. 5
( 42)


second input pulse. At any instant, the total bi- vice. 2. The arithmetic operation of converting a
nary count in a multistage counter thus is shown binary number into a decimal number; this can
by the on and off states of the various stages in be done by noting the powers of 2 represented by
sequence. the various binary digits in a number, and then
binary decoder A device or stage that accepts bi- adding the decimal values of these powers.
nary signals on its input lines, and provides a binary word A binary numeral that has a particu-
usually exclusive output (representing a decimal lar meaning, agreed upon by convention. For ex-
digit, for example). ample, the letters A through Z can be represented
binary digit See BIT. by binary numbers 00001 through 11010; a word
binary number system The base-two system of can be represented by several blocks of five digits.
notation. This system uses only two symbols, 0 binaural Literally, two-eared. In sound recording
and 1, and accordingly is easily applied to two- and reproduction, the transcription of a broad
position switches, relays, and flip-flops. sound source using two microphones spaced at
binary preset switch In a binary counter or binary approximately the distance between the ears on a
control circuit, a selector switch that allows the human head, and played back using headphones
74 binaural • biofeedback monitor

to re-create the stereo effect. The technique Uses two optical sensors spaced a fixed distance
evolved into multichannel stereophonic repro- apart. The left sensor sees a slightly different im-
duction. age than the right sensor. These two images are
binaural machine hearing Also called stereo ma- combined and processed by a computer, allowing
chine hearing. The ability of a machine, such as a the machine (such as a mobile robot) to deter-
robot, to sense the direction and distance to a mine the distances to various objects in its envi-
source of sound, using two acoustic transducers ronment. Functions on the same principle as
and a computer to process their output signals. stereoscopic human vision.
The machine determines the location of the bin picking In robotics, the selection of a particu-
sound source by comparing the relative ampli- lar object from a container (bin) in which there
tude and phase of the signals from the two trans- are many objects. Can be done using object
ducers. It functions according to the same recognition, bar coding, or passive transponders.
principle as human hearing, in which a person It requires a sensor, operating in conjunction
can determine the general direction and distance with a computer that processes the sensed data
to a sound source by subconsciously comparing and controls the movements of the robot.
the relative amplitude and phase of the sounds binomial An algebraic expression containing two
arriving at the left and right ears. terms joined by a plus or minus sign. Examples:
a2 + b2, 3x 3 “ 6x.
binaural sound The equivalent of a listener hear-
ing a concert through a pair of earholes; it takes binomial theorem The theorem, proven by Isaac
earphones to reproduce the signal. If speakers Newton, permits a binomial to be raised to any
are substituted for the earphones, the listener desired power without performing the multiplica-
hears monophonically, as if standing back sev- tions. In electronics, power series are convenient
eral feet from the earholes. for expressing such expressions.
binder A material (such as lacquer) that acts as a biochemical cell A fuel-cell energy source in
holder and cohesive medium for the particles of which electricity is generated chemically through
another material. It is used in carbon resistors, the oxidation of biological substances. Also called
ceramic dielectric bodies, powder cores, and re- biochemical fuel cell.
sistive and metallic paints. biochip 1. A natural, living organism with a physi-
binding energy A property of the nucleus of an cal structure that in some way resembles that of
atom. The binding energy of a nucleus is equal to an electronic integrated circuit (IC). 2. A theoreti-
the difference between the nuclear weight and the cal possibility, according to some scientists, but
sum of the weights of the lighter particles making not yet a practical reality: An IC manufactured by
up the nucleus. The nucleus is stable when the a laboratory process that mimics the way in
binding energy is high. which nature builds living organisms. A form of
binding force Any one of the electrostatic forces artificial life, harnessed for electronic and/or
that bind crystals together. computing applications.
binding post A screw-type terminal of various bioelectricity 1. Electric currents in living tissues,
styles, often having a hole into which a wire or tip generated by the organism and not applied by ex-
can be inserted and gripped. It is used for tempo- ternal means. 2. The science or study of such
rary indoor connections only. currents.
bioelectrogenesis The study and application of
electricity generated by living animals, including
humans, in the powering and control of electronic
bioelectronics Electronics in relation to the life
sciences”especially the electronic instrumenta-
tion of biological experiments.
bioengineering 1. The engineering of equipment,
such as electron microscopes, electroencephalo-
graphs, centrifuges, irradiators, etc., for study
and experimentation in the life sciences. 2. The
engineering of equipment, such as pacemakers,
hearing aids, X-ray apparatus, shock-therapy
binding post
units, etc., for aid or support-of-life processes.
biofeedback A technique in which changes in skin
temperature and resistance are detected and dis-
binistor A semiconductor switching device that ex-
played by an electronic device.
hibits two stable states and also negative resis-
biofeedback monitor A system that provides an
indication of skin temperature and resistance to
binocular machine vision Also called stereoscopic
a user. Because skin temperature and resistance
machine vision. The ability of a machine vision
are affected by emotions, such as fear, nervous-
system to provide depth and perspective data.
biofeedback monitor • Birmingham wire gauge

bipolar The condition of possessing two pole sets. In
ness, anger, etc., these monitors might be of
a conventional (non-FET) transistor, one pole set
value to people who wish to gain improved control
exists between the base and collector, and another
of their emotions, and thus perhaps minimize the
pole set exists between the base and emitter.
physiological effects of stress.
bipolar driving unit A magnetic headphone or
biological robot Believed by some researchers to
loudspeaker in which both poles (north and
be possible, but not yet a practical reality: A living
south) of a magnet actuate a diaphragm or lever.
organism created by biological cloning, whose
bipolar operation See AUTOMATIC POLARITY.
brain has been programmed exactly as a com-
bipolar transistor A two-junction transistor whose
puter is programmed.
construction takes the form of a pnp or an npn
biological shield An absorbent shield that blocks
“sandwich.” Such devices are current-operated,
or attenuates ionizing radiation to protect per-
compared with field-effect transistors, which are
sonnel working near radioactive materials.
voltage-operated. The bipolar transistor (of which
bioluminescence 1. The emission of light by a liv-
the familiar npn and pnp types are examples)
ing organism. 2. The light itself so produced by
uses both electron and hole conduction.
living organisms.
biquinary code A variety of binary-coded-decimal
biomechanism An electromechanical device that
notation in which seven bits are used to repre-
simulates the workings of some part of a living
sent each decimal digit. A number is written in
being™s body. Examples are electromechanical
two groups of bits: a two-bit group followed by a
hands, arms, and legs. Such a device is often dif-
five-bit group. The positional values are 5 and 0
ficult to distinguish from its biological counter-
for the two-bit group, and 4, 3, 2, 1, and 0 for the
part when obscured by clothing.
five-bit group.
biomechatronics A contraction of the words biol-
biquinary decade A decade counter that consists
ogy, mechanics and electronics. Research, devel-
of a binary stage, followed by a quinary stage.
opment and manufacturing that encompasses
bird 1. Slang for orbiting SATELLITE. 2. Slang for
aspects of all three fields. This is especially im-
guided missile.
portant in robotics.
birdie 1. A spurious beat note in a superhetero-
biometrics Mathematics, and in particular, statis-
dyne receiver. So called because of the character-
tics and probability, applied to biology.
istic chirping sound it makes as the operator
biometric security system An advanced intru-
tunes by the frequency on which it occurs. 2. A
sion-prevention system that measures biological
parasitic oscillation in a radio transmitter, also
characteristics of the people who are authorized
called a spurious emission or spur.
to enter a property. Such a machine can employ
Birmingham wire gauge Abbreviation, BWG. Also
vision systems, object recognition, and/or pat-
called Stubs gauge. A method of designating the
tern recognition to check a person™s face. The ma-
various sizes of solid wire. BWG diameters are
chine might use speech recognition to identify
somewhat larger than corresponding AMERICAN
people by the waveforms of their voices. It might
WIRE GAUGE diameters for a given wire-size
record a hand print, a fingerprint, or an iris print,
or a combination of all these things. A powerful
computer analyzes the data obtained by the sen-
sors and determines whether the person is au- Birmingham Wire Gauge (BWG) Diameters
thorized to enter the premises. BWG Millimeters Inches
bionics The study, design, and application of mi- 1 7.62 0.300
croelectronic systems that simulate the functions 2 7.21 0.284
of living organisms. 3 6.58 0.259
biotelemetry The use of telemetry to collect data 4 6.05 0.238
from living organisms or to direct their move- 5 5.59 0.220
ment. 6 5.16 0.203
biotelescanner An instrument that monitors body 7 4.57 0.180
functions via radio, from a great distance. 8 4.19 0.165
Biot/Savart law A principle of electromagnetism 9 3.76 0.148
that expresses the intensity of magnetic field H in 10 3.40 0.134
the vicinity of a long, straight wire carrying a 11 3.05 0.120
steady current I. The basic formula is H = 2I/r, 12 2.77 0.109
where H is in oersteds, I is in amperes, and r is 13 2.41 0.095
the distance in centimeters from the wire. 14 2.11 0.083
bip Abbreviation of binary image processor. 15 1.83 0.072
biphase half-wave rectifier An alternative term 16 1.65 0.064
for FULL-WAVE RECTIFIER; also, each leg of a 17 1.47 0.058
two-diode full-wave rectifier. 18 1.25 0.049
BIPM Abbreviation of International Bureau of 19 1.07 0.042
Weights and Measures. 20 0.889 0.035
76 bismuth • black box

