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limit f1 and a specified upper limit f2. 2. A range
X “ ••“ of electromagnetic frequencies that exhibits simi-
Y “ •““ lar behavior between its lower and upper limits.
Z ““ •• continuous stationery Also called fanfold paper.
The pack of paper a line printer uses. It consists
0 “““““ of sheets connected by perforated or tear-off
1 •““““
edges, folded in accordion fashion. It usually has
2 ••“““
tear-off perforated strips along either side to facil-
3 •••““
itate feed through the printer mechanism.
4 ••••“
continuous variable A variable that can attain any
5 •••••
value within a specific range of values. An exam-
6 “ •••• ple is a frequency within the 75- to 80-meter am-
7 ““ ••• ateur radio band, from 3.5 to 4.0 MHz.
8 “““ •• continuous wave Abbreviation, CW. 1. A periodic
9 ““““• wave, such as a radio-frequency (RF) carrier, that
Period •“ •“ •“
is not interrupted at any point between its normal
Comma ““ ••““ start and termination, and that is unmodulated.
Query ••““ ••
2. An RF carrier that is interrupted digitally with
Slash “ ••“ • a keying device according to some code (such as
Dash “ ••••“ Morse), for the purpose of conveying information.
Break (pause) “ •••“ continuous-wave laser See CW LASER.
Semicolon “ •“ •“ • continuous-wave radar See CW RADAR.
Colon “““ ••• contour A control on an audio reproduction sys-
tem that increases the base and treble ampli-
Continental code tudes at low levels to compensate for the ear™s
natural losses in these ranges. Alternatively, this
control can attenuate signals in the 3-kHz region,
where the human ear is most sensitive.
contours of equal loudness See AUDIBILITY
CURVES.
Test probe
CONTRAN A computer language that requires no
compiler, or translating, interface between the
operator and the machine. The programming is
+ done in a language similar to machine language.
contrast 1. In a video image, the degree to which
adjacent areas of a picture are differentiated. In-
sufficient contrast makes for a “flat” picture; ex-
continuity tester
145
contrast • controlling file


max cess. 2. In a digital computer, a circuit that han-
dles and interprets instructions and commands,
particularly in the arithmetic and logic unit
(ALU).
Treble
control computer A computer that receives sig-
Bass
Output level




nals concerning the parameters in some process,
and responds with signals that control those pa-
rameters.
control counter See CONTROL REGISTER.
control data 1. In a computer record having a key,
information used to put the records in some se-
Midrange
quence. 2. Information affecting a routine™s selec-
tion or modification.
min control electrode An electrode to which an input
low Frequency high signal can be applied to control an output signal.
Common examples are the base of a bipolar tran-
contour sistor, the gate of a field-effect transistor, and the
inputs of a logic gate.
control field 1. In direct-current generators of the
cessive contrast, a “hard” picture. 2. In optical amplifying type, an auxiliary field winding used
character recognition, the degree to which a char- for feedback and regulation, in contrast to the
acter is distinguishable from its background. self-excited field winding (which is the conven-
contrast control A potentiometer for adjusting the tional field winding of the generator). 2. A com-
gain of the video in a television receiver or cath- puter record field containing control data.
ode-ray-tube (CRT) computer display and, ac- control flux In an amplidyne, magnetic flux gener-
cordingly, the image contrast. ated by current flowing through the control wind-
contrast range In an image or pattern, the bright- ing.
ness range from the lightest to the darkest parts. control grid See GRID, 1.
contrast ratio In a video image, the ratio of maxi- control-grid bias The negative dc voltage applied
mum to minimum luminance. between ground and the control grid of a vacuum
control 1. An adjustable component, such as a tube to establish the operating point.
rheostat, potentiometer, variable capacitor, or control language Within the operating system of a
variable inductor, that allows some quantity to be computer, the command set that the operator or
varied at will. 2. A test or experiment conducted programmer uses to control the running of a pro-
simultaneously with another similar test con- gram or the operation of peripherals. Also called
ducted under conditions lacking the factor under job control language or system control language.
consideration. Thus, if 100 resistors coated with control language interpreter See CONTROL LAN-
a special varnish are tested at 120°F, 100 identi- GUAGE and INTERPRETER.
cal unvarnished resistors could be tested (as a controlled avalanche diode Also called avalanche
control) under the same conditions; in this way, diode or Zener diode. A diode that has a well-
the effect of the varnish would be ascertainable. defined avalanche voltage. Used primarily for
3. As a computer function, understanding and voltage regulation in power supplies.
implementing instructions or carrying out tasks, controlled-carrier modulation See QUIESCENT
according to specific conditions. CARRIER OPERATION.
control ampere-turns The ampere-turns of the controlled-carrier transmission See QUIESCENT
control winding in a magnetic amplifier. CARRIER OPERATION.
control block A storage block for control informa- controlled rectifier A rectifier whose dc output
tion in a computer. can be varied by adjusting the voltage or phase of
control bus In a digital computer, the electrical a signal applied to the control element. See
conductors linking the central-processing-unit SILICON-CONTROLLED RECTIFIER.
(CPU) control register to the memory circuits. controller 1. The control signal of an electronic
control card A card that provides control informa- control (or servo), system. 2. A device, such as a
tion for a computer. specialized variable resistor, used to adjust cur-
control character A character (bit group) used to rent or voltage. 3. A computer that oversees and
start the control of a peripheral. controls the operation of a robot or fleet of robots.
control characteristic A representation (such as a controller function The control of the movements
collector-current versus collector-voltage curve) of a servo system.
depicting the extent to which the value of one controlling file A computer storage area encom-
quantity affects or controls the value of another. passing several complete magnetic disk cylin-
control circuit 1. A circuit in which one signal or ders; its size can be changed to accommodate a
process is made to control another signal or pro- number of files.
146 control loop • convergence magnet


control loop See CONTROL TAPE. Air currents
control mark See TAPE MARK.
control panel 1. An accessible surface on which are
mounted switches, buttons, potentiometers, me-
Transistor
ters, digital indicators, monitoring devices, and Heatsink
other apparatus essential to regulating and super-
vising an electronic system. 2. The console that a
computer operator or programmer uses to com-
municate with the central processing unit (CPU).
control plate The metallic plate or disk that serves
as the antenna of a CAPACITANCE RELAY or
TOUCHPLATE RELAY.
Air currents
control program A program that arranges com-
puter-operation programs in a certain order. Puts
convection
information in the computer memory for later
cooling
use.
control rectifier A semiconductor diode device,
used for the purpose of switching large currents. convection current 1. The motion of current car-




Y
A small control signal can provide switching of riers or a charge across the surface of a conduc-
high-power devices. tor or dielectric. 2. Air currents rising above a




FL
control register In a computer, the register that heat source or heated body.
stores the address of the next instruction in the convective discharge The continuous high-
program being run. voltage current discharge across a spark gap.
control sequence The order in which instructions convectron A device that indicates the angle, with
AM
are executed in a digital computer. respect to the vertical, based on convection cool-
control stack In a computer system, a unit of ing of a straight wire. The temperature difference
hardware having storage locations and used to is greatest when the angle is 0 degrees (the wire is
perform arithmetic, assist in allocating memory vertical); the temperature difference decreases as
to programs, and to control internal processes. the angle increases, reaching a minimum at 90
TE

control statement In a programming language, an degrees (when the wire is horizontal).
instruction that causes some action to be taken, convenience outlet 1. In North America, a wall
as specified by a condition; it is also applicable to outlet providing a nominal 117 volts alternating
source program statements that affect the com- current (ac) at 60 Hz for common household ap-
piler™s operation without modifying the machine pliances. 2. An outlet in a laboratory that pro-
code. vides power for a certain application.
control tape Punched paper or plastic tape in the conventional current The notion that current
form of a closed loop and used to control printing flows from the positive pole to the negative pole in
devices. Also called control loop. an electric circuit. This representation is used
control total For a file or record group, a total de- most often by physicists. Electron flow is opposite
rived during an operation; it is used to verify that to conventional current flow; positively charged
all the records have been processed similarly. particles, such as holes, move in the same direc-
control transfer The situation in which the control tion as the conventional current.
unit of a digital computer leaves the main se- convergence 1. The eventual meeting of values or
quence of instructions and takes its next instruc- bodies at some point (sometimes at infinity, as in
tion from an out-of-sequence address. certain mathematical series). 2. The intersection
control transfer instruction See BRANCH IN- point of the beams from separate electron guns in
STRUCTION. a cathode-ray tube (CRT).
control-voltage winding In a servomotor, the convergence coil One of a pair of coils used in a
winding that receives a varying voltage of a phase color television receiver to produce dynamic beam
different from that applied to the fixed-voltage convergence (see CONVERGENCE, 2).
windings. convergence control In a color television receiver,
control winding In a magnetic amplifier, the wind- a potentiometer in the high-voltage circuit for con-
ing that conducts the control-signal current. vergence adjustment (see CONVERGENCE, 2).
control word A word (a bit group) stored in a com- convergence electrode An electrode that provides
puter memory and used for a control function. an electrostatic field for converging electron
convection The flow of a gas or liquid that results in beams. Compare CONVERGENCE MAGNET.
the transfer of heat from one location to another. convergence frequency The frequency of the last
convection cooling The removal of excess heat member of a spectrum series.
from a component, such as a power vacuum tube convergence magnet An assembly that provides a
or transistor, via upward movement of surround- magnetic field to converge electron beams. Com-
ing air that has been heated by the component. pare CONVERGENCE ELECTRODE.




