The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 276
magneto or, as they are some-times termed, generator exchanges. At the outgoing end the bush of the jack (branching)is connected to a relay, which, when a plug is inserted, isactuated by the test battery. This cuts off the batterynormally connected to the A or tip wire of the line.If break-jacks… … being then directly connected to the inner contact spring ofthe A wire, as shown in dotted lines. At the incoming end the line is connected through alistening and ringing key to the plug, but the tip wireconnection passes through the inner contact and armatureof a 250-ohm relay. This relay is…
Telephone
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