bismuth Symbol, Bi. A metallic element. Atomic terrelated smaller capacity processors (e.g., a 16-
number, 83. Atomic weight, 209. bit unit derived from eight 2-bit “slices”).
bismuth flux meter A flux meter in which the sen- bits per second Abbreviation, bps. An expression
sor contains a length of bismuth wire, which acts of digital data speed. Commonly used in com-
as a magnetoresistor. puter communications. This unit is often con-
bismuth thermocouple A thermocouple that uses fused with, and improperly called, the baud.
the junction between bismuth and antimony There is generally a difference between the speed
wires. Used in thermocouple-type meters. of a signal in baud, and the speed of the same sig-
bistable Having two stable states. nal in bps. Compare BAUD.
bistable device Any device, such as a flip-flop, the bitter pattern A pattern produced in a suspension
operation of which exhibits two stable states and of ferromagnetic powder in the presence of an im-
which can be switched at will from one state to perfection in a magnet. The pattern appears as an
the other. irregularity that is easy to see.
bistable multivibrator A multivibrator, the opera- Bjerknes™ equation An expression for the total
tion of which exhibits two stable states. More (primary plus secondary) decrement of a tuned
commonly known as a FLIP-FLOP. These circuits circuit, based on measurements of the tank cur-
are abundant in digital electronic equipment. rent at the resonant frequency and at a frequency
Compare ASTABLE MULTIVIBRATOR and near resonance.

MONOSTABLE MULTIVIBRATOR. BK 1. Radiotelegraph signal for BREAK. 2. Abbre-
viation of BREAK-IN.

Bk Symbol for BERKELIUM.
black-and-white Also called monochrome and
Q gray-scale. Any system of image reproduction,
transmission, or reception in which the image is
composed of opaque elements (black) and white
or bright areas, as in noncolor television recep-
black area An area in which there is only an en-
crypted signal.

blackboard system A method via which comput-
’ ers can recognize, and to some extent determine
Set the meaning of, spoken words and visual images.
Incorporates machine vision and/or machine
hearing in conjunction with artificial intelligence
bistable multivibrator (AI). Incoming voices and/or images are digitized
and entered into a large-capacity random-access
memory (RAM). The data is evaluated by sophisti-
bistable relay A relay that has two stable states:
cated software to determine the most logical or
open and closed. Successive actuating pulses
probable interpretations of the sounds and im-
open and close the relay, two consecutive pulses
being required to return the relay to a given state.
blackbody An ideal surface or object, that com-
Also called binary relay, relay flip-flop, and elec-
pletely absorbs energy of any wavelength that
tromechanical flip-flop.
strikes it. Such an object is a theoretically perfect
bistatic radar A radar set in which the transmit-
radiator of energy at all wavelengths.
ting and receiving antennas are separate.
blackbody radiation Electromagnetic radiation
bistate Having two states. Example: the perfor-
from a heated ideal BLACKBODY. This radiation
mance of a FLIP-FLOP.
is conceived as covering the entire ELECTRO-
bit An acronym formed from the words binary digit.
The smallest or elementary unit of data in digital
expressed graphically as a characteristic curve
electronics. Represented either by logic 0 (low) or
with a peak at a wavelength that depends on the
logic 1 (high). These states can be represented by
absolute temperature of the object. As the abso-
any dichotomy, such as off/on, false/true, mi-
lute temperature increases, the peak occurs at
nus/plus, dark/bright, red/green, etc.
progressively shorter wavelengths (higher fre-
BIT Abbreviation of built-in test.
quencies). This enables radio astronomers to get
bit density The number of digital bits per unit area
a reasonably good idea of the temperatures of dis-
or volume, as the number of bits per square cen-
tant celestial objects, such as planets.
timeter of magnetic tape.
black box 1. Any “box” or “block” that can be in-
BITE Abbreviation of built-in test equipment.
cluded in an analysis or synthesis based upon
bit rate The speed in BITS PER SECOND (bps) at
the BLACK-BOX CONCEPT. 2. Any functional
which digital data bits are transmitted or handled.
unit (such as a module) whose operating charac-
bit-slice processor A microprocessor whose word
teristics are known, and that can be inserted into
or byte capacity is achieved through the use of in-

black box • bleeder resistor

a system in development or maintenance opera- which nothing is recorded. 6. A location (such as
tions. 3. Any subcircuit or stage that can be spec- a symbol or space) that is used to verify proper
ified in total as required in a system, in terms of data character grouping and values.
its known or prescribed performance, but whose blanketing A form of radio interference accompa-
internal structure need not be known. nied by severe degradation of reception, virtually
black-box concept A technique for development of unaffected by tuning, over a wide range of fre-
equivalent circuits and of considering their oper- quencies. An example is ac line noise caused by
ation. The “box” has a pair of input terminals and an arcing power transformer or electrical appli-
a pair of output terminals; one input terminal is ance in the vicinity of a receiving antenna. It
often common to one output terminal. The con- tends to occur most often at low, medium, and
tents of the box need not be known, but from the high frequencies.
input and output current and voltage relation- blanking Obscuring or momentary elimination of a
ships, its nature can be determined. Moreover, signal (see BLANK, 2).
from the available input signal and desired out- blanking interval The short period during which
put signal, the internal circuit of the box can be the electron beam of a cathode-ray tube is cut off
specified. Integrated circuits (ICs) are often so that the beam can return to its start position
treated as black boxes by engineers designing without creating a trace on the screen.
complex electronic equipment. blanking level The discrete, predetermined level
black compression Attenuation of the level of dark (usually a threshold voltage) at which BLANKING
areas in a television picture. occurs.
blacker than black The video-signal amplitude re- blanking pedestal In the horizontal pulse of a tele-
gion above the level that just darkens the screen. vision signal, the lower portion between zero volts
Signal information (such as control pulses) in and the blanking level.
this region are therefore not seen. blanking pulse A pulse that produces momentary
black light 1. Ultraviolet radiation”especially blanking (see BLANK, 2).
when used to cause visible fluorescence in cer- blanking time The time interval during which the
tain materials. 2. A lamp that produces a princi- electron beam of a cathode-ray tube is inter-
pal portion of its radiation in the ultraviolet rupted by a blanking signal.
region, causing visible fluorescence of certain blank tape 1. Magnetic tape that has never been
substances. Such lamps are used in some scien- subjected to the recording process and that is
tific experiments, and also for creating special ef- substantially free from noise. 2. Magnetic tape
fects at presentations or parties. It is hazardous from which all preexisting information has been
to look directly at the output of such a lamp with erased.
unprotected eyes. blasting 1. Severe overloading of a sound system,
blackout 1. A complete interruption of ac utility usually caused by setting the volume control at
power to numerous customers at the same time. or near maximum and then applying a significant
2. A complete cessation of ionospheric radio-wave input signal to the amplifier. Accompanied by dis-
propagation, such as might be caused by a solar tortion, in its worst form, it can cause damage to
flare. 3. Complete blanking of the screen of an os- speakers and/or headsets. 2. In a communica-
cilloscope or picture tube. tions receiver, the result of a strong signal coming
black reference In a television signal, the blanking in unexpectedly when the automatic gain control
level of pulses, beyond which the sync pulse is in (AGC) has been switched off, and the audio-
the blacker-than-black region. frequency (AF) and radio-frequency (RF) gain con-
black reference level In a television signal, the trols are set high for reception of weak signals.
voltage threshold of the BLACK REFERENCE bleeder A resistor or group of resistors, used per-
(i.e., its level above zero volts). manently to drain current from charged capaci-
black transmission A system of picture or facsim- tors. It establishes the predetermined initial load
ile transmission in which the maximum copy level for a power supply or signal source, and it
darkness corresponds to the greatest amplitude serves as a safety device in high-voltage power
(in an amplitude-modulated transmitter) or the supplies.
lowest instantaneous frequency (in a frequency- bleeder current The current normally flowing
modulated transmitter). Compare WHITE through a bleeder.
TRANSMISSION. bleeder divider A network of resistors, series-
blank 1. A piezoelectric plate cut from a quartz strung across the output of a power supply or its
crystal, but not yet finished to operate at a de- regulator. As a load resistor, the bleeder improves
sired frequency. 2. To obscure or interrupt a sig- regulation and protects against no-load voltage
nal or electron beam (usually momentarily), as in surges. The resistor junctions allow various volt-
z-axis blanking in an oscilloscope. 3. A silicon ages to be drawn from the supply.
wafer cut from a large slab, containing dopants bleeder power Power dissipated as heat in a
only. 4. A magnetic diskette or tape on which bleeder.
nothing is recorded. 5. An optical diskette on bleeder resistor See BLEEDER.
78 bleeder temperature • blocking interference

