. American telephone practice . imes the ringing 46 722 AMERICAN TELEPHONE PRACTICE. key is pressed. This closes the off-normal switch of the connectorand establishes a circuit from the busy test apparatus to the verticalside of the line, thus throwing a tone upon the talking circuit. Thecircuit by which this tone is given to the calling subscriber may bebest seen in Fig. 519. In this, B is a test battery of low voltageconnected in series with an interrupter wheel, /, and a lamp, thiscircuit terminating on one side in the main battery lead, L, and onits other side in the off-normal switch, 0 N
. American telephone practice . imes the ringing 46 722 AMERICAN TELEPHONE PRACTICE. key is pressed. This closes the off-normal switch of the connectorand establishes a circuit from the busy test apparatus to the verticalside of the line, thus throwing a tone upon the talking circuit. Thecircuit by which this tone is given to the calling subscriber may bebest seen in Fig. 519. In this, B is a test battery of low voltageconnected in series with an interrupter wheel, /, and a lamp, thiscircuit terminating on one side in the main battery lead, L, and onits other side in the off-normal switch, 0 N, of the connector. Whenthis switch is closed and the side switch of the connector is in itsnormal position the test circuit is completed, as shown in Fig. 519,with the result that a certain amount of interrupted current passesto the receiver of the calling subscriber, causing the buzz whichsignifies to him that the called line is busy. It is true that this cir-cuit is bridged in several places by the various relay magnets, but. [ VR [ V R 3 [ V2R ] E BRR ] o- v [ RR 3 IRRJ tR2R] [BSR] L-T r rJ£ OFF NORMAL SWITCH■■5
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Keywords: ., boo, bookcentury1900, bookdecade1900, bookidamericantelepho00mill
