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( 42)


moving mobile apparatus such as robots. Offers
whisker resistance In a semiconductor material,
simplicity and low cost. The main disadvantage is
the resistance of a whisker component (see
the inability to negotiate irregular terrain.
Wheeler™s formula A formula for calculating the
Whiskey Phonetic alphabet code word for the letter
inductance of a multilayer air-core coil:
L = (0.8a2n2)/(6a + 9l + 10b) whistle A high-pitched tone (e.g., a beat note or
where L is in microhenrys, a is the mean radius acoustic feedback).
(inches) of the winding (axis to center of cross whistle filter A notch filter used to eliminate a
section), b is the depth of winding (inches), l is the whistle in an amplifier or other audio-frequency
length of winding (inches), and n is the number of circuit. This filter can be of several versions,
turns. ranging from a simple resistance-capacitance
whistle filter • Wide Area Telephone Service

(RC) null circuit tuned to remove the offending white recording 1. In amplitude modulation,
frequency to a feedback-type band-suppression recording characterized by a correspondence of
amplifier. maximum received power to minimum recording-
whistle interference The appearance of extrane- medium density. 2. In frequency modulation,
ous whistles in audio-frequency circuits. In some recording characterized by a correspondence of
equipment, whistles result from oscillating ampli- lowest received frequency to minimum recording-
fiers; in radio receivers, they are usually audible medium density.
beat notes (heterodynes) produced by interfering white room See CLEAN ROOM.
carriers. white saturation See WHITE COMPRESSION.
whistler A type of very-low-frequency (VLF) radio white signal The facsimile signal (see FACSIMILE)
noise. They are thought to be caused by electro- corresponding to scanning the copy area having
magnetic fields from distant lightning strokes, maximum density.
circulating in the earth™s magnetic field. The white-to-black amplitude range 1. At a point in a
name is derived from the peculiar sound the positive amplitude-modulated (AM) facsimile sys-
noise makes in a VLF radio receiver. tem (see FACSIMILE), the ratio (in dB) of signal
whistler mode propagation Radio transmission current or voltage corresponding to white in the
from the northern hemisphere to the southern picture to that for black in the picture. 2. At a
hemisphere along the flux lines of earth™s point in a negative AM facsimile system, the ratio
magnetic field. (in dB) of signal current or voltage corresponding
whistlestop See WHISTLE FILTER. to black in the picture to that for white in the
whistling atmospheric See WHISTLER. picture.
white The color that results from mixing all the ad- white-to-black frequency swing At a point in a
ditive primary colors: red, green, and blue. frequency-modulated facsimile system, the fre-
white acid Hydrofluoric acid. Formula, HF. Used quency difference fw “ fb, where fb is the fre-
as an etchant, especially of glass. quency corresponding to black in the picture, and
white brass Brass that is more than 49% zinc. fw is the frequency corresponding to white.
white compression In television transmission, re- white transmission A system of picture or facsim-
duction of gain at highlight levels in the picture. ile transmission in which the maximum copy
white-dot pattern In color-television tests with a darkness corresponds to the smallest amplitude
dot generator, the one-white-dot pattern obtained (in an amplitude-modulated transmitter) or the
when beam convergence has been secured. highest instantaneous frequency (in a frequency-
white lamp See DAYLIGHT LAMP. modulated transmitter). The opposite of BLACK
white level The lower-voltage point in a video sig- TRANSMISSION.
nal, corresponding to full brilliance of the line on white X radiation X rays of the continuous, or
the screen (i.e., to the condition of whiteness in general, type.
the picture). whizzer An attachment that can improve the high-
white light See WHITE RADIATION, 2. frequency reproduction in some audio loud-
white noise Random noise (acoustic or electric) speakers.
equally distributed over a given frequency band, whole-number division Arithmetic division (as in
an example being the noise resulting from the the division of binary numbers) in which the quo-
random motion of free electrons in conductors tient is a whole number (i.e., division in which the
and semiconductors. divisor is contained in the dividend an integral
white-noise generator A test device that generates number of times).
electrical noise over a wide frequency spectrum. A whorl See WHIRL.
simple type uses a reverse-biased silicon diode, WHP Abbreviation of water horsepower.
the output of which is useful for testing audio wick action 1. The absorption of a liquid by, and
amplifiers and radio receivers. its flow through, a cloth or thread, such as a lamp
white-noise record A phonograph record contain- wick or lubricating wick. 2. The flow of molten
ing recorded bands of white noise, each accompa- solder along and under the insulation of a wire.
nied by voice announcements (e.g., instructions), wicking See WICK ACTION.
and used to test the frequency response of a wide-angle diffusion A form of diffusion charac-
sound system. terized by the wide-angle scattering of light;
white object A body that reflects and diffuses light causes the source to have the same brightness at
of all wavelengths equally well. all viewing angles.
white peak In a television picture signal, the max- wide-area network A group of computers linked
imum excursion in the white direction. together, but separated by large geographic dis-
white radiation 1. See WHITE NOISE. 2. Visible tances. Links can be made via telephone lines or
light radiated with more or less equal intensity radio.
throughout the visible spectrum; seen as gray or wide-area service A teletype network that operates
white. over long-distance wire lines.
white raster See CHROMA-CLEAR RASTER. Wide Area Telephone Service See WATS.
750 wideband • width mode

wideband 1. Having a bandwidth greater than the special external probes or converters). An exam-
minimum necessary to transmit a signal with ac- ple is an electronic ac voltmeter with a range ex-
ceptable intelligibility. 2. For a voice signal, hav- tending from 10 Hz to 2.5 MHz.
ing a bandwidth greater than 6 kHz. 3. Having wide-base diode A junction diode in which the p
the capability to operate, without adjustment, region is considerably wider than the n region.
over a broad and continuous range of frequencies wide-open 1. Pertaining to wideband, untuned re-
or wavelengths. 4. In a digital network, a channel sponse. 2. Pertaining to maximum-gain operation
having a bandwidth of more than 64 kbps but (e.g., a wide-open amplifier or receiver).
less than 2 Mbps. wide-range ammeter An ammeter that employs
wideband amplifier An amplifier that exhibits rea- one or more shunt resistances to increase the
sonably flat response to a broad band of frequen- full-scale deflection, usually by a power of 10 (10,
cies. The term is relative, depending on the 100, 1000, etc.). The resistor must be capable of
application. carrying the current without burning out.
wideband antenna An antenna that transmits or Shunts are used when it is necessary to measure
receives signals over a broad frequency range, very large currents, such as hundreds of am-
usually without the need for tuning. peres. Shunts also allow a microammeter or mil-
wideband axis In a color-television signal, the di- liammeter to be used as a multimeter with many
rection of the fine chrominance primary phasor. current ranges.
wideband communications 1. Communications wide-range reproduction High-fidelity audio-
carried out over a band of frequencies wider than frequency reproduction.
the minimum necessary for effective transfer of width 1. The horizontal dimension of a pulse, usu-
the information. 2. A method of transmitting and ally corresponding to its effective duration; also
receiving signals by deliberately varying the called PULSE DURATION. 2. The horizontal di-
channel frequency over a wide range. Also called mension of an image, such as a television picture.
spread-spectrum communications.
wideband generator A signal generator covering a
wide frequency range. Typical coverage in a labo-
ratory-type instrument is 10 kHz to 1000 MHz.
wideband oscilloscope An oscilloscope whose hor-
izontal, vertical, and sweep channels operate over
a wide band of frequencies. Although the term
wideband is relative, a wideband oscilloscope is

usually assumed to be capable of displaying both
radio and audio frequencies.
wideband ratio The ratio B1/B2, where B1 is fre-
quency bandwidth and B2 is intelligence band-
width. Width
wideband receiver A radio receiver that can tune
in signals over a broad range of frequencies. An
example is a communications receiver that can
cover 10 kHz to 30 MHz continuously.
wideband repeater A repeater capable of operating
over a wide range of input and output frequen-
cies. Such repeaters are used in active commu-
width, 1.
nications satellites handling many different
channels at the same time.
wideband signal generator See WIDEBAND GEN-
ERATOR. width coding The modification of pulse duration
wideband sweep 1. In the operation of an oscillo- according to a code.
scope, a repetitive sweep of the electron beam, width coil See WIDTH CONTROL, 1.
the frequency of which is adjustable to any de- width control 1. In a television receiver, the vari-
sired point within a wide range. The basic sweep able component for adjusting the swing of the
rate in simple oscilloscopes is restricted to the horizontal deflection voltage and, therefore, the
audio-frequency spectrum (up to about 20 kHz), width of the picture. It is often a slug-tuned coil
but a wideband sweep extends to much higher connected in parallel with a portion of the sec-
frequencies, typically several tens of MHz. 2. A ondary winding of the horizontal output trans-
sweep circuit that produces the wideband sweep former. 2. Sometimes, the horizontal gain control
action described in 1. in an oscilloscope.
wideband test meter An alternating-current (ac) width mode In electronic-counter operations, a
meter that can measure quantities over a wide time-interval mode in which the signal is
frequency range in its basic form (i.e., without measured.
width modulation • Wilson cloud chamber

width modulation Modulation of the interval dur- Wien-bridge heterodyne eliminator A notch filter
ing which a gate circuit is open. composed of a continuously variable Wien-bridge
Wiedemann effect See DIRECT WIEDEMANN EF- circuit (see WIEN BRIDGE). The device is con-
FECT. nected in the audio-frequency channel of a radio
Wiedemann-Franz law For metals that are good receiver, and is tuned to remove a troublesome
electrical conductors, the ratio of thermal con- heterodyne whistle.
ductivity to electrical conductivity is nearly con- Wien-bridge oscillator An oscillator in which the
stant, and is proportional to the absolute frequency-selective feedback network is a Wien-
temperature. bridge circuit (see WIEN BRIDGE). Also see
Wien bridge A frequency-sensitive bridge in which BRIDGE-TYPE OSCILLATOR.
two adjacent arms are resistances and the other
two adjacent arms are resistance-capacitance
(RC) combinations. One of the latter contains re-
sistance and capacitance in series; the other con-
tains resistance and capacitance in parallel. R2 Output
Because the bridge can be balanced at only one
frequency at a time, it is useful as a simple audio C2 R5
frequency meter (see BRIDGE-TYPE AF METER).
It is used also for capacitance and resistance R6
+B +B
measurements. When inductors are substituted
for the capacitors, the Wien bridge can be used
for inductance measurements (see WIEN INDUC-
Wien-bridge oscillator

