. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . f A has called B, or if B has called A manually, so that there is aplug inserted in the line jack at A, the ring of the jack will be connectedto earth through the third conductor of the cord circuit and consequentlythe manual cut-off relay will be operated opening the connectionbetween each side of the line and the repeating coil installed in the circuitto the automatic switchboard. If C finds the line from B to A in use, she leaves her calling-device keyin operated position. This does not interfere with
. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . f A has called B, or if B has called A manually, so that there is aplug inserted in the line jack at A, the ring of the jack will be connectedto earth through the third conductor of the cord circuit and consequentlythe manual cut-off relay will be operated opening the connectionbetween each side of the line and the repeating coil installed in the circuitto the automatic switchboard. If C finds the line from B to A in use, she leaves her calling-device keyin operated position. This does not interfere with operations betweenB and A, and as soon as that section of the line is clear the visual at Coperates. At the same time the through-switching relay at B operates, cuttingoff both of the taps at B, switching both sides of the line straight throughto A, and bridging out Bs calling-device key so that B can not break theconnection from B to A by throwing her calling-device key. It should benoted that if such a station as B should be connected in through a cable 302 A l! TOM A TIC TELEPHON Y. LONG DISTANCE AND SUBURBAN EQUIPMENT 303 of considerable length, that a transmission loss in the through circuit canbe eliminated by installing the through-switching relay and repeatingcoil at B on the pole where the cable connects to the through line. When Cs visual signal indicates that the line is clear, she operatesher calling device in the usual way and the Morse relay at A operates theautomatic switches as already described. Whenever C or B calls automatically into A, the automatic cut-offrelay at A operates, due to the grounding of the release trunk of theautomatic switches, and cuts off the manual cut-off relay, while at thesame time it closes the circuit through the visual signal at A, whichoperates and indicates that the line is in use.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttelephone, bookyear19