Bloch functions Solutions of the Schrodinger
wave equation for a single electron surrounded
by an electric field. The field varies periodically
with distance from the source.
Bloch wall The transition layer between adjacent
ferromagnetic domains (see DOMAIN).
block 1. A group of data words or digits. 2. A group
of memory storage spaces. 3. A circuit that oper-
ates as an identifiable unit. 4. The symbol for a
circuit, stage, unit, or device in a BLOCK DIA-
block diagram A simplified diagram of an elec-
tronic system, in which circuits, stages, units, or
+V2 devices are shown as two-dimensional boxes with
the internal wiring and detail circuitry omitted.
This makes it possible to clearly show the inter-
’ connection among circuits, stages, units or de-
vices. It also provides a concise rendition of the
overall functional concept of the system.



Control Modulator
bleeder divider

block diagram
bleeder temperature The operating temperature
(of a radio transmitter)
in a bleeder. It is generally high because of power
dissipation in the form of heat.
bleeding whites A flowing of the white areas of a
blocked impedance The input impedance of a
television picture into the black areas; an over-
transducer, whose output load is a theoretically
load condition.
infinite impedance.
blemish See BURN.
blockette In a computer, the subdivision of a char-
blind flight The flying of aircraft entirely by means
acter block that is handled as a unit during data
of instruments and electronic communications.
blind landing Landing of an aircraft entirely by
blocking action Obstruction of circuit action, usu-
means of instruments and electronic commnica-
ally abrupt, through internal action or by the
application of an external signal. Thus, the
blind zone 1. In radar operations, an area that gives
operation of an amplifier can be blocked (output
no echoes. 2. Skip zone (see ZONE OF SILENCE).
reduced to zero) by an input signal or by exces-
blip 1. The pulse-like figure on a radar scan, indi-
sive feedback, either of which overloads the
cating the transmission or reflection (see A-SCAN
and J-SCAN). Also called PIP. 2. In visual align-
blocking capacitor A capacitor inserted into a cir-
ment of a tuned circuit using a sweep generator
cuit to prevent the passage of direct current while
and marker generator, the pulse or dot produced
easily passing alternating current.
on the response curve by the marker signal. 3. A
blocking choke Any inductor, such as a choke
short, momentary signal pulse, such as a single
coil, that is used to prevent the flow of an alter-
Morse dot.
nating current while allowing direct current to
BLIP Abbreviation for background-limited infrared
pass with little resistance.
blocking interference Radio interference from sig-
blip-scan ratio The number of radar scans neces-
nals strong enough to reduce the receiver output
sary to show a visible blip, or echo, on a radar
through blocking action.
blocking oscillator • BNC

ence. 2. A parasitic oscillation in a radio trans-
mitter. 3. In broadcasting, a statement in which a
radio or television announcer makes an embar-
rassing error or breach of etiquette.
blow The opening of a fuse or circuit breaker as a
result of excessive current.
blower A fan used to remove heat from electronic
circuits. These are often used in tube-type radio-
frequency (RF) power amplifiers, where much
heat is generated, and in computers to cool the
microprocessor and surrounding components.
blowout 1. An alternate term for BURNOUT. 2. The
forceful opening of a circuit breaker. 3. The extin-
guishing of an arc.
blowout coil An electromagnet that provides a field
to extinguish an arc.
blowout magnet A permanent magnet that pro-
vides a field to extinguish an arc.
blst Abbreviation of ballast.
blue-beam magnet In a color television picture-
tube assembly using three electron guns, a small
permanent magnet to adjust the static conver-
gence of the beam for blue phosphor dots.
blue box An accessory device (sometimes unlaw-
fully used) that generates tones that switch a tele-
blocking oscillator An oscillator that turns itself
phone circuit in the placing of calls.
off after one or more cycles. It does this as a re-
blue glow 1. In a neon lamp, a bluish light that
sult of an accumulation of negative charge on its
results from high-voltage arcing. 2. The normal
input electrode (base of a bipolar transistor or
color of the gas discharge in an argon glow
gate of a field-effect transistor). The action is
lamp. 3. The bluish glow between anode and
repetitive. In the self-pulsing type of blocking os-
cathode of a gassy vacuum tube. 4. The normal
cillator, a series of pulses consisting of trains of
color of the discharge that fills a mercury-vapor
sine waves with intervening spaces is generated.
In the single-swing type of blocking oscillator, the
blue gun The electron in a three-gun color picture
output consists of a series of single cycles with
tube, the beam from which strikes the blue phos-
long intervals between them.
phor dots.
blocking oscillator synchronization 1. In the
blueprint 1. A type of contact-print reproduction
BLOCKING OSCILLATOR used in the vertical de-
in which a sheet of sensitized paper is exposed to
flection circuit of a television receiver, the oscilla-
an image on a translucent or transparent film,
tor is synchronized with vertical sync pulses
under strong light, and is then developed and
arriving in the video signal. 2. Synchronization of
fixed. Although this process is still used to repro-
the repetition rate of any blocking oscillator with
duce electronic illustrations and typescripts, it
a suitable external control signal.
has been superseded largely by other (dry) pro-
blocking system In a telephone system, a method
cesses. 2. Loosely, any plan or design for the de-
of dealing with the condition of having more sub-
velopment of a system.
scribers than connection paths. Allocation is
blue restorer In a three-gun color television cir-
made on a demand basis. If all channels are in
cuit, the dc restorer in the blue channel.
use, it is impossible to make new calls. This pre-
blue ribbon program A computer program that
vents excessive degradation of the quality of ex-
has been hand-prepared and debugged com-
isting connections.
pletely before its first computer run.
block length The number of characters, bits, or
blue video voltage The signal voltage presented to
words that compose a defined unit word or char-
the grid of the blue gun of a three-gun color pic-
acter group.
ture tube.
block transfer The conveyance of a word or char-
blurring 1. BLOOMING. 2. A defocusing of a televi-
acter grouping in a computer register to another
sion picture or oscilloscope trace. 3. An obscur-
register or a peripheral device.
ing of a signal by echoes or trailing (e.g., the slow
blooming On a cathode-ray-tube (CRT) screen, an
decrement of a Morse code signal element).
enlargement of the electron-beam spot, caused by
B-minus Also called B-negative. The negative ter-
poor focusing. This results in poor image
minal of a B-power supply.
BNC Abbreviation of bayonet Neill-Concelman. A
blooper 1. A radio receiver that is in oscillation,
type of coaxial connector that can be quickly con-
and is transmitting a signal that causes interfer-
80 BNC • Boltzmann™s principle

