Abbreviation for "ampere" a unit of electrical current.
absorption
Loss or dissipation of energy as it travels through a
medium, Example: radio waves lose some of their energy
as they travel through the atmosphere.
AC
Abbreviation for "Alternating Current"
AC coupling
Circuit that passes an AC signal while blocking a DC
voltage.
AC generator
Device used to transform mechanical energy into AC
electrical power.
AC load line
A graph representing all possible combinations of AC
output voltage and current for an amplifier.
AC power supply
Power supply that delivers an AC voltage.
AC voltage
A voltage in which the polarity alternates.
AC/DC
Equipment that will operate on either an AC or DC power
source.
acceptor atoms
Trivalent atoms that accept free electrons from
pentavalent atoms.
active component
A component that changes the amplitude of a signal
between input and output.
active filter
A filter that uses an amplifier in addition to reactive
components to pass or reject selected frequencies.
active region
The region of BJT operation between saturation and
cutoff used for linear amplification.
ADC
Abbreviation for "analog to digital converter"
Admittance
(symbol "Y") Measure of how easily AC will flow through
a circuit. Admittance is the reciprocal of impedance and
is measured in siemens.
AF
Abbreviation for "audio frequency".
AFC
Abbreviation for "automatic frequency control".
AGC
Abbreviation for "automatic gain control"
alkaline cell
A primary cell that delivers more current than a
carbon-zinc cell. Also known as an "alkaline manganese
cell".
alligator clip
Spring clip on the end of a test lead used to make a
temporary connection.
alpha
Ratio of collector current to emitter current in a
bipolar junction transistor (BJT). Greek letter alpha "a"
is the symbol used.
alternating current
An electric current that rises to a maximum in one
direction, falls back to zero and then rises to a
maximum in the opposite direction and then repeats.
alternator
Name for an AC generator.
AM
Abbreviation for "amplitude modulation"
ammeter
A meter used to measure current.
ampere
Unit of electrical current.
amplifier
A circuit that increases the voltage, current, or power
of a signal.
amplitude:
Magnitude or size of a signal voltage or current.
analog
Information represented as continously varying voltage
or current rather than in discrete levels as opposed to
digital data varying between two discrete levels.
anode
The positive electrode or terminal of a device. The "P"
material of a diode.
antenna, receiving
A device that converts a radiated electromagnetic wave
into an electrical wave.
antenna, transmitting
A device that converts an electrical wave into an
electromagnetic wave that radiates away from the
antenna.
apparent power
Power attained in an AC circuit as a product of
effective voltage and current which reach their peak at
different times.
arc
Discharge of electricity through a gas such as lightning
discharging through the atmosphere.
armature:
The rotating or moving component of a magnetic circuit.
armstrong oscillator
An oscillator that uses an isolation transformer to
achieve positive feedback from output to input.
astable multivibrator
An oscillator that produces a square wave output from a
DC voltage.
atom
The smallest particle that an element can be broken down
into and still maintain its unique identity.
atomic number
The number of positive charges or protons in the nucleus
of an atom.
attenuate
To reduce the amplitude of an action or signal. The
opposite of amplification.
audio
Relating to frequencies that can be heard by the human
ear. Approximately 20 Hz. to 20 kHz.
autotransformer
A single winding transformer where the output is taken
from taps on the winding.
AVC
Abbreviation for "automatic volume control"
average value
A value of voltage or current where the area of the wave
above the value equals the area of the wave below the
value.
avionics
Aviation electronics.
AWG
Abbreviation for "american wire gauge". A gauge that
assigns a number value to the diameter of a wire.