Glossary of Electronic & Microwave Oven Related Terms|
Copyright © 1989-2013 J. Carlton
Gallawa . All Rights Reserved Worldwide
Excerpts from the book
The Complete Microwave
Oven Service Handbook
on CD-ROM (CLICK HERE)
and from the video
You Can Fix Your Microwave
Oven, Plus VCR Know-How
Copyright ©, 1996-2013 by
J. Carlton Gallawa
Click here to comment, suggest a correction or to submit a relevant term we have not
AC VOLTAGE: An electric current that reverses
its direction regularly and continually, thus it is
AMPERAGE: The strength of an electric current measured in amperes.
One ampere is the amount of
current that flows through one ohm of resistance with one volt applied.
AMPLITUDE: The maximum instantaneous value of an alternating
wave of voltage or current measured
from a reference line to either a maximum positive value or maximum
ANALOG: A variable that remains similar to another variable in
proportional relationships over a
ANODE: The positive electrode in an electrochemical device. In
a magnetron tube, the anode is usually
the outer casting and is at ground potential.
ANODIZE: A process that electrolytically produces an insulating
oxide film on a conducting surface.
ANTENNA PIN: See tuning stub.
BIAS: A DC voltage applied to the control electrode of an electronic
device to establish the desired
CAPACITANCE: The property of a capacitor that determines how
much charge can be stored in it for a
given potential difference across its terminals. The basic unit is the
farad. However, the small microfarad
unit is more commonly used: abbreviated MFD.
CATHODE: The general name for any negative electrode. In a magnetron
tube, the cathode is centered
within the anode and at high negative voltage potential.
CAVITY RESONATOR: A space totally enclosed by a metallic conductor
and supplied with energy in
such a way that it becomes a source of electromagnetic oscillations.
In a microwave oven, the food
compartment is a resonant cavity
CHOKE: (1) An inductance (usually a coil) used in a circuit to
impede the flow of pulsed DC or AC
without appreciably affecting the flow of DC. (2) A groove, channel,
or other discontinuity that is
dimensioned so as to reflect guided electromagnetic waves of a certain
CONVECTION: The transmission of heat by the mass movement of
the heated air.
CORE: A magnetic material that affords an easy path for magnetic
lines of flux.
CUMULATIVE EFFECT: Many exposures to small doses add up to a
CURRENT LIMITER: A protective device, used in some two-fold applications
as a fuse, that is designed
to limit current flow in high-amperage circuits.
CYCLE: One complete positive and one complete negative alternation
of a current or voltage.
DC VOLTAGE: An electric current that flows in one direction only,
thus it is Direct Current.
DIELECTRIC: A material of poor conductivity that serves as an
insulator, usually in reference to the
insulating material between the plates of a capacitor. The dielectric
separates the metal plates electrically,
stores an electric charge, and undergoes polarization when subjected
to an electric field.
DIFFERENCE OF POTENTIAL: The voltage existing between two points.
If a circuit is established
between the two points, a flow of electrons will result.
DIRECTLY HEATED CATHODE: A wire or filament that is designed
to emit electrons when an
electric current flows through it. The current heats the filament to
the point where electrons are emitted.
DUMMY LOAD: A device used at the end of a waveguide to convert
transmitted energy into heat so no
energy is radiated outward or reflected back.
DUTY CYCLE: In a magnetron tube: The ratio of oscillating time
to total time.
ELECTRODE: The terminal at which electricity passes from one
medium into another, such as in a
humidity sensor unit where the current leaves or returns to the semi-conducting
ELECTROMAGNETIC RADIATION: The process in which waves of electromagnetic
energy are sent
out into space.
ELECTROMAGNETIC WAVE: A wave of energy propagated by the combined
interaction of electric
and magnetic fields that are traveling at right angles to each other,
and to the direction of travel.
ELECTRON: A high-speed, negatively-charged particle that revolves
around the nucleus, and forms a
part, of all atoms.
ELECTROSTATIC: Pertaining to electricity at rest or to stationary
electricity (static electricity), such as
a static charge on an object.
FERRITE: A ferric oxide material that has both magnetic properties
and a high resistance to current
flow. The high electrical resistivity makes any current losses extremely
low at high frequencies.
FET: Field-effect transistor.
FILAMENT: A resistance wire or ribbon that, in a magnetron tube,
is also the cathode. When an electric
current flows through it, the filament heats up to a temperature by
which electrons are liberated, thus the
filament produces free (or floating) electrons.