operation of the internal heater element (if the
thermistor has one).
bof Abbreviation of barium oxide ferrite.
boffle A loudspeaker enclosure consisting of
stretched screens that are sound absorbing and
bogie Also called bogey. 1. The exact value of a
specified characteristic. Thus, if resistance is
given as 1 k„¦ ±0.5%, the bogie value is 1 k„¦. 2.
nected and disconnected. It is commonly used The average value (i.e., the ARITHMETIC MEAN).
with test equipment. 3. A false or unidentified echo on a radar screen.
B-negative Alternative expression for B-MINUS. Bohr atom The concept of the nature of the atom,
BNL Abbreviation of Brookhaven National proposed by Niels Bohr in 1913 partly to explain
Laboratory. why the electrons in the Rutherford atom do not
BO Abbreviation of beat oscillator. Also abbreviated fly off into space or fall into the nucleus. The Bohr
BFO. theory places the electrons in permissible orbits
board 1. A panel containing patch jacks. 2. A where they cannot radiate energy (see BOHR RA-
printed circuit. DIUS). They can radiate or absorb energy, how-
boat A type of crucible in which a semiconductor ever, if they go to a lower orbit or to a higher orbit,
material is melted and sometimes processed. The respectively. Compare RUTHERFORD ATOM.
material of which the boat is made (e.g., graphite) bohrium Symbol, Bh. Also called unnilseptium
does not react with or contaminate the semicon- (Uns). Atomic number, 107. The most common
ductor material. isotope has atomic weight 262. Classified as a
bobbin 1. A usually nonmetallic spool on which a transition metal. It is human-made and is not
coil is wound. 2. The form onto which the voice known to occur in nature.
coil of a loudspeaker is wound. Bohr radius Symbol, a0. A physical constant
whose value is approximately 5.291772 — 10“11
Bode plot A pair of curves plotted to the same fre-
quency axis, one showing the gain of a network or meter.
amplifier and the other showing its phase shift. boiling point Abbreviation, bp. The temperature at
Phase and amplitude of active and passive net- which a liquid vaporizes. The boiling point of wa-
works can be exhibited. Also called Bode curve ter in air at a pressure of one atmosphere is
and Bode diagram. 100°C or 212°F.
body-antenna effect The tendency of the human bolometer Any device that is essentially a small,
body to act as a receiving antenna when a finger nonrectifying, temperature-sensitive resistor that
is touched to the antenna input terminal of a re- can be used for heat sensing, radio-frequency
ceiver or when a hand (or the whole body) is power measurement, curve changing, demodula-
brought close enough to the circuit to provide ca- tion, circuit protection, etc. Included in this cate-
pacitive coupling. gory are the BARRETTER, the THERMISTOR, and
body capacitance Capacitance between the body the wire-type FUSE.
of the operator (as one plate of an equivalent ca- bolometer bridge A dc bridge in which a bolometer
pacitor) and a piece of electronic equipment (as is one of the four arms. The bridge is balanced
the other plate). This phantom capacitance is of- first with the bolometer cold. The bolometer then
ten the cause of detuning and of the injection of is excited with a radio-frequency (RF) current,
interfering signals and noise because the body whereupon the resultant heating changes the
acts as a pickup antenna. bolometer resistance. The bridge is rebalanced for
body electrode 1. An electrode attached to the the new resistance. The RF power driving the
human body (or to the body of a laboratory ani- bolometer is determined according to a predeter-
mal) to conduct body-generated currents to an mined function of bridge settings versus RF input
instrument, as in cardiography, electroenceph- power.
alography, and myography. 2. An electrode at- Boltzmann constant Symbol, k. A figure that en-
tached to the human body (or to the body of a ters into the calculation of thermionic emission
laboratory animal) to conduct currents into the and of thermal noise factor. It represents the tem-
body, as in shock therapy and skin-resistance perature equivalent of work function, in electron
measurement. volts per Kelvin (eV/K) or joules per Kelvin (J/K).
body leakage Leakage of current through the bulk The values are approximately:
or body of a dielectric material, as opposed to
k = 8.617 — 10“5 eV/K = 1.38 — 10“23 J/K
Boltzmann™s principle A description of the statis-
body temperature In a thermistor, a rating that
tical distribution of large numbers of tiny parti-
represents the temperature measured on the
cles under the influence of a force, such as an
surface of the device. It is any combination of
electric or magnetic field. When the system is in
ambient temperature, power dissipation, and
Boltzmann™s principle • booster

Boolean truth table
statistical equilibrium, the number of particles in
any portion of the field is given by:
NE = N0e“E/kT x y xy x x+y
where E is the potential energy of a particle in the
0 0 0 1 0
observed area, N0 is the number of particles per
0 1 0 1 1
unit volume in a part of the field where E is zero,
1 0 0 0 1
k is the BOLTZMANN CONSTANT, T is the abso-
1 1 1 0 1
lute temperature of the system of particles, and e
is approximately equal to 2.718.
bombardment The usually forceful striking of a
target with rays or a stream of particles.
Boolean function In mathematical logic, a func-
bond 1. An area in which two or more items are se-
tion that makes use of BOOLEAN ALGEBRA.
curely and intimately joined. 2. The attractive
force that holds an atomic or subatomic particle
or particle group together. Boolean theoreams
bonded-barrier transistor A bipolar transistor in
1. x + 0 = x (additive identity)
which the connection at the base region is al-
loyed. 2. x1 = x (multiplicative idenity)
bonded negative-resistance diode A diode that 3. x+1=1
displays a negative-resistance characteristic over 4. x0 = 0
part of its current curve. This results from 5. x+x=x
avalanche breakdown. 6. xx = x
bond energy In a molecule, the energy necessary
7. (x™)™ = x (double negation)
to break an atomic bond.
8. x + x™ = 1
bonding 1. The formation of bonds between adja-
9. x™x = 0
cent atoms in a crystalline material, such as a
10. x + y = y + x (commutativity of addition)
semiconductor. See specifically COVALENT
BINDING FORCES, IONIC BINDING FORCES, 11. xy = yx (commutativity of multiplication)
and METALLIC BINDING FORCES. 2. The secure 12. x + xy = x
fastening together of conducting surfaces, as by 13. xy™ + y = x + y
soldering or brazing, to produce a high-conduc- 14. x + y + z = (x + y) + z = x + (y + z)
tance, leak-free continuum. (associativity of addition)
bond strength The minimum stress required to
15. xyz = (xy)z = x(yz) (associativity of multiplication)
separate a material from another to which it is
16. x(y + z) = xy + xz (distributivity)
17. (x + w) (y + z) = xy + xz + wy + wz (distributivity)
bone-conduction transducer A device used in
place of the earphone in a hearing aid to convey
sound energy to the bone structure of the head.
Bongard problem A method of evaluating how well boom 1. A horizontal support for a microphone,
a machine vision system can differentiate among enabling the microphone to be suspended over a
patterns. Similarities and differences are noted sound source, but out of the sight of a camera.
between objects in two sets of boxes. It was devel- 2. A horizontal support for a small antenna that is
oped for object-recognition systems, mainly for undergoing tests or sampling the field of another
use in intelligent robots. antenna. 3. The supporting element in a Yagi,
book capacitor A variable capacitor in which the quad, or log-periodic antenna. It establishes the
metal plates are bonded along one edge and sep- center of gravity and directional axis of the radi-
arated from each other by means of mica sheets. ation pattern. The driven element(s) and para-
The capacitance is varied by opening and closing sitic element(s) are attached, usually at right
the assembly book fashion. It is used as a padder angles.
or trimmer. boost capacitor In the damper circuit of a televi-
Boolean algebra A system of symbolic logic. State- sion receiver, the capacitor that is used to boost
ments are represented as symbols, usually vari- the B-plus voltage. Also called booster capacitor.
ables such as x, y, and z. The logical AND opera- boost charge A high-current, short-interval charge
tion is represented by multiplication; the logical used to revitalize a storage battery quickly. Also
inclusive OR operation is represented by addi- called booster charge.
tion; the logical NOT operation is represented by booster 1. Any device used to increase the ampli-
a minus sign or a line over the element symbol. tude of a signal (e.g., as an amplifier or preampli-
The system has rules, definitions and axioms via fier) or of an energy source (e.g., to boost the
which theorems can be derived. Used by engi- output of a power supply). 2. A radio-frequency
neers in the design of digital electronic circuits. preamplifier used ahead of a television receiver.
82 booster battery • bow-tie test

