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Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems (1921)
Smith, Arthur Bessey, b. 1875, Campbell, Wilson Lee · New York : McGraw-Hill · leaf 388
Jacks3rd Board Prid Board 1st Board ToOfherBoards SupyPilot SupyPilot #2 tH| |*2 #1 First Selector Boards (1st. Board) TootherBoards h Low Bat, m +J—J rrmh n Same asHigh Bay +L.RTo Jacks otZOSels Ind.Coil Rise Ply To JacksofPOSels High Bay ©Pilotw £J /TJTOI5-, #*«-=- Tnd. Coil WS*-i To 0 ther… … To Other Shelves ZrdSel Like 2ndSel.Fig. 290.—Selector and connector supervisory scheme. The action of connectors on the lineswitch boards is supervised bythe line relay and the back-bridge relay. As long as both subscribersare on the line, no supervisory lamp need show. If the calling subscriber…Telephone
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