Wien capacitance bridge A Wien bridge arranged
for the measurement of unknown capacitance.
Wien effect For an electrolytic substance, an in-
crease in conductivity (decrease in resistivity)
R1 R2 that occurs when a very large voltage is placed
across the material. This voltage must be greater
than approximately 1 megavolt per 50 cm.
Wien inductance bridge A Wien bridge containing
inductors in place of capacitors and used for the
R3 R4 measurement of unknown inductance.
Wien™s displacement law The wavelength of maxi-
mum radiation of a black body is inversely pro-
portional to the absolute temperature.
Wien™s first law See WIEN™S DISPLACEMENT
Wien bridge Wien™s laws See WIEN™S FIRST LAW, WIEN™S
Wien™s radiation law See WIEN™S SECOND LAW.
Wien-bridge audio frequency meter See WIEN- Wien™s second law The emissive power of a black
BRIDGE FREQUENCY METER. body is proportional to the fifth power of the ab-
Wien-bridge distortion meter A distortion meter solute temperature.
in which a Wien bridge circuit is used to remove Wien™s third law An empirical law for the spectral
the fundamental frequency from the complex distribution of energy radiated from a black body
waveform. The bridge is inserted between ampli- at a specified temperature. The distribution is a
fier stages, and its notch response is sharpened curve with a peak (maximum) at a wavelength
by means of overall negative feedback. that depends on the temperature. The higher the
Wien-bridge equivalent A resistance-capacitance temperature, the shorter the wavelength at which
null circuit, such as the parallel-tee (twin-tee) maximum radiation occurs.
network, which has the same balance equation as willemite See ZINC ORTHOSILICATE PHOSPHOR
the Wien bridge. and ZINC SILICATE PHOSPHOR.
Wien-bridge filter A Wien bridge used as a band- Williams tube A type of electrostatic cathode-ray
suppression filter (notch circuit). storage tube.
Wien-bridge frequency meter A bridge-type audio Wilson chamber See WILSON CLOUD CHAMBER.
frequency meter in which the continuously vari- Wilson cloud chamber An airtight chamber con-
able frequency-selective circuit is a Wien bridge. taining water vapor or alcohol vapor at low pres-
Also see BRIDGE-TYPE AF METER. sure, and provided with a viewing window.
752 Wilson cloud chamber • wing

Radioactive particles penetrating the chamber Windom antenna 1. A multiband antenna in
are made visible as droplets form trails when the which a single-wire feeder is attached to a hori-
vapor condenses on them. zontal half-wave radiator wire somewhat off cen-
ter, at a point about 1„6 wavelength from one end
Wilson effect Electric polarization of a dielectric
material being moved in a magnetic field. of the radiator. The antenna operates with rea-
Wilson electroscope A leaf-type electroscope (see sonable efficiency at the first several harmonics
of the frequency at which it measures 1„2 wave-
ELECTROSCOPE) using a single leaf hanging ver-
tically. length. 2. A similar antenna using a parallel-
Wilson experiment An experiment demonstrating wire feeder.
the WILSON EFFECT. It consists of rotating
about its axis a hollow dielectric cylinder (whose
135 Ft
inner and outer surfaces are metallized) in a mag-
44 Ft
netic field parallel to the axis. The result: An al-
ternating voltage appears between the metallized f0 =3.5 MHz
surfaces. and harmonics
Wimshurst machine A rotating machine used to
Feed line
produce high-voltage static electricity. The ma-
to Xmtr
chine contains two glass disks, each having
(300 ohms)
separate sectors of metal foil spaced around its
face. The disks rotate in opposite directions,
Windom antenna, 2
and the foil sectors passing each other form
variable capacitors. Metal brushes pick up
charges from the sectors passing under them window 1. Radar-interference material (see
and deliver this energy to one or more Leyden CHAFF). 2. An interval during which a circuit is
jars for storage. gated open to permit signal sampling. During this
wind charger A wind-driven generator used specif- interval, a window is figuratively open to the
ically to supply direct current for charging stor- signal. 3. The open spaces between the legs of an
age batteries. iron core for a transformer or choke coil. 4. An
wind-driven generator A dynamo-type generator, electromagnetic frequency band easily trans-
either stationary or mobile, powered by a wind- mitted by earth™s atmosphere. 5. The period during
mill-like device. which conditions are ideal for a complex opera-
wind gauge See ANEMOMETER. tion, such as a rocket or spacecraft launch. 6. An
winding 1. A coil in an inductor or transformer application space in a computer program that
(e.g., primary winding, secondary winding, output uses a graphical interface.
winding, etc.). 2. A coil in a motor or generator. window area See WINDOW, 3.
winding arc The winding length of a coil, ex- window comparator A comparator that detects
pressed in degrees. voltage levels within a certain range of values,
winding cross section The cross section of a mul- rather than simply indicating whether a voltage is
tilayer coil. more or less than a certain specified value.
winding depth The depth of a multilayer coil, mea- window corridor An area where window (see WIN-
sured from the outermost layer to the innermost DOW, 1) has been dispersed.
layer. window jamming The disturbance of electronic
winding factor For a transformer or choke coil (or communications, especially radar, by dumping
for a toroidal coil), the ratio of the total area of reflective material, such as metal foil, from an air-
wire in the window to the window area. craft. Also see CHAFF; JAMMING; and WINDOW,
winding length The length of a coil from the first 1.
turn to the last in a single-layer coil, or from the Windows Trade name (Microsoft) for a personal-
first turn to the last in one layer of a multilayer computer interface scheme. The several versions
coil when all layers are identical. all use selectable icons and menus.
winding space The window area of the core of a window strip An insulated, flat, metal strip for
transformer or choke (see WINDOW, 3). bringing an antenna lead-in through a window.
wind loading 1. The total wind pressure on an an- The window can be closed on the strip.
tenna system, generally measured in pounds wind screen A foam covering that can minimize
or kilograms. The greater the wind speed, the roar caused by wind blowing against or
the greater the wind loading for a given antenna. across a microphone.
The greater the exposed surface of the antenna, wind shield A radio-transparent cover placed over
the greater the wind loading for a given wind a radar antenna to protect it against damage from
speed. 2. The highest wind speed, in miles per high winds. It is used especially in radar systems
hour or meters per second, that an antenna sys- aboard aircraft.
tem can safely withstand, assuming no accumu- wing In an antenna or other radiator, a (usually
lation of ice on the antenna structure. flat) member attached to, and sticking out from,
wing • wire gauge

another member. Its name is derived from its Utility line
characteristic shape.
winterization The protective treatment and prepa-
ration of electronic equipment for winter storage
or for operation in frigid regions.
wipeout Severe interference that obliterates all de-
sired signals.
Coupler Hot
wipeout area An area in which WIPEOUT occurs.
wiper 1. A thin metal blade or strip in sliding con-
tact with a coil or other element over which it is
turned to vary some quantity (such as resistance,
inductance, voltage, current, etc.). 2. A brush in
a motor or generator.
wiper arm See WIPER, 1.
wiper blade See WIPER, 1.
wiping action The movement of contacts against
each other when they slide as they mate or with-
draw. Ground
wiping contact A contact that makes and breaks
with a sliding motion. Transceiver
wire 1. A metal strand or thread serving as a con-
ductor of electricity. 2. To connect wires between
points in a circuit. 3. See TELEGRAM. 4. To send
a TELEGRAM. Neutral
wire bonding 1. The interconnection of compo-
nents within a discrete package, by means of fine
wire conductors welded to the individual compo-
nents. 2. A method of temporarily splicing the
outer conductors of two coaxial cables. 3. In gen-
eral, any solderless method of splicing between
two conductors. wired radio
wire broadcasting Broadcasting by means of
carrier-current communication (see WIRED
RADIO). rectifies a radio signal picked up from wires that
wire cloth A net of fine wire, used as an electrical conduct it from a transmitting station.
shield when air circulation is necessary. wired-radio transmitter The complete device or
wire communication Communication carried on system that generates radio-frequency power,
by means of signals transmitted over wire lines, adds signals (for communication, remote control,
as opposed to wireless (radio) communication. telemetry, etc.), and delivers the power to wires or
wire control The control of remote devices by to a cable for reception at a distant point.
means of signals transmitted over wire lines, as wire drawing In the manufacture of wire, pulling
opposed to radio control. metal through special dies to form wire of se-
wire core A magnetic core consisting of a bundle of lected diameter.
iron (or magnetic alloy) wires. wire dress The careful arrangement of wires in a
wired AND See DOT AND. chassis to ensure optimum performance. Also
wired-in component A component to which wires called lead dress (see DRESS).
are permanently connected in a circuit, as op- wire duct A conduit through which wires are run.
posed to a plug-in component. Such ducts have several shapes, but generally
wired OR See DOT OR. are rectangular.
wired-program computer A computer in which in- wired wireless See WIRED RADIO.
structions are wired-in by making appropriate wire-equivalent security See LEVEL-1 SECU-
connections to a panel with patch cords. RITY.
wired radio The transmission and reception of wire fuse A fuse in which the fusible element is a
voice and other sounds, telegraph signals, pic- wire of low-melting-point metal. Compare STRIP
tures, control signals, telemetry signals, and the FUSE.
like by means of radio-frequency energy con- wire gauge 1. A system for specifying the charac-
ducted by wire lines. Usually, the lines are used teristics of wire. See AMERICAN WIRE GAUGE
primarily for some other purpose (e.g., power and BIRMINGHAM WIRE GAUGE. 2. A wire num-
lines or telephone lines). ber governed by diameter (e.g., 18-gauge wire for
wired-radio receiver The complete device or sys- #18 wire). 3. A tool or instrument for measuring
tem that selects, amplifies, and demodulates or wire diameter or for determining wire number.
754 wire gauze • wire splice

