. An elementary manual of radiotelegraphy and radiotelephony for students and operators . in an outer sheath of thin ebonite and mounting it on abox baseboard on supports of ebonite. The ends of the secondarywire are brought to two terminals carried on ebonite pillars andprovided with adjustable spark points (see Fig. 6). Two otheradjuncts are then necessary. In the first place some means has tobe provided for rapidly interrupting or reversing the primai-y 44 RADIOTELEGRAPHY current, since it is only by so doing that we can create electro-motive force in the secondary circuit. This appliance i
. An elementary manual of radiotelegraphy and radiotelephony for students and operators . in an outer sheath of thin ebonite and mounting it on abox baseboard on supports of ebonite. The ends of the secondarywire are brought to two terminals carried on ebonite pillars andprovided with adjustable spark points (see Fig. 6). Two otheradjuncts are then necessary. In the first place some means has tobe provided for rapidly interrupting or reversing the primai-y 44 RADIOTELEGRAPHY current, since it is only by so doing that we can create electro-motive force in the secondary circuit. This appliance is called aninterrupter. Also it is necessary, as first shown by Fizeau, toplace a condenser of a certain capacity across the points betweenwhich interruption of the priniary circuit occurs. This is calledthe primary condc^iser. In reference to the construction of induction coils for radio-telegiaphy, it should be noticed that the value of a coil is not tobe judtjed simply by the length of spark it can give between theends of the secondary wire when the primary circuit is interrupted,. Fig. 6. {ReproduceA by permission of Sfessrs. Neiolon <t Co. but by the spark length which can be obtained when a condenserof a certain capacity, say 0*1 microfarad, is connected across theends of the secondary circuit. At each make and break of the primary circuit an electro-motive force is created in the secondary circuit, the magnitude ofwhich depends upon the rate at which the magnetic flux createdin the core is linked or unlinked with the turns of the secondarycircuit. This flux grows up when the primary current startsmore slowly than it decays as the primary current stops, and hencethe secondary electromotive force at the make of the primarycircuit is very small compared with that at the break. Thelatter may be several hundred times greater than the , if the primary circuit is rapidly made and broken, anintermittent electromotive force appears in the secondary circuitwhich is
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1916
