. 6
( 42)


bulk-erase noise 1. The residual magnetic im-
pulses that remain on a magnetic tape after it has
been bulk-erased. 2. Noise generated by bulk-
erased tape when the latter passes through deen-
ergized record or erase heads in a tape machine.
bulk eraser A type of power-line-frequency de-
gausser that erases an entire reel of magnetic
tape without requiring that the tape be unreeled
and passed continuously under an erase head.
This saves considerable time, but often leaves
some BULK-ERASE NOISE on the tape. Also
Bunet s formula
bulletin board In personal computing or amateur
packet communications, a system that allows
subscribers to leave messages for each other for
access via a modem or terminal node controller. which is in a nitric acid solution. The zinc rod
bulletin station A station intended for the trans- serves as the negative pole; the positive pole is a
mission of bulletins of interest to certain parties, piece of hard carbon. The cell produces about 1.9
such as military personnel or amateur radio op- volts and delivers relatively high current.
erators. An example is W1AW in Newington, Con- burden See VOLTAGE BURDEN.
necticut, an amateur radio station that transmits burn 1. A blemish on the screen of a cathode-ray
bulletins and code practice. tube (CRT), caused by destruction of the phos-
buncher In a Klystron, a cavity resonator that con- phor there. This results from prolonged focusing
tains two grids mounted parallel to the electron of an intense electron beam in one spot. 2. A
stream. The electrostatic field of the grids alter- blemish on the screen of a television picture tube,
nately accelerates and retards the electrons, ve- usually resulting from ions that reach the screen
locity-modulating the stream into bunches. when the ion trap is not working correctly.
buncher grids In a Klystron, the closely spaced burn-in A long, thorough, carefully controlled pre-
grids that velocity-modulate the electron beam liminary test of a component, device, or system,
into successive bunches. to stabilize its electrical characteristics after
buncher resonator In a velocity-modulated tube, manufacture and to ensure that it will function
such as a Klystron, the input cavity resonator. according to rated specifications. An important
buncher voltage The radio-frequency (RF) grid-to- test for equipment whose reliability must be
grid voltage in the buncher resonator of a guaranteed, such as an emergency commun-
Klystron. ications transceiver.
bunching The production of electron bunches in a burnout 1. Failure of a conductor or component
velocity-modulated tube, such as a Klystron. Also caused by overheating from excess current or
see BUNCHER. voltage. 2. The open-circuiting of a fuse. 3. Elec-
bunch stranding A technique for combining sev- trical failure of any type.
eral thin wires into a single thick wire. Often used burst 1. The abrupt ionization of the gas in an ion-
in guy wires and electrical conductors to improve ization chamber by cosmic rays. 2. An abrupt in-
tensile strength and flexibility. At radio frequen- crease in the amplitude of a signal. Also, the type
cies, bunch stranding also improves electrical of signal that results from burst action. 3. See
conductivity by increasing the ratio of surface COLOR BURST.
area to cross-sectional area. This minimizes burst amplifier In a color-television receiver, the
losses caused by skin effect. amplifier that separates the burst pulse from the
Bunet™s formula A formula for calculating the in- video signals and amplifies the former. See
ductance of a multilayer air-core coil that has a COLOR BURST.
diameter less than three times the length: burst gate timing In a color-television receiver,
the timing of the gating pulse with the input sig-
L = a2N 2/(9a + 10l + 8.4c + 3.2cl/a)
nal of the burst amplifier.
burst generator A signal generator delivering a
where N is the number of turns, a is the average
burst output (see BURST, 2) for testing various
coil radius, c is the winding thickness, and l is the
types of equipment. Its output is intermediate
length of the coil.
between sine waves and square waves, and is
Bunsen cell A cell consisting of a zinc rod in a sul-
convenient for rapidly appraising the perfor-
furic acid solution contained in a porous pot,
burst generator • button microphone

mance of such devices as amplifiers, filters, elec- circuit. The ring supplies the inductance, and the
tronic switches, transducers, and loudspeakers. butterfly supplies the capacitance. It is also
burst transmission A short transmission at high called butterfly tank and butterfly resonator.
speed. This method of transmission saves time, Butterworth filter A high-pass, low-pass, band-
but increases the necessary bandwidth of a sig- pass or band-rejection filter, characterized by a
nal by the same factor as the ratio of the high flat passband (absence of passband ripple) and
speed to the original speed. high attenuation at frequencies far removed from
bus 1. A main conductor in a circuit. A bus can be the passband.
high in the sense that its potential is above or Butterworth function A mathematical function
below ground, or it can be low or at ground refer- that is used in the design of a BUTTERWORTH
ence. 2. In computer operations, a common FILTER.
group of paths over which input and output sig- button 1. Usually, a small switch that is actuated
nals are routed. by finger pressure. It is also called pushbutton
bus driver A buffering device designed to increase and pushbutton switch. Sometimes, the term is
the driving capability of a microprocessor, which applied only to the insulated knob or pin which is
itself might be capable of driving no more than a pushed to operate the switch. 2. A tiny lump of
single load. impurity material, placed on the surface of a
business machine Any piece of electronic or elec- semiconductor wafer for alloying with the wafer
tromechanical equipment used mainly, or entirely, to form a junction. See ALLOY JUNCTION. 3. The
for business purposes. Examples are photocopiers, carbon element(s) in a BUTTON MICROPHONE.
facsimile (fax) machines, printers, and computers. button capacitor A button-shaped ceramic or sil-
busing The parallel interconnection of circuits. vered-mica fixed capacitor. Because of its disk
busy test A check conducted to find out whether or shape and mode of terminal connection, it offers
not a certain telephone subscriber line is in use. very low internal inductance.
busy tone Also called busy signal. An intermittent button microphone A microphone in which a but-
tone that indicates that the subscriber line being ton-shaped carbon element is attached to a di-
called is in use. aphragm, which is set into vibration by sound
Butler oscillator An oscillator that consists of a waves. This motion causes the button resistance
two-stage amplifier with a quartz crystal in the to vary, modulating a direct current that passes
positive-feedback path from output to input.
butterfly capacitor A plate-type variable capacitor Single button
that has two stator sections and a single rotor
section common to the two stators. External con-
nections are made to the stators only. Thus, no Diaphragm
wiping contact is required to the rotor, and the
troubles associated with such a contact are
avoided. The butterfly capacitor is actually two Carbon
variable capacitors in series. The unit is so called granules
from the shape of its rotor.

Stator 1


Sound Double button
buttons Output
Stator 2
butterfly capacitor Diaphragm
butterfly circuit A combination of a butterfly ca-
pacitor and a ring, of which the stator plates of
the capacitor are an integral part. The resulting
button microphone
structure is a compact variable-frequency tuned
92 button microphone • byte

through the button. A single-button microphone BWO Abbreviation of BACKWARD-WAVE OSCIL-
has only one button, whereas a double-button LATOR.
microphone has two”one mounted on each side BX Symbol and abbreviation for armored and insu-
of the center of the diaphragm. lated flexible electrical cable.
buzz 1. A low-pitched rough sound with high- bypass A route (either intended or accidental)
frequency components, usually the result of electri- through which current easily flows around a
cal interference from nonsinusoidal voltages component or circuit instead of through it.
generated by neighboring equipment or devices. bypass capacitor A capacitor that is used to con-
2. The waveform associated with such a sound. duct an alternating current around a component
3. Fastening two conducting surfaces by a KEL- or group of components. Often the ac is removed
LIE BOND. from an ac/dc signal, the dc being free to pass
buzzer A nonringing device used principally to through the bypassed component.
generate sound other than that achievable with
sine waves. In an electromechanical vibrating-
reed buzzer, the reed acts as an armature, which
is mounted close to the core of an electromagnet.
At quiescence, the reed rests against a station-
ary contact. When voltage is applied to the elec-
tromagnet, the reed is attracted to the core,
moving away from the contact; but this breaks
the circuit, the magnetism ceases, and the reed
springs back to the contact. The action is re-
peated continuously at a frequency that depends
on the reed dimensions and its distance from the