Team-Fly®
147
convergence phase control • coordinates


convergence phase control In a three-gun color conversion rate Also called sampling rate. The
picture tube, a variable resistor or variable induc- number of samples per second taken by an
tor used to adjust the phase of the dynamic con- ANALOG-TO-DIGITAL CONVERTER.
vergence voltage. conversion time In digital computer operation,
convergence plane 1. In a color picture tube, the the time required for the machine to read out all
plane in which the red, green, and blue beams all the digits in a coded word.
focus. 2. In a cathode-ray tube, the plane in conversion transconductance See CONVERSION
which the electron beam reaches its sharpest fo- EFFICIENCY.
cus. convert 1. To perform frequency conversion (see
convergent series A mathematical series that ap- CONVERSION, 1). 2. To perform voltage conver-
proaches a specific, finite numerical value as the sion (see CONVERSION, 2 and 3). 3. In computer
number of terms increases. Thus, the series 0.3 + operations, to change information from one num-
0.03 + 0.003 + . . . approaches a limiting value of ber base to another. 4. To perform data conver-
1„3. Compare DIVERGENT SERIES and INFINITE sion (see CONVERSION, 4 and 5).
SERIES. converter 1. A heterodyne mixer in which two in-
converging lens A lens having a real focus for par- put signals of different frequency are mixed to
allel rays; generally a convex lens. yield a third (output) signal of yet a different fre-
conversational compiler In computer operations, quency. 2. A machine for converting direct cur-
a compiler that, using the CONVERSATIONAL rent (dc) to alternating current (ac) (e.g., a
MODE of operation, shows the programmer chopper converter). 3. A transistor circuit for con-
whether or not each statement entered into the verting a low-voltage dc to higher-voltage dc. 4.
computer is valid, and whether or not to proceed Conversion equipment. 5. A circuit or device that
with the next instruction. changes analog data to digital data or vice versa.
conversational mode High-level computer opera- converter amplifier See CHOPPER AMPLIFIER.
tion or programming, in which the computer converter stage A circuit used principally to mix
gives responses to the operator™s input. two signals (such as a received signal and local-
conversion 1. The deliberate mixing of radio- oscillator signal in a superheterodyne receiver),
frequency (RF) signals to produce signals at the and deliver the resultant signal.
sum and/or difference frequencies. 2. The pro- convexo-concave Pertaining to a lens having a
cess of changing direct current (dc) to alternating convex face of greater curvature than its concave
current (ac). 3. The process of changing low-volt- face.
age dc to high-voltage dc. 4. The changing of a coolant A liquid (often water or oil) used to remove
computer file to another format and, possibly, heat from an electronic component.
transferring it to a different storage medium (e.g., Coolidge X-ray tube An X-ray tube containing a
from tape to internal memory). 5. The processing heated filament (with focusing shield) and a
of a program or file written for one computer or slanting tungsten target embedded in a heavy
application into a form suitable for another com- copper anode.
puter or application. cooling Maintenance of the operating temperature
conversion efficiency In a converter (see CON- of an electronic component or system at a safe
VERTER, 1), the ratio of output-signal ampli- level. Common devices for cooling are heatsinks,
tude to input-signal amplitude. For example, in circulating or forced air, and circulating liquid.
a superheterodyne converter, a large intermedi- coordinate bond A covalent bond that consists of
ate-frequency (IF) output for a low radio- a pair of electrons supplied by only one of the
frequency (RF) input indicates high conversion atoms joined by the bond.
efficiency. Coordinated Universal Time Abbreviation, UTC.
conversion equipment In a computer system, an Astronomical time at the Greenwich meridian
offline device for transferring data from one (zero degrees longitude). The UTC day begins at
medium to another [e.g., a disk-to-tape converter 0000 hours and ends at 2400 hours. Based on
(tape drive)]. Also called CONVERTER. the mean, or average, synodic (sun-based) rota-
conversion exciter An exciter for transmitters, in tional period of the earth. The earth is slightly be-
which an output signal of a desired frequency is hind UTC near June 1, and is slightly ahead near
obtained by beating the output of a variable- October 1.
frequency self-excited oscillator with the output coordinate digitizer A device or circuit that en-
of a fixed-frequency oscillator (such as a crystal codes a coordinate graph into digital signals for
oscillator). storage or transmission.
conversion gain Amplification as a byproduct of coordinate of chromaticity See CHROMATICITY
conversion. See CONVERSION EFFICIENCY. COORDINATE.
conversion loss Conversion gain of less than 1. coordinates A set of axes with points that can be
conversion program In computer operations, a uniquely defined or located on a line, in a plane,
program for data conversion (see CONVERSION, or in space. See CARTESIAN COORDINATES and
4 and 5). POLAR COORDINATES.
148 coordinate system • cordless modem


coordinate system A mathematical means of vice; they were widely used before the advent of
uniquely defining or locating a point on a line, in germanium, silicon, and selenium rectifiers.
a plane, or in space. The most common coordi- copper pyrites See CHALCOPYRITE.
nates are CARTESIAN COORDINATES (also copper-sulfide rectifier A rectifier in which the
called rectangular coordinates), consisting of unilateral junction is between copper-sulfide and
numbered lines intersecting at right angles. magnesium elements. Like the copper-oxide rec-
tifier, the copper-sulfide unit was once widely
used in low-voltage applications.
y copy 1. Also called hard copy. Printed or written
text. 2. In communications, a qualitative expres-
sion of the extent to which received data is intel-
6
ligible (e.g., a radio operator™s signal report, “You
are solid (perfect) copy.”). 3. To duplicate data in
4
a storage system, the original being in another
system, or in a different location in the same
2
system. 4. An exact duplicate of data in any
form.
x
’6 ’4 ’2 2 4 6 copying telegraph A descriptive term for a facsim-
’2 ile system.
Corbino disk A variable resistor consisting of a
’4 semiconductor disk capable of exhibiting the
CORBINO EFFECT. The disk is inserted into an
’6 adjustable magnetic field, which serves as the
control medium.
Corbino effect A phenomenon similar to the HALL
EFFECT, in which a current flows around a disk
coordinate system
carrying a radial current when the disk is in-
(Cartesian)
serted into a magnetic field whose lines of flux are
perpendicular to the disk. Compare HALL EF-
FECT.
coordination complex An ion or compound hav-
ing a central (usually metallic) ion combined by
coordinate bonds with a definite number of sur-
rounding groups, ions, or molecules. Semiconductor
coplanar array A set of antennas that lie in the disk
same plane, and are fed by a common transmis-

sion line.
copper Symbol, Cu. A metallic element. Atomic
number, 29. Atomic weight, 63.546. An excellent
conductor of electricity and heat, commonly used
+
in the manufacture of wires and cables. Current
copper-clad wire Iron or steel wire plated with flow
Magnetic
copper.
field
copper-constantan thermocouple A thermocou-
ple consisting of a junction between wires or
Corbino effect
strips of copper and constantan. Typical output
is 4.24 mV at 100°C.
copper loss Power (I 2R) loss in copper wires, ca- cord 1. A length of flexible, insulated cable, usually
having two or three conductors. 2. Tough, insu-
bles, and/or coils.
lating string (e.g., dial cord or lacing cord).
copper-oxide diode A small diode in which the
cordless 1. Descriptive of a plug without a flexible
semiconductor material is copper oxide. Such
cord. 2. Pertaining to radio-frequency (RF) or in-
diodes, widely used before the ready availability
frared short-range links for communications and
of selenium and silicon, are still occasionally
control (e.g., a cordless telephone set).
found in meter-rectifier service.
cordless keyboard A computer keyboard that em-
copper-oxide modulator An amplitude modulator
ploys an infrared (IR), very-high frequency (VHF),
whose action is derived from the nonlinear con-
or ultra-high-frequency (UHF) transmitter and re-
duction characteristic of copper-oxide diodes.
ceiver. Commonly used with so-called Web TV
copper-oxide photocell A photoelectric cell in
systems and in presentations using a display pro-
which the light-sensitive material is copper oxide.
jection system. Operates according to the same
copper-oxide rectifier A rectifier in which the
electronic scheme as a CORDLESS MOUSE.
semiconductor material is copper oxide. Recti-
cordless modem See WIRELESS MODEM, 3.
fiers of this type are suitable for low-voltage ser-
149
cordless mouse • corner reflector