program that is used to establish an alternate
booster battery 1. A battery used to forward bias a
version of the program.
diode detector into a favorable region of its con-
borax-aluminum cell An electrolytic cell that con-
duction curve, or to bias a bolometer into the
sists essentially of an aluminum electrode and a
square-law region of its response. 2. A battery
lead electrode in a saturated solution of sodium
supplying power to a booster.
tetraborate (borax). After electroforming, such a
booster gain The amplification (usually in terms of
cell can be used either as a rectifier or as an elec-
voltage gain) provided by a booster (see especially
trolytic capacitor.
boric acid Formula, H3BO3. A compound used var-
boot 1. The powering-up routine in a digital com-
iously in electronics”especially as the electrolyte
puter, in which the machine executes a series of
in electrolytic capacitors.
programs to get itself ready for use. 2. The
bornite Formula, Cu5FeS4. A natural mineral that
resetting of a computer, by pressing certain key-
is a sulfide of copper and iron. Its crystalline
board keys (e.g., CTRL-ALT-DEL), pressing a re-
structure made it important in early semiconduc-
set button, or by powering-down, waiting about
tor diodes (crystal detectors).
two minutes, and then powering-up again. 3. To
boron Symbol, B. A metalloidal element. Atomic
install a computer diskette and instruct the com-
number, 5. Atomic weight, 10.82. It is used as a
puter to execute one or more programs on the
dopant in semiconductor processing.
diskette. 4. A usually flexible protective nipple or
bot 1. Abbreviation for beginning of tape. 2. Abbre-
jacket pulled over a cable or connector, so called
viation of bottom.
from its resemblance to a foot boot.
bottoming Excessive movement of the cone of a
boot loader A form of computer program that op-
loudspeaker or the diaphragm of a headphone so
erates on the BOOTSTRAP ROUTINE.
that the magnet or supporting structure is struck
bootstrap A technique for making a device or pro-
by the moving-coil piston assembly. It produces a
cess achieve a condition through its own actions;
clapping sound, particularly on bass (low-
see BOOTSTRAP CIRCUIT, for example.
frequency) audio peaks.
bootstrap circuit A specialized form of follower
bounce 1. The springback or vibration of the ar-
circuit that presents very high input impedance.
mature of a relay on closure. 2. An abnormal,
Its chief feature is the return of the control-ele-
abrupt change in the brightness of the image in a
ment resistor to a tap on the source or emitter re-
television receiver or cathode-ray-tube (CRT)
sistor. The technique takes its name from the
computer monitor.
figurative notion that such a circuit “lifts its input
boundary 1. In a polycrystalline substance, the
impedance by its own bootstraps.”
area of contact between adjacent crystals. 2. The
area of meeting of two regions (such as n and p)
Vdc in a semiconductor.
+ ’
boundary defect A condition in which a piezoelec-
tric crystal has two regions, intersecting in a
plane, with different polarizations.
boundary effect In audio systems, a pheno-menon
in which the proximity of an acoustic transducer
C2 to a flat surface enhances the pickup and/or
transmission of sound. Occurs because of reflec-
R1 R2 tion of acoustic waves from the surface.
bound charge The portion of the electric charge on
Signal input Signal output a conductor that does not escape to ground when
R3 the conductor is grounded. This occurs because
of induction from neighboring charge carriers.
bound electron An electron held tightly in its orbit
within an atom so that it is not ordinarily free to
bootstrap circuit
drift between atoms and contribute to electric
(with junction-type field-effect transistor)
current flow.
bow-tie antenna A center-fed antenna in which
the two horizontal halves of the radiator are tri-
bootstrap routine 1. Also called bootstrap pro-
angular plates that resemble a bow tie. A flat re-
gram. In a digital computer, and especially in a
flector consisting of closely spaced horizontal
personal computer, the routine that the machine
wires is mounted behind the triangles.
follows when first powered-up. See BOOT, 1.
bow-tie test An oscilloscope-display checkout of a
2. In a digital computer, a routine in which the first
single-sideband (SSB) signal, in which the ap-
few instructions put in storage are later used to
pearance of the display indicates the signal qual-
complete the routine, as supplemented by some
ity. The transmitter output signal is fed to the
operator instruction. 3. A portion of a computer
bow-tie test • brass pounder

vertical deflection plates of the oscilloscope. The branch circuit In electrical wiring, a group of out-
exciter audio output is fed to the horizontal sweep lets served through a single cutout from a source
input of the scope. of power-line ac voltage. The source can be a dis-
boxcars Long pulses with short separating spaces tribution center, subdistribution center, main, or
between them. submain. Interior lighting circuits are usually
box-shaped loop The characteristic square-loop branch circuits because many lights are con-
hysteresis curve (B-H loop) that result when a nected to one circuit controlled by a single fuse or
sine wave of current is used to magnetize a sam- circuit breaker.
ple of magnetic material. In this plot, which cov-
ers all four quadrants, the horizontal axis (H) Subdistribution center
displays magnetizing force, and the vertical axis Main
(B) displays magnetization. Also see HYSTERE- distribution
SIS. center
Boys radiomicrometer A detector for radiant en-
Subfeeder Subfeeder
ergy. The device consists of a thermocouple and a Feeder
galvanometer. When energy falls on the thermo- Service
couple, a voltage is produced, and this is mea-
sured by the galvanometer.
bp 1. Abbreviation of BOILING POINT. 2. Abbrevia-
tion of BANDPASS.
bpi Abbreviation of bits per inch.
B-plus Also called b-positive. 1. Symbol, B+. The
positive dc voltage required for certain electrodes
of vacuum tubes, transistors, etc. 2. The positive Subdistribution
terminal of a B power supply. center
B positive See B-PLUS. Submain
B power supply A name used sometimes for the
unit that supplies high-voltage dc energy to a
vacuum tube plate or screen circuit.
bps Abbreviation of BITS PER SECOND.
Br Symbol for BROMINE.
bracketing A troubleshooting routine character-
branch circuit
ized by isolating progressively smaller areas in a
(enclosed in broken lines)
circuit or chain of stages until the defective sub-
circuit or stage is located.
branch current Current flowing through a branch
Bradley detector A locked-oscillator circuit that
of a circuit, whose magnitude, with respect to the
was once used as an FM detector.
total current of the circuit depends on the nature
braid 1. A woven network of fine metal wires used
of the branch.
for grounding purposes. It is usually made of fine
branched In molecular polymers, the condition of
copper conductors. The increased surface-area-
side chains being attached to the main chain.
to-volume ratio improves the conductivity, at ra-
branched windings Forked windings of a poly-
dio frequencies, over a single conductor that has
phase transformer.
the same cross-sectional area. Braid can be
branching In robotics and artificial intelligence
tinned (saturated with solder) to retard corrosion.
(AI), a set of routines or programs containing
2. It is also called a shield. The outer conductor in
points at which a computer must select from
prefabricated coaxial cable.
among two or more alternatives. Such routines
braided wire A length of braid. Used for grounding
are used in critical processes, such as the manu-
or shielding purposes.
facture of precision equipment.
brain waves Alternating or pulsating voltages that
branch point See JUNCTION POINT.
are caused by electrical activity in the brain of an
branch voltage The voltage, or voltage drop,
animal or human being. The voltages can be
across a branch of a circuit.
picked up by electrodes attached to the scalp,
brass 1. An alloy of copper and zinc that is widely
and amplified to be viewed on a cathode-ray-tube
used in electronics. Compared to annealed cop-
(CRT) screen, heard by headphones or speakers,
per, this metal has four times the resistivity (or 1„4
or traced by an electroencephalograph.
the conductivity), half the temperature coeffi-
branch 1. Any one of the separate paths of a
cient, more than twice the tensile strength, and a
circuit. With respect to the layout of its compo-
lower melting point (900°C). 2. A colloquialism for
nents, a branch can be series, parallel, series-
an old-fashioned, straight telegraph key.
parallel, parallel-series, or any combination of
brass pounder 1. Colloquialism for telegraph oper-
these. It is also called a LEG. 2. See BRANCH
ator or radiotelegraph operator. 2. A radio ama-
84 brass pounder • brevity code

