. An elementary manual of radiotelegraphy and radiotelephony for students and operators . g coil of fine silk-covered wire,and over this coil and separated fromit by guttapercha tissue another de-magnetising coil of somewhat thickerinsulated wire. The magnetising coilsare all connected in series in sucha manner that when a current passesthrough them, it magnetises thewhole of the wires so that contiguousends have the same magnetic outer or demagnetising coils are joined in parallel. Over thisbobbin is wound a long secondary circuit consisting of 6000 turnsof very fine silk-covered
. An elementary manual of radiotelegraphy and radiotelephony for students and operators . g coil of fine silk-covered wire,and over this coil and separated fromit by guttapercha tissue another de-magnetising coil of somewhat thickerinsulated wire. The magnetising coilsare all connected in series in sucha manner that when a current passesthrough them, it magnetises thewhole of the wires so that contiguousends have the same magnetic outer or demagnetising coils are joined in parallel. Over thisbobbin is wound a long secondary circuit consisting of 6000 turnsof very fine silk-covered copper wire. Associated with this induc-tion coil is a rotating commutator (see Fig. 9) carrying fourinsulating discs secured to a steel shaft. These discs have brasssectors let into their circumference, and against them four springsof brass wire press. As the commutator rotates, these springs anddiscs are made to close or open various electric circuits. Thefunction of the first disc is to make a break in the circuit ofthe magnetising coils placed round the iron bundles, to magnetise. [Reproduced from The Electricianpermission of the Proprietors. Fig. 8. iy OSCILLA TIOS DETECTORS ao5 thoin duiinjj; (»ue jutrtinii of its rotation, and loavo thuin maj^netiseddurinj, the other jKuliou. Tlie function of tlio discs 2 and 3 is toshort, circuit the terminals of the secondary coil durinf^ the timethe magnelisin-, current is being applied by disc 1. A sensitive{galvanometer is connected to the ends of this secondary coil,one bLin;j[ permanently connected and the other through theintermittent contact made by disc 4. Tiie operations which go onduring one complete revolution of the discs are as follows: Firstthe current of a battery of secondary cells is employed to magnetisethe iron bundles, and during this time the terminals of the tinewire secondary coil are short circuited, and the galvanometerdisconnected. Shortlyafter the magnetisingcurrent is interrupted,the secondary bobbin isuns
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1916
