18WuD2x

278 feedback input current • feedthrough terminal
feedback input current In a feedback network,
the current drawn by the feedback input. This
current affects the design parameters of a network.
feedback loop The part of a circuit that provides
controlled feedback in an operational-amplifier
circuit.
feedback oscillator A circuit in which oscillation
is obtained by feeding a portion of the output of
an active amplifying device back to the input circuit
by inductive coupling. Also called tickler oscillator.
feedback path A path over which feedback, either
positive or negative, can occur in a circuit. The
feedback can be intentionally produced, or it can
be undesirable.
feedback percentage Symbol, n. In a feedback circuit,
the percentage of output voltage that is fed
back; n = 100V f /V o , where V f is the feedback voltage
and V o is the open-loop output voltage. Compare
FEEDBACK RATIO.
feedback ratio For a feedback system, the ratio
V f /V o , where V f is the voltage that is fed back
and V o is the open-loop output voltage of the
system.
feedback rectifier See DIODE FEEDBACK RECTI-
FIER.
feedback regulator In a controlled-feedback circuit,
the device that determines the amount of
feedback.
feedback resistance 1. The internal base resistance
of a point-contact transistor. 2. The resistance
in a feedback loop.
feedback transfer function The transfer function
of a feedback loop exclusively.
feedback winding A special winding on a magnetic
amplifier or saturable reactor, for the introduction
of feedback currents.
feeder 1. A conductor or set of conductors that
carries electric power from one point to another.
2. The transmission line connecting a transmitter
to an antenna.
feeder cable 1. A communication cable running in
a primary route from a central station (or in a secondary
route from a main feeder cable) as a
means of making connections to distribution cables.
2. In a cable television system, the cable
carrying transmission from the head end to the
trunk amplifier. Also called TRUNK CABLE.
feeder loss Loss of energy resulting from resistance
in, or radiation from, feeder lines.
feeding In character recognition, a system in
which documents go into the transport of a character
reader at a steady, specified rate.
feed pitch The distance between feed holes.
feed reel The tape supply reel of a tape recorder.
feedthrough 1. The usually undesirable transmission
of a signal through a circuit without being
processed by the circuit, because of unavoidable
capacitive coupling, for example. 2. Contraction
of FEEDTHROUGH COMPONENT.
feedthrough capacitor A capacitor whose design
is like that of a feedthrough terminal; it is
mounted in a hole in a chassis. The center screw
or wire is the “high” terminal of the capacitor, to
which connections can be made above or below
the chassis. The body of the device is the “low”
terminal of the capacitor; it is soldered to the
chassis or secured with a nut.
Nuts
Insulating
material
Chassis wall
Metal flange
feedthrough capacitor
Panel or
chassis
feedthrough insulator
Center
conductor
feedthrough component A passive device permanently
installed in a panel or plate (e.g., a
FEEDTHROUGH CAPACITOR or FEED-
THROUGH INSULATOR).
feedthrough insulator An insulator mounted
tightly in a hole in a wall or chassis, and provided
with a center hole for a lead.
Threaded
shaft
Nuts
feedthrough terminal A terminal mounted tightly
in a hole in a chassis or wall; it consists of a
screw going through a feedthrough insulator.
Connections can be made to either end of the
screw.