cordless mouse A hand-controlled computer corner 1. An abrupt turn in the axis of a wave-
mouse that employs an infrared (IR), a very-high guide. 2. The line, and the region in the vicinity
frequency (VHF), or an ultra-high-frequency thereof, at which two intersecting plane surfaces
(UHF) transmitter and receiver. The transmitter meet (e.g., the reflector screen of a CORNER-
is inside the device, and the receiver is contained REFLECTION ANTENNA). The plane surfaces are
either inside the computer main unit, or in a usually perpendicular to each other. 3. The point,
small box attached to the computer main unit by and the region in the vicinity thereof, at which
a cord. The box can be placed somewhere out of three intersecting plane surfaces meet. Generally,
the way; for example, at the back of the desk. the plane surfaces are mutually perpendicular. 4.
Then the mouse can be moved around freely. This The passband frequency limit(s) of a bandpass,
link is effective at distances of up to 20 or 30 feet. band-rejection, high-pass, or low-pass filter. 5. A
cordwood A type of construction in which elec- sharp bend in the attenuation-versus-frequency
tronic components are sandwiched perpendicu- curve of a bandpass, band-rejection, high-pass,
larly between layers of components. So called or low-pass filter, depicting the limit(s) of the
because it looks somewhat like stacked cord- passband.
wood. corner diffraction 1. The bending of sound waves
cordwood module A module containing discrete around a corner. 2. The bending of radio-
components mounted perpendicularly between frequency (RF) energy around an object, when the
two parallel printed circuits. wavelength is great, compared with the size of the
core 1. The body or form on which a coil or trans- object.
former is wound. Can be made of ferromagnetic corner effect A rounding off of the frequency re-
or dielectric material. The properties depend on sponse of a filter at the corner(s) [i.e., at the
the application. 2. CORE MEMORY. limit(s) of the passband].
core dump Dumping core memory content to an corner frequency See CORNER, 4.
output peripheral. Also see DUMP. corner reflection The reflection of a beam of light
coreless induction heater An induction heater in (or of microwave energy or other short-wave-
which the body to be heated receives energy di- length energy) from a corner reflector, so the
rectly from the field of the energizing coil (there is beam leaves the reflector in exactly the opposite
no intervening core). Compare CORE-TYPE IN- direction from which it approaches. See CORNER
DUCTION HEATER. REFLECTOR, 2.
core loss Loss of energy in a magnetic core, caused corner-reflection antenna A directional antenna
by eddy currents and hysteresis in the core mate- consisting of a dipole radiator situated at the
rial. apex formed by two nonparallel, flat reflecting
core memory An older memory technology, con- sheets or a single folded sheet. See CORNER RE-
sisting of a series of small ringshaped magnetic FLECTOR, 1.
cores, into or out of which data can be written or
read by changing the magnetization of the cores.
core plane A usually flat assembly of special mag-
netic cores, through which pass associated
current-conducting wires to provide a CORE
MEMORY.
core saturation The condition in which a core of
magnetic material accommodates the maximum
number of magnetic lines characteristic of that
material. Increasing the magnetizing force pro-
duces no additional magnetization.
core shift register A shift register that uses spe-
cial magnetic cores as bistable components. See
CORE MEMORY.
core storage A high-speed magnetic core storage
unit. Also see CORE MEMORY and CORE PLANE.
core transformer A transformer whose coils are
wound around a ferromagnetic core.
core wrapping The placing of an insulating layer
over an inductor or transformer core. This mini-
mizes the chances of short-circuiting between the
windings and the core material. corner reflector 1. An antenna with a half-wave
core-type induction heater An induction heater driven element and a reflector made of wire mesh,
in which the body to be heated is magnetically screen, or sheet metal that resembles an open
linked, by a core, to the energizing coil. Compare folder. The flare angle of the reflecting element is
CORELESS INDUCTION HEATER. about 90 degrees. The antenna is used at ultra-
150 corner reflector • corrosion-resistant


the voltage source. The air density in the tube is
varied until corona occurs.
corpuscle A tiny particle. It was the name given to
the ELECTRON by some early experimenters and
theorists.
correction 1. The addition of a factor that provides
greater accuracy in a measurement. 2. A change
in the calibration of an instrument to increase the
accuracy.
correction factor A percentage, or numerical fac-
tor, added to or subtracted from a reading to pro-
corner reflector, 2
vide a greater degree of accuracy. Often used with
instruments known to be inaccurate by a certain
amount.
high and microwave frequencies for television re-
corrective feedback Feedback that is used to cor-
ception and satellite communications. Some-
rect (bring to a prescribed level) a quantity consti-
times several half-wave dipoles are fed in phase
tuting the input to a system.
and arranged along a common line with a single,
corrective maintenance The repair of a circuit or
elongated reflector. 2. Also called tricorner reflec-
system after it has malfunctioned or broken
tor. A set of three flat metal surfaces or screens,
down.
attached together in a manner identical to the
corrective network A network that improves the
way two walls meet the floor or ceiling in a room.
performance of the circuit into which it is in-
Such a device, if it is at least several wavelengths
serted.
across, returns electromagnetic energy in exactly
corrective stub A combination tuning-matching
the same direction from which it arrives. Devices
stub used in some antenna systems. It matches
of this type are used as radar dummy targets and
the resistive component of the antenna imped-
in optical and infrared (IR) wireless ranging
ance to the characteristic impedance of a feed
systems.
line, and also eliminates any reactance that
corona A luminous discharge in the space sur-
might be present at the antenna feed point.
rounding a high-voltage conductor; caused by
correed relay A sealed reed relay used as a high-
ionization of the air. The discharge constitutes a
speed switching device in communications equip-
loss of energy.
ment.
corona effect The production of a luminous dis-
correlation A statistical expression or measure of
charge, especially at the end of a pointed termi-
the degree to which two sets of data are related.
nal, when the voltage gradient reaches a critical
Can be given qualitatively (high-positive, low-
value.
positive, zero, low-negative, or high-negative) or
corona failure A form of high-voltage failure, re-
quantitatively (as a number between “1 and 1).
sulting from the erosion of an object (such as an
Does not necessarily imply causation.
electrical insulator) by corona.
correlation detector A detector that compares a
corona loss Loss caused by energy dissipation
signal of interest with a standard signal at every
through a corona. It occurs as a result of the
point, delivering an output that is proportional to
emission of electrons from the surface of electri-
the correspondence between the two signals.
cal conductors at high potentials, and depends
correlation distance The smallest distance between
on the curvature of the conductor surface, with
two antennas that results in fading of signals un-
most emission occurring from sharp points and
der conditions of tropospheric propagation. It is
the least from surfaces with a large radius of cur-
used at very-high frequencies (VHF) and above, to
vature. It is often accompanied by a blue glow
determine the maximum range over which com-
and a crackling or hissing sound.
munications can be carried out reliably.
corona resistance The length of time that an insu-
correlation tracking A method of target tracking
lating material can withstand a specified level of
in which phase relationships are used to deter-
field-intensified ionization before completely
mine positions.
breaking down.
correspondence The ability of a binocular ma-
corona shield A shield surrounding a high-voltage
chine vision system to tell when both of its optical
point to prevent corona by redistributing the elec-
sensors are processing an image from the same
tric flux.
object; also, the ability of the system to keep both
corona starting voltage The minimum voltage be-
sensors tracking the same object.
tween two electrodes, or on a single electrode in
corrosion-resistant Pertaining to materials that
free space, at which corona occurs.
are treated to be immune to corrosion by the ele-
corona voltmeter A voltmeter used to measure the
ments. Such substances are preferable for use in
peak value of a voltage in terms of corona dis-
marine or tropical environments, where corrosion
charge. It consists of a metal tube in which a cen-
is especially severe.
tral wire is mounted, the parts being connected to
151
corruption • counterpoise


corruption The altering of data or a code as a re- charge quantity, equal to the charge contained in
6.24 — 1018 electrons. A current of one ampere
sult of a program error or machine fault.
COS Abbreviation of COMPLEMENTARY-SYMME- (1 A) represents 1 coulomb per second (C/s).
TRY CIRCUIT. Coulomb™s law The force between two electrically
cosecant Abbreviation, csc. A trigonometric func- charged objects is directly proportional to the
tion; csc q = c/a, where c is the hypotenuse of a product of the charge quantities in coulombs,
right triangle and a is the side opposite q. The and inversely proportional to the square of the
cosecant is the reciprocal of sine: csc q = 1/sin q. distance between the charge centers. This force is
cosecant-squared antenna A radar antenna that an attraction for opposite charges, and a repul-
radiates a COSECANT-SQUARED BEAM. sion for similar charges.
cosecant-squared beam A radar beam whose in- coulometer An instrument that measures electri-
tensity varies directly with the square of the cose- cal charge quantity in coulombs. A typical version
cant of the angle of elevation. keeps a cumulative count of coulombs (ampere-
cosech Abbreviation of HYPERBOLIC COSECANT. seconds) by integrating current, with respect to
Also abbreviated as csch. time. Also called coulombmeter.
cosh Abbreviation of HYPERBOLIC COSINE. Coulter counter See CELL COUNTER.
cosine Abbreviation, cos. A trigonometric function; count 1. The number of pulses tallied by a count-
cos q = b/c, where b is the side adjacent to q and ing system in a given period of time. 2. A single
c is the hypotenuse of the right triangle. response by a radioactivity counter. 3. A record of
cosine law The brightness in any direction from a the number of times an instruction or subroutine
perfectly diffusing surface is proportional to the in a computer program is executed (by increasing
cosine of the angle between the direction vector the value of a variable by one, as stated in a FOR-
and a vector perpendicular to the surface. NEXT loop, for example).
cosine wave A periodic wave that follows the co- countdown A decreasing count of time units re-
sine of the phase angle. It has a shape identical maining before an event or operation occurs
with a SINE WAVE, but differs by 90 degrees of showing time elapsed and time remaining.
phase. counter 1. A circuit, such as a cascade of flip-
cosine yoke A magnetic-deflection yoke that has flops, that tracks the number of pulses applied to
nonuniform windings for improved focus at the it and usually displays the total number of
edges of a television picture. Also called anastig- pulses. 2. A mechanism, such as an electrome-
matic yoke and full-focus yoke. chanical indicator, that tracks the number of im-
cosmic noise Radio noise produced by signals pulses applied to it and displays the total. 3. An
from extraterrestrial space. electronic switching circuit, such as a flip-flop or
cosmic rays Extremely penetrating rays consisting stepping circuit, that responds to sequential in-
of streams of atomic nuclei entering the earth™s put pulses applied to it, giving one output pulse
atmosphere from outer space. after receiving a certain number of input pulses.
COS/MOS IC An integrated circuit (IC), such as an counter- Prefix meaning “opposite to” or “contrary
operational amplifier, utilizing metal-oxide-semi- to.” Examples: counter EMF, counterclockwise.
conductor (MOS) field-effect transistors in a com- counterclockwise Abbreviation, ccw. Pertaining to
plementary-symmetry (COS) arrangement. rotational motion in a sense opposite that of a
cost analysis In a commercial or industrial organi- typical analog clock. Movement is to the left at the
zation, ascertaining the expense associated with top of the rotational circle, and to the right at the
a service, process, or job. bottom of the circle. Compare CLOCKWISE.
cot Abbreviation of COTANGENT. counterclockwise-polarized wave An elliptically
cotangent Abbreviation, cot. A trigonometric func- polarized electromagnetic wave whose electric-
tion; cot q = b/a, where a is the side adjacent to q intensity vector rotates counterclockwise as ob-
and b is the side opposite q (in a right triangle). served from the point of propagation. Compare
Cotangent is the reciprocal of tangent: cot q = CLOCKWISE-POLARIZED WAVE.
1/tan q. counter efficiency The sensitivity of a radiation
coth Abbreviation of HYPERBOLIC COTANGENT. counter or scintillation counter to incident X-rays
Cotton-Mouton effect See KERR MAGNETO- or gamma rays.
OPTICAL EFFECT. counterelectromotive cell A cell used to counter-
Cottrell process Dust precipitated by high voltage. act a direct-current voltage.
Dust in the air is made to flow through a counter EMF See BACK VOLTAGE and KICK-
grounded metal chamber that contains a wire BACK.
maintained at high voltage. The dust particles be- counter-meter A radioactivity instrument, such as
come charged and adhere to the chamber walls, a Geiger counter, that indicates the number of ra-
from which they are later collected. dioactive particles per unit time.
coul-cell A coulometer of the electrolytic-cell type. counterpoise A means of obtaining a radio-
coulomb (Charles Augustin Coulomb, 1736“ frequency (RF) ground by using a grid of wires or
1806). Abbreviation, C. The unit of electrical tubing in a plane parallel to the earth™s surface or
152 counterpoise • CPU


