Page 22 - The Illustrated Dictionary of Electronics

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accw • ac magnetic bias 7

accw Abbreviation of ALTERNATING-CURRENT ac generator 1. A rotating electromagnetic ma-
CONTINUOUS WAVE. chine that produces alternating current (e.g., a
ac/dc Abbreviation of ALTERNATING CURRENT/ dynamo or alternator). 2. An oscillator or com-
DIRECT CURRENT. Pertains to equipment that bination of an oscillator and an output ampli-
will operate from either ac utility power or a dc fier.
power source. A notebook computer is a good ex- ac grid voltage Symbol, V G(ac). The ac component
ample. of control grid voltage in an electron tube. The ac
ac directional overcurrent relay A relay that input signal voltage in a common-cathode ampli-
works on a specific value of alternating overcur- fier or cathode follower.
rent that is rectified for a desired polarity. A channel The left channel of a two-channel stereo
ac drain current Symbol, I D(ac). The ac component system.
of drain current in a field-effect transistor. achieved reliability A statement of reliability based
ac drain resistance Symbol, R D(ac). The dynamic on the performance of mass-produced parts or
drain resistance in a field-effect transistor; R D(ac) systems under similar environmental conditions.
equals dV D/dI D for a constant value of gate volt- Also called OPERATIONAL RELIABILITY.
age V G. achromatic 1. Without color. In a TV image, the
ac drain voltage Symbol, V D(ac). The ac component tones from black through gray to white. The term
of drain voltage in a field-effect transistor. The ac occasionally refers to black-and-white television,
output signal voltage in a common-source FET although MONOCHROMATIC is more often used
amplifier. in this sense.
ac dump The removal of all ac power from a system achromatic locus Also called achromatic region.
or component. An area on a chromaticity diagram that contains
ac emitter current Symbol, I E(ac). The ac compo- all points, representing acceptable reference
nent of emitter current in a bipolar transistor. white standards.
ac emitter resistance Symbol, R E(ac). The dynamic achromatic scale A musical scale without acci-
emitter resistance of a bipolar transistor; R E(ac) dentals.
equals dV E/dI E for a constant value of base cur- ACIA Abbreviation of asynchronous communica-
rent I B (in an emitter-follower circuit) or collector tions interface adapter.
voltage V CC (in a common-base circuit). acicular Pertaining to the shape of magnetic parti-
ac emitter voltage Symbol, V E(ac). The ac compo- cles on recording tape. Under magnification,
nent of emitter voltage in a bipolar transistor. The these particles look like thin rods.
ac input signal voltage in a common-base ampli- acid A substance that dissociates in water solution
fier; the ac output signal voltage in an emitter- and forms hydrogen (H) ions (e.g., sulfuric acid).
follower amplifier. Compare BASE, 2.
ac equipment An apparatus designed for opera- acid depolarizer Also called acidic depolarizer.
tion from an ac power source only. Compare DC An acid, in addition to the electrolyte, used in
EQUIPMENT and AC/DC. some primary cells to slow the process of polar-
ac erasing In tape recording, the technique of us- ization.
ing an alternating magnetic field to erase material ac line A power line that delivers alternating cur-
already recorded on the tape. rent only.
ac erasing head Also called ac erase head. In tape ac line filter A filter designed to remove extrane-
and wire recording, a head that carries alternat- ous signals or electrical noise from an ac power
ing current to erase material already recorded on line, while causing virtually no reduction of the
the tape or wire. Also see AC ERASING. power-line voltage or power.
acetate Cellulose acetate, a tough thermoplastic ac line voltage The voltage commonly delivered
material that is an acetic acid ester of cellulose. It by the commercial power line to consumers. In
is used as a dielectric and in the manufacture of the United States, the two standards are 117 V
photographic films. and 234 V (~ about 5 percent). The lower voltage
acetate base 1. The cellulose acetate film that is used by most appliances; the higher voltage is
served as the base for the magnetic oxide coating intended for appliances and equipment that
in early recording tape. Most such tapes today draws high power, such as electric ovens, cook-
are of polyester base. 2. The cellulose acetate ing ranges, clothes dryers, and amateur-radio
substrate onto which certain photosensitive ma- amplifiers. In Europe, 220 V is the common
terials are deposited for lithographic reproduc- standard.
tion. Also see ACETATE and ANCHORAGE. aclinic line Also called magnetic equator. An imag-
acetate tape Recording tape consisting of a mag- inary line drawn on a map of the world or of an
netic oxide coating on a cellulose acetate film. area that connects points of zero inclination (dip)
Also see ACETATE BASE. of the needle of a magnetic compass.
ac gate voltage Symbol, V G(ac). The ac component ACM Abbreviation for Association for Computing
of gate voltage in a field-effect transistor. The ac Machinery.
input signal voltage. ac magnetic bias See AC BIAS.