teur who handles large amounts of message traf- breaking current The momentary current that
fic, particularly via Morse code. 3. A radio ama- flows when the contacts of a switch or relay are
teur proficient in Morse code operation. broken.
Braun electroscope An electroscope consisting es- break-in keying A system of radiotelegraph keying
sentially of a fixed metal vane to which a movable in which the receiver is in operation whenever the
needle is fastened at a pivot. The repulsion be- key is open. See BREAK-IN, 2.
tween the two, when an electric charge is applied, break-in operation In radiotelegraph or single-
causes the needle to move over a calibrated scale. sideband (SSB) communications, the practice of
bravo Phonetic representation of the letter B. interrupting at any time to “talk back” to the
brazing The joining of two metal (usually iron or other transmitting station. This operation is
steel) parts together with a suitable melted cop- made possible by high-speed transmit/receive
per-alloy metal. Compare SOLDERING. switching. See BREAK-IN, 2.
breadboard 1. A perforated board, a chassis, or break-in relay An electromechanical or solid-state
any basic framework on which electronic compo- relay that enables break-in operation. Largely
nents can be mounted and quickly wired for the supplanted by solid-state switching devices.
preliminary test of a circuit. It is so called be- breakover point In a silicon-controlled rectifier,
cause the first such foundation units of this sort the source-voltage value at which the load cur-
actually were wooden breadboards. 2. Any pre- rent is suddenly triggered to its steep climb. Also
production electronic prototype circuit. 3. To set called TRIGGERING POINT.
up a circuit on a breadboard. breakover voltage In a silicon-controlled rectifier
breadboard model 1. The preliminary model of an with open gate circuit, the anode voltage at which
electronic device, often built on a breadboard (see anode current is initiated.
BREADBOARD, 1). 2. Loosely, any prototype. breakpoint A point in a computer program when,
break 1. An open circuit. 2. To open a circuit. 3. In for the purpose of obtaining information for the
communications, a word indicating a desire to program™s analysis, the sequence of operations is
transmit on a wavelength already occupied by ra- interrupted by an operator or a monitor program.
dio traffic. 4. See BREAK-IN, 1. breakpoint frequencies The upper- and lower-
break-before-make contacts Contacts, especially frequency points at which the gain-versus-
in a rotary selector switch, that open one circuit frequency response of an amplifier or network
before closing the next one. departs from flatness.
breakdown 1. Failure of a circuit or device, caused breakpoint instruction An instruction that stops
mainly by excessive voltage, current, or power. A a computer.
sudden high current, however, does not always breakthrough 1. A new discovery, insight, or solu-
indicate failure. 2. AVALANCHE BREAKDOWN. tion to a problem that results in an advancement
3. The separation of an electronics problem or in the state of the art. 2. See PUNCHTHROUGH.
project into its constituent parts for an easier 3. See BREAKDOWN, 1. 4. See AVALANCHE
solution. BREAKDOWN.
breakdown diode See ZENER DIODE. break time The time taken for a relay to drop out
breakdown region The region, in a pn junction, in completely or a switch to open. Compare MAKE
which avalanche breakdown occurs. TIME.
breakdown strength See DIELECTRIC STRENGTH. breathing Slow, rhythmic pulsations of a quantity,
breakdown voltage 1. The voltage at which cur- such as current, voltage, brightness, beat note,
rent suddenly passes in destructive amounts etc.
through a dielectric. 2. The voltage at which a gas breezeway In a sync pulse in NTSC color televi-
suddenly ionizes, as in a gas tube. 3. The voltage sion, the part of the back porch between the trail-
at which the reverse current of a semiconductor ing edge of the pulse and the color burst.
junction suddenly rises to a high value (non- B-register An index register in a computer for stor-
destructive if the current is limited). See ing words that are used to change an instruction
AVALANCHE BREAKDOWN. before it is executed by the program.
break-in 1. A technique of radio communication in Bremsstrahlung radiation The radiation emitted
which one station interrupts a transmission from by a charged particle whose speed is altered when
another station, rather than waiting until the end it passes through the electric field in the vicinity
of the latter™s transmission. 2. Also called full of an atomic nucleus.
break-in. In a radio communications transceiver brevity code A code not intended to conceal infor-
or transmitter/receiver combination, extremely mation, but to shorten the number of characters
rapid transmit/receive switching, approaching in a message or data file. The Q SIGNALS are an
full duplex communications. Every pause in example of a brevity code used in communica-
transmission, even of only a few milliseconds, tions. In computer data transfer and communica-
creates a “receive window” allowing reception tions, brevity codes allow compression, speeding
between spoken words or Morse code elements. up the transfer rate and reducing the storage
3. BURN-IN. space for a given amount of data.
Brewster angle • bridge-type meter

Brewster angle From BREWSTER™S LAW, the po- C1
larizing angle at which the reflected and refracted
rays of incident light are perpendicular to each R1 R2 R3
Brewster™s law (Sir David Brewster, 1781“1868).
For any dielectric reflector, the relationship in
which the refractive index is equal to the tangent C2 C3
Input Output
of the polarizing angle.
bridge 1. A network, usually consisting of four
branches, connected so that an input signal can
be applied between two opposite points and the
output taken between the other two opposite
points. When the component values are in a cer- C1 = C 2 = C 3
tain ratio, the voltage between the output points
R1 = R2 = R3
is zero, and the bridge is said to be balanced or
set to null. 2. A circuit such as that described in
fnull = 1.732
(1) used for electrical measurements. 3. An audio 2πR1C1
or servo amplification system in which the load is
driven from two outputs having opposite polarity,
bridged integrator
neither of which are at ground potential. 4. A
communications path between or among two or
bridged-tee oscillator A low-distortion oscillator
more networks. This allows the subscribers in
circuit whose frequency is determined by a
any network to obtain data from, or send data to,
bridged-tee null network inserted into the nega-
any other network, in effect creating a network of
tive-feedback path of the circuit.
bridge feedback A combination of current feed-
bridge balance control A potentiometer, variable
back and voltage feedback around an amplifier
capacitor, or variable inductor that is used to ad-
circuit. It is so called because, in the feedback cir-
just a bridge circuit to balance.
cuit, the resistors and the output resistance of
bridge-connected amplifier 1. A dc amplifier
the amplifier form a four-arm bridge.
stage in which the transistors and resistors are
bridge generator The power source (e.g., a battery
connected in a four-arm bridge circuit, with re-
or oscillator) that supplies the signal to a BRIDGE
spect to dc. When the bridge is initially balanced,
used for electrical measurements.
all dc is eliminated in the output load. The input
bridge indicator See BRIDGE DETECTOR.
signal unbalances the bridge, which results in an
bridge oscillator See BRIDGE GENERATOR.
amplified output signal in the load. 2. An ampli-
bridge rectifier A full-wave rectifier circuit in
fier pair having opposing outputs across which a
which four rectifying diodes are connected in a
load can be bridged to obtain twice the power out-
bridge configuration. Each half-cycle of ac input
put of either amplifier alone.
is rectified by a pair of diodes in opposite quarters
bridged differentiator See HALL NETWORK.
of the bridge and in series with each other. The
bridge detector The output-indicating device
bridge does not require a transformer with a
(e.g., meter, oscilloscope, or headphones) that
center-tapped secondary, as does the FULL-
indicates whether a bridge is balanced or un-
balanced. Also called null detector or null indi-
bridge source See BRIDGE GENERATOR.
bridge-type meter A frequency-sensitive bridge
bridged integrator A null network that consists of
(such as the Wien bridge) that can be used to
a two-stage resistance-capacitance (RC) integra-
measure audio frequency. Because the bridge
tor circuit bridged by a capacitor. This network
can be balanced at only one frequency at a time,
produces a shallow null at a single frequency de-
termined by the R and C values in the integrator.
bridged-tee attenuator An attenuator consisting
of a tee section, between the input and output of
which is bridged a single-series arm.
bridged-tee circuit Any circuit (of resistors, ca-
pacitors, inductors, or a combination of these)
that consists of a tee section, bridged by a single-
series section, from input to output.
bridged-tee null network A bridged-tee circuit of
resistance (R) and capacitance (C), proportioned
so that at some setting of the R and C values, the
output of the circuit is zero.
86 bridge-type meter • British Standard wire gauge

