Page 21 - The Illustrated Dictionary of Electronics

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6 accentuator • accuracy rating

accentuator A circuit or device, such as a filter, R C(ac) equals dV C/dI C for a constant value of base
tone control, or equalizer, used to emphasize a current I B (in a common-emitter circuit) or emit-
band of frequencies, usually in the audio- ter current I E (in a common-base circuit).
frequency spectrum. Also see ACCENTUATION. ac collector voltage Symbol, V C(ac). The ac compo-
acceptable-environmental-range test A test to nent of collector voltage in a bipolar transistor.
disclose the environmental conditions that equip- The ac output signal voltage in a common-emitter
ment can endure while maintaining at least the or common-base amplifier.
minimum desired reliability. accompanying audio channel The RF signal that
acceptable quality level Abbreviation, AQL. A per- supplies television sound. Also called Cochannnel
centage that represents an acceptable average of sound frequency.
defective components allowable for a process, or ac component In a complex wave (i.e., one con-
the lowest quality that a supplier is permitted to taining both ac and dc), the alternating, fluctu-
regularly present for acceptance. ating, or pulsating part of the combination.
acceptance sampling plan A probabilistic method Compare DC COMPONENT.
of sampling a quantity of units from a lot, and de- accordion A printed-circuit connector contact with
termining from the sample whether to accept the a Z-shaped spring that allows high deflection
lot, reject the lot, or perform another sampling. with low fatigue.
acceptance test A test performed on incoming ac-coupled flip-flop A flip-flop that is operated by
equipment or on submitted samples to determine the rise or fall of a clock pulse.
if they meet tester’s or supplier’s specifications. ac coupling Transformer coupling or capacitive
acceptor 1. Any device or circuit, such as a series- coupling, which transmit ac, but not dc. Compare
resonant circuit, that provides relatively easy DIRECT COUPLING.
transmission of a signal, in effect accepting the
signal. 2. A hole-rich impurity added to a semi-
conductor 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 ampli-
fier. 2. In a computer, the action of going to a spe-
cific 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 inter-
ference between different software modules.
access method A method of transferring informa-
tion or data from main storage to an input/out-
put 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 accumulator 1. In a digital computer, a circuit or
storage has been interrogated. register device that receives numbers, totals
accidental error An unintentional error commit- them, and stores them. 2. Storage battery.
ted by a person making measurements and accuracy 1. Precision in the measurement of
recording data. quantities and in the statement of physical char-
accidental triggering The undesired chance- acteristics. 2. Degree of precision. Usually ex-
operation of a flip-flop or other switching circuit pressed, in terms of error, as a percentage of the
caused by a noise pulse or other extraneous sig- specified value (e.g., 10 V plus or minus 1%), as a
nal. percentage of a range (e.g., 2% of full scale), or as
ac collector current Symbol, I C(ac). The ac compo- parts (e.g., 100 parts per million).
nent of collector current in a bipolar transistor. accuracy rating The maximum error in an instru-
ac collector resistance Symbol, R C(ac). The dy- ment, given as a percentage of the full-scale
namic collector resistance of a bipolar transistor. value.