18WuD2x

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