its adjustable arm can be calibrated to read the light, per unit area, emitted or reflected perpen-
frequency directly. dicular to a light-emitting surface.
bridge-type impedance meter An impedance- brightness control 1. In a computer monitor, tele-
measuring circuit in which unknown impedance vision receiver, or oscilloscope, a potentiometer
Z is connected in series with a calibrated variable that varies the negative bias voltage on the con-
resistor R. An ac voltage is applied to the series trol grid of the cathode-ray tube (CRT). The
circuit. The separate voltage drops across the re- brightness of the image is inversely proportional
sistor and impedance are measured successively to this negative bias voltage. 2. The control of the
as the value of R is varied. When the two voltage brightness of an illuminated area.
drops are identical, Z equals R, and the brilliance See BRIGHTNESS.
impedance can be read from a calibrated dial on brilliance control 1. The BRIGHTNESS CONTROL
the variable-resistor control. in a television receiver or computer monitor. 2.
bridge-type oscillator A resistance-capacitance The brightness control in a cathode-ray oscillo-
(RC) tuned oscillator in which a Wien bridge is scope. 3. A control for adjusting the level of the
used as the frequency-determining circuit in the tweeter output in a speaker system.
feedback loop. British Standard wire gauge Abbreviation, NBS
bridge-type power meter 1. See BOLOMETER SWG. A classification of wire sizes sometimes
BRIDGE. 2. A four-arm bridge specially designed used in England, Australia, and New Zealand.

to operate at radio frequencies. At null, the The higher the number, the thinner the wire. The
impedance of the unknown is read directly from designator does not take into account any coat-

the balancing dial or calculated from bridge con- ings on the wire, such as enamel, rubber, or plas-
stants. This instrument is used to measure the tic insulation. In the United States, the American
impedance of circuit components, antennas, and wire gauge is more often used. See AMERICAN
transmission lines. WIRE GAUGE.
bridge-type SWR meter A four-arm bridge that is
specially designed to operate at radio frequencies.
At null, the standing-wave ratio (SWR) is calcu- British Standard Wire Gauge (NBS SWG) Diameters
lated from the bridge resistance values or read NBS SWG Millimeters Inches
from a direct-reading scale on the null-indicating 1 7.62 0.300

meter. 2 7.01 0.276
bridging amplifier An amplifier whose input im- 3 6.40 0.252
pedance is so high that it can be considered infi- 4 5.89 0.232
nite for practical purposes. Thus, the amplifier 5 5.38 0.212
can be connected across a load or line without 6 4.88 0.192
significantly affecting the operation of the system. 7 4.47 0.176
bridging coupler A voltage-dependent resistor that 8 4.06 0.160
permits an occasionally used device (such as a bell) 9 3.66 0.144
to be connected permanently across a regularly 10 3.25 0.128
used device (such as a telephone) without continu- 11 2.95 0.116
ously short-circuiting the latter. Thus, the bridging 12 2.64 0.104
coupler ordinarily has very high resistance; but 13 2.34 0.092
when the line voltage is momentarily raised, the re- 14 2.03 0.080
sistance lowers and the occasionally used device is 15 1.83 0.072
actuated (e.g., the bell rings). 16 1.63 0.064
bridging gain The gain of a bridging amplifier ex- 17 1.42 0.056
pressed as the ratio (in decibels) of the power de- 18 1.22 0.048
veloped in the amplifier load to the power in the 19 1.02 0.040
load to which the input terminals of the amplifier 20 0.91 0.036
are connected. 21 0.81 0.032
bridging loss The loss that results from the shunt- 22 0.71 0.028
ing of a speaker, microphone, earphone, or other 23 0.61 0.024
transducer by a resistor, capacitor, or inductor. 24 0.56 0.022
Generally, the loss is expressed as a power ratio 25 0.51 0.020
in decibels. 26 0.46 0.018
Briggsian logarithm (Henry Briggs, 1556-1631). A 27 0.42 0.0164
base-10 logarithm, generally known as a 28 0.38 0.0148
COMMON LOGARITHM. Compare NAPIERIAN 29 0.345 0.0136
LOGARITHM. 30 0.315 0.0124
brightness SI unit, candela per square meter 31 0.295 0.0116
(cd/m2); cgs unit, lambert (L). The quantity of 32 0.274 0.0108

British thermal unit • broad response

quencies without requiring retuning at individual
NBS SWG Millimeters Inches
frequencies. Examples are the log-periodic and
33 0.254 0.0100
discone antennas.
34 0.234 0.0092
broadband electrical noise Electrical noise that is
35 0.213 0.0084
present over a wide frequency spectrum (e.g., 3
36 0.193 0.0076
kHz to 30 MHz).
37 0.173 0.0068
broadband I-F An intermediate-frequency (IF) am-
38 0.152 0.0060
plifier or amplifier chain. The wide frequency re-
39 0.132 0.0052
sponse is important when an increased bandpass
40 0.122 0.0048
is preferred to high selectivity, as in high-fidelity
radio tuners.
British thermal unit Abbreviation, Btu. The broadband interference Interference, other than
amount of heat required to raise the temperature of noise, that is present over a wide band of fre-
a pound of water by one degree Fahrenheit, in an quencies. An example is over-the-horizon short-
ambient environment of slightly greater than 39°F. wave radar, recognizable by its characteristic
broadband Also called wideband. Possessing a “woodpecker” sound in communications receivers
characteristic wide bandwidth or range of operat- at high frequencies.
ing frequencies. This term can be applied at audio broadband Klystron A Klystron oscillator with a
frequencies (AF) or radio frequencies (RF), and is broadbanded tuned circuit.
frequently used to describe the performance of broadband tuning Receiver tuning characterized
oscillators, amplifiers, antennas, and various by a selectivity curve having a pronounced flat
types of networks. The term can also be applied to top or broad nose that passes a wide band of fre-
describe the nature of electromagnetic emissions quencies. Also called broadband response.
or noise. Examples are given in the following sev- broadcast 1. A radio-frequency transmission of an
eral definitions. Compare NARROWBAND. intelligence-bearing signal that is directed to nu-
broadband amplifier An amplifier that has very merous unspecified receiving stations. 2. The
wide frequency response, such as 10 Hz to 10 transmission or dissemination of signals to a
MHz. Examples are an instrument amplifier and large, unspecified number of receiving stations.
a video amplifier. broadcast band Any band of frequencies allocated
broadband antenna An antenna that operates sat- for broadcasting (see BROADCAST SERVICE, 1),
isfactorily over a comparatively wide band of fre- but particularly the U.S. standard amplitude-
modulation (AM) and frequency-modulation (FM)
radio broadcast bands at 535 to 1605 kHz (AM)
+12 V and 88 to 108 MHz (FM).
broadcasting The dissemination of signals for re-
ception by the general public, not for communi-
cations purposes.
broadcast interference Abbreviation, BCI. Inter-
ference to normal reception by broadcast re-
ceivers, usually arising from signals emitted by
other stations.
broadcast receiver A receiver intended primarily
to pick up standard broadcast stations. Also see
broadcast service 1. Any radio transmitting ser-
vice (including television) that exists for the pur-
pose of sending out electromagnetic signals for
Input general reception, rather than addressing them to
specific receiving stations. 2. The service provided
by a station operating in the broadcast band.
broadcast station Any station in the broadcast
service, but especially one assigned to operate in
the standard U.S. broadcast bands. Also called
broadcasting station.
broadcast transmitter A radio transmitter de-
signed specifically for, and operated in, the
broadcast service.
broad response Slow deflection of an indicator,
such as a meter, over a relatively wide range of
values of the input quantity.
broadband amplifier
88 broadside • bubble memory

