REMOTE CONTROLLED LINE CONCENTRATOR 



285 



relay HG which operates on all originating and terminating calls to the 

 particular concentrator served by these trunks. The end chain relay 

 TC of the lockout trunk selection circuit^^ connects battery from the 

 SR relay windings of idle trunks to the windings of the TS relays to 

 permit one of the latter relays to operate and to steer circuits, not shown 

 on Fig. 29, to the hold magnet of the trunk and to the tip-and-ring con- 

 ductors of the trunk to apply the selection voltages shown on Figs. 13 

 and 14. 



The path for operating the hold magnet originates in the marker. 

 The path looks like that which the marker uses on the line hold mag- 

 net when setting up a call on a regular line link frame. For this reason 

 and other similar reasons this concentrator line link frame concept has 

 been nicknamed the "fool-the-marker" scheme. 



Should a hold magnet release while a new call is being served the 

 ground from the TC relaj^ normal or the TS relay winding holds relay 



CONCENTRATOR TRUNK 

 SWITCH CROSSPOINTS 



SR [ 



LINE LINK 

 NUMBER FROM 

 MARKER I 



-48 V 



Fig. 29 — Trunk selection and identification. 



