18WuD2x

dc plate voltage • dead band 169
dc plate voltage Symbol, V P(dc) . The static dc voltage
at the plate electrode of an electron tube.
dc positioning Alignment of the spot on the screen
of an oscilloscope tube, by means of adjustable dc
voltages applied to the horizontal and vertical deflecting
plates.
dc power Symbol, P dc . Unit, watt. The power in a
dc circuit; P dc = EI, where E is in volts and I is in
amperes. Compare AC POWER. Also see POWER.
dc power supply A power unit that supplies direct
current only. Examples: battery, transformer/
rectifier/filter circuit, dc generator, and photovoltaic
cell. Compare AC POWER SUPPLY.
dc relay A relay having a simple coil and core system
for closure by direct current, which can be
rectified ac.
dc resistance Resistance offered to direct current,
as opposed to in-phase ac resistance.
dc resistivity The resistivity of a sample of material
measured using a pure dc voltage under
specified conditions (physical dimensions, temperature,
etc.).
dc restoration The reinsertion of the dc component
into a signal from which the component has
been extracted through a capacitor or transformer.
dc restorer A circuit that reinserts the average dc
component of a signal after the component has
been lost because the signal passed through a capacitor
or transformer.
DCS Abbreviation of DORSAL COLUMN STIMULA-
TOR.
dc shift A shift in the DC OPERATING POINT.
dc short A coaxial fitting providing a dc path between
the center and outer conductors, while
permitting radio-frequency (RF) current to flow
easily through the coaxial section. Compare DC
BLOCK.
dc signaling A signaling procedure that uses direct
current as the medium (e.g., simple wire telegraphy
or telephony).
dc source 1. DC GENERATOR. 2. A live circuit
point from which one or more direct currents can
be taken.
dc source current Symbol, I S(dc) . The static direct
current in the source element of a field-effect
transistor.
dc source resistance Symbol, R S(dc) . The static dc
resistance of an FET’s source element.
dc source voltage Symbol, V S(dc) . The static dc
voltage at the source element of a field-effect
transistor.
DCTL Abbreviation of DIRECT-COUPLED TRAN-
SISTOR LOGIC.
dc-to-dc inverter See DC INVERTER.
dc transducer 1. A transducer that depends on direct
current for its operation (i.e., it has a dc
power supply whose output is modulated by the
sensed phenomenon). 2. A transducer that converts
a direct current into some other form of energy,
such as heat, pressure, or sound.
dc transformer A dc-to-dc converter providing
voltage step-up. The applied dc is usually first
converted to ac, which is then stepped up by a
transformer. The higher-voltage ac is then rectified
to produce a high dc output voltage.
+
In
−
Chopper Rectifier Filter
dc transformer
+
Out
−
dc transmission 1. Sending dc power from a generating
point to a point of use. 2. In television
transmission, the retention of the dc component
in the video signal.
dc tuning voltage The capacitance-varying dc
voltage applied to a varactor in an inductancecapacitance
(LC) tuned circuit.
dcu Abbreviation of decimal counting unit.
dc undercurrent relay A relay or relay circuit that
is actuated as a result of the dc coil current dropping
below a specified level. Compare DC OVER-
CURRENT RELAY.
dc undervoltage relay A relay or relay circuit that
is actuated as a result of the dc voltage dropping
below a specified level. Compare DC OVERVOLT-
AGE RELAY.
dcv Abbreviation of DC VOLTS or DC VOLTAGE.
dc voltage Abbreviation, dcv. A voltage that does
not change in polarity, an example being the voltage
delivered by a battery or dc generator. Also
see VOLTAGE.
dc working voltage Abbreviation, dcwv. The rated
dc voltage at which a component can be operated
continuously with safety and reliability.
dc working volts Abbreviation, dcwv. The actual
value, expressed in volts, of a DC WORKING
VOLTAGE.
dcwv Abbreviation of DC WORKING VOLTAGE.
dD Symbol for differential of electric displacement.
DDA Abbreviation of digital differential analyzer.
DDD Abbreviation of DIRECT DISTANCE DIALING
(telephone).
D display See D SCOPE.
DE Abbreviation of decision element.
dE Symbol for differential of voltage.
deac In frequency-modulation (FM) receivers, a device
used for deemphasis. The name is short for
deaccentuator.
deactuating pressure For an electrical contact,
the pressure at which contact is made or broken
as the pressure reaches the level of activation.
dead 1. Unelectrified. 2. Lacking electromagnetic
signals or fields. 3. Electrically or mechanically
inoperative.
dead band 1. A radio-frequency band on which no
signals are heard. 2. A range of values for which
an applied control quantity (e.g., current or voltage)
has no effect on the response of a circuit.