. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . B is for ring-downsupervision from a toll line when the latter is manually operated. RelayA is for supervision from the local automatic switchboard. The sleeveconductor is grounded. When it is desired to dial toward the automaticswitchboard (local) the operator throws the calling-device key to localwhich operates the springs marked CD-L. This cuts off the toll endof the cord and switches the calling device CD into the sleeve of thelocal plug. Toll Selector, with Operating Trunk.—The circuit of a toll sele
. Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems . B is for ring-downsupervision from a toll line when the latter is manually operated. RelayA is for supervision from the local automatic switchboard. The sleeveconductor is grounded. When it is desired to dial toward the automaticswitchboard (local) the operator throws the calling-device key to localwhich operates the springs marked CD-L. This cuts off the toll endof the cord and switches the calling device CD into the sleeve of thelocal plug. Toll Selector, with Operating Trunk.—The circuit of a toll selectorwhich may serve as first, second, etc., is shown in Fig. 249. Here it is 292 A UTOMA TIC TELEPHON Y shown with a jack on the toll board. The insertion of the plug by theoperator closes the sleeve circuit to the operating relay OpRy and operatesthe visual busy signal. The operating relay in the selector acts on themagnets and other relays exactly as was described in connection withregular selectors. When the selector cuts through to the next switch Operators TelephoneTalk Monitor. Local Fig. 248.—Toll to local cord circuit, sleeve dialing. ahead, the operating wire is switched from the operating relay in thisswitch to that of the next switch. The release trunk is carried throughseparately. Toll Third Selector, with Repeating Coil.—The toll third selector,as it is called, has a circuit like that shown in Fig. 250. Whether it is a Visualdust/
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttelephone, bookyear19