B voltage The dc voltage required by certain elec-
trodes of vacuum tubes and transistors. It espe- B-Y signal In a color television receiver, the color-
cially pertains to voltages required by the plate difference signal which, when combined with a
and screen of a vacuum tube, as opposed to the luminance (Y) signal, forms a blue primary signal
filament voltage and control-grid voltage. for the three-gun picture tube.
bw 1. Abbreviation of bandwidth. 2. Abbreviation byte In digital-computer and data-communica-
of black-and-white. tions operations, a unit of data consisting of eight
BWA Abbreviation of backward-wave amplifier. contiguous bits. In packet communications, the
BWG Abbreviation of BIRMINGHAM WIRE GAUGE. term octet is often used.
C 1. Abbreviation of CAPACITANCE. 2. Symbol for cabled wiring Insulated leads connecting circuit
COLLECTOR of a transistor. 3. Symbol for CAR- points; they are tied together with lacing cord or
BON. 4. Abbreviation of CELSIUS. 5. Symbol for with spaced fasteners.
COULOMB. 6. Abbreviation of CALORIE. cablegram A (usually printed) message transmit-
c 1. Abbreviation of CENTI. 2. Abbreviation of ted or received via undersea cable. Compare
for SPEED OF LIGHT in a vacuum. cable loss See CABLE ATTENUATION.
Ca Symbol for CALCIUM. cable run The path taken by a cable.
cabinet An enclosure for a piece of apparatus. It cable splice 1. An electrical attachment between
might or might not incorporate electromagnetic two sections of cable that has identical or simi-
shielding. lar construction, with or without the use of con-
cable 1. A usually flexible (but sometimes rigid) nectors. 2. To electrically attach two sections of
medium, via which electrical power or signals are cable that have identical or similar construction,
transferred. Although the term is occasionally ap- with or without the use of connectors.
plied to a single conductor, especially when it is a cable tie A short piece of wire or plastic that holds
braid or weave of a number of wires, cable usually wires or cables in a bundle.
means a bundle of separate, insulated wires or cable TV See COMMUNITY-ANTENNA TELEVI-
strands of fiberoptic material. 2. CABLEGRAM. SION.
cable address A code word that specifies the recip- cache memory A short-term, high-speed, high-
ient of a CABLEGRAM. capacity computer memory. Similar to a scratch-
cable assembly A special-purpose cable with con- pad or read-write memory.
nectors. CAD Acronym for computer-aided design.
cable attenuation Reduction of signal intensity CAD/CAM Acronym for computer-aided design and
along a cable, usually expressed in decibels per manufacturing.
foot, hundred feet, mile, etc. cadmium Symbol, Cd. A metallic element. Atomic
cable capacitance Capacitance between conduc- number, 48. Atomic weight, 112.41. Many elec-
tors in a cable or between conductors and the tronic structures are cadmium plated for protec-
outer sheath of a cable. 2. Sometimes, capaci- tion.
tance between a cable and earth. cadmium borate phosphor Formula, (CdO +
cable clamp A support device for cable runs in B2O3): Mn. A substance used as a phosphor coat-
equipment and systems. ing on the screen of cathode-ray tubes. The char-
cable communications Telegraphy or telegraphy acteristic fluorescence is green-orange.
via a (usually undersea) cable. cadmium cell Also called Weston standard cell.
cable connector A connector, such as a coaxial fit- An electrochemical standard cell used as a refer-
ting, that joins cable circuits or connects a cable ence voltage source. Produces 1.0186 volt at
to a device. 20°C.

Copyright © 2001 by The McGraw-Hill Companies, Inc.
Click here for Terms of Use.
94 cadmium plating • calibrated sweep

cadmium plating The process of coating a conduc- ing on the screen of cathode-ray tubes; the char-
tor or component with cadmium to increase its acteristic fluorescence ranges from green to
resistance to corrosion. orange.
cadmium selenide photocell A photoconduc- calcium tungstate phosphor Formula, CaWO4. A
tive cell in which cadmium selenide is the light- substance used as a phosphor coating on the
sensitive material. screen of short-persistence cathode-ray tubes;
cadmium silicate phosphor Formula, (CdO + the characteristic fluorescence is blue, as is the
SiO2). A substance used as a phosphor coating on phosphorescence.
the screen of cathode-ray tubes; the characteris- calculate To perform the steps of an intricate
tic fluorescence is orange-yellow. mathematical operation. Compare COMPUTE.
cadmium standard cell See STANDARD CELL. calculating punch A data-processing peripheral
cadmium sulfide photocell A photoconduc- that reads punched cards, makes calculations,
tive cell in which cadmium sulfide is the light- and punches new data into those cards or new
sensitive material. cards.
cadmium tungstate phosphor Formula, CdO + calculator A machine that performs mathematical
WO3. A substance used as a phosphor coating on operations, especially arithmetic. Typically, the
the screen of cathode-ray tubes; the characteris- device is a small box with buttons and a minia-
tic fluorescence is light blue. ture numeric display. Used only in mathematical
cage A completely shielded enclosure, such as a applications. In contrast, a COMPUTER can be
screen room, which is covered with a grounded used for a much wider variety of jobs, such as
fine-mesh conductive screen on all sides. word processing, graphics, and data-base. Many
cage antenna An antenna, usually center-fed and personal computers have calculator programs;
balanced, that consists of multiple parallel con- the “buttons” are actuated by pointing and click-
ductors arranged in a cylindrical cage config- ing with a mouse.
uration. The cage results in a much broader calculus 1. The symbology and rules comprising a
bandwidth than is the case with an antenna system of logic, such as BOOLEAN ALGEBRA. 2.
made up of a single conductor. Cage antennas A branch of mathematical analysis concerned
are typically used at frequencies between about with rates of change and accumulation. See DIF-
calendar age The age of a piece of equipment, mea-
sured since the date of manufacture. Specified in
years, months, and days. The actual manufac-
ture date might alternatively be given.
calendar time The time available in a working pe-
riod [i.e., a 40-hour work week represents a cal-
Multiple endar time of 120 hours (five days times 24 hours
Feed conductors per day)].
calibrate To compare and bring into agreement
with a standard.
calibrated measurement 1. A measurement made
with an instrument that has been calibrated with
a standard reference source. 2. A measurement
that is corrected for instrument error.
cage antenna
calibrated meter An analog or digital meter that
has been adjusted to agree as closely as possible
CAI Abbreviation for computer-assisted instruction. with a reference source.
CAL An acronym for conversional algebraic lan- calibrated scale 1. A scale whose graduations
guage, a general-purpose problem-oriented com- have been carefully checked for accuracy (i.e.,
puter programming language used in time-sharing they correspond to the true values of the quantity
systems. that they represent). The scale is graduated to
calcium Symbol, Ca. A metallic element of the read directly in units of the quantity, such as mil-
alkaline-earth group. Atomic number, 20. Atomic liamperes, kilohertz, volts, etc. 2. A scale with
weight, 40.08. fixed, plain numeric graduations (e.g., 0 to 100)
calcium phosphate phosphor Formula, Ca3(PO4)2. that do not directly indicate the magnitude of a
A substance used as a phosphor coating on the quantity, but that can be converted to various
screen of long-persistence cathode-ray tubes; the quantities via graphs, nomographs, tables, or
characteristic fluorescence is white, as is the charts. See CALIBRATION CURVE.
phosphorescence. calibrated sweep In an oscilloscope, a sweep cir-
calcium silicate phosphor Formula, (CaO + cuit calibrated to indicate sweep frequency or
SiO2): Mn. A substance used as a phosphor coat- time at all control settings.
calibrated triggered sweep • CAN

calibrated triggered sweep In an oscilloscope, a sage, or alerting all receiving stations to prepare
triggered sweep circuit calibrated in terms of them for a general broadcast message. 2. In a
sweep time or frequency. computer program, a branch to a closed subrou-
calibration 1. Determining the accuracy with tine; also, to branch to such a subroutine.
which an instrument indicates a quantity. 2. De- call direction code Abbreviation, CDC. In tele-
termining the degree to which the response of a graph networks, a special code that, when trans-
circuit or device corresponds to desired perfor- mitted to a terminal, causes the teleprinter to be
mance. 3. Marking a scale to show actual values automatically switched on.
of a quantity in the form of a direct readout. For calling sequence 1. Computer program instruc-
example, the scale of an analog meter might be tions needed to establish the conditions for a call
calibrated in milliamperes (mA) from 0 to 50 in in- (see CALL, 2). 2. Subroutine instructions provid-
crements of 1 mA. ing a link to the main program.
calibration accuracy 1. A quantitative expression call instruction A computer program instruction
of the agreement between the value of a quantity, that makes a program controller branch to a sub-
as indicated by an instrument, and the true routine; it also locates and identifies the parame-
value. Usually expressed as the maximum per- ters needed for the subroutine™s execution. Also
centage of the true value by which the indicated known as subroutine call.
value can be expected to deviate in either direc- call letters Letters and/or numbers assigned to,
tion (e.g., ±0.5 percent). 2. The precision of a di- and used to identify, licensed radio stations.
rect-reading meter in terms of its full-scale calorie Abbreviation, cal or C. The amount of heat
deflection (e.g., ±2.0 percent of full scale). energy, at a pressure of 1 atmosphere, that will
calibration curve A graph showing the relation be- raise the temperature of 1 gram of water by 1 de-
tween the actual values of a quantity and the set- gree Celsius.
ting or indication of an instrument or component. calorimeter An instrument for measuring heat en-
Usually plotted in rectangular coordinates. ergy. By adaptation, a calorimeter can be used to
measure radio-frequency (RF) power”especially
at microwave frequencies (see CALORIMETRIC
106 calorimeter system See CALORIMETRIC POWER
104 METER.
102 calorimetric power meter A specialized form of
Frequency (MHz)