to average terrain. The radius of the grid is usu- vices by electric flux. 2. Also called magnetic cou-
ally at least 0.25 wavelength, but might be pling or inductive coupling. The linking of two cir-
smaller if the feed-point impedance of the an- cuits or devices by magnetic flux. 3. Also called
tenna is very high. direct coupling. The linking of two circuits or de-
counterpoise ground system A counterpoise with vices by direct connection. 4. Also called resistive
a radius such that resonance is obtained with a coupling. The linking of two circuits or devices
quarter-wavelength antenna operated at a height through a resistance. 5. Also called optical cou-
of more than 0.25 wavelength above actual pling. The linking of two circuits or devices
ground. Usually such a system consists of three through an optoisolator.
or four radials measuring 0.25 wavelength each, coupling aperture A hole in a waveguide that is
and extending outward from the base of the an- used to transmit energy to the waveguide, or re-
tenna nearly parallel to the average terrain. ceiving energy from outside the waveguide.
coupling capacitor A capacitor used to conduct ac
energy from one circuit to another. Also see CA-
PACITIVE COUPLING.
Antenna coupling coefficient See COEFFICIENT OF COU-
element PLING.
Radials
coupling diode A semiconductor diode connected
between the stages of a direct-coupled amplifier.
When the diode is connected in the correct polar-
ity, it acts as a high resistance between stages
when there is no signal, and does not pass the
Radials
high dc operating voltage from one stage to the
next. When a signal is present, the diode resis-
tance decreases, and the signal gets through.
coupling efficiency A measure of the effectiveness
of a coupling system (i.e., the degree to which it
Feed
delivers an undistorted signal of correct ampli-
line
tude and phase).
coupling loop 1. A single turn of a coupling trans-
counterpoise
former. 2. A small loop inserted into a waveguide
ground system
to introduce microwave energy.
coupling probe A usually short, straight wire or
counter tube A tube, such as the Geiger-Meuller pin protruding into a waveguide to electrostati-
tube, in which a penetrating radioactive particle cally introduce microwave energy into the waveg-
ionizes a gas and produces an output pulse. uide. It acts like a miniature whip antenna.
counter voltage See BACK VOLTAGE and KICK- coupling transformer A transformer used primar-
BACK. ily to transfer alternating-current (ac) energy
counting-type frequency meter A direct-reading electromagnetically into or out of a circuit.
analog or digital frequency meter that indicates covalent binding forces In a crystal, the binding
the number of pulses (or cycles) per second ap- forces resulting from the sharing of valence elec-
plied to it. trons by neighboring atoms.
count-remaining technique See COMPLEMENT- covalent bonding The binding together of the
SETTING TECHNIQUE. atoms of a material as a result of shared electrons
couple Two dissimilar metals in contact with each or holes.
other or immersed in an electrolyte. coverage 1. The area within which a broadcast or
coupled circuits Circuits between which energy is communication station can be reliably heard. 2.
transferred electrostatically, electromagnetically, The shielding effectiveness of a coaxial cable.
by some combination of the two, or by direct con- coversed sine Abbreviation, covers. The trigono-
nection. metric functional equivalent of the versed sine of
coupled impedance The impedance that a circuit the complement of an angle [i.e., the difference
“sees” when it is coupled to another circuit. Thus, between the sine of an angle and unity (1)]. Thus,
when the secondary of a transformer is termi- covers q = 1 “ sin q.
nated with an impedance, the primary “sees” a CP Abbreviation of chemically pure.
combination of that impedance and its own. cp 1. Abbreviation of CANDLE POWER. 2. Abbrevi-
coupler A device for transferring energy between ation of central processor.
two circuits and using capacitive coupling, direct cps 1. Abbreviation of CYCLES PER SECOND. Cy-
coupling, inductive coupling, or some combina- cles per second, to denote ac frequency, has been
tion of these. supplanted by HERTZ. 2. Abbreviation of charac-
coupling 1. Also called electrostatic coupling or ca- ters per second.
pacitive coupling. The linking of two circuits or de- CPU Abbreviation of CENTRAL PROCESSING UNIT.
153
CQ • critical field


CQ A general call signal used in radio communica- netic field subtends, with respect to the horizon
tion, especially by amateur stations, to invite a at the transmitting (TX) point, below which the
response from any station that hears it. ionosphere will reliably return the signal to the
Cr Symbol for CHROMIUM. earth, and above which the ionosphere will not
cracked-carbon resistor A high-stability resistor reliably return the signal. This angle (shown by
in which the resistance material is particulate the double arc marked X in the drawing) depends
carbon. on the frequency of the transmitted electromag-
cracker A hacker with malicious intent (also see netic wave, and also on ionospheric conditions. 2.
HACKER). Such a person attempts to gain access For an electromagnetic wave or ray approaching
to computer systems or databases in order to a boundary at which the index of refraction
steal something or inflict damage. Examples in- abruptly decreases, the minimum angle of inci-
clude theft, erasure, or mutilation of data; fraud- dence (relative to a line perpendicular to a plane
ulent debiting of bank accounts; alteration of tangent to the boundary) at which the energy is
credit information; and identity theft. totally reflected.
cradle guard See GUARD WIRE.
cradlephone A telephone set in which the micro-
phone and earphone are mounted on opposite
ends of a handle. This handle, called the receiver,
rests on the crossmember of a stand connected to
a base containing the dial and ringing circuits.
Also called French phone, French telephone, and Ionized layer
handset.
crash 1. A condition in which a computer or net-
work server becomes inoperative because of a
software or memory-management problem. 2. In
a computer hard disk or diskette drive, contact of
the read/write head with the surface of a disk or
platter. Usually, it is the result of excessive phys- X
ical vibration or shock.
crate A foundation unit into which modules are Earth™s surface
TX
plugged to establish a circuit.
crawl 1. See CREEPING COMPONENT. 2. The
credits (names of staff and their contribution to
content) superimposed and moving on a televi-
sion picture at the end of a program.
crazing The formation of tiny cracks in materials,
critical angle, 1
particularly in such dielectrics as plastic and ce-
ramic.
creep See COLD FLOW. critical characteristic A parameter that has a dis-
creepage Current leakage across the surface of a proportionate effect on other variables. A small
dielectric. change in this characteristic can result in a large
creeping component A quantity, such as current, change in the operating conditions of a circuit or
voltage, or frequency, that slowly changes in system.
value with time. critical component A component or part that is
crest factor See AMPLITUDE FACTOR. especially important in the operation of a circuit
crest value The maximum amplitude of a compos- or system.
ite current or voltage. critical coupling The value of coupling at which
crest voltmeter A peak-reading (or sometimes maximum power transfer occurs. Increasing the
peak-responsive) voltmeter. extent of coupling beyond the critical value de-
crippled mode The mode of operation for a com- creases power transfer.
puter or other hardware in which some of the critical damping The value of damping that yields
components are inoperable. Compare GRACE- the fastest transient response without overshoot.
FUL DEGRADATION. critical dimension The cross-sectional size of a
crisscross neutralization See CROSS-CON- waveguide that determines its minimum usable
NECTED NEUTRALIZATION. frequency.
crisscross rectifier circuit A conventional bridge critical failure A component or circuit failure that
rectifier circuit configured in such a way that two results in shutdown of a system, or a malfunction
of the diodes are connected in crisscross fashion that results in improper operation.
between the input and output terminals. critical field The smallest magnetic-field intensity
critical angle 1. In radio communications, an an- in a magnetron that keeps an electron, emitted
gle of departure that a transmitted electromag- from the cathode, from reaching the anode.
154 critical frequency • cross modulation


