. The practical telephone handbook and guide to the telephonic exchange . Fig. 279 required, it is necessary to make the bell branch to earth,of a very high resistance, so that the current passing throughis insufficient to operate the line relay, for which reason thebells are wound to about 2500 ohms, and a resistance coil offrom 5000 to 20,000 ohms is added to the circuit. This highresistance reduces the loudness of the ring of the biassed bells,and the shunt gives rise to a continuous leakage of the common-battery current to earth. In a large system such leakagemay become a serious item in t
. The practical telephone handbook and guide to the telephonic exchange . Fig. 279 required, it is necessary to make the bell branch to earth,of a very high resistance, so that the current passing throughis insufficient to operate the line relay, for which reason thebells are wound to about 2500 ohms, and a resistance coil offrom 5000 to 20,000 ohms is added to the circuit. This highresistance reduces the loudness of the ring of the biassed bells,and the shunt gives rise to a continuous leakage of the common-battery current to earth. In a large system such leakagemay become a serious item in the maintenance cost. Thedirect connection to earth of the lines is also objectionable, asit gives rise to troubles from the unbalancing of the lines,and for other reasons. For such reasons the condensermethod of ringing is much preferable when it can be used. Thomson & Robes System.—This is a modification of theHibbard system, designed to dispense with the need for directearth connections on the lines. PARTY-LINE WORKING 275 Under normal conditions the bells are
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Keywords: ., bookcentury1900, bookdecade1900, booksubjecttelephone, bookyear19