100 wattmeter, in which the power to be measured is
98 dissipated in an oil or water bath that has a
96 known and fixed mass. The wattage is deter-
94 mined indirectly, by measuring the extent to
92 which the temperature of the liquid increases in a
90 certain amount of time.
88 CAM 1. Abbreviation of computer-aided manufac-
0 20 40 60 80 100 turing. 2. Abbreviation of content-addressed
Log scale reading
cambric Finely woven cotton or linen used for in-
sulation. One type of spaghetti (conductor insula-
calibration curve
tion), for example, is varnished cambric tubing.
camera cable A multiwire cable that conducts the
calibration marker A pip or blip, superimposed on video signal from a television camera to control
a pattern displayed on a cathode-ray-tube (CRT) equipment.
screen, to identify a point closely as to frequency, camera chain In television, the camera and the
voltage, distance, or some similar term. equipment immediately associated with it, ex-
calibrator A device used to perform a calibration cluding the transmitter and its peripherals.
(e.g., a signal generator). camera signal The output signal delivered by a
calibrator crystal A highly accurate and stable television camera.
quartz crystal, used in an oscillator as a fre- camera tube Any video pickup tube, such as an
quency standard. An example is the 100-kHz iconoscope or orthicon, that converts light re-
crystal oscillator and harmonic generator used in flected by a scene into a corresponding television
some communications receivers. signal.
californium Symbol, Cf. A radioactive element pro- Campbell bridge A circuit that is used for compar-
duced artificially. Atomic number, 98. Atomic ing mutual inductance with capacitance.
weight, 251. camp-on In a telephone system, a method of en-
call 1. In communications, a transmission by a gaging a line that is busy until it becomes avail-
station for the purpose of either alerting a partic- able for use.
ular receiving station for which there is a mes- CAN Abbreviation of CANCEL CHARACTER.
96 can • capacitive coupling

can 1. A metal enclosure or container roughly re- maintain its voltage and smooth out the ripples in
sembling a tin can (though not necessarily cylin- the voltage applied to it.
drical), used for shielding or potting components. capacitance-inductance bridge A combination ac
2. Colloquial expression for HEADPHONE. bridge that can be used for either capacitance or
Canada balsam A transparent cement derived inductance measurement. Both capacitance and
from the turpentine distilled from balsam fir inductance can be measured in terms of a stan-
resin. It is useful in optical technology and in cer- dard capacitance; however, some of these bridges
tain areas of electro-optics. use standard inductors in the inductance-
Canadian Standards Association The Canadian measuring mode.
equivalent of the National Bureau of Standards in capacitance meter A direct-reading meter for
the United States. An agency that publishes measuring capacitance. In most available types, a
agreed-on standards for industries. stable ac voltage is applied to the meter circuit, to
cancel character 1. IGNORE CHARACTER. 2. A which an unknown capacitor is connected in se-
control character indicating that the associated ries; meter deflection is roughly proportional to
data is erroneous. the reactance of the capacitor. Also called MI-
cancellation The elimination of one quantity by CROFARAD METER.
another, as when a voltage is reduced to zero by capacitance ratio In a variable capacitor, the ratio
another voltage of equal magnitude and opposite of maximum to minimum capacitance.

sign. capacitance relay A relay circuit that operates
candela Symbol, cd. The SI unit of luminous inten- from a small change in its own capacitance. It

sity; 1 cd represents 1„60 of the radiating power of consists of an RF oscillator whose tank capaci-
one square centimeter of a perfect radiator at the tance is very low. When a finger is brought near
temperature of freezing platinum. the circuit™s short pickup antenna, the attendant
candle Abbreviation, c. Also called international increase in capacitance detunes the oscillator,
candle. A unit of light intensity that is the value of activating the relay. Also called PROXIMITY RE-
emission by the flame of a sperm-whale-oil candle LAY and PROXIMITY SWITCH.
burning at the rate of 7.776 grams per hour. capacitance-resistance bridge A combination ac
candle power Abbreviation, cp. Luminous inten- bridge that can be used for either capacitance or
sity in international candles: the luminous in- resistance measurement. The unknown resis-

tensity resulting from the burning of a tance is measured against a standard resistor;
sperm-whale-oil candle at 7.776 grams per hour. the unknown capacitance against a standard ca-
candoluminescence White light produced without pacitor.
extreme heat. capacitance sensor See CAPACITANCE TRANS-
cannibalization The deliberate use of parts from DUCER.
operational equipment to temporarily repair or capacitive amplifier See DIELECTRIC AMPLI-
maintain other equipment. It is a last-resort, FIER.
emergency measure. capacitive attenuator An ac attenuator whose el-
cap 1. Abbreviation of CAPACITANCE. 2. Abbrevia- ements are capacitors in any desired combination
tion of CAPACITOR. of fixed and/or variable units. The desired atten-
capacimeter See CAPACITANCE METER. uation is afforded by the capacitance ratio.
capacitance Symbol, C. Unit, farad. The property capacitive coupling A means of coupling between
exhibited by two conductors separated by a di- circuits that uses a series capacitor for direct-
electric, whereby an electric charge becomes current blocking. The signal passes through the
stored between the conductors. Capacitance is capacitor, but the blocking effect allows different
thought of as analogous to mechanical elasticity. bias voltages to be applied to the two stages.
Also see FARAD.
capacitance bridge A four-arm ac bridge for gaug- +
ing capacitance against a standard capacitor. In
its simplest form, it has a standard capacitor in
one arm and resistors in the other three.
capacitance coupling The transfer of ac energy
between two circuits or devices by a capacitor or
capacitance effect. Also see COUPLING.
capacitance diode See VARACTOR.
capacitance divider An alternating-current volt-
age divider that uses capacitors, rather than re-
sistors. It is used in certain oscillators, such as
the Colpitts type.
capacitance filter A filter consisting of only a
high-capacitance capacitor. Because the capaci-
capacitive coupling
tor cannot discharge instantaneously, it tends to

capacitive diaphragm • capacitive window

capacitive diaphragm A metal plate deliberately capacitive proximity sensor A transducer used in
placed in a waveguide to introduce capacitive reac- mobile robots that detects the presence of certain
tance and, thereby, cancel an inductive reactance. kinds of objects. It consists of an oscillator whose
capacitive-discharge ignition An electronic igni- frequency is determined by an inductance-
tion system for automotive engines. Provides capacitance (LC) circuit to which a metal plate
nearly constant high voltage, regardless of engine is connected. When a conducting or partially con-
speed. A dc-to-dc step-up converter charges a ducting object comes near the plate, the mutual
large capacitor (typically to 300 volts) when the capacitance changes the oscillator frequency.
distributor breaker points are closed; when they This change is detected and sent to the robot
are open, the capacitor discharges through the controller.
ignition coil, thereby generating an ignition pulse
of several thousand volts.
capacitive division Reduction of an ac voltage by
a capacitive voltage divider.
capacitive feedback Feeding energy back from the
output to the input of an amplifier or oscillator
through a capacitor.
capacitive-input filter A smoothing filter for ac
power supplies, in which the element closest to
the rectifier is a capacitor, regardless of the com-
ponents or circuits placed subsequently.
capacitive load A load consisting of a capacitor or
a predominantly capacitive circuit.
capacitive loading In an antenna, the addition of
capacitance in series with the element(s). This
raises the resonant frequency for a radiator hav-
ing a given physical length. It can also serve to in-
crease the physical length required for a radiator
having a specified resonant frequency. Compare
capacitive post A protrusion inside a waveguide
for the purpose of introducing capacitive reac- capacitive reactance Symbol, XC. Unit, ohm. The
tance to cancel an inductive reactance. reactance exhibited by an ideal capacitor, con-
capacitive potentiometer See CAPACITIVE VOL- sidered as a negative pure-imaginary quantity;
TAGE DIVIDER. XC = “j/(6.28f C), where f is the frequency in
capacitive pressure sensor A pressure sensor hertz, C is the capacitance in farads, and j is the
that uses a radio-frequency oscillator and a pair unit imaginary number (the square root of “1).
of metal plates separated by dielectric foam. The Alternatively, f can be specified in megahertz
circuit is designed so a change in the capacitance and C in microfarads. In a pure capacitive reac-
between the plates causes the oscillator fre- tance, current leads voltage by 90 degrees. Also
quency to change. This change is sensed. A signal see CAPACITANCE, CAPACITOR, and REAC-
is sent to an analog-to-digital converter (ADC) TANCE.
and then to a microcomputer that calculates the capacitive speaker See ELECTROSTATIC SPEAKER.
extent of the pressure. capacitive transducer A transducer consisting es-
sentially of a refined variable capacitor whose
value is varied by a quantity under test, such as
pressure, temperature, liquid level, etc.
capacitive tuning Variable-capacitor tuning of a
capacitive voltage divider A capacitive attenuator
usually consisting of two series-connected capac-
itors whose values are such that an applied ac
voltage is divided across them in the desired ra-
capacitive welding An electronic welding system
in which energy stored in a capacitor is dis-
charged through the joint to be welded. This de-
velops the heat necessary for the operation.
capacitive window A pair of capacitive dia-
phragms used in a waveguide to introduce capac-
itive reactance.
98 capacitor • carbon-button amplifier