critical frequency For a particular layer of the cross color In the chrominance channel of a color
ionosphere, the high frequency at which a verti- television receiver, crosstalk interference caused
cally propagated wave is no longer reflected back by monochrome signals.
to the earth. cross-connected neutralization Neutralization of
critical inductance In a choke-input power- a push-pull amplifier by feedback through two
supply filter, the minimum inductance that will capacitors”each connected from the output cir-
maintain a steady value of average load current. cuit of one transistor to the input circuit of the
critical potential The potential difference required other.
for an electron to excite or ionize an atom with cross-coupled multivibrator A multivibrator cir-
which it collides. cuit in which feedback is provided by a coupling
critical voltage The voltage at which a gas ionizes. capacitor between the output of the second stage
critical wavelength The wavelength that corre- and the input of the first stage; the stages are
sponds to CRITICAL FREQUENCY. forward-coupled by a capacitor of the same value.
CRO Abbreviation of cathode-ray oscilloscope. cross coupling 1. The state of being cross-coupled
Crookes dark space In a glow-discharge tube, the (see, for example, CROSS-COUPLED MULTIVI-
narrow dark space next to the cathode. Also see BRATOR). 2. Undesired coupling between two cir-
CROOKES TUBE. cuits.
Crookes tube A glow-discharge tube containing an cross current A current that flows in the opposite
anode, cathode, and a small amount of gas under direction from some other current.
low pressure. crossed-pointer indicator 1. Also called crossed-
cross antenna An antenna in which two (usually needle meter. A combination of two analog meter-
equal-length) horizontal radiators cross each ing instruments in one case. Each needle has its
other at right angles and are connected together own independently calibrated scale. A third scale
to a feeder at their point of intersection. It takes corresponds to the intersection point of the nee-
its name from its horizontal-cross shape. dles. Commonly used in directional wattmeters
cross assembler A program used with one com- that simultaneously show forward power, re-
puter to translate instructions for another com- flected power, and standing-wave ratio (SWR). 2.
puter. A two-pointer meter used in aircraft to show the
crossband operation 1. Communications in which position of the aircraft, relative to the glide path.
two frequency bands are used. Station X, for ex- crossed-wire thermoelement Two wires or strips
ample, might transmit on frequency fA in band A of dissimilar metals joined or twisted at a point
and receive on frequency fB in band B; station Y that constitutes a thermoelectric junction. In
would then transmit on fB and receive on fA. 2. In usual operation, a high-frequency current is
satellite communications, the use of two fre- passed through one wire, and a proportional
quency bands to facilitate full-duplex operation direct-current (dc) voltage, generated by thermo-
and to allow the satellite transponder to effec- electric action, appears at the other wire.
tively function. The transponder receives signals cross flux The magnetic flux component that is
from the earth within a specific frequency band, perpendicular to the flux produced by field mag-
and converts this entire band of signals to a set of nets.
signals that occupies an equal amount of spec- cross-hair pattern A television test pattern con-
trum space on another frequency band. The con- sisting of a single vertical line and a single hori-
verted signals are then retransmitted back to zontal line, which form a simple cross. The
earth. pattern resembles the cross hairs of an optical in-
crossbar switch A three-dimensional array of strument.
switch contacts in which a magnetic selector crosshatch generator A modulated radio-
chooses individual contacts, according to their frequency (RF) signal generator that produces a
coordinates in the matrix. crosshatch pattern on a picture-tube screen.
cross bearings A method of radionavigation, in crosshatch pattern A grid of horizontal and verti-
which directional readings are taken from a re- cal lines produced on a picture-tube screen by a
ceiving station (such as a ship or aircraft) for two cross-hatch generator. It is used in checking hor-
fixed transmitting stations whose locations are izontal and vertical linearity.
known. Lines are drawn on a map from the trans- cross modulation 1. A type of radio-frequency in-
mitting stations, in directions 180 degrees oppo- terference (RFI) between two strong stations that
site the bearings obtained from the receiving are close in frequency. The desired carrier is mod-
station. The intersection point of these lines is the ulated by the interfering signal. 2. The produc-
location of the receiving station. tion of signals by rectifier junctions in pipes and
cross beat A spurious frequency arising from wiring near a radio receiver. These objects pick
CROSS MODULATION. up waves and deliver energy at a different fre-
cross-check To compare the result of a calculation quency, which finds its way into the receiver. Also
or computer routine with the result obtained by a called external cross modulation. 3. The interac-
different method. tion between signals of different frequency when
155
cross modulation • cryotron


they magnetize a core of nonlinear magnetic ma- cross-sectional area 1. The surface area of a face
terial. Also see CROSSTALK. of a conductor after cutting through it at a right
cross-modulation factor An expression of the angle. Specified in square inches, square millime-
amount of cross modulation (or crosstalk) pre- ters, or circular mils. 2. The total of the cross-
sent in a particular instance. It is equal to M1/M2, sectional areas of all the wires in a stranded
where M1 is the modulation percentage that a conductor.
modulated wave produces in a superimposed un- cross-sectional testing In quality assurance and
modulated wave, and M2 is the modulation per- quality control (QA/QC), a method of checking a
centage of the modulated wave. large lot of units or components. Instead of test-
cross-neutralized circuit See CROSS-CON- ing every device, a fraction of the devices is
NECTED NEUTRALIZATION. tested. The sampling is taken uniformly from the
crossover 1. In a circuit diagram, a point at which group (e.g., every fifth unit).
lines representing wires intersect, but are not crosstalk Undesired transfer of signals between or
connected. 2. In a characteristic curve, point at among telephone lines, data lines, or system
which the plot crosses an axis or operating point. components. In computer operations, this effect
3. See CROSSOVER NETWORK. places a practical limit on the lengths of parallel
crossover distortion Distortion of a characteristic data cables.
at a crossover point (see CROSSOVER, 2); for ex- crosstalk coupling Undesired coupling between
ample, a bend in the curve where the plot of a circuits, caused by crosstalk.
waveform passes through zero. crosstalk factor See CROSS-MODULATION FAC-
crossover frequency The frequency at which a TOR.
crossover network delivers equal power to the two crosstalk level The amplitude of crosstalk, usually
circuits it supplies. expressed in decibels above a reference level.
crossover network Following final amplification in crosstalk loss Loss of energy caused by crosstalk.
a sound-reproduction system, an outboard filter crowbar An action producing a high overload on a
circuit that facilitates delivery of the low and high circuit protection device.
audio frequency (AF) components to the correct crowfoot 1. A pattern formed by the cracking or
speakers. crazing of solid plastics of solidified encapsulat-
crossover point See CROSSOVER, 2. ing compounds, so called from its resemblance to
crossover S-curve The S-shaped image obtained a bird™s footprint. 2. In a gravity battery cell, the
on an oscilloscope screen during sweep-generator zinc electrode, so called from its resemblance to a
alignment of a frequency-modulation (FM) detec- bird™s foot.
tor. In correct alignment, the exact center of the CRT Abbreviation of CATHODE-RAY TUBE.
S-curve (the crossover point) coincides with the crud 1. Broadband electrical noise, originating in-
zero point on the screen. side and/or outside a system. 2. Undesired sig-
cross product Also called vector product. For vec- nals that interfere with a desired signal.
tors A and B having lengths A and B, respectively, cryogenic device A device that exhibits unique
and subtending an angle θ relative to each other, electrical characteristics (such as superconduc-
the cross product A — B points in a direction per- tivity) at extremely low temperatures.
pendicular to the plane containing both A and B. cryogenic motor A motor designed for operation
The length of A — B is equal to AB sin θ. at extremely low temperatures.
cryoelectronics The study of the behavior of elec-
y tronic devices, circuits, and systems at extremely
low temperatures.
cryogenics The branch of physics dealing with the
behavior of matter at temperatures approaching
absolute zero. Also concerned with methods of
obtaining such temperatures in controlled envi-
ronments.
A—B cryosar A semiconductor switch utilizing low-
temperature avalanche breakdown.
cryoscope An instrument used to determine freez-
x ing point.
θ cryostat A chamber for maintaining a very low
A B
temperature for cryogenic operations. Also see
CRYOGENICS.
cryotron A switching device consisting essentially
of a straight tantalum wire, around which a
single-layer control coil is wound. The magnetic
z
field generated by control current flowing through
the coil causes the tantalum wire to become
cross product
156 cryotron • crystal loudspeaker


superconductive at a temperature of approxi-
Z axis
mately 4.4 degrees K.
(center of crystal)
cryotronics Low-temperature electronics, con-
cerned with such phenomena as superconductiv-
ity. The term is an acronym from cryogenics and X
electronics. Also see CRYOGENICS. Y Y cut
cryptanalysis The breaking of ciphers. X cut 35°
crypto- A prefix added to words, that implies en-
coding for the purpose of changing or hiding the AT cut
meaning of a message or signal.
cryptography The creating and writing of ciphers.
cryptology The art and science of creating, writ-
crystal cuts
ing, unscrambling, and breaking ciphers.
crystal 1. A material distinguished by the arrange-
ment of its atoms into a redundant pattern called quency, temperature, and thickness. Also see
a lattice that presents, in fragments of various CRYSTAL AXES.
sizes, a characteristic polyhedral shape. Common crystal detector A rudimentary form of semicon-
shapes include cubes, parallelepipeds, and ductor diode consisting of a mounted lump of




Y
hexagonal prisms. 2. A fragment of material as mineral (the crystal) in contact with a springy
defined in (1). 3. A plate or bar cut from a piece of wire (“cat™s whisker”). The point of the wire is




