The Illustrated Dictionary of Electronics - Loscha

source impedance • special character 645source impedance 1. The impedance of a generatorin a circuit. 2. The impedance of the sourceelectrode of a field-effect transistor.source language A computer programming languagefrom which is derived (by a compiler) themachine (object) language on which the computeroperates.source program A computer program written in asource language.south magnetic pole The south pole of the equivalentbar magnet constituted by earth’s magneticfield (see EARTH’S MAGNETIC FIELD). The southmagnetic pole lies close to the geographic southpole. Compare NORTH MAGNETIC POLE.south-seeking pole Symbol, S. The so-calledsouth pole of a magnet. When a bar magnet issuspended horizontally, this pole points toearth’s south magnetic pole. Compare NORTH-SEEKING POLE.SP Abbreviation of STACK POINTER.sp 1. Abbreviation of single pole. 2. Abbreviation ofspecial.space-charge field 1. The electric field existingwithin a group of charged particles. 2. The electricfield existing in a plasma.space diversity See DIVERSITY RECEPTION.space-diversity reception See DIVERSITY RE-CEPTION.space division A method of data transfer in whichdifferent paths are used for the transmission ofdifferent signals.space-division switch A switch having two or moreports and different paths connecting the ports.space lattice The three-dimensional, redundantpattern formed by atoms and molecules in a crystaland having a shape that is characteristic of aparticular crystalline material.spacer An insulating rod or bar that serves to holdapart the conductors of a two-wire, four-wire, orcoaxial air-dielectric transmission line.space suppression Following the printing of a lineby a printer, the prevention of normal paper travel.space-time-space switch Abbreviated STS switchor STSS. A large switching array with two spaceswitch blocks and a time switch block betweenthem.space wave One of the components of an electromagneticground wave. The space wave, unlikethe surface wave, is not earth-guided. It has twocomponents: the direct wave and the groundreflectedwave.spaghetti Slender, varnished-cambric tubing usedas slipover insulation for wires and busbars.span On an instrument scale, the difference betweenthe highest value and the lowest value.spark See ELECTRIC SPARK.spark absorber 1. See SPARK SUPPRESSOR. 2.See KEY-CLICK FILTER.spark coil A small induction coil. Its name is derivedfrom its initial purpose of supplying thehigh voltage for spark plugs in gas engines.spark energy The energy dissipated by an electricarc or spark.spark gap A device consisting essentially of twometal points, tips, or balls that are separated by asmall air gap. A high voltage applied to the electrodescauses a spark to jump across the gap.sparking distance The maximum separation ofthe electrodes of a spark gap at which a givenvoltage will produce a spark.sparking voltage The lowest voltage that willcause a spark to jump across a gap of a givenwidth.spark killer See SPARK SUPPRESSOR.sparkover A discharge in air, a vacuum, or a dielectric.It is characterized by sparking betweenelectrodes in the medium.spark plate In some automobile radios, a noiseinterference-eliminatingbypass capacitor inwhich the chassis is one plate.spark-plug suppressor A small resistive deviceconnected in series with a spark plug to suppresselectrical noise arising from the ignition in an internalcombustion engine.spark quencher See SPARK SUPPRESSOR.spark suppressor A resistor, capacitor, and/ordiode used to eliminate or minimize sparking betweenmake-and-break contacts.spark suppressorTo keyedcircuitspark-suppressor diode See SUPPRESSORDIODE.spatial distribution The three-dimensional directionalpattern of a transducer (such as an antenna,microphone, or speaker).spc 1. Abbreviation of silicon point contact. 2. Abbreviationof silver-plated copper.SPDT Abbreviation of SINGLE-POLE/DOUBLE-THROW (switch or relay).speaker See LOUDSPEAKER.speaker damping See DAMPED LOUDSPEAKER.speaker-level audio In a sound reproduction system,radio receiver, or other audio circuit, an audio-frequencysignal of sufficient amplitude todrive a speaker or speaker system directly, withoutthe need for additional amplification.speaking arc A method of modulated-light transmission.An electric arc is modulated by audiofrequencysignals.special character A printed, displayed, or encodedcharacter other than a numeral or letter, such as