18WuD2x

248 electronic precipitator • electronic watch
electronic precipitator See DUST PRECIPITATOR.
electronic product Any commercially manufactured
electronic device, intended for purchase by
the public, by industry, or by government.
electronic profilometer An electronic instrument
for measuring surface roughness.
electronic ratchet A stair-step circuit or other arrangement
functioning in the manner of an
equivalent electromechanical stepping switch.
Also see COMMUTATOR.
electronic reconnaissance In military applications,
the use of electronic systems to locate enemy
installations (such as radio stations,
guided-missile sites, and radar bases).
electronic rectifier A rectifier that uses active devices
to change alternating current (ac) to direct
current (dc).
electronic regulator A voltage regulator that uses
active electronic circuits, as opposed to a reactortype
or electromechanical device. See, for example,
VOLTAGE REGULATOR.
electronic relay 1. A switching circuit that uses
one or more transistors, and performs the relay
function without moving parts. 2. An electronic
component designed to switch when gating signals
are applied (e.g., triac, diac, or siliconcontrolled
rectifier).
electronic resistor 1. The effective internal collector-emitter
resistance of a common-emitter bipolar-transistor
stage. 2. The effective internal
drain-source resistance of a field-effect transistor
(FET) stage.
electronics The branch of physics concerned with
the behavior and application of electric charge
carriers in components, devices and systems that
accomplish amplification, oscillation, signal processing,
and/or switching.
electronics engineer A trained professional
skilled in the physics and mathematics of electronics,
and in the theory and application of basic
engineering and related subjects. Compare
ELECTRICAL ENGINEER.
electronics service person An electronics technician
skilled in repairing and maintaining electronic
equipment. Also called electronics service
technician.
electronic shutter See KERR CELL.
electronics technician A professional skilled in
building, testing, repairing, or maintaining electronic
equipment.
electronics technology The theory and practical
application of electronics. Taught as a subengineering
major, usually in two-year junior colleges
or technical institutes, awarding the degree of associate
in arts (AA) or associate in science (AS).
electronic stethoscope A stethoscope employing
a miniature microphone, amplifier, and earphones.
The amplifier gain is continuously controllable,
and its bandwidth often selectable for
emphasizing particular heart sounds and other
body noises.
electronic stimulator A device for applying controlled
electrical pulses to the body to stimulate
muscles or nerves during diagnosis or therapy.
electronic stroboscope A stroboscope that uses a
rate-calibrated oscillator, rather than a mechanical
contactor to generate pulses that strobe the lamp.
electronic subtracter An electronic circuit for performing
arithmetic subtraction.
electronic surge A sudden, large increase in the
current in a conductor. Can be caused by an electromagnetic
pulse; can also occur when utility
power is restored following a blackout.
electronic switch 1. A nonmechanical device,
such as a flip-flop or gate, whose characteristic
on-off operation can be used to make and break
an electric circuit. Compare CONTACT SWITCH.
2. A device using electronic gating and sequencing
circuits to present several signals alternately
to the single input of an oscilloscope, allowing simultaneous
viewing of the signals.
electronic tachometer An instrument for measuring
angular velocity, usually in revolutions per
minute (rpm). Ideally, the response is independent
of sensor voltage amplitude, showing only
the number of pulses per unit time reaching the
meter circuit.
electronic thermal conductivity The thermalconductivity
component, resulting from the
transfer of heat by electrons and holes.
electronic thermometer An instrument for measuring
temperature as a result of variations in a
temperature-sensitive component, such as a resistor,
thermocouple, or thermistor.
electronic timer An electronic circuit or device for
automatically timing a process or observed event.
Most are based on the time constant of a stable
resistance-capacitance (RC) circuit. Compare
ELECTROMECHANICAL TIMER.
electronic tube See ELECTRON TUBE.
electronic tuning Variation of the resonant frequency
of a device or circuit by changing the bias
voltage or current of a controlling electronic component.
electronic voltmeter A voltmeter that uses electronic
amplification ahead of the indicating meter
to provide high input impedance and increased
sensitivity. Also see FET VOLTMETER and TRAN-
SISTOR VOLTMETER.
electronic voltohmmeter A voltohmmeter that
uses electronic amplification ahead of the indicating
meter to provide high input impedance
and increased sensitivity.
electronic typewriter A typewriter with a microcomputer
that provides features, such as buffering,
automatic repeat, erase memory, and
paragraph/page memory.
electronic warfare The use of electronic systems
for military purposes, including interfering with
an enemy’s use of similar systems.
electronic watch 1. A watch whose movement is
a tiny, high-frequency, alternating-current (ac)