FLUX: In electrical or electromagnetic devices, a general term
used to designate collectively all the
electric or magnetic lines of force in a given region.
FREQUENCY: The number of times a wave makes one full cycle in
one second of time. Usually
expressed in hertz (Hz).
FULL- WAVE RECTIFIER: A circuit that uses both positive and negative
alternations of an alternating
current to produce a direct current.
GROUND: Zero potential with respect to the ground or earth. A
metallic connection with the earth is
used to establish ground potential, and to provide a common return to
a point of zero potential. When
connected to a properly grounded and polarized circuit, the chassis
of a microwave oven is at ground
HALF- WAVE RECTIFIER: A circuit that uses only ½ of each
cycle to change AC to pulsating DC.
HARMONIC FREQUENCIES: Integral multiples of a primary frequency.
HEATER: See filament.
HEATSINK: A metal device that is clamped onto a heat-sensitive
component for the purpose of diverting
and dissipating soldering iron heat.
HENRY: The basic unit of inductance.
HERTZ: Cycles per second.
IC: Integrated Circuit. An interconnected network of electrochemical
elements integrated into a tiny
electronic circuit that performs at least one, and usually more, logic
IMPEDANCE: A combination of resistance and reactance that offers
opposition to the flow of current in
a circuit. Impedance is usually expressed in ohms.
INDUCTANCE: The property of a circuit that causes a magnetic
field to be produced which tends to
oppose any change in the existing current flow. The basic unit of inductance
is the henry.
INDUCTION: The act or process by which a voltage is produced
by the relative motion of a magnetic
field across a conductor. Or, the process by which a magnetic field
is produced by the variance of an
electric current through a conductor.
INFINITE OHMS: An incalculably high amount of electrical resistanceessentially
an open circuit.
INSULATOR: An implement having high electrical resistance, used
for supporting, surrounding, or
separating conductors so as to prevent undesired current flow between
the conductors or to other objects.
INTERFACE CIRCUITRY: Serves to link the otherwise incompatible
high-impedance circuits of the
microprocessor and the high-potential circuits of external components.
IONIZING: The dislodging of orbital electrons from atoms, creating
electrically charged, highly
unstable, and chemically reactive atoms, called ions, which are damaging
to living cells.
LAYER SHORT: A condition in a transformer in which two adjacent
windings come into abnormal
contact with each other through the insulating layer.
LC CIRCUIT: A circuit containing inductive reactance and capacitive
LCD: Liquid Crystal Display. A digital display which utilizes
a liquid crystal material to form digits and
characters without generating any light. The liquid crystal material
separates and is sealed-in by two
sheets of glass, one of which has character-forming segments etched
into it and serves as the viewing
side. When voltage is applied to the electrodes that extend from each
of the etched segments, the liquid
adjacent to the segments changes tone (usually darkens), thus forming
LED: Light-Emitting Diode. A semi-conductor diode that efficiently
converts electric signals into light,
and thus glows when current passes through it. In microwave ovens, LEDs
are generally used for control
panel displays and indicators.
LOAD: An object or device that consumes electrical energy, and
thus changes the energy into another
form. Food products change microwave energy into heat energy.
MEG OHM: One million ohms.
MICRO: A prefix meaning one-millionth.
MICROFARAD: One millionth of a farad; abbreviated MFD.
MICROPROCESSOR: A microprocessor incorporates various computer
functions such as memory,
calculation, data processing, and control into a tiny silicone chip.
The microprocessor receives input and
generates output signals in a sequence of logic, which is either externally
programmed or internally
MILLI: A prefix meaning 1/1000.
MILLIWATT: 1/1000 of a watt of electricity.
MODULATION/DEMODULATION: Modulation is the ability to impress
intelligence upon a
transmission medium. A transmission medium may be described as radio
waves, light or infrared beams,
wire lines, sound, or other communication systems. The characteristics
(intelligence) of one waveform are
impressed onto a second waveform by varying the frequency, amplitude,
phase, or other characteristics of
the second waveform. Demodulation is the removal or recovery of the
intelligence from the medium.
MOSFET: Metal oxide semiconductor field-effect transistor.
NEGATIVE CHARGE: An electrical medium which has an excess of
electrons, thus having the ability to
NEGATIVE TEMPERATURE COEFFICIENT: A factor that expresses the
amount of reduction in the
value of a quantity relative to ambient temperature. For example, a
given decrease in a resistance for each
degree of increase in temperature.
