C

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 inversly 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 dialectric 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 midband 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 multisegment light emitting diode (LED) with a single positive voltage input connection. Separate cathode connections are provided for each individual segment.

common cathode display
A multisegment 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.

comparitor
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 complementry transistors. Does not require a phase inverter for push-pull output.

complementry transistors
Two transistors, one NPN and one PNP having near identical charastics. N-channel and P-channel FETs can also be complementry.

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 souce 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.
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