capacitor A passive electronic-circuit component several useful fixed capacitance values can be
consisting of, in basic form, two metal electrodes thus obtained.
or plates separated by a dielectric (insulator). capacitor voltage 1. The voltage at the terminals
capacitor amplifier See DIELECTRIC AMPLIFIER. of a capacitor. 2. The maximum voltage rating of
capacitor antenna See CONDENSER ANTENNA. a capacitor.
capacitor bank A network of capacitors connected capacitor voltmeter See ELECTROSTATIC VOLT-
in combination, yielding a desired characteristic. METER.
capacitor braking The connection of a capacitor to capacity 1. A measure of a cell™s or battery™s ability
the winding of a motor after the removal of power, to supply current during a given period. 2. CA-
to speed up the process of braking. PACITANCE. 3. The number of bits or bytes a
capacitor color code See COLOR CODE. computer storage device can hold. 4. The limits of
capacitor decade See DECADE CAPACITOR. numbers that a register can process.
capacitor-discharge ignition CAPACITIVE- capacity lag In an automatic control system, a de-
DISCHARGE IGNITION. lay caused by the storing of energy by the compo-
capacitor filter In a direct-current power supply, a nents. For example, in a heating system, capacity
filter consisting simply of a capacitor connected lag results from the time taken to heat the air or
in parallel with the rectifier output. fluid after the thermostat turns on the heat.
capillary electrometer A sensitive voltage indica-
tor, consisting of a column of mercury in a
+ + transparent capillary tube, in which is sus-
+ pended a small drop of acid. When a voltage is
Pulsating Pure applied to both ends of the mercury column, the
dc input dc output acid drop moves toward the low-potential end of
the column over a distance proportional to the
’ ’
capstan The driven spindle or shaft of a magnetic
capacitor filter
tape recorder or transport.
capture area The effective ability of a radio antenna
to pick up electromagnetic signals. The larger the
capacitor-input filter A filter whose input compo-
capture area, the greater the antenna gain.
nent is a capacitor. The capacitor-input power-
capture effect 1. In frequency-modulation (FM)
supply filter is distinguished by its relatively high
radio receivers, the effect of domination by the
dc output voltage, but somewhat poorer voltage
stronger of two signals, or by the strongest of sev-
regulation, compared with the CHOKE-INPUT
eral signals, on the same frequency. 2. In an
automatic-frequency-control system, the tendency
capacitor leakage Direct current flowing through
of the receiver to move toward the strongest of
the dielectric of a capacitor. In a good nonelec-
several signals near a given frequency. 3. In gen-
trolytic capacitor, this current is normally less
eral, the tendency of one effect to totally predom-
than 1 microampere. In an electrolytic capacitor,
inate over other effects of lesser amplitude.
it can be up to several milliamperes, depending
capture ratio A measure of frequency-modulation
on the capacitance and the applied voltage.
(FM) tuner selectivity: The amplitude difference,
capacitor loudspeaker See ELECTROSTATIC
in decibels, between unwanted signals and the
one being tuned in.
capacitor microphone See CONDENSER MICRO-
carbon Symbol, C. A nonmetallic element. Atomic
number, 6. Atomic weight, 12.011. Carbon, be-
capacitor motor An ac motor that uses a capaci-
sides being an invaluable material in electronics,
tor in series with an auxiliary field winding for
is an important constituent of organic com-
starting purposes. Initially out-of-phase current
in the auxiliary field (starting winding) causes a
carbon arc The arc between two electrified pencils
rotating field that turns the rotor. When the rotor
of carbon or, as in an arc converter, between a
reaches a safe speed, a centrifugal switch dis-
carbon pencil and a metal electrode.
connects the capacitor and auxiliary field, and
carbon brush A contact made of carbon or some
the motor continues running as an induction
mixture of carbon and another material, used in
motors, generators, variable auto-transformers,
capacitor series resistance The ohmic loss in
rheostats, and potentiometers.
a capacitor. It results partly from conductor
carbon-button amplifier An audio-frequency
losses, and partly from losses in the dielectric
amplifier having as the active component an
earphone whose diaphragm is attached to a car-
capacitor substitution box An enclosed assort-
bon microphone button. The input signal ap-
ment of selected-value capacitors arranged to be
plied to the earphone makes its diaphragm
switched one at a time to a pair of terminals. In
vibrate. The vibrating button modulates a local
troubleshooting and circuit development, any of
carbon-button amplifier • cardistimulator

direct current. Amplification results from the carbon-pile rheostat See CARBON-DISK RHEO-
large ratio of modulated local current to input- STAT.
signal current. carbon recording 1. A record made with a
carbon-composition resistor A non-inductive re- CARBON-PAPER RECORDER. 2. The use of a car-
sistor made from a mixture of finely powdered bon-paper recorder in data acquisition, facsimile,
carbon with a non-conductive substance, usually communications, and similar applications.
phenolic. The resulting clay-like material is carbon resistor A resistor made from carbon,
pressed into a cylindrical shape, and wire leads graphite, or some composition that contains car-
are inserted in the ends. The resistance depends bon.
on the ratio of carbon to the non-conducting ma- carbon/silicon-carbide thermocouple A thermo-
terial, and on the physical distance between the couple that is a junction between carbon and sil-
wire leads. This type of resistor is useful from di- icon carbide.
rect current to ultra-high radio frequencies. Com- carbon transfer recording A method of facsimile
pare FILM RESISTOR, WIREWOUND RESISTOR. reception in which the image is reproduced by
carbon/disk rheostat A rheostat consisting of a carbon particles sprayed on the paper, a process
stack of carbon disks or washers, arranged so controlled by the received signal.
that a controllable pressure can be exerted on the carbon-zinc cell See ZINC-CARBON CELL.
stack. As a knob is turned, a screw increases or Carborundum Formula, SiC. Trade name for a
decreases the pressure, varying the total resis- synthetic silicon carbide used as a semiconduc-
tance of the stack. tor, refractory, or abrasive. Also see SILICON
carbon-film resistor A stable resistor whose resis- CARBIDE.
tance element is a film of carbon, vacuum- Carborundum crystal Trade name for a character-
deposited on a substrate, such as a ceramic. istically superhard crystal of silicon carbide.
carbonization The application of a coat of carbon Carborundum varistor A voltage-dependent resis-
onto an electrode, either by electroplating or by tor made from Carborundum.
any other means. carcinotron A special kind of oscillator tube used
carbon microphone A microphone that includes at ultra-high and microwave frequencies.
one or two carbon buttons. See BUTTON MICRO- card 1. A usually thin, rectangular board contain-
PHONE. ing a PRINTED CIRCUIT, often equipped with an
carbon-paper recorder A recorder in which a edge connector that makes it easy to install, re-
signal-actuated stylus writes, by impression only, move, or replace. Common in electronic and com-
through a sheet of carbon paper onto a plain puter equipment having modular construction. 2.
sheet underneath. This eliminates the need for an The usually flat, thin insulating strip on which a
ink-carrying stylus. resistor element is wound.
carbon-pile regulator A voltage regulator in cardiac monitor An electronic device that displays
which a stack of carbon disks or washers is in or records electrical impulses from the heart for
series with the shunt field. The pile resistance medical observation or diagnosis.
and field current depend on pressure applied to cardiac pacemaker An electrical cardiac stimula-
the pile by a wafer spring acting through a mov- tor that causes the heart to beat at certain inter-
able iron armature. Voltage drops increase the vals. Used when the patient has heart disease
pressure and voltage rises decrease the pres- that prevents the heart from regulating itself.
sure, thus regulating the generator with which cardiac stimulator An electronic device (some-
it is associated. times implanted in the subject) that supplies
electric pulses to stimulate heart action. Also
To dc load card image In memory storage, the data contained
on a single card.
cardioid diagram A polar response curve in the
Carbon Rheostat
shape of a cardioid pattern.
cardioid microphone A microphone with a (roughly)
heart-shaped sound-field pickup pattern.
cardioid pattern A radiation/response pattern
with one sharp null in the direction opposite the
Shunt Spring
single main lobe. The lobe is extremely broad. In
field Iron
two dimensions, the curve is shaped somewhat
’ armature
like a “Valentine” heart.
cardiotachometer A device that indicates the
pulse rate.
cardistimulator See CARDIAC STIMULATOR.
carbon-pile regulator
100 Carey-Foster bridge • carrier line

