18WuD2x

6 accentuator • accuracy rating
accentuator A circuit or device, such as a filter,
tone control, or equalizer, used to emphasize a
band of frequencies, usually in the audiofrequency
spectrum. Also see ACCENTUATION.
acceptable-environmental-range test A test to
disclose the environmental conditions that equipment
can endure while maintaining at least the
minimum desired reliability.
acceptable quality level Abbreviation, AQL. A percentage
that represents an acceptable average of
defective components allowable for a process, or
the lowest quality that a supplier is permitted to
regularly present for acceptance.
acceptance sampling plan A probabilistic method
of sampling a quantity of units from a lot, and determining
from the sample whether to accept the
lot, reject the lot, or perform another sampling.
acceptance test A test performed on incoming
equipment or on submitted samples to determine
if they meet tester’s or supplier’s specifications.
acceptor 1. Any device or circuit, such as a seriesresonant
circuit, that provides relatively easy
transmission of a signal, in effect accepting the
signal. 2. A hole-rich impurity added to a semiconductor
to make the latter p-type. It is so called
because its holes can accept electrons. Compare
DONOR.
acceptor circuit See ACCEPTOR, 1.
acceptor impurity See ACCEPTOR, 2.
access 1. To gain entrance to something, such as
the interior of the cabinet of a high-fidelity amplifier.
2. In a computer, the action of going to a specific
memory location for the purpose of data
retrieval. 3. A port or opening into a piece of
equipment, placed there to make the equipment
easy to maintain and repair.
access arm A mechanical device that positions the
read/write mechanism in a computer storage unit.
access control register A register that is part of a
computer protection system that prevents interference
between different software modules.
access method A method of transferring information
or data from main storage to an input/output
unit.
access right The access status given to computer
system users that indicates the method of access
permitted (e.g., read a file only or write to a file).
access time The time required by a computer to
begin delivering information after the memory or
storage has been interrogated.
accidental error An unintentional error committed
by a person making measurements and
recording data.
accidental triggering The undesired chanceoperation
of a flip-flop or other switching circuit
caused by a noise pulse or other extraneous signal.
ac collector current Symbol, I C(ac) . The ac component
of collector current in a bipolar transistor.
ac collector resistance Symbol, R C(ac) . The dynamic
collector resistance of a bipolar transistor.
R C(ac) equals dV C /dI C for a constant value of base
current I B (in a common-emitter circuit) or emitter
current I E (in a common-base circuit).
ac collector voltage Symbol, V C(ac) . The ac component
of collector voltage in a bipolar transistor.
The ac output signal voltage in a common-emitter
or common-base amplifier.
accompanying audio channel The RF signal that
supplies television sound. Also called Cochannnel
sound frequency.
ac component In a complex wave (i.e., one containing
both ac and dc), the alternating, fluctuating,
or pulsating part of the combination.
Compare DC COMPONENT.
accordion A printed-circuit connector contact with
a Z-shaped spring that allows high deflection
with low fatigue.
ac-coupled flip-flop A flip-flop that is operated by
the rise or fall of a clock pulse.
ac coupling Transformer coupling or capacitive
coupling, which transmit ac, but not dc. Compare
DIRECT COUPLING.
accumulator 1. In a digital computer, a circuit or
register device that receives numbers, totals
them, and stores them. 2. Storage battery.
accuracy 1. Precision in the measurement of
quantities and in the statement of physical characteristics.
2. Degree of precision. Usually expressed,
in terms of error, as a percentage of the
specified value (e.g., 10 V plus or minus 1%), as a
percentage of a range (e.g., 2% of full scale), or as
parts (e.g., 100 parts per million).
accuracy rating The maximum error in an instrument,
given as a percentage of the full-scale
value.