cable - Group of two or more insulated wires.
CAD - Abbreviation for "computer aided design"
calibration - To adjust the correct value of a reading by comparison to a standard.
capacitance - The ability of a capacitor to store an electrical charge. The basic unit of capacitance is the Farad.
capacitive reactance - The opposition to current flow provided by a capacitor. Capacitive reactance is measured in ohms and varies inversely with frequency.
capacitor - An electronic component having capacitive reactance.
capacitor microphone - Microphone whose operation depends on variations in capacitance caused by varying air pressure on the movable plate of a capacitor.
carbon-film resistor - Device made by depositing a thin carbon film on a ceramic form.
carbon microphone - Microphone whose operation depends on pressure variation in carbon granules causing a change in resistance.
carbon resistor - Resistor of fixed value made by mixing carbon granules with a binder which is moulded and then baked.
cascaded amplifier - An amplifier with two or more stages arranged in a series configuration.
cascode amplifier - A high frequency amplifier made up of a common-source amplifier with a common-gate amplifier in its drain network.
cathode - The negative terminal electrode of a device. The "N" material in a junction diode.
cathode ray tube - (CRT) Vacuum tube used to display data in a visual form. Picture tube of a television or computer terminal.
cell - Single unit used to convert chemical energy into a DC electrical voltage.
center frequency - Frequency to which an amplifier is tuned. The frequency half way between the cut-off frequencies of a tuned circuit.
center tap - Midway connection between the two ends of a winding.
center tapped rectifier - Circuit that make use of a center tapped transformer and two diodes to provide full wave rectification.
center tapped transformer - A transformer with a connection at the electrical center of a winding.
ceramic capacitor - Capacitor in which the dielectric is ceramic.
charge - Quantity of electrical energy.
charge current - Current that flows to charge a capacitor or battery when voltage is applied.
chassis - Metal box or frame into which components are mounted.
chassis ground - Connection to a chassis.
chebyshev filter - A type of active filter characterized by high roll-off rates (40 dB per decade per pole) and mid-band gain that is not constant.
choke - Inductor used to oppose the flow of alternating current.
circuit - Interconnection of components to provide an electrical path between two or more components.
circuit breaker - A protective device used to open a circuit when current exceeds a maximum value. In effect a reusable fuse.
clamper - A diode circuit used to change the DC level of a waveform without distorting the waveform.
clapp oscillator - A variation of the Colpitts oscillator. An added capacitor is used to eliminate the effects of stray capacitance on the operation of the basic Colpitts oscillator.
class A amplifier - A linear amplifier biased so the active device conducts through 360 degrees of the input waveform.
class B amplifier - An amplifier with two active devices. The active components are biased so that each conducts for approximately 180 degrees of the input waveform cycle.
class C amplifier - An amplifier in which the active device conducts for less than 180 degrees of the input waveform cycle.
clipper - A diode circuit used to eliminate part of a waveform
clipping - Distortion caused by overdriving an amplifier.
clock - A square waveform used for synchronizing and timing of several circuits.
closed circuit - Circuit having a complete path for current flow.
closed-loop gain - Gain of an amplifier when a feedback path is present.
coaxial cable - Transmission line in which the signal carrying conductor is covered by a dialectric and another conductor.
coefficient of coupling - The degree of coupling between two circuits.
coercive force - (H) Magnetizing force needed to reduce residual magnetism in a material to zero.
collector - The semiconductor region in a bipolar junction transistor through which a flow of charge carriers leaves the base region.
collector characteristic curve - A graph of collector voltage over collector current for a given base current.
color code - Set of colors used to indicate value of a component.
colpitts oscillator - An oscillator with a pair of tapped capacitors in the feedback network.
common-anode display - A multi-segment light emitting diode (LED) with a single positive voltage input connection. Separate cathode connections are provided for each individual segment.
common cathode display - A multi-segment light emitting diode (LED) with a single negative voltage input connection. Separate anode connections are provided for each individual segment.
common base amplifier - A BJT circuit in which the base connection is common to both input and output.
common collector amplifier - A BJT circuit in which the collector connection is common to both input and output.
common drain amplifier - A FET circuit in which the drain connection is common to both input and output.
common emitter amplifier - A BJT circuit in which the emitter connection is common to both input and output.
common gate amplifier - A FET circuit in which the gate connection is common to both input and output.
common source amplifier - A FET circuit in which the source connection is common to both input and output.
common-mode rejection ratio - (CMRR) The ratio of op-amp differential gain to common-mode gain. A measure of an op-amp's ability to reject common-mode signals such as noise.
common-mode signals - Signals that appear simultaneously at two inputs of an operational amplifier (op-amp). Common mode signals are always equal in amplitude and phase.
comparator - An op-amp circuit that compares two inputs and provides a DC output indicating the polarity relationship between the inputs.
complementary symmetry amplifier - A class B amplifier using matched complementary transistors. Does not require a phase inverter for push-pull output.
complementary transistors - Two transistors, one NPN and one PNP having near identical characteristics. N-channel and P-channel FETs can also be complementary.
complex numbers - Numbers composed of a real number part and an imaginary number part.
compliance - The maximum possible peak-to-peak output of an amplifier.
constant current circuit - Circuit used to maintain constant current to a load having resistance that changes.
contact - Current carrying part of a switch, relay or connector.
continuity - Occurs when a complete path for current exists.
conventional current flow - Concept of current produced by the movement of positive charges towards the negative terminal of a source.
copper loss - Power lost in transformers, generators, connecting wires and other parts of a circuit due to current flow through the resistance of copper conductors.
core - Magnetic material within a coil used to concentrate the magnetic field.
coulomb - Unit of electric charge. A negative coulomb charge consists of 6.24 × 1018 electrons.
counter electromotive force - (counter emf) Voltage induced into an inductor due to an alternating or pulsating current. Counter emf is always in polarity opposite to that of the applied voltage. Opposing a change of current.
coupling - To electronically connect two circuits so that signal will pass from one to the other.
covalent bond - The way some atoms complete their valence shells by sharing valence electrons with neighbouring atoms.
crossover distortion - Distortion caused by both devices in a class B amplifier being cut-off at the same time.
crowbar - Circuit used to protect the output of a source from a short circuited load. Load current is limited to a value the source can deliver without damage.
CRT - Abbreviation for cathode ray tube.
crystal - Natural or synthetic piezoelectric or semiconductor material with atoms arranged with some degree of geometric regularity.
crystal-controlled oscillator - Oscillator that uses a quartz crystal in its feedback path to maintain a stable output frequency.
current - Measured in amperes, it is the flow of electrons through a conductor. Also know as electron flow.
current amplifier - Amplifier to increase signal current.
current divider - Parallel network designed to divide the total current of a circuit
current feedback - Feedback configuration where a portion of the output current is fed back to the amplifier input.
current-limiting resistor - Resistor in the path of current flow to control the amount of current drawn by a device.
current mirror - Term used to describe the fact that DC current through the base circuit of a class B amplifier is approximately equal to the DC collector current.
cutoff - Condition when an active device is biased such that output current is near zero or beyond zero.
cutoff frequency - Frequency at which the power gain of an amplifier falls below 50% of maximum.
cycle - When a repeating wave rises from zero to a positive maximum then back to zero and on to a negative maximum and back to zero it is said to have completed one cycle.