Carey-Foster bridge A special version of the slide- in a receiver. 2. A heterodyne in a facsimile or
wire bridge that is useful for measuring an un- television signal, resulting in a pattern of cross
known resistance, whose value is close to that of hatches in the received image.
a standard resistance. carrier choke A radio-frequency (RF) choke, in-
serted in a line to block a carrier component.
carrier chrominance signal For conveying color
R1 R2
television information, sidebands of a modulated
chrominance subcarrier.
carrier color signal For conveying color informa-
tion in color television transmission, the side-
bands of a modulated chrominance subcarrier
(plus the unsuppressed chrominance subcarrier)
added to the monochrome signal.
RX carrier concentration In a semiconductor material,
the number of charge carriers per unit volume.
carrier control 1. The modification, adjustment,
S1 or switching of a carrier wave. 2. Adjustment of a
circuit or device by means of a carrier wave.
carrier current The current component of a carrier
wave, or the amplitude of that current. Compare
carrier-current communication See WIRED
Carey-Foster bridge WIRELESS.
carrier-current control 1. Control of the current
component in a carrier wave. 2. Remote control
Carey-Foster mutual inductance bridge An ac
by means of wired wireless.
bridge that permits the measurement of mutual
carrier-current receiver See WIRED-RADIO RE-
inductance in terms of a standard capacitor.
carrier-current relay A radio-frequency (RF) relay
circuit, operated over a wire line by means of a
R2 = 0 carrier-current transmitter See WIRED-RADIO
carrier deviation See CARRIER SWING.
M carrier dispersion In a semiconductor, the spread-
R1 M = R1R4C ing out of electrons and holes that leave the emit-

() ter simultaneously, but arrive at the collector at
R3 = R4 L1 ’1
various times after following different paths.
carrier frequency The center frequency of a CAR-
carrier-frequency pulse A pulse that contains
radio-frequency oscillation.
Gen carrier-frequency range The band of carrier fre-
quencies over which a transmitter or signal gen-
erator can operate.
carrier injection The apparent emission (injection)
Carey-Foster mutual inductance bridge
of electrons or holes into a semiconductor when a
voltage is applied to the junction.
carrier leak 1. A point at which carrier-wave en-
carnauba wax A wax obtained from the Brazilian
ergy escapes a circuit or enclosure. 2. The resid-
wax palm. Used as an electrical insulator, and as
ual carrier voltage present in the output of a
the dielectric in some electrets.
carrier-suppressing circuit.
Carnot theorem In thermodynamics, the proposi-
carrier level The amplitude of an unmodulated
tion that in a reversible cycle, all available energy
carrier wave.
is converted into mechanical work. Also called
carrier lifetime In a semiconductor, the interval
Carnot™s principle.
before an injected current carrier (see CARRIER
carrier 1. See CARRIER WAVE. 2. See CHARGE
INJECTION) recombines with an opposite carrier
and ceases to be mobile.
carrier amplifier See DIELECTRIC AMPLIFIER.
carrier line In carrier-current systems (see WIRED
carrier beating 1. The mixing of two radio-
WIRELESS), the line or cable conducting the
frequency carriers that are separated by a small
carrier-wave energy.
amount of frequency, resulting in an audible tone
carrier mobility • carry system

carrier mobility Symbol, µ. In a semiconductor est to highest instantaneous frequency) of the
material, the average drift velocity of electrons carrier wave.
and holes per unit electrostatic field. carrier system The transmission of many signals
carrier noise Modulation of a carrier when there is over one circuit, accomplished by modulating
no input from the modulator itself; unwanted various different carriers at different frequencies.
modulation. Different signals can use different modulation
carrier noise level The noise signal amplitude that methods.
results from unintentional fluctuations of an un- carrier telegraphy 1. Continuous-wave telegraphy
modulated carrier. by WIRED WIRELESS. 2. Wired-wireless telegra-
carrier-on-light transmission A form of transmis- phy in which a radio-frequency carrier is modu-
sion in which many different signals are sent si- lated by an audio-frequency keying wave.
multaneously by modulating a beam of light at carrier telephony Telephone communication by
multiple frequencies. WIRED WIRELESS.
carrier-on-microwave transmission A form of carrier terminal 1. At each end of a carrier-current
transmission in which many different signals are line or cable, the equipment for generating, modi-
sent simultaneously by modulating a microwave fying, or utilizing the carrier energy. 2. In a bal-
signal at multiple lower frequencies. anced modulator, the point of carrier insertion.
carrier-on-wire transmission A form of transmis- carrier-to-noise ratio The ratio of carrier ampli-
sion in which many different signals are sent at tude to noise-voltage amplitude.
the same time over a wire, by using radio- carrier transmission Transport of information by
frequency carriers. Also called CARRIER-CURRENT a carrier, as by an amplitude-modulated radio
COMMUNICATIONS or WIRED RADIO. wave that carries the low-frequency information
carrier oscillator In a single-sideband receiver, as the AF modulation envelope and delivers it to
the radio-frequency (RF) oscillator that supplies the demodulator at the receiving station.
the missing CARRIER WAVE. carrier-type dc amplifier A high-frequency ac am-
carrier power The actual power represented by a plifier, ahead of which is operated a generator
radio-frequency (RF) carrier applied to an an- and transducer. A dc voltage applied to the trans-
tenna, measured by either the direct or indirect ducer modulates the carrier supplied by the gen-
method. The direct method involves determina- erator; the amplifier boosts the modulated wave,
tion of power according to the formula P = I 2R, and the resultant output is rectified at a level
where I is antenna current and R is antenna re- higher than that of the dc input signal.
sistance at the point of current measurement. carrier voltage The voltage component of a carrier
The indirect method involves determination of wave; also, the amplitude of this component. Com-
power according to the formula P = EIF, where E pare CARRIER CURRENT and CARRIER POWER.
and I are antenna voltage and current, and F is a carrier wave A sine wave that is modulated to
factor less than 1.0, whose value depends on the convey information in wireless and cable com-
type of modulation used. munications systems. The lowest frequency nor-
carrier power-output rating The power delivered mally used for wireless signal transmission is 9
by an unmodulated transmitter or generator to kHz, corresponding to a wavelength of approxi-
the normal load or its equivalent. mately 33 km. The highest frequency is less well
carrier shift In an amplitude-modulated transmit- defined; some systems make use of visible light
ter or generator, the undesired change of average waves, whose wavelengths are as short as ap-
proximately 4 — 10“7 m. For modulation to work
carrier voltage during modulation.
carrier-shift indicator An instrument for detect- effectively, the carrier must have a frequency at
ing carrier shift. It usually contains only a least 10 times the highest frequency of the mod-
pickup coil, semiconductor diode, and dc mil- ulating signal.
liammeter in series. Meter deflection is steady carry 1. In adding a column of figures, the digit
until carrier shift is detected; then, the needle added to the column at the left when the sum ex-
fluctuates. ceeds one less than the radix value. 2. In digital
carrier signaling In wire telephony, the use of computers and counters, a pulse that corre-
carrier-wave signals to operate such functions as sponds to the arithmetic operation in which a fig-
dialing, ringing, busy signal, etc. ure is carried to the next column in addition.
carrier storage In a semiconductor device, the ten- carrying capacity The ability of a conductor, such
dency of mobile carriers to stay near a junction as copper wire, to carry current safely (expressed
for a short time after the junction voltage has in maximum amperes).
been removed or reversed in polarity. carry-complete signal In an arithmetic computa-
carrier suppression The elimination of the carrier tion by a computer, an adder-produced signal in-
in an amplitude-modulated signal so that only dicating that the pertinent carries have been
the sideband energy remains. generated.
carrier swing In frequency-modulated or phase- carry system A communications system in which
modulated transmission, the total deviation (low- several carries occupy one circuit.
102 carry time • cascaded amplifier

