The Illustrated Dictionary of Electronics - Loscha

dc plate voltage • dead band 169dc plate voltage Symbol, V P(dc) . The static dc voltageat the plate electrode of an electron tube.dc positioning Alignment of the spot on the screenof an oscilloscope tube, by means of adjustable dcvoltages applied to the horizontal and vertical deflectingplates.dc power Symbol, P dc . Unit, watt. The power in adc circuit; P dc = EI, where E is in volts and I is inamperes. Compare AC POWER. Also see POWER.dc power supply A power unit that supplies directcurrent only. Examples: battery, transformer/rectifier/filter circuit, dc generator, and photovoltaiccell. Compare AC POWER SUPPLY.dc relay A relay having a simple coil and core systemfor closure by direct current, which can berectified ac.dc resistance Resistance offered to direct current,as opposed to in-phase ac resistance.dc resistivity The resistivity of a sample of materialmeasured using a pure dc voltage underspecified conditions (physical dimensions, temperature,etc.).dc restoration The reinsertion of the dc componentinto a signal from which the component hasbeen extracted through a capacitor or transformer.dc restorer A circuit that reinserts the average dccomponent of a signal after the component hasbeen lost because the signal passed through a capacitoror 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 betweenthe center and outer conductors, whilepermitting radio-frequency (RF) current to floweasily through the coaxial section. Compare DCBLOCK.dc signaling A signaling procedure that uses directcurrent as the medium (e.g., simple wire telegraphyor telephony).dc source 1. DC GENERATOR. 2. A live circuitpoint from which one or more direct currents canbe taken.dc source current Symbol, I S(dc) . The static directcurrent in the source element of a field-effecttransistor.dc source resistance Symbol, R S(dc) . The static dcresistance of an FET’s source element.dc source voltage Symbol, V S(dc) . The static dcvoltage at the source element of a field-effecttransistor.DCTL Abbreviation of DIRECT-COUPLED TRAN-SISTOR LOGIC.dc-to-dc inverter See DC INVERTER.dc transducer 1. A transducer that depends on directcurrent for its operation (i.e., it has a dcpower supply whose output is modulated by thesensed phenomenon). 2. A transducer that convertsa direct current into some other form of energy,such as heat, pressure, or sound.dc transformer A dc-to-dc converter providingvoltage step-up. The applied dc is usually firstconverted to ac, which is then stepped up by atransformer. The higher-voltage ac is then rectifiedto produce a high dc output voltage.+In−Chopper Rectifier Filterdc transformer+Out−dc transmission 1. Sending dc power from a generatingpoint to a point of use. 2. In televisiontransmission, the retention of the dc componentin the video signal.dc tuning voltage The capacitance-varying dcvoltage applied to a varactor in an inductancecapacitance(LC) tuned circuit.dcu Abbreviation of decimal counting unit.dc undercurrent relay A relay or relay circuit thatis actuated as a result of the dc coil current droppingbelow a specified level. Compare DC OVER-CURRENT RELAY.dc undervoltage relay A relay or relay circuit thatis actuated as a result of the dc voltage droppingbelow a specified level. Compare DC OVERVOLT-AGE RELAY.dcv Abbreviation of DC VOLTS or DC VOLTAGE.dc voltage Abbreviation, dcv. A voltage that doesnot change in polarity, an example being the voltagedelivered by a battery or dc generator. Alsosee VOLTAGE.dc working voltage Abbreviation, dcwv. The rateddc voltage at which a component can be operatedcontinuously with safety and reliability.dc working volts Abbreviation, dcwv. The actualvalue, expressed in volts, of a DC WORKINGVOLTAGE.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 deviceused for deemphasis. The name is short fordeaccentuator.deactuating pressure For an electrical contact,the pressure at which contact is made or brokenas the pressure reaches the level of activation.dead 1. Unelectrified. 2. Lacking electromagneticsignals or fields. 3. Electrically or mechanicallyinoperative.dead band 1. A radio-frequency band on which nosignals are heard. 2. A range of values for whichan applied control quantity (e.g., current or voltage)has no effect on the response of a circuit.