wire gauze A fine screen of thin wires. of short-range (on the order of a few feet) radio or
wire grating See WAVEGUIDE GRATING. infrared transceivers. One unit connects to a tele-
wire-guided Pertaining to guiding a machine, such phone jack or cable port, and the other unit con-
as a robot, by means of signals sent by wire from nects to a computer. Can protect a portable
the control point. computer against damage by lightning, assuming
wire leads Leads that are (usually thin, flexible) the computer uses batteries and is not connected
wires, rather than pins, bars, strips, etc. An ex- to utility mains.
ample is the wire leads of some transistors (as op- wireless tap A method of eavesdropping on com-
posed to terminal pins). munications in which a portion of the circuit
wireless 1. Pertaining to data communications makes use of a radio-frequency wireless link. An
and control systems that operate without wires eavesdropping receiver can be positioned within
(e.g., an infrared link between a notebook com- range of the wireless transmitting antenna, and
puter and a desktop computer). 2. An early name the signals intercepted. The existence of such a
for radio; it is still used in some countries. Some- tap causes no change in the electronic character-
times for specificity, radio is referred to as wire- istics of any equipment in the system, so its
less telegraphy or wireless telephony. See deployment is difficult to detect even if
RADIOTELEPHONY. eavesdropping is anticipated.
wireless access protocol Acronym, WAP. A com- wireless telegraphy See RADIOTELEGRAPHY.
munications standard used on a worldwide basis wireless telephone 1. A radio transceiver inter-
with portable cellular telephone sets incorporat- connected with the telephone lines. 2. A tele-
ing electronic mail, online service access, and/or phone in which a short-range radio link replaces
Internet access. the cord between the receiver and the base unit.
wireless broadcaster See WIRELESS MICRO- It normally has a range of several hundred feet.
PHONE. wireless telephony See RADIOTELEPHONY.
wireless compass A radio compass (see DIREC- wire line One or more wires or cables conducting
TION FINDER). currents for communication, control, or measur-
wireless device A device that operates over a dis- ing purposes.
tance, without the use of interconnecting wires. wire link A line for wire communication or wire
wireless e-mail 1. The use of electronic mail control.
(e-mail) in conjunction with a wireless Internet ser- wire-link telemetry Telemetry carried on over a
vice. 2. The use of a specialized portable wireless wire link.
communications device, resembling a stripped- wireman 1. An electrician who specializes in the
down computer or an enhanced cell phone, to installation and servicing of electrical wiring.
send and receive e-mail messages. 2. See LINEMAN.
wireless intercom An intercom using wired-radio wire mile A unit of measure equal to the product
for transmission and reception over the power ns, where n is the number of separate, equal-
line from which it is operated. Also see WIRED length conductors in a line, and s is the length of
RADIO. a conductor in miles.
wireless Internet 1. The use of a personal com- Wirephoto 1. A system for transmitting and receiv-
puter, usually a notebook or portable, in con- ing photographs over wire lines. Also called
junction with a wireless modem connected to the Telephoto. See FACSIMILE. 2. A photograph
Internet. Services of this type are provided with transmitted and/or received, as defined in 1. 3. A
high-end cellular telephone subscriptions. As- trademark for a photograph transmitted and re-
sets and limitations are similar to those associ- ceived over telephone lines.
ated with cell phone services. 2. The use of a wire printer A printout device consisting of a wire
specialized portable or mobile wireless communi- array in which each wire is activated by an elec-
cations device, resembling a stripped-down com- tromagnet. When a wire is selected (electrically),
puter or an enhanced cell phone, for basic it is pushed against, and makes a dot on the
Internet communications and information recording paper. The letters and figures, then, are
retrieval. dot patterns. Compare WHEEL PRINTER.
wireless microphone A device consisting of a wire radio See WIRED RADIO.
small radio-frequency oscillator modulated by the wire recorder In audio applications and data
microphone to which it is attached, and provided recording, a machine that records sounds or data
with a tiny antenna. The modulated signal is pulses in the form of magnetized spots on a thin
picked up and reproduced by a radio receiver. wire.
wireless modem 1. A modem that facilitates con- wiresonde A system for transmitting weather in-
nection of a computer to the Internet using a cell formation data through a cable that holds a cap-
phone set. 2. A wireless transceiver that facili- tive balloon. Compare RADIOSONDE.
tates connection of a computer to the Internet. A wire splice A strong, low-resistance joint between
cellular telephone connection can be included as (usually two) wires. See, for example, WESTERN
an option. 3. Also called cordless modem. A pair UNION JOINT.
wire stripper • Wolf™s equation

wire stripper A hand tool or power machine for wire-wrapping tool A device used to make a wire-
cutting the insulating jacket on a wire and re- wrap connection.
moving it without cutting or nicking the wire. wiring 1. The system of wires or similar conduc-
wiretap 1. An instance of wiretapping. 2. A wire- tors connected between circuit components. 2.
tapping device. Connecting and dressing such wires, as in wiring
wiretapper 1. A device for wiretapping. 2. A person a circuit. 3. Collectively, the connections (either
who practices wiretapping. actual wire or printed metal lines or processed
wiretapping The act of making direct or indirect semiconductor paths) between terminals and
connections to a communications line to overhear components in an electronic circuit. 4. The pro-
or record a conversation. cess of installing or making such connections.
wire telegraphy Telegraphic communication car- wiring board The control panel of a computer (i.e.,
ried on by means of signals transmitted over wire a plugboard).
lines, as opposed to wireless (radio) telegraphy. wiring capacitance Unavoidable capacitance be-
wire telephony Voice communication carried on tween wires in a circuit, or between the wires and
by means of signals transmitted over wire lines, nearby metal bodies.
as opposed to wireless (radio) telephony. wiring connector A small (usually metal) fitting
wire tie See TIE. used to tie wires together.
wire wave communication See WIRED RADIO. wiring diagram See CIRCUIT DIAGRAM.
wireways Hinged-cover metal troughs for contain- wiring impedance Unavoidable impedance in the
ing and protecting wires and cables. Also see wires in a circuit, and in associated terminals
WIRE DUCT. and hardware conducting alternating current.
wirewound potentiometer A potentiometer in This impedance is the vector sum of WIRING RE-
which the resistance element is a coil of resis- ACTANCE and WIRING RESISTANCE.
tance wire wound on a cord bent into a cylinder, wiring inductance Unavoidable inductance in the
or on a rigid, circular core. wires in a circuit, and in associated terminals
wirewound resistor A resistor made from a coil of and other hardware, through which alternating
wire that is a poor conductor. The wire is usually currents flow.
wound around a cylindrical form; some compo- wiring reactance Unavoidable reactance in the
nents use toroidal forms. The resistance is deter- wires in a circuit, and in associated terminals
mined by how well the wire metal conducts, by its and other hardware, conducting alternating cur-
diameter (gauge), and by its length. This type of rent. This reactance is caused by WIRING CA-
resistor can be manufactured to precision toler- PACITANCE and/or WIRING INDUCTANCE.
ance. If the wire gauge is heavy, it can dissipate wiring resistance Unavoidable resistance in the
large amounts of power. The component has in- wires in a circuit and in associated terminals and
ductive reactance, making it unsuitable for use at other hardware.
radio frequencies. Compare CARBON-COMPOSI- Witka circuit A voltage-tripler circuit using only
TION RESISTOR, FILM RESISTOR. two diodes and two capacitors. Its no-load direct-
wirewound rheostat A rheostat in which the resis- current output voltage is approximately three
tance element is a coil of resistance wire wound times the peak value of the alternating-current
on a card bent into a cylinder, or on a rigid, cir- input voltage. Also see VOLTAGE TRIPLER.
cular core. wk 1. Abbreviation of WORK. 2. Abbreviation of
wire wrap A method of circuit-board wiring in which week.
components are interconnected by individual wire WL 1. Abbreviation of WAVELENGTH. 2. Abbrevia-
conductors, the ends of which are wrapped tion of waterline.
around terminal posts using a special tool. WM Abbreviation of WATTMETER.
Wm2 Symbol for watt square meter (unit of the first
wire-wrap connection An electrical connection
made by tightly wrapping a bare wire around a radiation constant).
special terminal. W/(MK) Symbol for watts per meter kelvin (unit of
thermal conductivity).
WMO Abbreviation of World Meteorological Organi-
wobbulator A device that sweeps the frequency
of an oscillator. There are several types, from a
motor-driven, rotating, tank capacitor to sophisti-
cated, fully electronic variable capacitors or
variable inductors.
wolfram See TUNGSTEN.
Wolf™s equation A sunspot-number equation used
to forecast maximum usable frequency: R =
k(10G + N), where R is relative sunspot number, k
is a constant for the telescope used, G is the
wire wrap
756 Wolf™s equation • working voltage

