AI-6
RC FILTER—This filter is used in applications where load current is low and constant, and voltage
regulation is not necessary.
RECTIFIER—A device which, by its conduction characteristics, converts alternating current to a
pulsating direct current.
REGULATOR—The section in a basic power supply that maintains the output of the power supply at a
constant level in spite of large changes in load current or in input line voltage.
REVERSE BIAS—When an external voltage is applied to a PN junction and the junction offers a high
resistance to current flow.
RIPPLE FREQUENCY—The frequency of the ripple current. In a full-wave rectifier, it is twice the
input-line frequency.
RIPPLE VOLTAGE—The alternating component of unidirectional voltage. (This component is small
compared to the direct component.)
SELENIUM—A chemical element which has rectification and light-sensitive properties that make it
widely used as a semiconductor material.
SERIES VOLTAGE REGULATOR—A regulator with a regulating device that is in series with the
load resistance.
SHUNT VOLTAGE REGULATOR—A regulator whose regulating device is in parallel with the load
resistance.
SILICON—A metallic element which, in its pure state, is used as a semiconductor.
SILICON-CONTROLLED RECTIFIER (SCR)—A semiconductor device that functions as an
electrically controlled switch.
SOLID-STATE DEVICE—An electronic device which operates by the movement of electrons within a
solid piece of semiconductor material.
THERMAL RUNAWAY—A conduction that exists when heat causes more electron-hole pairs to be
generated; which, in turn, causes more heat and may eventually cause diode destruction.
TRANSISTOR—A semiconductor device with three or more elements.
TRIAC—A three-terminal device that is similar to two SCRs back to back with a common gate and
common terminals. Although similar in construction and operation to the SCR, the TRIAC controls
and conducts current flow during both alternations of an ac cycle.
TRIVALENT IMPURITY—Acceptor impurities containing only three valence electrons.
TUNNEL DIODE—A heavily doped semiconductor device that has high gain and fast switching
capabilities.
UNIJUNCTION TRANSISTOR (UJT)—A three-terminal, solid-state device that resembles a transistor
but is stable over a wide range of temperatures and allows a reduction of components when used in
place of a transistor. Used in switching circuits, oscillators, and wave-shaping circuits.