broadside In a perpendicular direction; for exam- sions of molecules with the particles. Einstein
ple, broadside radiation from an antenna. showed, in his early work, a connection between
broadside antenna See BROADSIDE ARRAY. this movement and the Boltzmann constant.
broadside array Also called broadside antenna. A brownout A deliberate lowering of line voltage by a
phased group of antennas arranged so maximum power company to reduce load demands. Minor
radiation occurs in directions perpendicular to events of this type often pass unnoticed by the
the plane containing the driven elements. This re- average consumer. More pronounced events pro-
quires that all of the antennas be fed in phase. duce observable effects, such as shrinkage of
The elements can be half-wave dipoles or full- television and cathode-ray-tube (CRT) computer-
wave, center-fed conductors. Full-wave elements display images.
have a slight gain over half-wave elements. At Bruce antenna A vertical collinear array that con-
high frequencies, this type of array is usually sists of several resonant sections connected by
constructed from two driven antennas. At very- short, rigid, parallel-conductor stubs. The cur-
high and ultra-high frequencies there can be sev- rents in the radiating sections are in phase. Max-
eral driven antennas. The antennas can each imum radiation and response occur broadside to
consist of a single element, or they can be Yagis, the antenna (omnidirectional in the horizontal
loops, or other systems with individual directive plane). Polarization is vertical. The antenna
properties. In general, the larger the number of produces gain at low radiation and response
elements in the entire array, the greater the gain angles, and is commonly used in repeater instal-
and directivity. lations and fixed communications stations at
very-high frequencies (VHF) and ultra-high fre-
quencies (UHF).
brush A usually metal or carbon strip, blade, or
block, that slides in contact with another part, as
in a motor commutator.
In-phase brush discharge Also called Saint Elmo™s fire. A
dipoles cloud of repelled ions around the tip of a pointed
conductor charged to a high voltage. It often pro-
duces a visible glow in the air.
brush holder The housing for a brush in a motor,
generator, rheostat, slip-ring junction in a rotat-
ing data-transmission system, etc.
brute force 1. The transmission of a signal of ex-
cessive or unnecessary power. 2. An inefficient
Phasing approach to a problem, which might solve the
lines problem, but requires far more energy, effort, or
computer memory/storage space than the mini-
To mum needed to accomplish the same result.
TX brute-force filter A pi-type lowpass dc power
supply filter, so called because of the extremely
broadside array large inductances and capacitances that are
generally used.
brute supply An unregulated power supply.
broad tuning Tuning that is characterized by
B-scope A cathode-ray tube (CRT), used in radar,
pronounced signal width, often resulting in
that presents a B DISPLAY.
adjacent-channel interference. A common cause
B service A teletype communication system oper-
of such impaired selectivity is low Q in the tuned
ated by the Federal Aviation Administration
Broca galvanometer A device consisting of an
B-supply The dc power supply that provides anode
astatic magnetic arrangement, with a coil enclos-
operating voltages, such as plate and screen volt-
ing central consequent poles. The device is char-
ages in a vacuum-tube radio-frequency (RF)
acterized by fast response and high sensitivity.
power amplifier.
bromine Symbol, Br. A nonmetallic element of the
BT-cut crystal A piezoelectric plate cut from a
halogen family. Atomic number, 35. Atomic
quartz crystal at an angle of rotation (relative to
weight, 79.90.
the x-axis) of -49°. It has a zero temperature coef-
bronze An alloy of copper and tin that has various
ficient of frequency at approximately 25°C. Also
uses in electronics. Also see PHOSPHOR BRONZE.
Brown and Sharpe gauge See AMERICAN WIRE
Btu Abbreviation of BRITISH THERMAL UNIT.
BuAer Abbreviation of Bureau of Aeronautics.
Brownian movement (Robert Brown, 1773 “1858).
bubble memory In digital-computer practice, a
Random movement of microscopic particles”
special type of static magnetic memory. The mag-
especially in solutions. It occurs because of colli-
bubble memory • bulk effect

netic material is divided into regions that are buffer amplifier See BUFFER, 1.
magnetized in different directions. So called be- buffer capacitor A high-voltage fixed capacitor
cause the flux lines of the tiny magnetized regions that is placed across a transformer secondary to
are shaped somewhat like, and move around af- suppress voltage spikes and sharp waveforms”
ter the fashion of, bubbles on the surface of a especially when the input is a square wave.
glass of soda. buffer circuit 1. In a data system that uses a key-
bubble shift register A shift register that uses a board, an electronic circuit that allows the opera-
magnetic bubble (see BUBBLE MEMORY) that tor to type ahead of the data output. 2. See
can be moved sequentially from electrode to elec- BUFFER, 1, 2 and 3.
trode on a wafer. buffered output An output (power, signal, etc.)
bubbling See MOTORBOATING. that is delivered from the generating device
bucket A computer memory or a designated loca- through an isolating stage, such as a buffer am-
tion in such a memory. plifier. This arrangement protects the device from
bucking The process of counteracting one quan- variations in the external load. Compare UN-
tity, such as a current or voltage, via series or BUFFERED OUTPUT.
parallel application of a similar quantity that has buffer storage 1. A buffer that is used to interface
opposite polarity (180 degrees out of phase). between data systems with different rates of
bucking circuit 1. A circuit used to obtain buck- transmission. 2. See BUFFER, 2.
ing action. The simplest form is a battery and po- bug 1. Slang for WIRETAP, 1. 2. Slang for circuit
tentiometer that supply a variable voltage of fault, 1. 3. A semiautomatic key that some ra-
polarity opposite to that of the voltage to be diotelegraph operators use to send Morse code.
bucked. A more sophisticated form is an ac trans- bug key See BUG, 3.
former, the secondary of which is connected in building-block technique The process of assem-
series and out of phase with the ac utility line. 2. bling electronic equipment by quickly connecting
The zero-set circuit in an electronic voltmeter. together already completed stages (in the form of
bucking coil A coil placed and positioned so that boxes or blocks) and supplying power and signals
its magnetic field partially or completely cancels to the setup. Also called modular technique and
the field of another coil. Troublesome hum fields modular construction.
sometimes are neutralized with such a coil. building-out circuit A short section of transmis-
bucking voltage See BACK VOLTAGE, 2. sion line shunting another line; it is used for
buckling The warping of storage-battery plates, usu- impedance matching. Also called building-out
ally resulting from excessive charge or discharge. section.
buckshot In an amplitude-modulated (AM) or sin- buildup 1. The process whereby the voltage of a ro-
gle-sideband (SSB) radio transmission, broad- tating generator starts at a point that is deter-
band signal splatter caused by excessive modula- mined by the residual magnetism of the machine,
tion, or detuned multiplier circuits. and gradually increases to a voltage representing
buffer 1. An amplifier used principally to match the point at which the resistance line crosses the
two dissimilar impedance points and isolate one magnetization curve. 2. The (usually gradual) ac-
stage from a succeeding one in a cascaded sys- cumulation of a quantity (e.g., the buildup of
tem, and thus to prevent undesirable interaction charge in a capacitor).
between the two. 2. In a digital computer, a stor- bulb A globe-like container having any of a number
age site used temporarily during data transfers to of characteristic shapes from spherical to tubular
compensate for differences in data flow rates. 3. and usually evacuated, for enclosing the ele-
In digital-computer operations, a follower stage ments of an electron device, such as a vacuum
that is used to drive a number of gates without tube, gas tube, photocell, or lamp.
overloading the preceding stage. bulge 1. A nonlinear attenuation-versus-frequency
curve in a transmission line. 2. A localized non-
linearity in a function.
bulk The body or mass of a semiconductor speci-
men, as opposed to junctions within the speci-
men. Current flows through a junction, but it can
also flow, more or less, through the mass of semi-
conductor wafer into which the junction has been
input formed.
bulk effect An effect, such as current, resistance,
or resistivity, observed in the overall body of a
sample of material, as opposed to a region within
the material or on its surface. Thus, a silicon
diode can display junction resistance (i.e., resis-
tance offered by a junction processed in a wafer of
silicon), as well as bulk resistance (i.e., the effec-
buffer, 2.
90 bulk effect • burst generator

tive resistance of all paths around the junction, l
through the mass of the wafer). Compare SUR-
bulk-erased tape Recording tape whose signal
content has been removed via a bulk eraser. c


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