number of sunspot groups observed, and N is the replaced, or deleted prior to the final printout.
total number of sunspots. 2. A computer used for writing, as defined in 1.
Wollaston wire An extremely fine wire made by 3. Software that allows a computer to be used for
coating platinum with silver, drawing it thinner, writing, as defined in 1.
and dissolving the silver coat. word rate In a communications or computer sys-
womp A sudden surge in amplitude that causes a tem, the number of words per unit time (e.g.,
flare up of brightness in a television picture. WORDS PER MINUTE).
woodpecker A slang term used to describe the word size See WORD LENGTH.
sound of the signal from over-the-horizon radar. words per minute In telegraphy, a measure of
Operating in the high-frequency part of the spec- data speed. It is approximately equal to the num-
trum and changing in wavelength, roughly follow- ber of characters (including spaces) per minute
ing the maximum usable frequency, the signal divided by 6.
consists of repeated “spikes” that can interfere word time In computer operations, the time re-
with routine communications. quired to process one word that is in storage.
woodpecker filter A special type of blanking filter work 1. Symbol, W. Units: joule, erg, foot-pound,
used to quiet a shortwave receiver during strong, kilogram-meter. That which is accomplished by
brief “spikes.” It is similar to a noise blanker, but the transfer of energy from one body to another,
is designed to filter out the longer peaks charac- as when an exerted force causes a displacement.

teristic of the over-the-horizon radar, known as The amount of work performed is equal to force
the WOODPECKER. times distance: W = Fd. 2. An amateur radio term

Wood™s alloy See WOOD™S METAL. meaning to engage in two-way communication
Wood™s metal A low-melting-point (159.8°F) alloy with another station.
containing bismuth (50%), cadmium (12.5%), work area In computer operations, a temporary
lead (25%), and tin (12.5%). The alloy looks like area of memory for data items being processed.
lead and is used to mount rectifying crystals Also called INTERMEDIATE STORAGE, WORK-
(such as galena) whose electrical sensitivity ING MEMORY, and WORKING STORAGE.
would be destroyed by the high temperatures re- work coil The alternating-current-carrying coil
quired to melt most soft metals. that induces energy in the workpiece in induction
woofer A large loudspeaker, often a foot or more in heating.

diameter, designed specifically to reproduce very work envelope The range of motion over which a
low (bass) audio frequencies. It is commonly used robot arm can move. It can be two-dimensional or
in high-fidelity stereo sound systems. Compare three-dimensional.
TWEETER. work function Unit, eV. The energy required to
word 1. In computer operations, a group of bits or bring an internal particle to the surface of a ma-
characters treated as a unit. 2. In telegraphy, a terial and out into space, as when an electron is
data unit consisting of five characters plus one emitted by the hot cathode of a vacuum tube. The
space. work function is the voltage required to extract 1
word-address format A method of addressing a electrostatic unit of electricity from the material.
word by means of a single character, such as the working data file A temporary accumulation of
first letter of the word. data sets that is erased or otherwise discarded af-
word code 1. A cipher in which word meanings are ter its transferal to another medium.
interchanged, rather than letter symbols. 2. A working life The expected or guaranteed lifetime of
word having an altered meaning in a cipher sys- a material, device, or system in actual operation
tem, as defined in 1. For example, “word” might or use. Compare SHELF LIFE.
mean “code.” working memory See WORK AREA.
word format The specific sequence of characters working point The operating point of an active de-
that forms a word of data. vice (i.e., the point along one of the characteristic
word generator A special signal generator that de- curves around which operation is fixed).
livers pulses in selected combinations corre- working Q The Q of a loaded circuit or device (e.g.,
sponding to digital words (see WORD, 1). It is tank-circuit Q of a radio transmitter loaded with
used in testing computers and digital systems. an antenna or dummy load).
word length 1. In computer operations, the num- working range 1. The usable maximum distance
ber of bits in a word. 2. In telegraphic communi- between a transmitter and receiver in a wireless
cations (radio or wire), the average number of communications circuit. 2. The allowed range
letters in a word. over which specified parameters can vary in a
word pattern The shortest meaningful word (see particular system while facilitating normal opera-
WORD, 1, 2) that can be recognized by a ma- tion, or operation within rated specifications.
chine. working storage See WORK AREA.
word processor 1. An electronic device, similar to working voltage The (usually maximum) voltage
a typewriter, used for writing. Words, phrases, at which a circuit or device can be operated con-
sentences, or paragraphs can be changed, tinuously with safety and reliability.

workout • wrong color

workout 1. A dry run; a test. Example: checking a are occupied) and additional data is traced from
computer™s processing power using a set of top to bottom.
benchmark programs. 2. An exacting test of wrap joint See WIRE-WRAP CONNECTION.
equipment; a burn-in procedure. wrapper A paper or tape wound around a compo-
workpiece The object heated by an induction or di- nent, such as a coil or capacitor, for insulation
electric heater. and protection.
worm A cylindrical gear whose spiral “teeth” re- wrapping 1. See WRAPPER. 2. Insulating a wire or
semble a screw thread. other conductor by wrapping insulating tape
worm drive A mechanism for transferring motion around it.
from a tuning-knob shaft through a right angle to wrap post A terminal post, tip, pin, or lug used in
the shaft of an adjustable component, such as a a wire-wrap connection.
potentiometer or variable capacitor. The knob wrap-up The (usually successful) completion of a
turns a threaded shaft that mates with a gear design, fabrication, test, or investigation.
wheel. Wratten filter A light filter for separating colors. It
is available in transparent sheets of various col-
ors and is useful in photography and in several
Threaded phases of electronics, including the operation of
shaft color meters and color matchers.
wrinkle finish A pattern of fine wrinkles created by
To special paint when it dries on a surface, such as
that of a metal cabinet for a piece of electronic
wrist-force sensor In robotics, a set of strain
gauges that detects the various forces in the joint
connecting an end effector to an arm, and sends
signals back to the robot controller. The con-
troller can use the signals to direct the move-
ments of the arm and end effector.
write 1. In computer operations, to transfer data
worm drive
from one form of memory or storage to another
form. Example: To transfer data in a computer
worst-case circuit analysis Analysis that seeks from random-access memory (RAM) to the hard
the worst possible effects of variations in circuit disk. Compare READ. 2. To produce an image on
parameters on circuit performance”especially the storage mesh in the cathode-ray tube of a
variations in component characteristics. storage oscilloscope.
worst-case noise pattern See DOUBLE-CHECK- write enable ring See WRITE PERMIT RING.
worst-case design The design of electronic equip- write head In a magnetic memory or in a tape
ment in such a way that normal operation is ob- recorder or wire recorder used for recording data,
tained”even though the characteristics of circuit the head that magnetizes the drum, tape, disk, or
components might vary widely. wire. Compare READ HEAD.
woven resistor A resistance element made of write pulse In computer operation, the pulse that
strands of resistance material woven in the form causes information to be recorded in a magnetic
of gauze. cell, or sets it to the one-state. Compare READ
wow Slow, periodic variations in the pitch of repro- PULSE.
duced sound because of variations in the speed of write time The time taken to write data to a stor-
the drive mechanism. Its name is derived from its age device.
characteristic sound. Compare FLUTTER. writing gun In a storage oscilloscope, the electron
wow meter An instrument that indicates the gun that produces the image electronically on the
amount of wow produced by a turntable or other storage mesh. It is mounted in the rear of the
moving part. cathode-ray tube. Compare FLOOD GUN.
Wpc Abbreviation of watts per candle. writing head See WRITE HEAD.
wpm Abbreviation of words per minute. writing rate In photographing the image on a cath-
wrap See WIRE-WRAP CONNECTION. ode-ray tube screen, the highest spot speed at
wrap-around 1. The extent of curvature in mag- which an acceptable picture can be made.
netic tape passing over the heads during record- writing speed See WRITING RATE.
ing or playback. 2. An enclosure that resembles a writing telegraph See TELAUTOGRAPH.
sheet (wrapped around a piece of electronic wrong color The instance of an undesired color
equipment). 3. In computer and data-processing (e.g., purple instead of red) in a color-television
operations, a technique in which the display is picture. The condition is often caused by a mal-
cleared of data once it is filled (all available lines function of the chroma demodulator(s).
758 W/(sr•m2) • wye-wye circuit