OHM: The basic unit of resistance. One volt will cause one ampere
of current to flow through one ohm of
OPEN CIRCUIT: A circuit that does not provide a complete path
for the flow of current.
OPTO-COUPLER: See photo-coupler.
PARALLEL CIRCUIT: Two or more electrical devices connected to
the same pair of terminals so more
than one current path is available. Current flows through each device
in the parallel circuit.
PHASE: The relationship in time and polarity between two waves.
A phase difference results when one
wave leads or lags another.
PHOTO-COUPLER: An isolated coupling device which, when energized
by an input, sends a signal to a
semiconductor switching device, such as an SCR.
POLARITY: The relative condition of being positive or negative
with respect to a given potential.
POLARIZED RECEPTACLE: A receptacle designed to ensure that the
neutral side of an AC line is
always connected to the neutral side of an appliance, such as a microwave
POSITIVE CHARGE: An electrical medium that has become deficient
in electrons, thus having the
ability to attract electrons.
POTENTIAL: The amount of charge held by a body as compared to
another point or body. A difference
in voltage potential between two connected points results in current
flow between the two points. The
difference in potential is measured in volts.
PROTONS: One of the fundamental particles of the nucleus of an
atom and carries a unitary positive
RADIATION: The process of emitting radiant energy in the form
of waves or particles.
RC CIRCUIT: A circuit having a resistance and a capacitance in
RESONANCE: The condition produced when the frequency of vibrations
is the same as the natural
frequency of a cavity. The cavity is sympathetic to the frequency; thus,
the vibrations reinforce each
RESONANT CIRCUIT: (explained in detail in part 3) A coil and
capacitor connected in parallel form a
capacitive-inductive resonant circuit. Energy supplied to the circuit
will charge up the capacitor. When
the energy supply is removed, the capacitor discharges through the coil.
Current flow through the coil
causes a magnetic field to develop around coil. The magnetic field then
collapses around the coil, selfinducing
a current flow in the opposite direction, which then charges the capacitor
in the opposite
polarity. Consequently, the capacitor discharges again, starting the
process all over.
SCR: A semiconductor device that is controlled by a gate signal.
Normally the SCR acts as an open
switch, but upon application of an appropriate gate signal to its gate
terminal, the SCR instantly switches
to a conducting state, becoming as a closed switch.
SERIES CIRCUIT: An arrangement of electrical devices that are
connected so that the total current must
flow through all the devices in order to complete the circuit.
SHORT CIRCUIT: A low resistance (usually zero ohms) connection
across a voltage source or between
two points in a circuit that are of different electrical potential.
A short circuit usually results in excessive
and possibly damaging current flow.
SOLENOID: An electromagnetic coil that contains a movable plunger.
STANDING WAVE: The distribution of waves in a reflective enclosure
in which the waves coincide at
maximum and minimum points on a resultant wave that appears to stand
SUBSONIC: Sound waves beyond the lower limits of human audibility.
SYNTHESIZER: See Voice Synthesizer.
TERMINAL: (1) A point to which electrical connections can be
made. (2) The electrical input or output
of a circuit or component.
TRIGGER: A short pulse, either positive or negative, which can
be used to cause an electrical function to
TUNING STUB: A rod, screw, or post of conductive material that
projects into a waveguide for one or
more of the following purposes: impedance matching, producing desired
phase relationships, or to
minimize reflected energy.
ULTRASONIC: Pertaining to sound waves having a frequency that
is generally above the limits of
VOICE SYNTHESIZER: An instrument that simulates speech by digital
control. The synthesizer
assembles and digitizes the various elements of a dialect, so the appropriate
inflections and other speech
characteristics of any language can be simulated.
VOLT: The unit of electrical potential (electromotive force or
electrical pressure). One volt is the pressure
required to send one ampere of current through one ohm of resistance.
VOLTAGE: Voltage is the force (or pressure) that causes current
to flow through a conductor. The
voltage of a circuit is the greatest effective difference of potential
between any two conductors of a
VOLTAGE DROP: Ratio of voltage (or electrical pressure) lost
(or dropped) across a specified load as a
result of forcing current flow through that load.
WATT: The practical unit of electric power. In a DC circuit,
one watt of power is used when one ampere
of current flows through a resistance of one ohm.
WAVEGUIDE: A rectangular, circular, or elliptical hollow metal
tube designed to transport
electromagnetic energy through its interior from one point to another.
WAVELENGTH: (1) The distance in space occupied by one cycle of
an electromagnetic wave at any
given instant. (2) The distance a wave travels during one cycle.
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