. The practical telephone handbook and guide to the telephonic exchange . ween the right-hand coils of the translator, and the line connections passthrough the two ringing keys ekx and rk2, the latter beingfitted with ringing control and RKj^ being without machinecontrol so that it may be used for code ringing on party A or tip wire connection passes through the top contactsof relays J and o (when these are energised) to the tip of the 3-way plug on which the junction line ends. Nearly all kinds ofincoming junction lines end in this manner on a single cord andplug. The relay J is use
. The practical telephone handbook and guide to the telephonic exchange . ween the right-hand coils of the translator, and the line connections passthrough the two ringing keys ekx and rk2, the latter beingfitted with ringing control and RKj^ being without machinecontrol so that it may be used for code ringing on party A or tip wire connection passes through the top contactsof relays J and o (when these are energised) to the tip of the 3-way plug on which the junction line ends. Nearly all kinds ofincoming junction lines end in this manner on a single cord andplug. The relay J is used in place of the 40-ohm shunt to the 12-voltclearing lamp and serves to prevent the called-for subscriberbeing rung unless the junction line connection is properly com-pleted to the calling subscriber, as the connecting cord contactsare only completed when this relay is actuated. The 360-ohmshunt also serves to prevent the 12,000-ohm relay sticking atthe contacts, which it was apt to do owing to the capacity orinductance of the local circuit. JUNCTION-LINE WORKING 241. 242 PRACTICAL TELEPHONE HANDBOOK The upper part of the diagram shows the connections offour order wires to the operators telephone, the break-jacksto which they are connected being for use only when any ofthe order wires become faulty, the insertion of a plug cuttingoff the faulty wire. A switch is also inserted, so that theorder wires may be switched on to the next operator, and alamp for use at slack times, when the operator is not con-tinuously listening. Not more than four order wires shouldbe allotted to one operator. Operating.—The A operator at the outgoing end, onreceiving a call from one of her subscribers for a line con-nected to another exchange, asks for the required numberover an order wire connecting to that exchange, and is informedby the incoming or B operator which junction line is tobe used for the connection, as the latter can see which linesare disengaged. When the A operator connects theca
Size: 1117px × 2237px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjecttelephone, bookyear19