W/(sr•m2) Abbreviation of watts per steradian wye junction See WAVEGUIDE WYE.
wye-matched-impedance antenna An antenna in
square meter.
which the impedance of a nonresonant open-wire
WT 1. Abbreviation of wireless telegraphy. 2. Ab-
feed line is matched to that of the center of the ra-
breviation of WATERTIGHT.
diator by spreading the end of the feeder wires
wt Abbreviation of WEIGHT.
out into a Y-shaped or delta-shaped match-
WUI Abbreviation of Western Union International.
ing section. Also called DELTA-MATCHED-
Wulf electrometer See BIFILAR ELECTROMETER.
Wullenweber antenna An electronically steerable
wye point The star point in a three-phase system.
antenna composed of two concentric circular ar-
rays of masts connected to the steering circuitry.
WUX Abbreviation of Western Union telegram.
WVdc Abbreviation of direct-current working volt-
age: the maximum continuous direct-current Radiator
voltage that can safely be placed across a compo-
ww Abbreviation of wirewound. Matching section
W/sr Abbreviation of watts per steradian (unit of
radiant intensity). Insulating
WWV The call letters of a standard-frequency/ spreader
standard-time broadcasting station operated by
the National Bureau of Standards and located
in the continental United States. Also see Feeders
WWVH The call letters of a standard-frequency/
standard-time broadcasting station operated by
the National Bureau of Standards and located in
Hawaii. Also see WWV.
wx Radiotelegraph abbreviation of weather.
WXD International Telecommunications Union
symbol for meteorological radar station.
To transmitter
WXR International Telecommunications Union
symbol for radiosonde station.
wye-matched-impedance antenna
wye adapter A connector that provides two out-
puts for a single input, or vice versa. It is com-
monly used in audio applications.
wye box In a three-phase power-measuring setup, wye potential In a three-phase armature, the volt-
a special arrangement of two impedances, each of age between a terminal and the neutral point.
which is equal to the impedance of the potential wye rectifier A three-phase rectifier circuit in
element of the wattmeter used in the setup. The which the transformer or generator windings are
box permits a single wattmeter to be used, which arranged in a wye connection.
indicates one-third the total power. Without the wye-wye circuit A circuit consisting a wye-
box, three wattmeters would be needed. connected generator and a wye-connected load.
wye connection A method of connecting three
windings in a three-phase system so that one ter-
minal of each winding is connected to the neutral
point. It is shaped like the letter Y. Also called
star connection.
wye current Current through one of the branches
of a three-phase star (wye) connection.
wye delta starter A starter circuit for a three-
phase squirrel-cage induction motor. When the Source Load
starter switch is thrown in one direction, the sta-
tor of the motor is wye-connected for starting;
thrown in the opposite direction, the stator is
delta-connected for continued operation.
wye equivalent circuit A wye-connected three-
phase circuit equivalent to a delta-connected
circuit when the impedance of any pair of
corresponding lines for both wye and delta are
the same; the third line is unconnected. wye-wye circuit
X 1. Symbol for REACTANCE. 2. Symbol for no con- X bridge An alternating-current bridge for measur-
nection. (Also, NC.) 3. Symbol for the HORIZON- ing reactance.
TAL AXIS of a graph or screen in the rectangular XC Symbol for CAPACITIVE REACTANCE.
(Cartesian) coordinate system. 4. Symbol for an X channel The horizontal channel of an oscillo-
unknown quantity. scope or recorder. Compare Y CHANNEL and Z
x 1. Symbol for number of carriers drawn from col- CHANNEL.
lector to base of a transistor, for each carrier col- X-channel gain See X GAIN.
lected. 2. Symbol for an unknown quantity. 3. X component In a complex impedance, the reac-
Symbol for the HORIZONTAL AXIS of a graph or tive component (either inductive or capacitive).
screen in the rectangular (Cartesian) coordinate x coordinate See ABSCISSA.
system. X-cut crystal A piezoelectric plate cut with its
x amplifier The horizontal amplifier of an oscillo- faces perpendicular to the X-axis of a quartz crys-
scope or recorder. Compare Y AMPLIFIER and Z tal. See CRYSTAL CUTS.
AMPLIFIER. xcvr Abbreviation of TRANSCEIVER. Often capital-
X and Z demodulation Color television demodula- ized.
tion based on the 60-degree difference between X deflection Horizontal deflection of the spot on
the two reinserted 3.58-MHz subcarrier signals. the screen of a cathode-ray tube. Compare Y DE-
The R-Y, B-Y, and G-Y voltages derived from the FLECTION.
demodulated signals control the three guns of the X diode The decoding diode in each of the X lines
picture tube. Compare Q MODULATION. of a memory matrix. Compare Y DIODE.
x-axis 1. The horizontal axis of a chart, graph, or X direction The horizontal direction in deflections
screen in the rectangular (Cartesian) coordinate and in graphical presentations of data.
system. 2. In a quartz crystal, the axis drawn X drive The driving source or energy for the X lines
through the corners of the hexagon. of a computer memory matrix.
x-axis amplifier See X AMPLIFIER. xducer Abbreviation of TRANSDUCER.
XB Abbreviation of crossbar. Xe Symbol for XENON.
X balance The reactance balance (either the vari- xenon Symbol, Xe. An inert gaseous element.
able component or the adjustment of it) in an Atomic number, 54. Atomic weight, 131.29.
impedance bridge in which separate resistance Xenon is present in trace amounts in the earth™s
(R) and reactance (X) balancing is provided. atmosphere and is used in some thyratrons, elec-
X band The frequency band extending from 5.2 to tric lamps, and lasers.
11 GHz. xenon tube A flash tube filled with xenon.
X bar A rectangular, piezoelectric quartz bar cut xerography A system for the reproduction of
from a Z-section, whose faces are parallel to the printed matter, drawings, and other graphic mat-
X-axis and whose edges are parallel to the X-, Y-, ter. It is an electrostatic process in which a
and Z-axes. See CRYSTAL CUTS. charged photoconductive surface is exposed to an

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760 xerography • X-ray photograph

image of the material to be copied. A latent image If they agree, the next data block is sent. If they
is formed on the surface and is developed (by do not agree, the current data block is retrans-
dusting with black powder attracted to the mitted. Compare YMODEM and ZMODEM.
charged image) to make the image visible. xmt Abbreviation of transmit. Also, xmit.
xeroradiography Xerography using X RAYS. xmtr Abbreviation of TRANSMITTER. Also, xmitter.
xerothermic A condition characterized by both XOR Abbreviation of EXCLUSIVE-OR.
heat and dryness. xover Abbreviation of CROSSOVER.
Xerox 1. Name of a company that manufactures a X particle See MESON.
wide variety of office and computer equipment. xponder Abbreviation of TRANSPONDER.
2. Trade name for a XEROGRAPHY machine. X position 1. The alignment of a cathode-ray beam
3. The reproduction obtained by means of along the horizontal axis of an oscilloscope
XEROGRAPHY (generic term). 4. To make a screen. 2. The position of a point, with respect to
xerographic reproduction (generic term). the horizontal axis of a graph in the rectangular
X factor 1. An unknown or unidentifiable quantity (Cartesian) coordinate system.
or parameter. 2. See X COMPONENT. XR Abbreviation of INDEX REGISTER.
xformer Abbreviation of TRANSFORMER. X radiation Electromagnetic energy in the form of
X gain The gain (or gain control) of the horizontal X rays.
channel of an oscilloscope or X-Y recorder. Com- X-ray 1. Phonetic alphabet communications code
pare Y GAIN and Z GAIN. word for the letter X. 2. Pertaining to, or consist-
X-H array See LAZY-H ANTENNA. ing of, X rays.
XHV Abbreviation of EXTREMELY HIGH VACUUM. X-ray astronomy The science of observing celes-
x intercept The x coordinate of the point at which tial objects and the sky in the X-ray band of wave-
a line or plane intersects the X-AXIS. lengths. Generally, this must be done from above
x irradiate To expose to X RAYS. the earth™s atmosphere because the atmosphere
xistor Abbreviation of TRANSISTOR. absorbs X rays.
XL Symbol for INDUCTIVE REACTANCE. X-ray crystallography The science of observing
X line A horizontal line in a memory matrix. Com- atomic patterns in a crystal by means of X rays.
pare Y LINE. X-ray detecting device 1. An X-ray instrument for
XLR connector A microphone connector with a spotting flaws in solid bodies. 2. A device, such as
locking device to prevent unintentional discon- a fluoroscope, for showing the presence of X rays.
nection. It has three pins and is commonly used X-ray diagnosis The use of X rays in the diagnosis
with balanced audio systems. of disease and in the observation of internal parts
X meter 1. An instrument for measuring reactance of the body.
and phase angle. 2. A form of simple capacitance X-ray diffraction The diffraction of X rays by a
meter whose dial is direct-reading in microfarads, material into or onto which they are directed.
although the deflection is actually proportional to Also see X-RAY DIFFRACTION CAMERA and
the reactance of the capacitor under measure- X-RAY DIFFRACTION PATTERN.
ment. X-ray diffraction camera A special camera that
furnishes a photograph of the pattern created by X
rays diffracted by a material. See X-RAY DIFFRAC-
under test X-ray diffraction pattern The pattern produced
on film exposed to X rays diffracted by a material.
Constant-voltage X-ray goniometer An instrument used to find the
ac input Very low position of the axes of a quartz crystal. It uses X
resistance rays reflected from the atomic planes of the
X-ray inspection The use of X rays in the exami-
nation and study of the internal features of mate-
rials and devices.
X meter, 2
X-ray laser A laser designed to emit coherent
X rays in a narrow beam.
X-ray load 1. An X-ray tube that is the terminal
xmission Abbreviation of transmission.
member of an electronic system. 2. A body, mass,
xmit Abbreviation of transmit. Also, xmt.
or material exposed to X rays.
xmitter Abbreviation of TRANSMITTER. Also, xmtr.
X-ray machine A device that generates X rays for a
XMODEM In data transmission, an error-correct-
specific purpose, such as medical diagnosis.
ing mode in which data is sent in blocks of 128
X-ray photograph A photograph made by expo-
kilobytes (128K), or 131,072 bytes. The source
sure to X rays, especially an X-ray shadowgram,
and destination tally up the bytes in each block.
X-ray photograph • x-y recorder