3 5
70 4
Current (amperes)

60 2
’5 ’4 ’3 ’2 ’1
50 x
1 2 3 4 5
’4 ’3
6 8 10 12 14 16 18 20 22
Wire size (AWG) Cartesian three-space

carrying capacity
(of some AWG sizes of copper wire) Cartesian three-space graph A three-dimensional
graph that shows an equation in one or two vari-
carry time The time taken for a digital computer or ables. Three-space graphs are often displayed
counter to perform a carry operation (See CARRY, more clearly by means of computer graphics, in
2). which the entire display can be rotated to show
Cartesian coordinate geometry Also called rect- the characteristics of the surface resulting from a
angular coordinate geometry. In robotic systems, a given equation or function.
movement scheme in two or three dimensions. Cartesian n-space The coordinate space defined
The position of the robot arm is determined by lin- by a Cartesian system of n coordinates, where n
ear coordinates, relative to an origin point. These is a whole number of 2 or greater.
coordinates are specified along linear axes”each cartridge 1. The replaceable transducer assembly
of which is perpendicular to the others at the ori- of a microphone. 2. A magnetic-tape magazine.
gin. See CARTESIAN COORDINATES, CARTE- Also see TAPE CARTRIDGE. 3. A removable com-
SIAN PLANE, and CARTESIAN THREE-SPACE. puter mass-storage medium, containing a tape,
Cartesian coordinates Also called rectangular co- magnetic diskette, or optical diskette. 4. An insu-
ordinates. A mathematical system that uniquely lating tube housing a fuse, semiconductor com-
defines the position of a point on a plane, in space, ponent, resistor, capacitor, or other part.
or in general, in an n-dimensional hyperspace cartridge fuse A fuse consisting of a fusible wire
when n is a whole number greater than 3. There enclosed in a cartridge, having a ferrule at each
are n axes for n dimensions, each axis intersects end for plug-in connection.
all the others at a single point, called the origin. cascadable Capable of, or designed for, being con-
The axes are mutually perpendicular at this origin. nected in cascade with other similar or identical
The axes are scaled in units with the origin having components.
coordinate values that are all equal to zero (usu- cascade 1. Components or stages connected and
ally). Positive values go along the axes in one di- operated in sequence, as in a three-stage ampli-
rection; negative numbers go in the opposite fier. The components or stages are often but not
direction for each axis. Usually, the axes are grad- necessarily identical. 2. To form a cascade.
uated in equal-sized units. The system gets its cascade control 1. In an automatic control sys-
name from the mathematician Rene Descartes. tem, a controller whose setting is varied by the
Cartesian plane A linear, two-dimensional coordi- output of another controller. 2. An automatic
nate plane commonly used for graphing equa- control system in which the control units are con-
tions in one variable. nected in stages, so that one unit must operate
Cartesian three-space A linear, three-dimensional before the next one can function.
graph-coordinate system used for rendering cascaded amplifier A multistage amplifier in which
equations in one or two variables. the stages are forward-coupled in succession.
cascaded carry • cathode

cascaded carry In digital computer practice, a sys- energy emerges from a waveguide and is directed to
tem of performing the carry operation (see a small convex reflector at the focal point of the
CARRY) in which the n + 1 place receives a carry dish. The small reflector directs the signal back to
pulse only when the nth place has received carry the dish, spreading the energy out to cover the en-
information to generate the pulse. tire surface of the dish. The dish reflects the energy
cascade thermoelectric device A thermoelectric again and collimates it in the desired direction of
component or circuit that consists of several cas- propagation. For reception, the process is reversed;
caded sensors (see CASCADE, 1). the dish focuses the energy on the small reflector,
cascade voltage doubler A voltage-doubler circuit which propagates it back to the feed point.
(see VOLTAGE DOUBLER) consisting of two cassette 1. A holder (magazine) of reels of mag-
diode-capacitor combinations in cascade. Unlike netic tape that is itself a mechanical subas-
the conventional voltage-doubler circuit with two sembly, which can be easily inserted into and
capacitors in the output, the cascade voltage dou- removed from a tape deck. 2. A lightweight holder
bler has one in the input and one in the output. of photographic film or X-ray plates (before, dur-
cascode A high-gain, low-noise, high-input- ing, and after exposure).
impedance amplifier circuit, consisting of a castor oil A viscous insulating oil extracted from
grounded-emitter or grounded-source input stage castor beans. Highly refined castor oil is used as
coupled directly to a grounded-base or grounded- an impregnant in some oil-filled capacitors. Di-
gate output stage. electric constant, 4.3 to 4.7. Dielectric strength,
380 V/mil.
catalysis The process whereby an agent, called a
catalyst, enhances a chemical reaction without
In entering into the reaction. Catalysts are used in
electronics, for example, to promote the setting of
resins in potting and encapsulating operations.
cascode catalytic agent A substance that accomplishes
(field-effect transistor catalysis.
arrangement) cataphoresis As caused by the influence of an
electrostatic field, the migration toward the cath-
ode of particles suspended in a liquid.
case temperature The temperature at a desig- catastrophic failure 1. Sudden, unexpected fail-
nated point on the outside surface of a compo- ure of a component or circuit. 2. Failure that can
nent™s case or housing. result in the breakdown of an entire system. Also
Cassegrain antenna A dish antenna that uses called catastrophic breakdown.
CASSEGRAIN FEED. catcher In a Klystron, the second reentrant cavity.
catcher diode A diode that is connected to regulate
the voltage at the output of a power supply. The
cathode is connected to a source of reference volt-
age. If the anode, connected to the source to be
regulated, becomes more positive than the cath-
Main dish
ode, the diode conducts and prevents the regu-
focus reflector
lated voltage from rising more than 0.3 volt above
the reference voltage (for germanium diodes) or 0.6
volt above the reference voltage (for silicon diodes).
catcher grids In a Klystron, the grids through
which the bunched electrons pass on their way
from the buncher to the collector. Catcher grids
absorb energy from the bunched electrons and
present it to the collector circuit.
category In a computer system, a group of mag-
netic disk volumes containing information related
by a common application.
category storage A computer-file storage section
Cassegrain antenna
that contains a number of categories and used by
an operating system.
catenation See CONCATENATION.
Cassegrain feed A dish-antenna feed system in
cathode 1. The negative electrode of a device (i.e.,
which the feed point is located at the center of the
the electrode from which electrons move when a
dish itself. For transmission, the radio-frequency
104 cathode • cavity laser