FL
piezoelectric material. moved to various points of contact on the crystal
crystal amplifier 1. A semiconductor diode circuit surface until the most-sensitive rectifying spot is
using carrier storage. Transistor action and, ac- found.
cordingly, pulse amplification is obtained by al- crystal diffraction The tendency of electromag-
AM
ternately making one electrode of the diode an netic waves to be scattered when passing through
emitter or collector. 2. Archaic term for TRANSIS- a crystal material.
TOR. crystal diode Archaic term for SEMICONDUCTOR
crystal audio receiver An audio radar receiver, DIODE. Also see GALLIUM-ARSENIDE DIODE;
consisting of a crystal detector and audio-ampli- GERMANIUM DIODE; JUNCTION DIODE; LASER
TE

fier stages. DIODE; POINT-CONTACT DIODE; SELENIUM
crystal axes The imaginary lines traversing a pie- DIODE; SIGNAL DIODE; SILICON DIODE.
zoelectric crystal, along which (or perpendicular crystal earphone An earphone in which the trans-
to which) plates are cut for oscillators, resona- ducer is a piezoelectric crystal. Electrical im-
tors, or transducers. pulses applied to the crystal vary its shape and
crystal calibrator A crystal oscillator used to cause a vibration that is transmitted to a di-
generate harmonic checkpoints for frequency aphragm; this in turn produces corresponding
calibration. Common fundamental calibrator sound waves.
frequencies are 100 kHz and 1 MHz. crystal filter See CRYSTAL RESONATOR.
crystal capacitor See VARACTOR. crystal headphone See CRYSTAL EARPHONE.
crystal control The control of the operating fre- crystal holder A fixture specially designed to hold
quency of a circuit by means of a piezoelectric a piezoelectric crystal; it ensures minimum dis-
crystal. tortion of crystal dimensions and minimum resid-
crystal-controlled receiver A superheterodyne ual capacitance, inductance, and resistance.
radio receiver whose local oscillator is crystal crystal imperfection A flaw in the lattice struc-
controlled. ture of a crystal.
crystal-controlled transmitter A radio transmit- crystal lattice The orderly, redundant pattern of
ter whose master oscillator is crystal controlled. atoms and molecules within a crystalline mate-
crystal counter A device for counting the fre- rial; it is a characteristic of a given material.
quency of subatomic particles, based on their crystal-lattice filter A crystal resonator in which
ability to change the conductivity of a crystal. The piezoelectric crystals are used to give a desired
particles can be photons, electrons, protons, neu- shape to the filter response curve.
trons, or the nuclei of atoms. crystalline material A material exhibiting the
crystal current Current flowing through a crystal; characteristic properties of a crystal (see CRYS-
specifically, the radio-frequency (RF) current TAL, 1).
flowing through a quartz plate in a crystal- crystallogram An X-ray photograph or other
controlled oscillator. record of crystal structure.
crystal cuts The classification of piezoelectric crystallography The science dealing with crystals
plates according to the angle at which they were and their properties (see CRYSTAL, 1).
cut from a quartz crystal. Common cut designa- crystal loudspeaker A loudspeaker whose trans-
tions are AT, BT, CT, DT, X, Y, and Z. Various ducer is a piezoelectric crystal. Electrical im-
cuts afford such complementary factors as fre- pulses applied to the crystal vary its shape and




Team-Fly®
157
crystal loudspeaker • crystal tester


cause vibrations that are transmitted to a di- crystal pulling 1. The extraction of a single crystal
aphragm or cone, which produces corresponding from a molten mass of crystalline material. Single
sound waves. crystals are used for high-quality semiconductor
crystal meter A rectifier-type ac meter using a devices. Also see CZOCHRALSKI METHOD, SIN-
semiconductor diode in series with a dc mil- GLE CRYSTAL, and SINGLE-CRYSTAL MATE-
liammeter or microammeter. RIAL. 2. The use of an inductor or capacitor in a
crystal microphone A microphone whose trans- crystal-controlled radio-frequency (RF) oscillator
ducer is a natural or synthetic piezoelectric circuit to allow adjustment of the frequency over
crystal. Sound waves striking the crystal (di- a small range.
rectly or via a diaphragm) vary its shape, mak- crystal receiver See CRYSTAL SET.
ing it produce an audio-frequency (AF) output crystal rectifier 1. A semiconductor diode used
voltage. for the purpose of rectifying alternating current
(dc), usually in a power supply.
crystal resistor A temperature-sensitive resistor
Sound made from silicon, and exhibiting a positive tem-
Crystal waves perature coefficient of resistance.
Electrodes crystal resonator A highly selective resonant cir-
cuit in which the center frequency is the resonant
Output
voltage frequency of a piezoelectric quartz-crystal plate.
crystal sensor See CRYSTAL TRANSDUCER.
crystal set A simple radio receiver that uses a
tuned circuit, semiconductor-diode detector, and
earphones.
Sound
waves
Crystal
Diaphragm

Output
voltage
Electrodes

crystal microphones

crystal mixer A mixer (converter) circuit utilizing
the nonlinearity of a semiconductor diode to mix
signals.
crystal operation 1. The characteristics of a piezo-
electric crystal in a particular circuit. 2. Crystal
frequency control.
crystal oscillator An oscillator whose operating
frequency is determined by the dimensions of an
oscillating piezoelectric quartz-crystal plate.
Compare SELF-EXCITED OSCILLATOR.
crystal oven A constant-temperature chamber for
stabilizing the frequency of a quartz crystal by
crystal set
maintaining its operating temperature at a fixed
point.
crystal photocell A photoelectric cell in which the
light-sensitive material is a crystalline substance, crystal slab See QUARTZ BAR.
such as germanium, selenium, silicon, etc. crystal socket 1. A low-capacitance, low-loss
crystal pickup A phonograph pickup whose trans- socket for a piezoelectric crystal. 2. A socket for a
ducer is a natural or synthetic piezoelectric crys- semiconductor diode.
tal. The crystal is attached (either directly or crystal tester 1. An oscillator used to check quartz
through a mechanical linkage) to a stylus, whose crystals. Most such units check only the crystal™s
movement in the disk groove varies the shape of ability to oscillate; more elaborate ones also check
the crystal. The resultant vibration generates a crystal current, frequency, temperature coeffi-
corresponding audio-frequency (AF) output volt- cient, activity, filter action, etc. 2. An instrument
age across the crystal. for checking the electrical characteristics of semi-
crystal probe A radio-frequency (RF) probe, whose conductor diodes. 3. An instrument for checking
rectifying element is a semiconductor diode. the performance of piezoelectric ceramics.
158 crystal tetrode • current antinode


crystal tetrode A transistor having four elements: cue A condition or signal that alerts an operator,
emitter, collector, and two bases. circuit or system to act in a specific manner.
crystal transducer A transducer using a piezo- cue circuit A device for transmitting cues used in
electric crystal as the sensitive element. Exam- program control.
ples: crystal earphone, crystal loudspeaker, cueing receiver 1. A (usually miniature) radio re-
crystal microphone, and crystal pickup. ceiver used to pick up cues. Example: a receiver
crystal triode See TRANSISTOR. carried by a technician, actor, or lecturer. 2. A re-
Cs Symbol for CESIUM. ceiver or other pickup circuit that receives a cu-
CS Abbreviation of COMPLEMENTARY SYMME- ing pulse, which it uses to set another circuit.
TRY. Also COS. cu ft Abbreviation of cubic foot or cubic feet.
CS 1. Symbol for standard capacitance. 2. Symbol cu in Abbreviation of cubic inch or cubic inches.
for source capacitance. cumulative error In a sum or other final value, the
csc Abbreviation of COSECANT. total error that has accumulated from the indi-
C scan See C DISPLAY. vidual errors in the terms. Also called systematic
csch Abbreviation of HYPERBOLIC COSECANT. error.
C scope A cathode-ray tube used in radar to pro- cup core A coil core that also forms a magnetic
vide a C DISPLAY. shield around the coil.
CT-cut crystal A piezoelectric plate cut from a cuprous-oxide rectifier See COPPER-OXIDE
quartz crystal at an angle of rotation around the RECTIFIER.
X-axis of +38°. Such a plate has a zero tempera- cur Abbreviation of CURRENT.
ture coefficient of frequency at 25°C. Also see curie Abbreviation Ci. A unit of radioactivity; 1
CRYSTAL AXES and CRYSTAL CUTS. curie is the amount of radiation from (or in equi-
CTL Abbreviation of complementary-transistor librium with) 1 gram of radium. Also equivalent to
3.7 — 1010 atomic breakdowns per second.
logic.
Cu Symbol for COPPER. Curie point 1. The temperature above which a fer-
cube 1. A regular polyhedron with six identical romagnetic material loses its magnetism or be-
square faces and eight vertices. At each vertex, comes paramagnetic. 2. The temperature at
three edges converge at mutual right angles. 2. which the ferroelectric properties of a substance
The third power of a number; thus the cube of n disappear.
is written n3. curie temperature As a magnetized substance is
cube tap An electrical adapter, in which a set of heated, the lowest temperature at which magne-
male prongs and three sets of female contacts are tization is lost. It is generally measured in degrees
on the sides of a molded cube. Allows three appli- Celsius or degrees Kelvin. For iron, this tempera-
ances to be used with a single electrical socket. ture is 760 degrees Celsius; for nickel, it is 356
degrees Celsius.
Curie™s law For a paramagnetic substance, the ra-
To tio of the magnetization to the magnetizing force
appliances is inversely proportional to the absolute tempera-
ture.
Curie-Weiss law Above the Curie point, the sus-
ceptibility of a paramagnetic material varies in-
versely as the excess of temperature above the
Curie point increases. This law is invalid for ap-
plications at or below the Curie point.
curium Symbol, Cm. A radioactive metallic ele-
ment produced artificially. Atomic number, 96.
Atomic weight, 247.
current Symbol, I or i. The movement of charge
To wall carriers, such as electrons, holes, or ions. Also
outlet
see AMPERE.
current amplification 1. An electronic process
in which the instantaneous, average, or peak
cube tap
magnitude of a current is increased. 2. The ex-
tent to which a current increases in a circuit;
cubical antenna An antenna in which the ele- the ratio (always greater than one) of output
ments form the outline of a geometric cube or current to input current, Iout/Iin. Also called cur-
rectangular prism. The most common example is rent gain.
the QUAD ANTENNA. current amplifier An amplifier operated primarily
cubical quad antenna See QUAD ANTENNA. to increase a signal current. Compare POWER
cubic equation A polynomial equation of the third AMPLIFIER and VOLTAGE AMPLIFIER.
degree. Its general form is ax 3 + bx2 + cx + d = 0. current antinode See CURRENT LOOP.
159
current attenuation • current relay