a picture made without a camera by interposing Electron
an object (such as a part of the human body) be- Anode
tween an X-ray tube and photographic film. (target) Cathode
X-ray radiation See X RADIATION.
X rays Invisible, electromagnetic radiation having
wavelengths ranging from approximately 0.01
nanometer (10“11 meter) to 0.15 nanometer (1.5 —
10“10 meter). These waves are shorter than ultra-
violet, but longer than gamma rays. They can be
produced by bombarding a target of heavy metal
(such as tungsten) with a stream of high-speed
electrons in a vacuum tube. X rays have high
penetrating power, can expose photographic film,
and cause some substances to fluoresce. Also see
X rays
X-ray tube
X-ray spectra The continuous band of ionizing
electromagnetic radiation having wavelengths
ranging from approximately 0.01 nanometers to
causing it to emit X rays. The target is tilted to re-
0.15 nanometers.
flect the X rays through the glass wall of the tube.
X-ray spectrograph A spectrograph used to dis-
X section Abbreviation of cross section.
perse and measure the wavelength of X rays.
X sink The circuit or device into which the X lines
X-ray spectrometer A spectrometer with which
of a memory matrix feed. Compare Y SINK.
the diffraction angle of X rays reflected from the
XT Symbol for total reactance.
surface of a crystal can be measured. The device
xtal Abbreviation of CRYSTAL.
allows the characteristics and composition of al-
xtalk Abbreviation of CROSSTALK.
most any material to be studied.
x unit A small unit of length, equal to approxi-
X-ray star A collapsed star that emits high-inten-
mately 10-13 meter or 10-4 nanometer. Now sel-
sity energy concentrated mainly in the X-ray re-
dom used, the x unit was once often used in the
gion of the electromagnetic spectrum.
expression of ultraviolet and X-ray wavelengths.
X-ray system Collectively, an X-ray tube and the
X wave One (the extraordinary) of the pair of com-
associated equipment required for a specific ap-
ponents into which an ionospheric radio wave is
plication, such as crystallography, irradiation, or
divided by the earth™s magnetic field. Compare
medical therapy.
X-ray technician 1. A professional skilled in the
XXX In radiotelegraphy, a signal meaning urgent.
operation and maintenance of X-ray systems,
X-Y counting A technique used with electronic
who usually works under the supervision of an
counters to determine the ratio of one frequency
engineer. 2. A professional skilled in the medical
(X) to another (Y). When X is the higher fre-
use of X rays, who works under the supervision of
quency, the counter readout shows the number
a medical doctor.
of pulses of X producing one cycle of Y.
X-ray therapy The use of X rays in the treatment
XY-cut crystal A piezoelectric plate cut from a
of certain physiological diseases.
quartz crystal at such an angle that its electrical
X-ray therapy system An X-ray system designed
characteristics fall between those of the X-cut
for X-ray therapy.
and Y-cut crystal.
X-ray thickness gauge An instrument used to
x-y plotter An output device similar to the x-y
measure the thickness of metal, such as a con-
recorder. It allows a digital computer to plot
tinuously moving sheet of steel. The measure-
graphs. Also called data plotter.
ment is in terms of the amount of absorption of
x-y recorder An instrument that produces a per-
an applied X-ray beam by the metal.
manent record (photographic print or directly
X-ray tube A specialized, very-high-voltage diode in
inked paper) of a variable quantity on a chart
which a high-speed electron beam bombards an
having Cartesian (rectangular) coordinates.
anode (target) of heavy metal, such as tungsten,
Y 1. Symbol for ADMITTANCE. 2. Symbol for
Parasitic Parasitic
y 1. Abbreviation of YEAR. (Also, yr.) 2. Abbrevia-
reflector directors
tion of YARD. (Also, yd.) 3. Symbol for the vertical

axis of a graph or screen in the rectangular
(Cartesian) coordinate system.
Y adapter See WYE ADAPTER.
YAG Abbreviation of yttrium-aluminum-garnet, the
stimulated substance in some lasers.
Yagi antenna Also called Yagi-Uda array or beam.
An antenna consisting of two or more parallel,
straight elements, including at least one parasitic
element and at least one driven element. The ele- Mast
ments all lie in the same plane. Each driven ele- Feeder
ment is connected to the feed line, half-wave
resonant, and center-fed. A two-element array yagi antenna
can be formed by adding a director or a reflector
alongside a single driven element. An array with
the English system. 1 yd = 3 ft = 36 inches =
one director and one reflector, along with the
0.9144 meter.
driven element, increases the gain and directivity
yaw Side-to-side movement in a vehicle or robotic
compared with a two-element system. The gain
end effector. Essentially horizontal displacement
and directivity increase further as elements are
about the vertical axis.
added. This is usually done by placing additional
yaw amplifier In an aircraft servo system, the unit
directors in front of a three-element array. Com-
that amplifies the yaw signal (the signal propor-
tional to the deviation of the aircraft from the line
y amplifier The vertical amplifier of an oscilloscope
of flight).
or recorder. Compare X AMPLIFIER and Z AMPLI-
yaw meter An instrument for measuring the angle
of yaw of an aircraft.
Yankee Phonetic alphabet communications code
y-axis 1. The vertical axis of a chart, graph, or
word for the letter Y.
screen in the rectangular coordinate system.
yard Abbreviation, yd. A unit of linear measure in

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y-axis • ytterbium metals

2. In a quartz crystal, the axis drawn perpendic- YIG Abbreviation of yttrium-iron-garnet, a crys-
ular to the faces of the hexagon. talline material used in certain types of acoustic
y-axis amplifier See Y AMPLIFIER. delay lines, parametric amplifiers, and filters.
Yb Symbol for YTTERBIUM. YIG crystal A crystal of yttrium-iron-garnet. See
Y box See WYE BOX. YIG.
Y channel See Y AMPLIFIER. YIG filter A filter using a YIG crystal and tuned
Y-channel gain See Y GAIN. electromagnetically.
Y circulator An interconnection among three YIG-tuned parametric amplifier A parametric
waveguides. When power is applied to the junc- amplifier in which tuning is accomplished by con-
tion through one waveguide, the wave is trans- tinuously varying direct current through the
ferred to the adjacent waveguide immediately to solenoid of a YIG filter.
the right or left. y intercept The y coordinate of the point at which
Y connection See WYE CONNECTION. a line or plane intersects the y-axis.
y coordinate See ORDINATE. ylem The material from which the primordial fire-
Y current See WYE CURRENT. ball is thought to have been made, and from
Y-cut crystal A piezoelectric plate cut from a which the entire known universe is believed to
have originated approximately 10 billion (1010)
quartz crystal in such a way that the plane of the
plate is perpendicular to the Y-axis of the crystal. years ago.
See CRYSTAL AXES and Y-AXIS, 2. Y line A vertical line of a memory matrix. Compare
yd Abbreviation of YARD. X LINE.
Y deflection Vertical deflection of the spot on the Y-matched-impedance antenna See WYE-
screen of a cathode-ray tube. Compare X DE- MATCHED-IMPEDANCE ANTENNA.
FLECTION. YMODEM In data transmission, an error-correct-
Y diode The decoding diode in each of the Y lines of ing mode in which data is sent in blocks of one
a memory matrix. Compare X DIODE. megabyte (1MB), or 1,048,576 bytes. The source
y direction The vertical direction in deflections and destination tally up the bytes in each block.
and in graphical presentations of data. If they agree, the next data block is sent. If they
Y drive The driving source or energy for the y lines do not agree, the current data block is retrans-
of a computer memory matrix. Compare X DRIVE. mitted. Compare XMODEM and ZMODEM.
year Abbreviation, y or yr. The period of the earth™s yoke 1. The ferromagnetic ring or cylinder that
revolution around the sun, with respect to holds the pole pieces of a dynamo-type generator
distant stars: approximately 365.25 days or and acts as part of the magnetic circuit. 2. The
3.15576 — 107 seconds. system of coils used for magnetic deflection of the
Yellow Book A specialized format for compact-disk electron beam in cathode-ray tubes.
read-only memory (CD-ROM) computer data stor- yoke method A method of measuring the perme-
age media, developed by Sony and Philips. It is ability of a sample of magnetic material. It in-
similar to RED BOOK, but it includes superior er- volves completing the magnetic circuit with a
ror correction and storage capacity. See also CD- heavy yoke of soft iron.
ROM, GREEN BOOK, ORANGE BOOK, and RED Young™s modulus Symbol, Y. The ratio of tensile
BOOK. stress to tensile strain.
yellow copper ore See CHALCOPYRITE. Y parameters The admittance parameters of a
yellow metal A copper-zinc alloy that is 60% cop- four-terminal network or device.
per. Y point See WYE POINT.
yellow pyrites See CHALCOPYRITE. Y position 1. On a cathode-ray screen, the vertical
Y-equivalent circuit See WYE-EQUIVALENT CIR- position of the beam spot. 2. On a graph, the po-
CUIT. sition of a point along the vertical axis.
Y gain The gain (or gain control) of the vertical Y potential See WYE POTENTIAL.
channel of an oscilloscope or x-y recorder. Com- yr Abbreviation of YEAR. Also, y.
pare X GAIN and Z GAIN. Y rectifier See WYE RECTIFIER.
yield In a phototube or photocell, the photoelectric Y signal In color television, the monochromatic
current per unit intensity of light. signal conveying brightness information.
yield map A diagram of an integrated circuit show- Y sink The circuit or device into which the Y lines
ing the locations of faulty components. of a memory matrix feed. Compare X SINK.
yield strength The lowest stress for plastic defor- ytterbium Symbol, Yb. A metallic element of the
mation of a material, below which the material is rare-earth group. Atomic number, 70. Atomic
elastic and above which it is viscous. weight, 173.04.
yield value The amount of physical stress that ytterbium metals The rare-earth metals dyspro-
causes a substance to become stretched perma- sium, erbium, lutetium, holmium, thulium, and
nently out of shape. ytterbium.
764 Yttralox • Y-Y circuit