current passes through the device). 2. In an elec- rays when operated at high voltage. 2. An oscillo-
trochemical cell, the electrode that gains elec- scope tube. 3. A picture tube.
trons. This is generally the positive electrode. 3. cathode terminal 1. In a diode (semiconductor or
In a vacuum tube, the electron-emitting electrode tube), the terminal to which a negative dc voltage
(filament or indirectly heated cathode sleeve). must be applied for forward-biasing the diode.
cathode current Symbol IK. The current flowing in Compare ANODE TERMINAL. 2. In a diode, the
the cathode circuit of a tube. Cathode current is terminal at which a positive dc voltage appears
the total of grid, plate, screen, and suppressor cur- when the diode acts as an ac rectifier. Compare
rents, and can have an ac and a dc component. ANODE TERMINAL. 3. The terminal connected
cathode dark current The electron emission from internally to the cathode element of device. 4. In
the photocathode of a camera tube when there is a vacuum tube, an indirectly heated electron
no illumination. emitter.
cathode element In a vacuum tube, an indirectly cathode voltage Symbol, EK. The voltage between
heated emitter of electrons. Also see CATHODE, 2. ground (or B-minus) and the cathode of a tube; it
cathode emission 1. The giving up of electrons by can have both ac and dc components.
the cathode element of a device, such as a vac- cathodic protection A method of preventing cor-
uum tube. Electrons can be emitted by either hot rosive galvanic action in underground metal
or cold cathodes, depending on the tube. 2. Col- pipes or the submerged hulls of ships. The part to
lectively, electrons released by a cathode. be protected is used as the cathode of a circuit
cathode heating time The time required for the through which a direct current is passed in the
temperature of a tube cathode to increase from direction opposite to that which caused the corro-
cold to its maximum specified operating tempera- sion, thus counteracting it.
ture after the cathode current has been initiated. cathodofluorescence Fluorescence resulting from
Also called cathode warmup time. a material™s exposure to cathode rays.
cathode luminous sensitivity For a photomulti- cathodoluminescence In a vacuum chamber in
plier tube, the cathode™s sensitivity to light. This which a metal target is bombarded with high-
sensitivity figure is the ratio of photocathode cur- velocity electrons (cathode rays), the emission of
rent to incident light flux. radiation of a wavelength characteristic of the
cathode-ray oscillograph An instrument that pro- metal.
vides a permanent record, by photographic or cation A positive ion. Also see ION.
other means, of the image on the screen of a CAT scanner The X-ray apparatus for COMPUT-
cathode-ray tube. ERIZED AXIAL TOMOGRAPHY.
cathode-ray oscilloscope See OSCILLOSCOPE. CATV Abbreviation of COMMUNITY-ANTENNA
cathode rays Invisible rays emanating from the TELEVISION (usually cable television).
cathode element of an evacuated tube operated caustic soda electrolyte Symbol, NaOH. Sodium
with a high voltage between the anode and cath- hydroxide solution, as used in some secondary
ode. Cathode rays (electrons) cause certain sub- cells and experimental devices.
stances, PHOSPHORS, to glow upon striking them. cavitation The local formation of cavities in a fluid
cathode-ray scanning tube Any tube in which an used in ultrasonic cleaning because of the reduc-
electron beam is deflected horizontally and verti- tion in pressure at those points.
cally to scan an area. These include oscilloscope cavitation noise In an ultrasonic cleaner, the
tubes, some computer monitors, radar displays, noise resulting from the collapse of bubbles pro-
and television camera tubes. duced by cavitation.
cathode-ray tube 1. An evacuated tube containing cavity A metallic chamber (can) in which energy is
an anode and cathode that generates cathode allowed to reflect, sometimes resulting in reso-
Lower Upper cavity filter A microwave (usually band rejection)
deflecting deflecting filter consisting of a resonant cavity and associ-
plates plates ated coupling devices.
Glass stem cavity frequency meter See CAVITY WAVEME-
cavity impedance The impedance across a cavity
at a particular frequency. At resonance, the cav-
ity impedance is purely resistive.
cavity laser A laser that employs a resonant cavity
Anode filled with gas, such as helium/neon or argon,
Cathode Stream and a pair of reflectors. Resonance occurs be-
Glass of tween the reflectors, one of which is totally reflec-
housing electrons Viewing screen tive and the other of which is approximately 95
percent reflective. Output is from the partially re-
cathode-ray tube flective end of the device.
cavity magnetron • cell constant

CCIT Abbreviation of Comite Consultatif Interna-
tional Telegrafique (International Telegraph Con-
sultative Committee).
CCITT Abbreviation of Comite Consultatif Interna-
tional Telegrafique et Telephonique (International
Telegraph and Telephone Consultative Committee).
CCS 1. Abbreviation of CONTINUOUS COMMER-
CIAL SERVICE. 2. Abbreviation of common-
channel signaling.
CCTV monitor A video monitor that receives a sig-
nal from a CCTV transmitter.
CCTV signal The picture signal in a CCTV system.
It can be either a modulated radio-frequency sig-
nal or a composite video signal.
ccw Abbreviation of COUNTERCLOCKWISE.
CD Abbreviation of COMPACT DISK.
Cd Symbol for CADMIUM.
cd Abbreviation of CANDELA.
CD-4 A method of obtaining quadraphonic repro-
duction on a phonograph disk using modulated
carriers with frequencies above the human hear-
ing range.
cavity magnetron A magnetron whose anode is a
series of resonant cavities.
C display A radar display showing the target as a
cavity oscillator An oscillator with a cavity-tuned
dot whose coordinates represent the bearing (hor-
izontal) and angle of elevation (vertical). Compare
cavity radiation Energy radiated from a tiny hole
in an otherwise sealed chamber. The radiation
cd/m2 Candelas per square meter, the SI unit of
occurs at all electromagnetic wavelengths; the
greater the temperature within the chamber, the
greater the frequency at which the radiation has
its maximum amplitude.
Ce Symbol for CERIUM.
cavity resonance The phenomenon whereby a
Ce Symbol for EMITTER CAPACITANCE of a tran-
hollow cavity resonates; specifically, resonance in
small metal cavities at microwave frequencies.
ceiling 1. The maximum possible power output
cavity resonator See RESONANT CAVITY.
from a transmitter. 2. The maximum possible
cavity wavemeter An absorption wavemeter whose
current or voltage that a circuit can deliver. 3. In
adjustable element is a tunable resonant cavity
aviation, the level of the cloud base.
into which radio-frequency (RF) energy is injected
ceilometer An instrument for measuring ceiling
through a waveguide or coaxial cable. Such an in-
(cloud height).
strument is useful at microwave frequencies.
cel In animated graphics, an individual image or
CB Abbreviation of CITIZENS BAND.
Cb Symbol for COLUMBIUM.
cell 1. A single (basic) unit for producing dc elec-
CB Symbol for BASE CAPACITANCE of a transistor.
tricity by electrochemical or photovoltaic action,
C band The band of radio frequencies between 3.9
as in a battery or a solar panel. Also see PRIMARY
and 6.2 GHz.
CC Symbol for collector capacitance of a transistor.
addressable, one-word-capacity storage element
cc 1. Alternative abbreviation of cubic centimeter.
in a computer memory. 3. The geographic region
The International Organization for Standardi-
zation recommends cm3. 2. Abbreviation of covered by a specified repeater in a cellular com-
munications network. See CELLULAR COMMU-
NICATIONS. 4. An electrostatic charge dipole in
the atmosphere, usually occurring in or near
thunderstorms. 5. A thunderstorm.
cell constant The surface area of the electrodes in
a cell divided by the distance between them. The
basic linear units must be the same: for example,
CCIR Abbreviation of Comite Consultatif Interna-
square centimeters for surface area and centime-
tional des Radiocommunications (International Ra-
ters for distance.
dio Consultative Committee).
106 cell counter • center-tapped filament

cell counter A bioelectronic instrument used to center frequency 1. The frequency, in a communi-
count blood cells and other minute particles. cations receiver, that is midway between the
cell reversal A condition that can occur in some lower and upper 3-dB-down amplitude points.
rechargeable electrochemical cells and batteries, 2. The average frequency of a modulated carrier.
such as nickel-cadmium batteries. It most often 3. The carrier frequency of a modulated signal,
results from neglecting to recharge the cell or bat- whether or not the carrier is suppressed.
tery when it has become fully discharged.
cell-type enclosure A room designed to prevent
the entrance or escape of radio-frequency (RF) Upper
electromagnetic fields, characterized by double- sidebands
walled copper-mesh shielding.
cellular coil A coil having a crisscross (usually
multilayer) winding. Examples: lattice-wound
coil, honeycomb coil, basket-weave coil.
cellular communications A radio, telephone, or
television communications network that makes
use of numerous fixed repeaters. Subscribers use
mobile or portable transceivers that are always


within range of at least one repeater. The most Center
common form is known as cellular telephone or (suppressed

cellular mobile radio telephone. carrier)
celluloid A thermoplastic dielectric material that is
a blend of cellulose nitrate and camphor. Dielec-
tric constant, 4 to 7. Dielectric strength, 250 to
780 V/mil. Min
cellulose acetate A plastic dielectric material used
as a substrate for magnetic tapes, photographic
film, and similar applications. Dielectric con- Higher
stant, 6 to 8. Dielectric strength, 300 V to 1

