

Unijunction transistor with a variable intrinsic stand-off ratio.

PROM

Programmable ROM. This memory type can be written once, then it behaves like a ROM. Series designator: 25xx, where xx is the number of kbits stored.

Propagation

Traveling of electromagnetic, electrical or sound waves through a medium.

Propagation delay

Time required for a signal to pass through a device or circuit.

Propagation time

Time required for a wave to travel between two points.

Protoboard

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

Proton

Sub atomic particle within the nucleus of an atom. Has a positive charge.

Pull-up/
pull-down resistor

Pull-ups (or pull-downs) have two primary purposes both of which are variations on a fundamental theme which is to prevent a short-circuit by adding a resistor in the path between Vcc and GND for a particular signal.
Configuration: Many ICs have pins which must be set to a HIGH or LOW to configure the chip. Unless the IC is defined to have an internal pull-up or pull-down you typically use a pull-up (the resistor is between the signal pin and Vcc) to set a HIGH (1) or a pull-down (the resistor is between the signal pin and GND) to set a LOW (0).
Floating Signals: If a signal is not being actively driven all the time it will float (i.e. take an arbitrary and maybe changing value). To prevent this it may be pulled-up (HIGH) or pulled-down (LOW) into a default state.
Pull-ups or pull-downs are usually weak (i.e high value resistors of 4.7K, 10K (most common) or 47K) since in the case of floating signals this allows the 'driven' level to overcome the resistance with a modest current. For minimum power loss especially in configuration functions use the highest value (47K). Since higher resistance values take longer to overcome than lower values if the signal needs to be stable very quickly you may need to go as low as 1K for the pull-up (pull-down).

Pulse

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

Pulse fall time

Time for a pulse to decrease from 90% of its peak value to 10% of its peak value.

Pulse repetition frequency

The number of times per second that a pulse is transmitted. Pulse rate.

Pulse repetition time

Time interval between the start of two consecutive pulses.

Pulse rise time

Time required for a pulse to increase from 10% of its peak value to 90% of its peak value.

Pulse width

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

Push>push-pull amplifier

Amplifier using two active devices operating 180° apart.

Pythagorean theorem

A theorem in geometry: The square of the hypotenuse of a right triangle equals the sum of the squares of the other two sides. In electronics used for vector analysis of AC circuits

Q

Quality factor of an inductor or capacitor. It is the ratio of a component's reactance (energy stored) to its effective series resistance (energy dissipated). For a tuned circuit, a figure of merit used in bandwidth calculations. Q is the ratio of reactive power to resistive power in a tuned circuit. Also the symbol for charge in coulombs (Q for quantity).

Quiescent

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

Quiescent point

(Q point) A point on the DC load line of a given amplifier that represents the quiescent (no signal) value of output voltage and current for the circuit.

R-2R ladder

Network or circuit composed of a sequence of L networks connected in tandem. Circuit used in digital to analog converters.

Radar

Acronym for "radio detection and ranging" A system that measures the distance and direction of objects.

Radio broadcast

Transmission of music, voice and other information on radio carrier waves that can be received by the general public.

Radio communication

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

Radio Frequency (RF)

Generic term defines equipment which works in the radio frequency range typically ? to ?.

Radioastronomy

Branch of astronomy that studies the radio waves generated by celestial bodies and uses these emissions to obtain information about them.

Radio-frequency amplifier

Amplifier having one or more active devices to amplify radio signals.

Radio-frequency generator

Generator capable of supplying RF energy at any desired frequency in the radio-frequency spectrum.

Radio-frequency probe

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

RAM

Random Access Memory. Information can be read and written in any order, the number of read or write accesses is not limited. RAM comes in different flavors: DRAM, SRAM, SDRAM, EDO-RAM, VRAM and many more.

RC

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

RC time constant

Product of resistance and capacitance in seconds.