Yttralox A transparent polycrystalline ceramic yttrium metal Any of the group of metals,
composed primarily of yttrium oxide, which has including yttrium, erbium, holmium, lutetium,
many applications in electro-optics. thulium, ytterbium, and sometimes dysprosium,
yttria Formula, Y2O3. Yttrium oxide, a white pow- gadolinium, and terbium.
der used in Nernst lamps. Yukon Standard Time Standard time of the ninth
yttrium Symbol, Y. A metallic element of the rare- time zone west of Greenwich, embracing the
earth-metals group. Atomic number, 39. Atomic Yukon Territory and a portion of southern Alaska.
weight, 88.906. Y winding See WYE CONNECTION.
yttrium-iron-garnet See YIG. Y-Y circuit See WYE-WYE CIRCUIT.
Z 1. Symbol for IMPEDANCE. 2. Symbol for Z-axis of the crystal and parallel to the
ATOMIC NUMBER. 3. Symbol for zenith distance X-axis. See CRYSTAL AXES.
(astronomy). ZD Abbreviation of zero defects.
z 1. Abbreviation of ZERO. 2. Symbol for ELEC- Z deflection Deflection of a cathode-ray beam be-
TROCHEMICAL EQUIVALENT. 3. Abbreviation of yond the (ordinarily defined) deflection area on
ZONE. 4. Symbol for the vertical axis of a three- the tube screen.
dimensional Cartesian graph. Zeeman effect The splitting of a spectral line of a
zag The short, straight deflection of a point or par- gas into closely spaced, polarized frequency com-
ticle, or of waves along a jagged path in a direc- ponents by an applied magnetic field.
tion opposite that of a ZIG; one of the components Zenely electroscope A sensitive alpha-ray electro-
of ZIGZAG DEFLECTION. scope (see ELECTROSCOPE) whose leaf is at-
Zamboni pile A high-voltage electrochemical cell tracted by a metal plate biased at 50 to 200 volts.
consisting of an aluminum anode, a manganese- On touching the plate, the leaf becomes charged
dioxide cathode, and an aluminum-chloride elec- and is repelled. But the gas ions around the leaf
trolyte. neutralize the charge, and the leaf returns to the
Z amplifier The intensity-modulation amplifier in plate to repeat the action. This sequence causes
an oscilloscope. Compare X AMPLIFIER and Y the leaf to oscillate, the number of oscillations per
AMPLIFIER. second being proportional to the strength of the
Z-angle meter An instrument, commonly of the ionizing source.
null-balance type, that indicates the impedance Zener See ZENER DIODE.
and phase angle of capacitors, inductors, and Zener breakdown See AVALANCHE BREAK-
sometimes of inductance-capacitance-resistance DOWN.
(ICR) combinations. Zener current See AVALANCHE CURRENT.
z-axis 1. The intensity-modulation input of an Zener diode Also sometimes called avalanche
oscilloscope, including the associated circuit. diode or Zener. A semiconductor diode (usually
2. The video-signal input of a television picture silicon) specially fabricated to take advantage of
tube, including the associated circuit. 3. The the effects of avalanche breakdown. It is available
third axis in a three-dimensional coordinate sys- in a wide variety of configurations and ratings; it
tem. 4. The lengthwise axis of a quartz crystal. is commonly used as a voltage regulating device
z-axis amplifier See Z AMPLIFIER. in low-voltage power supplies.
z-axis modulation See INTENSITY MODULATION. Zener-diode clipper A signal-amplitude clipper
Z bar See Z-CUT CRYSTAL. that does not require direct-current bias because
z channel See Z AMPLIFIER. it uses a Zener diode. Clipping takes place at
z-channel gain See Z GAIN. the avalanche voltage. Zener diodes can be
Z-cut crystal A plate cut from a quartz crystal so connected back to back for alternating-current
that the plane of the plate is perpendicular to the clipping.

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766 Zener-diode coupling element • Zener knee

dc Type
Zener-diode coupling element A Zener diode
used as a direct coupling element between ampli- Current-limiting
fier stages in an electronic system. When no sig- resistor
nal is present, the resistance of the diode is
extremely high because the direct-current volt-
ages of the diode-coupled amplifier stages reverse-
bias the diode to below the avalanche point, and Standard
Battery Diode
_ dc voltage
no current flows from one stage to the next. The _
signal raises the voltage enough to cause
avalanche breakdown; the signal is thus readily
transmitted from one stage to the following one.
ac Type
B Current-limiting


Source Diodes
ac output

zener-diode voltage reference

dc Type


+ +
diode Regulated
zener-diode coupling element
dc output
dc input _
Zener-diode voltage reference A device that uti-
lizes the constant voltage drop across a Zener
diode operated in its breakdown region, to pro-
vide a standard voltage for reference purposes. It
consists essentially of a direct-current (dc) volt- ac Type
age source, limiting resistor, and Zener diode. For
an alternating-current (ac) reference voltage, an resistor
ac voltage source, limiting resistor, and two Zener
diodes (connected in parallel, back to back) are
required. Zener diodes can be connected in series
to supply a higher reference voltage than can be
delivered by a single diode. Unregulated Regulated
ac input
Zener-diode voltage regulator A simple voltage ac output
regulator whose output is the constant voltage diodes
drop developed across a Zener diode conducting
in the reverse breakdown region. The simple reg-
ulator circuit consists of a Zener diode and an ap-
propriate limiting resistor connected in series zener-diode voltage regulator
across the output terminals of an unregulated
direct-current power supply. For alternating-
current voltage regulation, two Zener diodes can Zener effect See AVALANCHE BREAKDOWN.
be connected in parallel, back to back. Zener Zener knee In the response of a reverse-biased
diodes can be connected in series to regulate a Zener diode, the point of abrupt transition from
higher voltage than can be accommodated by a low current (high resistance) to high current (low
single diode. resistance). For voltage regulation and voltage