current attenuation 1. The reduction of current current gain See CURRENT AMPLIFICATION.
amplitude along a line. 2. The extent to which a current hogging 1. An undesirable condition that
current decreases in a line or circuit; the ratio (al- sometimes takes place when two or more transis-
ways less than one) of output current to input tors are operated in parallel. One device tends to
current, I out/I in. do all the work, taking all the current. The result
current balance An instrument for determining can be destruction of that device. 2. The tendency
the size of the ampere. This is done by measuring of one component in a group of identical parallel-
the force between two current-carrying conduc- connected components to dissipate most of the
tors. power.
current-balance switch A switch or relay, oper- current-hogging injection logic Acronym, CHIL.
ated by the existence of a difference between two A form of bipolar digital logic, similar to current-
currents. hogging logic but having the greater density char-
current-carrying capacity The maximum current acteristic of injection logic.
(usually expressed in amperes) that a conductor current instruction register A register in which
or device can safely conduct. are held instructions ready for execution by a
current coil The series coil in a nonelectronic program controller.
wattmeter. Compare POTENTIAL COIL. current lag A circuit condition in which current
current-controlled amplifier Abbreviation, CCA. variations are delayed by up to 180 degrees of
An amplifier in which gain is controlled by means phase relative to voltage variations. Compare
of a current applied to a control-input terminal. CURRENT LEAD.
current density The current (usually expressed in current lead A circuit condition in which current
amperes per square centimeter) passing through variations occur earlier than voltage variations by
a cross-sectional area of a conductor. up to 180 degrees of phase. Compare CURRENT
current drain 1. The current supplied to a load by LAG.
a generator or generator-equivalent. 2. The cur- current limiting The controlling of current so that
rent required by a device for its operation; also, it does not exceed a desired value.
the current taken by the device during standby current-limiting resistor A series resistor in-
periods. serted into a circuit to limit the current to a pre-
current echo Reflected current in a transmission scribed value.
line that is not terminated in an impedance ex- current loop A point on a transmission line or an-
actly matching its characteristic impedance. tenna radiator at which the current reaches a lo-
current-fed antenna An antenna in which the cal maximum. Compare CURRENT NODE.
transmission line is attached to the radiator at a current meter A usually direct-reading instru-
current loop (voltage node). Compare VOLTAGE- ment, such as an ammeter, milliammeter, or mi-
FED ANTENNA. croammeter, used to measure current strength.
current feed 1. The delivery of power to a device or Also see ELECTRONIC CURRENT METER.
circuit at a point where current dominates. Com- current-meter operation The operation of a volt-
pare VOLTAGE FEED. 2. In an antenna, feeding meter as a current meter by connecting it to re-
it at a current maximum. spond to the voltage drop across a resistor that
carries the current of interest.
current-mode logic In computer operations, tran-
Current sistor logic in which the transistors operate in the
unsaturated mode.
current node A point on a transmission line or an-
tenna radiator at which the current reaches a lo-
cal minimum. Compare CURRENT LOOP.
current noise Electrical noise produced by current
flowing through a resistor.
current probe A transformer usually having a
Current feed
snap-around, one-turn coil that picks up energy
from a conductor and couples it into an alternat-
ing-current ammeter.
current feedback 1. A feedback signal consisting
current rating 1. A specified value of operating
of current fed from the output to the input circuit
current. 2. See CURRENT-CARRYING CAPACITY.
of an amplifier. 2. A system or circuit for obtain-
current-regulated supply See CONSTANT-
ing current feedback.
CURRENT SOURCE.
current-feedback pair A two-stage, direct-coupled
current regulation The stabilization of current at
transistor amplifier having direct-current shunt-
a predetermined level or value.
series feedback.
current regulator See BARRETTER.
current flow Charge carriers passing through a
current relay A relay actuated by specific values of
solid, liquid, gas, or vacuum. Also see CURRENT
pickup and dropout current.
and CURRENT DENSITY.
160 current saturation • cutoff frequency


current saturation In the operation of a device cursor 1. A marker that indicates the position
(such as a transistor, saturable reactor, or mag- where a character can be entered in a video al-
netic amplifier), the leveling off of current at a phanumeric display. Commonly used in comput-
value beyond which no further increase occurs” ers and word processors. 2. The sweeping line on
even though an input parameter is further in- a radar display. 3. The movable marker on a slide
creased. rule.
current sense amplifier An amplifier used to in- curve trace 1. A device that supplies a special
crease the sensitivity of, or to decrease the load- variable test voltage to a component or circuit un-
ing of, a current-sensing component. der test, at the same time supplying a sweep volt-
current sensing Sampling a current (e.g., when age to an oscilloscope. The component™s output
the voltage drop across a series resistor is used as voltage is also presented to the oscilloscope. As a
a proportional indication of the current flowing result, the response curve of the component ap-
through the resistor). pears on the oscilloscope screen. 2. A device that
current-sensing resistor A low-value resistor in- produces a permanent record (photographic or
serted into a circuit primarily for current sensing. graphic) of an electrical phenomenon. Also called
current sensitivity In a current meter or gal- OSCILLOGRAPH or RECORDER.
vanometer, current (in amperes or fractions curvilinear trace A trace made on paper with
thereof) per scale division. curved vertical lines. The lines are curved to
current-sheet inductance Symbol, LS. The low- match the arc through which the recording pen
frequency inductance of a single-layer coil, calcu- swings.
lated with the formula L S = (0.10028 a2 N 2)/s, cut-in angle In a semiconductor rectifier circuit, a
where L S is in microhenrys, a is the coil radius in phase angle slightly greater than zero degrees, at
inches, N is the total number of turns, and s is which current conduction begins. Compare CUT-
the coil length in inches. OUT ANGLE.
current shunt 1. A resistor connected in parallel Cutler antenna A parabolic-dish antenna, in
with a voltmeter to convert it into an ammeter. 2. which the driven element consists of a wave-
A resistor connected in parallel with the input of guide that has two apertures on opposite sides of
a voltage amplifier to make the response of the a resonant cavity.
amplifier proportional to input-signal current. Cutler feed An aircraft antenna feed system in
current sink A circuit or device through which a which radio-frequency (RF) energy is fed to the re-
constant current can be maintained. flector by a resonant cavity at the end of a wave-
current-sinking logic A form of bipolar digital guide.
logic. Current flows from one stage to the input of Cutler tone control A dual resistance-capacitance
the stage immediately before. (RC) filter circuit of the general bridged-tee vari-
current-squared meter An ammeter or milli- ety. Variation of the series leg provides adjustable
ammeter whose deflection is proportional to the treble boost; variation of the shunt leg provides
square of the current. adjustable bass boost.
current-stability factor In a common-base con- cutoff 1. The process of reducing some operating
nected bipolar transistor, the ratio dIE/dIC, where parameter, such as collector current, to zero by
IE is the emitter current and IC is the collector adjusting the bias at the input electrode. 2. The
current. point on the characteristic curve of an amplifying
current strength The magnitude of electric cur- device, at which the output current drops to zero
rent (see CURRENT) (i.e., the number of carriers under no-signal conditions. 3. The lowest
flowing past a given point per unit time, ex- frequency at which a waveguide will efficiently
pressed in coulombs per second or in amperes). function. 4. The frequency or frequencies corre-
current transformer 1. A transformer used to in- sponding to the point or points in a filter
crease or decrease current flow. A primary-to- response, at which the attenuation is three
secondary step-up turns ratio reduces the decibels greater than the lowest attenuation within
current; a primary-to-secondary step-down turns the passband. See also CUTOFF FREQUENCY.
ratio increases the current. 2. A particular trans- cutoff attenuator A variable, nondissipating at-
former (as in 1) used to change the range of an al- tenuator consisting of a variable length of wave-
ternating-current milliammeter or ammeter. guide used at a frequency below cutoff.
current vector In a vector diagram, a line with an cutoff bias In a transistor or vacuum-tube circuit,
arrowhead (vector) showing the magnitude and the value of control-electrode bias that produces
phase of a current. Compare VOLTAGE VEC- output current cutoff.
TOR. cutoff current Symbol, Ico. In a transistor, the
current-voltage feedback In an amplifier or oscil- small collector current that flows when the emit-
lator, the process of applying some of the output ter current is zero (common-base circuit) or when
current and voltage to the input. This feedback the base current is zero (common-emitter circuit).
might be in phase (positive) or out of phase (neg- cutoff frequency 1. Symbol, fco. The high fre-
ative), with respect to the input. quency at which the current-amplification factor
161
cutoff frequency • cyclic variations


