Page 67 - The Illustrated Dictionary of Electronics

5059F-pA_1-55 4/9/01 4:41 PM Page 52

52 automatic secure voice communications • auxiliary contacts

to a security network that provides encoded voice automatic zero In an electronic meter, a means of
communications. automatically setting the indicator to zero in the
automatic send/receive set A teletypewriter or absence of an input signal.
terminal that is capable of receiving and trans- automation 1. The control of machines or pro-
mitting. cesses by self-correcting electronic systems. See
automatic sensitivity control 1. A self-actuating ROBOT. 2. The use of robots and/or computers,
circuit using principles similar to those used in rather than human beings, to perform repetitive
AUTOMATIC GAIN CONTROL. It varies the sensi- tasks. 3. The use of robots and/or computers to
tivity of the radio-frequency (RF) and intermedi- assist human beings in industrial, office, govern-
ate-frequency (IF) sections of a receiver in inverse mental, and educational work.
proportion to the strength of a received signal. 2. automaton A simple robot that performs a task or
In a bridge null detector, a circuit similar to the set of tasks without artificial intelligence (AI).
one described in 1, which operates ahead of the These machines have existed for decades. Com-
detector, varying the sensitivity of the latter auto- pare ANDROID.
matically. automonitor In digital computer operations, to re-
automatic sequencing The ability of a digital com- quire the machine to supply a record of its infor-
puter to perform successive operations without mation-handling operations. Also, the program
additional instructions from the operator. for such instructions.
automatic short-circuiter A device that automat- automotive battery A set of four or eight
ically short-circuits the commutator bias in some rechargeable lead-acid cells connected in series
single-phase commutator motors. and housed in a common enclosure. The elec-
automatic short-circuit protection A circuit that trolyte is a free-flowing liquid acid. Provides ap-
allows the output of a power supply to be short- proximately 6 volts (four cells) or 12 volts (eight
circuited without damage to the components cells) under no-load conditions when fully
in the supply. It usually consists of a current- charged. The high mass results in large energy-
limiting device. storage capacity. These batteries must be han-
automatic shutoff A switching arrangement that dled with care and always kept in an upright
automatically shuts off a device or circuit under position to prevent spillage of the acid. See
certain specified conditions. LEAD-ACID BATTERY, LEAD-ACID CELL.
automatic switch center A telephone-switching autonomous robot A self-contained robot with an
network that routes calls to their destinations independent computerized control system. It
without the need for a human operator. moves under its own power, usually by rolling on
automatic target control For a vidicon television wheels or a track drive. Compare INSECT ROBOT.
camera tube, a circuit that automatically adjusts autopatch A remotely controllable device that in-
the target voltage in proportion to brightness of terconnects a radio-communications system into
the scene. a telephone network.
automatic telegraph reception Telegraph recep- autopilot A self-correcting control and guidance
tion providing a direct printout of the received in- device for the automatic management of an air-
formation, without intervention by an operator. craft or missile.
automatic telegraph transmission Telegraph autoranging See AUTOMATIC RANGING.
transmission originating from tapes, disks, or other autosyn A device or system that operates on the
records, rather than from a hand-operated key. principle of the synchronous ac motor, in which
automatic telegraphy Communications that uti- the position of the rotor in one motor (the trans-
lize automatic telegraph transmission and recep- mitter) is assumed by the rotor in a distant motor
tion. (the receiver) to which the first is connected.
automatic time switch A time-dependent circuit auto tracking A method of controlling the output
or device that opens or closes another circuit at voltages of many different power supplies simul-
the end of a predetermined time interval. taneously.
automatic tracking A method of keeping a radar autotransducter A type of magnetic amplifier
beam automatically fixed on a target. whose power windings serve also as control wind-
automatic trip A circuit breaker that automati- ings.
cally opens a circuit. autotransformer A single-winding transformer in
automatic tuning A process whereby a circuit which the primary coil is a fraction of the entire
tunes itself to a predetermined frequency upon winding for voltage step-up, or the secondary coil
receiving a command signal. is a fraction of the entire winding for voltage step-
automatic voltage regulator A circuit that keeps down.
the output of a power supply constant, despite auxiliary circuit A circuit that is supplementary to
the load resistance or input voltage to the supply. the main system.
automatic volume control Abbreviated AVC. The auxiliary contacts In switches and relays, con-
use of AUTOMATIC GAIN CONTROL in an audio tacts that are supplementary to the main con-
amplifier system. tacts and are usually actuated with them.