Zener knee • zero capacitance

standardization, the knee should be as sharp as tenna is ease of installation; the main drawback
possible. is the fact that the feed line radiates to some ex-
Zener knee current In a Zener diode, the current tent because the system is not perfectly balanced.
that flows when the reverse bias reaches the zero 1. The number represented by the cipher
avalanche voltage. symbol (0). 2. To set a meter or other instrument
Zener-protected MOSFET See GATE-PRO- to its zero reading or condition. 3. To align one el-
TECTED MOSFET. ement of a system precisely with another. 4. In
Zener voltage The particular value of reverse volt- computer operations, to set a register to zero.
age at which a Zener diode or other reverse- 5. In computer operations, using zero pulses to
biased pn junction abruptly exhibits the replace what is in a storage area.
avalanche effect. Depending on the Zener diode, zero-access memory See ZERO-ACCESS STOR-
this potential can be less than 10 volts, or as AGE.
much as several hundred volts. zero-access storage Computer storage requiring
zenith In the sky, the point directly overhead, ex- negligible waiting time (latency).
actly 180 degrees opposite the direction of the zero-address instruction A computer instruction
earth™s center. requiring no address; the operation specified by
Zeolite process A method using certain artificial the instruction defines the locations of the
Zeolites (hydrous silicates) to soften water used in operands. Also called addressless instruction.
some electronic manufacturing and testing oper- zero adjust In an analog metering device, a me-
ations. chanical or electrical control that allows precise
zeppelin antenna Also called zepp. 1. A half-wave- setting of the reading to zero, when the parameter
length radiator, fed at one end with a quarter- to be measured is actually zero.
wavelength section of open-wire line. The feed zero adjustment 1. The act of setting an instru-
line can come away from the radiator at any ment or circuit to its zero reading or zero-operat-
angle, usually 90 degrees or more. The antenna ing condition. 2. A device or subcircuit used to
was originally used aboard zeppelins; the entire set a meter to its zero reading. Also see ZERO
system was dangled in flight and the feed line was SET, 1, 2.
collinear with the radiating element. The zero-angle cut An alternate term for X cut, as ap-
impedance at the feed point is high; the plied to quartz crystal plates. Also see CRYSTAL
impedance at the transmitter end of the feed line CUTS.
is low. The antenna will operate satisfactorily at all zero axis In a plot of a variable quantity, the (usu-
harmonics of the design frequency. 2. A radiator ally horizontal) reference line that indicates the
that is an integral multiple of a half wavelength, zero value of the quantity.
fed with open-wire line of any length. A trans- zero-axis symmetry The condition in which a
match is employed at the transmitter and of the waveshape is symmetrical about a zero axis.
feed line. This arrangement is popular among ra- zero beat Complete absence of a beat note (i.e., si-
dio amateurs. The primary advantage of this an- lence), a condition occurring when the frequen-
cies of the beating signals (or their harmonics) are
equal. See BEAT NOTE.
Radiator zero-beat detector A device or circuit used to
n(»/2) sense and indicate the condition of zero beat.
zero-beat indicator See ZERO-BEAT DETECTOR.
n = 1,2,3 . . . zero-beat method A means of adjusting the fre-
quency of one signal exactly to that of another
(usually standard) signal by setting the first sig-
nal frequency to zero beat with the second signal
zero-beat reception A system of reception entail-
ing zero beating an incoming signal with the sig-
nal from a local oscillator. Also called homodyne
zero-bias operation Operation of a transistor or
vacuum tube without direct-current base, gate,
or grid bias.
zero-bias tube A vacuum tube designed for opera-
tion (particularly in a class-B power amplifier)
Antenna without direct-current grid bias. In such a tube,
tuner the zero-signal plate current is very low because
of the large amplification factor.
zero capacitance 1. Absence of capacitance (a
theoretically ideal condition). 2. In some circuits,
zeppelin antenna
768 zero capacitance • zero pole

zero-gravity switch A switch actuated automati-
cally when the condition of zero gravity is reached.
zero impedance 1. Absence of impedance (a theo-
retically ideal condition). 2. In some circuits, the
lowest impedance level, to which all other
impedances are referred.
zero inductance 1. Absence of inductance (a theo-
retically ideal condition). 2. In some circuits, the
lowest inductance level, to which all other induc-
tances are referred.
zero input 1. Complete absence of input (signal or
noise). 2. Absence of operating voltage or power to
a system. 3. In a flip-flop, the input terminal that
is not receiving a trigger signal.
zero-input terminal In a flip-flop, the input-signal
terminal at which a trigger signal will switch the
flip-flop output to zero. Also called zero terminal
zero instant See ZERO TIME.
zero level The reference level for the comparison of
quantities. For example, it might be a voltage or
current level; in audio measurements, it is the
zero-dB reference level.
zero-line stability In an analog metering device,
the lowest capacitance point, to which all other the ability of the instrument to maintain proper
capacitances are referred. zero adjustment over a period of time.
zero compensation The elimination or minimizing zero magnet A permanent magnet used to set the
of the zero-signal output of a transducer or simi- pointer of a meter to zero.
lar device. zero magnitude 1. For a quantity, the state of be-
zero compression See ZERO SUPPRESSION, 1. ing valueless (i.e., a complete absence of the
zero condition See ZERO STATE. quantity). 2. In some tests, measurements, or
zero current 1. Absence of movement of electrical calculations, the lowest value of a quantity, to
charge carriers. 2. In some circuits, the lowest which all other values are referred.
current level, to which all other currents are re- zero meridian The meridian at Greenwich (near
ferred. London), England, from which longitude and
zero-cut crystal A piezoelectric plate cut from a standard time are reckoned. Also see TIME ZONE
quartz crystal in such a way that the frequency- and ZONE TIME.
temperature coefficient is zero. zero method A method of measurement entailing
zero-dB reference level An agreed-upon zero level adjustment of a circuit or device (such as a
for decibel ratings (which are by nature relative). bridge, tee network, or potentiometer) for zero re-
Zero dBm, for example, corresponds to 1 milli- sponse of the detector. Also called null method.
watt. Compare VOLUME UNIT. zero modulation The momentary lack of modula-
zero drift 1. The (usually gradual) drift of a zero tion in a communications or broadcast system,
point, such as the zero setting of an electronic as during a pause in speech.
voltmeter. 2. The condition of no change in the zero-modulation noise Noise produced by previ-
value of a quantity. ously erased tape that is run under specified op-
zero elimination See ZERO SUPPRESSION, 1. erating conditions.
zero energy The condition in which energy is nei- zero output 1. Complete absence of output signal
ther generated, consumed, nor dissipated. or output power, sometimes disregarding noise
zero error 1. In instruments and measurements, output. 2. In a flip-flop, the normal condition of
an error so small that it can be considered in- no signal pulse at a particular output terminal.
consequential. 2. In a radar system, the inher- zero-output terminal In a flip-flop, the output ter-
ent delay in the transmitter and receiver minal that is not delivering an output pulse.
circuits. zero phase In an alternating-current circuit, the
zero field emission Thermionic emission from a condition in which the current and voltage are in
cathode or hot conductor within a uniform elec- step. That is, the current peaks occur at exactly
trostatic field. the same times as the voltage peaks; the phase
zero fill See ZERO, 5. difference between the current and voltage is zero
zero gravity The condition of weightlessness (i.e., degrees.
the state in which gravitational pull by a celestial zero pole In a multiconductor line, the common or
body is completely absent or has been nullified). reference conductor.
zero potential • zero-zero

zero potential 1. Complete absence of voltage. zero shift See ZERO DRIFT.
2. In some circuits, the lowest voltage, to which zero signal 1. The condition of complete absence
all other voltages are referred. 3. The potential of of signal. 2. A finite signal level used as a refer-
the earth as a reference point. ence point against which all other signal levels
zero power 1. Complete absence of dissipated are measured.
power. 2. In some circuits and systems, the low- zeros of impedance For an alternating-current
est power level, to which all other power values network, the frequencies at which the impedance
are referred. is zero. Also called zeros.
zero-power resistance In a thermistor, the resis- zeros of network function The real or complex
tance at which power dissipation is zero. values at which the network function is zero.
zero-power resistance-temperature characteris- Compare POLES OF NETWORK FUNCTION.
tic For a thermistor, a figure that reveals the ex- zeros of transfer function The frequencies at
tent to which zero-power resistance varies with which a transfer function becomes zero. Compare
the temperature of the thermistor body. POLES OF TRANSFER FUNCTION.
zero-power temperature coefficient of resis- zero stability Constancy of the zero condition in an
tance A temperature coefficient that reveals instrument or system (i.e., absence of zero drift).
the extent to which the temperature of the ther- zero state The low, zero, off, or false logic state of a
mistor body causes the zero-power resistance to bistable device, such as a flip-flop or magnetic
change (expressed in ohms per ohm per degree cell. It might be actual zero output or a low-volt-
Celsius). age output. Compare ONE STATE. In binary
zero reactance 1. Absence of reactance (a theoret- notation and calculation, the zero state is
ically ideal condition in alternating-current cir- represented by a cipher.
cuits). 2. In some circuits, the lowest reactance, zero suppression 1. In computer operation, auto-
to which all other reactances are referred. matic nonsignificant leading-zero cancellation.
zero resistance 1. Absence of resistance (a theo- 2. Absence or removal of a restraining medium,
retically ideal condition). 2. In some circuits, the such as a noise-suppression voltage. 3. In an au-
lowest resistance, to which all other resistances dio recording system, the introduction of a volt-
are referred. age to cancel the steady-state component of the
zero scale current In a digital-to-analog (D/A) input signal.
converter, the current into the output when all zero temperature 1. The point from which tem-
logic inputs are low (off) and the output is at a peratures are reckoned on a thermometer scale.
certain predetermined value, in microamperes or On the Celsius (centigrade) scale, zero degrees
milliamperes. corresponds to the freezing point of pure water at
zero screw The mechanical zero adjuster of a standard atmospheric pressure. On the Fahren-
meter. heit scale, zero degrees is 32 degrees colder than
zero set 1. A (usually screwdriver-adjusted) mech- the freezing point of pure water at standard at-
anism for setting the pointer of a meter to zero. mospheric pressure. On the Kelvin or Rankine
2. An electrical circuit consisting of a resistance scales, zero degrees corresponds to the complete
bridge or adjustable bucking voltage for setting a absence of thermal energy; it is the coldest possi-
meter to read zero under specific conditions. ble temperature. 2. A temperature point relative
to which all other temperatures are reckoned.
zero temperature coefficient A temperature coef-
R1 ficient having the value zero (i.e., one that indi-
cates there is no temperature-dependent drift of a
Zero-set given quantity).
control zero terminal See ZERO-INPUT TERMINAL and
(dc µA) zero time 1. In some measurements, the first in-
stant of time, to which all other instants are re-
ferred. 2. See ZERO PHASE.
R3 R4 zero time reference During one cycle of radar op-
eration, the time reference of the schedule of
B zero vector A vector whose magnitude is zero.


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