18WuD2x

looper 1. A radio receiver that is in oscillation,
and is transmitting a signal that causes interferblocking
oscillator • BNC 79
B-minus Also called B-negative. The negative terminal
of a B-power supply.
BNC Abbreviation of bayonet Neill-Concelman. A
type of coaxial connector that can be quickly conblocking
oscillator An oscillator that turns itself
off after one or more cycles. It does this as a result
of an accumulation of negative charge on its
input electrode (base of a bipolar transistor or
gate of a field-effect transistor). The action is
repetitive. In the self-pulsing type of blocking oscillator,
a series of pulses consisting of trains of
sine waves with intervening spaces is generated.
In the single-swing type of blocking oscillator, the
output consists of a series of single cycles with
long intervals between them.
blocking oscillator synchronization 1. In the
BLOCKING OSCILLATOR used in the vertical deflection
circuit of a television receiver, the oscillator
is synchronized with vertical sync pulses
arriving in the video signal. 2. Synchronization of
the repetition rate of any blocking oscillator with
a suitable external control signal.
blocking system In a telephone system, a method
of dealing with the condition of having more subscribers
than connection paths. Allocation is
made on a demand basis. If all channels are in
use, it is impossible to make new calls. This prevents
excessive degradation of the quality of existing
connections.
block length The number of characters, bits, or
words that compose a defined unit word or character
group.
block transfer The conveyance of a word or character
grouping in a computer register to another
register or a peripheral device.
blooming On a cathode-ray-tube (CRT) screen, an
enlargement of the electron-beam spot, caused by
poor focusing. This results in poor image
resolution.
ence. 2. A parasitic oscillation in a radio transmitter.
3. In broadcasting, a statement in which a
radio or television announcer makes an embarrassing
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 radiofrequency
(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 extinguishing
of an arc.
blowout coil An electromagnet that provides a field
to extinguish an arc.
blowout magnet A permanent magnet that provides
a field to extinguish an arc.
blst Abbreviation of ballast.
blue-beam magnet In a color television picturetube
assembly using three electron guns, a small
permanent magnet to adjust the static convergence
of the beam for blue phosphor dots.
blue box An accessory device (sometimes unlawfully
used) that generates tones that switch a telephone
circuit in the placing of calls.
blue glow 1. In a neon lamp, a bluish light that
results from high-voltage arcing. 2. The normal
color of the gas discharge in an argon glow
lamp. 3. The bluish glow between anode and
cathode of a gassy vacuum tube. 4. The normal
color of the discharge that fills a mercury-vapor
tube.
blue gun The electron in a three-gun color picture
tube, the beam from which strikes the blue phosphor
dots.
blueprint
1. A type of contact-print reproduction
in which a sheet of sensitized paper is exposed to
an image on a translucent or transparent film,
under strong light, and is then developed and
fixed. Although this process is still used to reproduce
electronic illustrations and typescripts, it
has been superseded largely by other (dry) processes.
2. Loosely, any plan or design for the development
of a system.
blue restorer In a three-gun color television circuit,
the dc restorer in the blue channel.
blue ribbon program A computer program that
has been hand-prepared and debugged completely
before its first computer run.
blue video voltage The signal voltage presented to
the grid of the blue gun of a three-gun color picture
tube.
blurring 1. BLOOMING. 2. A defocusing of a television
picture or oscilloscope trace. 3. An obscuring
of a signal by echoes or trailing (e.g., the slow
decrement of a Morse code signal element).