of a transistor drops to 70.7% of its 1-kHz value. cyan Blue-green, one of the three primary pigments.
2. In a filter, amplifier, or transmission line, the cyber- A prefix that indicates relevance to, or in-
frequency point(s) at which transmission loss or volvement with, computers, computer systems,
filter rejection begins. It is generally specified as and electronic control systems.
the half-power point(s), or the point(s) at which cybernetics The study of control system theory in
the attenuation is three decibels, relative to terms of the relationship between animal and
the lowest attenuation. Examples: the high- machine behavior.
frequency cutoff of an amplifier and the upper Cyber Sapiens An expression for a computer or
and lower cutoff points of a bandpass filter. robot with artificial intelligence (AI) on the fore-
cutoff limiting Output-peak clipping that results front of current technology.
from overdrive in an amplifying device. Compare cyberspace 1. Alternative expression for INFOR-
SATURATION LIMITING. MATION SUPERHIGHWAY. 2. Alternative expres-
cutoff potential See CUTOFF BIAS. sion for VIRTUAL REALITY.
cutoff voltage See CUTOFF BIAS. cyborg Acronym of the words cybernetic and or-
cutoff wavelength 1. The wavelength correspond- ganism. 1. A human being with at least one arti-
ing to cutoff frequency. 2. For a waveguide, the ficial body part, such as a prosthesis (artificial
ratio of the velocity of electromagnetic waves in limb). 2. A human being who is largely composed
free space (3 — 108 meters per second) to the cut- of robotic body parts.
off frequency of the waveguide in Hz. The result is cycle 1. Abbreviation, c. One complete, 360-degree
thus expressed in meters. revolution of the current or voltage vector in an
cutout 1. A device, such as a circuit breaker, that alternating-current (ac) wave. An ac frequency of
automatically disconnects a circuit, usually to 1 cycle per second is 1 Hz (see HERTZ). 2. A com-
prevent overload, but occasionally to prevent un- plete sequence of operations.
derload. 2. Emergency switch. 3. Fuse. cycle counter A device that totals the number of
cut-out angle In a semiconductor rectifier circuit, cycles of a phenomenon repeated during a given
a phase angle slightly less than 180 degrees at period.
which current conduction ceases. Compare CUT- cycle index The number of times that a particular
IN ANGLE. cycle has been, or must be, iterated in a com-
cutout base A fuse block. puter program.
cut rate 1. The speed at which a cutter moves cycle index counter A variable that indicates how
across the surface of a blank vinyl disk during the often a cycle of computer program instructions
recording process. 2. The number of cut lines per has been executed. In a program, for example,
inch in a vinyl disk recording. this can be accomplished by increasing, through
CW 1. Abbreviation of CONTINUOUS WAVE. 2. Ab- instruction, the value of a location™s content every
breviation of CLOCKWISE. time a loop operation is performed.
CW filter In a communications receiver, a highly cycle life The total number of charge-discharge cy-
selective filter in the intermediate-frequency (IF) cles a rechargeable cell or battery can tolerate be-
or audio-frequency (AF) stage. The bandwidth is fore becoming useless.
typically 200 Hz to 500 Hz; some audio filters cycle reset To change the value of a cycle count
can be set for bandwidths as low as about 50 (making it zero or some other value).
Hz. cycle shift See CYCLIC SHIFT.
CW laser A laser that emits energy in an uninter- cycles per second Abbreviation, cps. Archaic term
rupted stream, rather than in pulses. for HERTZ.
CW monitor See KEYING MONITOR. cycle time Pertaining to an operation, the dura-
CW oscillator 1. In a radio receiver, a variable- tion of a complete cycle.
frequency oscillator that heterodynes a radiotele- cycle timer A timer that switches a circuit or de-
graph signal in the intermediate-frequency (IF) vice on and off, according to a predetermined cy-
amplifier chain, to make audible the continuous- cle. Also called programmed timer.
wave dits and dahs. 2. Sometimes, an external cyclic code See GRAY CODE.
variable-frequency radio-frequency (RF) oscilla- cyclic memory In computer operations, a memory
tor, whose output beats against the actual carrier whose locations can only be accessed points in a
of a continuous-wave radiotelegraph signal, mak- cycle, as of a magnetic diskette.
ing it audible as dits and dahs. 3. An unmodu- cyclic shift The moving of data out of one end of a
lated, unkeyed oscillator. storage register and reentering it character-by-
CW radar A radar system in which radio-frequency character or bit-by-bit at the other end in a closed
(RF) energy is transmitted continuously. loop (e.g., 87654 cyclically shifted one place to
CW reference signal A sinusoidal radio- the right becomes 48765).
frequency (RF) signal, used to control the con- cyclic variations Periodic changes in the features
duction time of a synchronous demodulator in of the ionosphere, occurring on a daily, seasonal,
color television. or sunspot-related basis. These changes are fairly
Cx Symbol for UNKNOWN CAPACITANCE. predictable.
162 cycling • Czochralski method


cycling The tendency of a parameter to oscillate cylindrical contour The most common curvature
back and forth between two different values. of the face of a magnetic tape recording head; it is
cyclogram A method of showing the relationship a section of a cylinder having a constant radius of
between two signals on an oscilloscope. The two 0.5 inch to 1 inch.
signals must have a fixed phase relationship. cylindrical coordinate geometry A scheme for
cyclotron A type of particle accelerator. An applied robot-arm movement. There are three coordi-
electromagnetic field, acting together with an in- nates, called reach, angle, and elevation. It allows
tense applied magnetic field, cause charged sub- precise positioning of a robot end effector within a
atomic particles to travel with increasing velocity region consisting of two concentric cylinders and
in a spiral path between two semicircular metal all the volume in between.
boxes called dees. When the particles go fast cylindrical coordinates A method of locating a
enough in the correct path, they are expelled and point in three-space in which height, distance,
strike a target in their path. and angle are used to uniquely define points.

h axis
Path of
accelerated
particles


P = (h, r,θ)
Dee 2
Dee 1

h r
Hot
cathode
θ=0
θ axis
Target
Deflector cylindrical coordinates

cyclotron
cylindrical magnet See CYLINDER MAGNET.
cylindrical wave An electromagnetic wave whose
cyclotron frequency The angular frequency of a field surfaces are nearly perfect cylinders.
charged particle in a cyclotron. The cyclotron fre- cylindrical waveguide A waveguide resembling a
quency depends on the number of times per sec- round pipe.
ond the magnetic field of the device is reversed. cylindrical winding A method of coil winding in
cyclotron radiation An electromagnetic field pro- which the wire is formed into a helix. There might
duced by the circular movement of charged parti- be only one layer, or there might be several lay-
cles in a fluctuating magnetic field. ers. The length of the coil is greater than the di-
cylinder In computer operations, the combination ameter. Also called a linear winding.
of equal-radius tracks on the platters of a hard Czochralski method A technique for obtaining a
disk. relatively large single crystal from a substance,
cylinder magnet A permanent magnet in the such as the semiconductors germanium and sili-
shape of a cylinder. con. The method consists essentially of dipping a
cylindrical capacitor See CONCENTRIC CAPACI- seed crystal into a molten mass of the same sub-
TOR. stance, then slowly withdrawing it while rotating it.
D 1. Symbol for DEUTERIUM. 2. Symbol for ELEC- Damon effect The change that the susceptibility of
TRIC DISPLACEMENT. 3. Symbol for ELECTRIC ferrite undergoes under the influence of high RF
FLUX DENSITY. 4. Symbol for DISSIPATION power.
FACTOR. 5. Symbol for drain (see DRAIN, 3). 6. damped galvanometer A galvanometer with a pro-
Abbreviation of DISSIPATION. 7. Symbol for de- vision for overswing limiting or oscillation preven-
terminant. 8. Symbol for DIFFUSION CONSTANT. tion.
d 1. Abbreviation of DECI. 2. Symbol for DIFFER- damped loudspeaker A loudspeaker in which un-
ENTIAL. 3. Symbol for distance. 4. Symbol for desirable excursions are prevented by damping in
DENSITY. 5. Symbol for drain (see DRAIN, 3). 6. the associated amplifier or speaker circuit.
Abbreviation of DISSIPATION. 7. Abbreviation of damped meter 1. A meter with a provision for
day. 8. Abbreviation of DEGREE. 9. Abbreviation overswing limiting or oscillation prevention. 2. A
of diameter. 10. Abbreviation of DRIVE. meter that is protected during transport by a
D/A Abbreviation of DIGITAL-TO-ANALOG. See shorting bus between the two meter terminals.
DIGITAL-TO-ANALOG CONVERSION. damped natural frequency 1. The frequency at
dA 1. Symbol for DIFFERENTIAL OF AREA. 2. which a damped system having one degree of
Symbol for differential of amplification. 3. Seldom- freedom will oscillate after momentary applica-
used abbreviation of deciampere. tion of a transient force. 2. In the presence of
da Abbreviation of DEKA. damping, the rate at which a sensing element os-
DAC Abbreviation of DIGITAL-TO-ANALOG CON- cillates freely.
VERTER. damped oscillations Oscillations in which the am-
DACI Abbreviation of direct adjacent-channel inter- plitude of each peak is lower than that of the pre-
ference. ceding one; the oscillation eventually dies out (the
DAGC Abbreviation of DELAYED AUTOMATIC amplitude becomes zero). Compare CONTINU-
GAIN CONTROL. OUS WAVE.
daisy chain A method of transferring a signal in a damped speaker See DAMPED LOUDSPEAKER.
computer from one stage to the next. damped wave A wave whose successive peaks de-
daisy wheel A form of printing device consisting crease in amplitude (i.e., it decays), eventually
of a disk having several dozen radial spokes, reaching an amplitude of zero. Compare CONTIN-
each of which has a character molded on its UOUS WAVE and UNDAMPED WAVE.
face. The disk rotates to the proper position in damped-wave decay See DECREMENT, 1.
the printing process, and a hammer strikes the dampen To cause the amplitude of a signal to
spoke to press the molding against the ribbon decay.
and paper. damper See DAMPING DIODE.
DAM Abbreviation of data-addressed memory. damper diode See DAMPING DIODE.


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164 damper winding • data-acquisition system


acid; the cup is in a jar filled with a saturated cop-
per-sulfate solution in which the copper electrode
is immersed. Typical voltage for the cell is 1.1 V.
daraf The unit of ELASTANCE. Elastance in darafs
is the reciprocal of capacitance in farads.
dark conduction The flow of dark current in a
photoconductive or glow-discharge device.
Amplitude


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