kV/mil. Also see ACETATE. center frequency, 3.
cellulose acetate base See ACETATE BASE.
cellulose acetate butyrate A thermoplastic dielec-
tric material that is an acetic and butyric acid es- centering control In an oscilloscope circuit, a po-
ter of cellulose. tentiometer used to position the image on the
cellulose acetate tape See ACETATE TAPE. screen (particularly in the center). Separate con-
cellulose nitrate The nitric acid ester of cellulose, trols are provided for horizontal and vertical cen-
a plastic insulating material. tering.
cellulose propionate A thermoplastic molding ma- center loading In an inductively loaded antenna,
terial that is a propionic acid ester of cellulose. placement of the loading coil(s) at or near a point
Celsius scale A temperature scale in which 0 de- or points midway between the feed point and the
grees is the freezing point of water, and 100 de- end(s) of the radiating element.
grees the boiling point of water. Also called center of beam 1. In a directional antenna system,
CENTIGRADE SCALE. Compare ABSOLUTE the direction, denoted by a straight ray, where
SCALE, and FAHRENHEIT SCALE. the signal strength or response is the greatest. 2.
cent An audio-frequency interval of 0.01 (1„100) of In a beam of visible light, the geometric center of
a half step. A half step is the frequency differ- the spot produced when the beam strikes a sur-
ence between two immediately adjacent keys on face perpendicular to the beam. 3. In a beam of
a piano. visible light, the axis within the beam where the
center channel In high-fidelity stereo, a phantom intensity is greatest.
sound source that appears to exist midway be- center of channel The frequency that is midway
tween the left and right speakers or earpieces. between the lowest and highest frequency compo-
The effect is caused by identical, or nearly identi- nents of a communications channel.
cal, signals in the left and right channels. center of radiation The point from which the en-
center-fed antenna An antenna in which the feed- ergy radiated by an object appears to arrive.
ers are connected to the center of the radiator. center tap A connection made to the centermost
center feed 1. Attaching a feeder or transmission turn of a coil or to the center-value point of a re-
line to the center of the radiator of an antenna. 2. sistor, filament, or capacitor pair.
Connection of signal-input terminals to the cen- center-tapped coil See CENTER-TAPPED WIND-
ter of a coil. 3. Descriptive of paper tape whose ING.
feed holes are aligned with character hole cen- center-tapped filament A tube or lamp filament
ters. Compare ADVANCE FEED TAPE. that has a tap at its center.

center-tapped inductor • ceramic-to-metal seal

center-tapped inductor An inductor that has a centrifugation potential An electric potential that
tap at half the total number of turns (the physical occurs in a colloidal solution when the solution is
center of the winding). centrifuged.
center-tapped potentiometer A potentiometer centrifugal switch A switch actuated by rotational
that has a tap at half the total resistance of the motion (e.g., the automatic disconnection switch
resistance element. in a capacitor motor).
center-tapped resistor A fixed resistor that has a centripetal force The force that draws the mass of
tap at half the total resistance. a rotating body toward the axis of rotation.
center-tapped transformer A transformer that ceramal See CERMET.
has one or more center-tapped windings. ceramet seal See CERAMIC-TO-METAL SEAL.
center-tapped winding A winding that has a tap ceramic-based microcircuit A tiny circuit printed
at half the total number of turns (the physical or deposited on a ceramic substrate.
center of the winding). ceramic capacitor A component made with sheets
of metal stacked alternately with wafers of ce-
ramic. This material, like mica, has low loss, and
therefore allows for high efficiency. For low val-
ues of capacitance, only one layer of ceramic is
needed, and two metal plates can be glued to a
disk of porcelain, one on each side. Alternatively,
a tube or cylinder of ceramic can be employed,
center-tapped winding and metal ink applied to the inside and outside of
the tube. These capacitors have values ranging
from a few picofarads to about 0.5 µF. Their volt-
center tracking frequency In three-frequency
age ratings are comparable to those of paper ca-
alignment (tracking) of a circuit, the frequency
between the upper and lower frequency limits
(alignment or tracking points of the circuit).
center-zero meter A meter that has its zero point
ceramic dielectric 1. A ceramic used as a dielec-
at the center of the scale (e.g., a dc galvanometer).
tric in capacitors. Examples: barium titanate,
centi- Abbreviation, c. Prefix meaning hun-
dredth(s) (10“2). barium strontium titanate, and titanium dioxide.
Ceramic dielectrics provide high dielectric con-
centigrade scale See CELSIUS SCALE.
stant. 2. A ceramic used as an insulator. Exam-
centimeter Abbreviation, cm. A unit of length
equal to 10-2 meter, or 0.3937 inch. ples: isolantite, porcelain, and steatite.
ceramic filter A resonant filter similar to a crystal
centimeter-gram-second system Abbreviation,
filter, but using a piezoelectric ceramic material.
cgs. A system of units, now seldom used, in
ceramic magnet A permanent magnet made of a
which the centimeter is the fundamental unit of
magnetic ceramic material, such as mixtures of
length, the gram is the fundamental unit of
barium oxide and iron oxide.
mass, and the mean solar second is the funda-
ceramic microphone A microphone that uses a
mental unit of time. Electrical units in the cgs
system fall into two categories: electrostatic and
waves into electrical impulses.
electromagnetic. The names of cgs electrostatic
ceramic piezoelement A component that uses a
units have the prefix stat- (e.g., STATAMPERE,
piezoelectric ceramic material. Examples: ceramic
STATVOLT, etc.). Cgs electromagnetic units
filter, ceramic microphone, ceramic phono pickup,
have the prefix ab- (e.g., ABAMPERE, ABVOLT,
ceramic transducer, and electrostrictive trans-
centimetric waves See MICROWAVES.
ceramic resistor A carborundum resistor whose
centipoise A cgs measure of the dynamic viscosity
of liquids. Equal to 10“2 poise. value is voltage-dependent. It usually displays a
negative temperature coefficient of resistance
central office In telephone systems, a switching
(but a positive coefficient is available) and a neg-
network at which numerous circuits or sub-
ative voltage coefficient of resistance.
scriber lines converge.
ceramics 1. Clay-based materials used as di-
central processing unit Abbreviation, CPU. In a dig-
electrics and insulators in electronics. Examples:
ital computer, the section containing the arithmetic
barium titanate, titanium dioxide, porcelain,
and logic unit (ALU), control circuits, and internal
isolantite, and steatite. 2. The science and art of
memory circuits. Also called central processor.
using and developing ceramics.
Central Radio Propagation Laboratory A gov-
ceramic-to-metal seal A bond in which ceramic
ernment laboratory that studies radio propaga-
and metal bodies are joined, for example, the
tion and collects, correlates, and analyzes data
bonding of a metal lead to a ceramic disk,
for predicting propagation conditions. The orga-
through which it passes to provide a leak-proof
nization also studies methods of measuring
seal. Also called ceramet seal.
108 ceramic transducer • change record

ceramic transducer A transducer that uses a CE- Cf Symbol for CALIFORNIUM.
RAMIC PIEZOELEMENT to translate such pa- cgs Abbreviation of CENTIMETER-GRAM-SECOND.
rameters as pressure and vibration into electrical chad The punched-out particle(s) constituting re-
pulses. fuse from paper-tape punching.
ceramic tube A high-temperature vacuum tube chadded tape Punched paper tape in which the
that uses a ceramic material, instead of glass, as chad is left partially attached to the tape™s
the envelope; the tube offers low losses at high punched holes.
frequencies. chadless tape Punched paper tape without CHAD.
Cerenkov radiation Light emanating from a trans- chafe 1. An area that has been abraded by rubbing
parent material that is traversed by charged par- or scraping. 2. To produce a chafe.
ticles, whose speed is higher than the speed of chaff Strips of metal foil used to create radar inter-
light through the material. ference or ambiguity in locating a target by multi-
ple reflections of the beam. Also called MIRROR.
chain broadcasting Simultaneous transmissions
from a number of broadcast transmitters con-
light nected together in a network by wire line, coaxial
sensor cable, or microwave link.
Internal chain calculation As performed by a calculator, a
reflecting calculation that can be entered as it would nor-
mirror mally be written (i.e., without the need for re-
grouping operands).
chain printer In the readout channel of a digital
computer, a high-speed printer carrying printer™s
type on a revolving chain.
chain radar system A number of radar stations
along a missile-flight path that are connected in a
communications or control network.
Atomic material
chain reaction A reaction (as in nuclear fission)
that is self-sustaining or self-repeating. Unless
controlled from outside, such a reaction runs to
Cerenkov radiation
chain switch A switch that is actuated by pulling a
Cerenkov rebatron device An apparatus for gen- light metal chain. Successive pulls turn the
erating radio-frequency energy by passing an switch alternatively on and off.
electron beam through a piece of dielectric having
a small aperture.
ceresin wax A yellow or white wax obtained by re-
fining ozocerite. Used as an insulant and sealant
against moisture. Dielectric constant, 2.5 to 2.6.
cerium Symbol, Ce. A metallic element of the rare-


. 6
( 42)