REMOTE CONTROLLED LINE CONCENTRATOR 



275 



relay packages similar to those used in the concentrator. The reed 

 relays are energized by transistor bi-stable circuits in the same manner 

 as described in Section 7c. The reed relay contacts in turn operate wire 

 spring relays or send the dc signals directly to the regular No. 5 crossbar 

 marker and line link marker connector circuits. 



Fig. 23 shows a block diagram of the central office circuits. A small 

 amount of circuitry is provided for each concentrator. It consists of the 

 following: 



1. The trunk connecting crossbar switch and associated slow relays 

 for disconnect control. 



2. The concentrator control triuik circuits and associated pulse ampli- 

 fiers. 



3. An originating call detector to identify which concentrator among 

 the ten served by the frame is calling. 



4. A multicontact relay to connect the circuits individual to each 

 concentrator with the common control circuits associated with the line 

 link frame and markers. 



The circuits associated with more than one concentrator are blocked 

 out in the lower portion of Fig. 23. Much of this circuitry is similar to 

 the relay circuits now provided on regular line link frames in the No. 5 

 crossbar system.^ Only those portions of these blocks which employ the 

 new techniques will be covered in more detail. These portions consist 

 of the following: 



1. The scanner pulse generator. 



2. The originating line number register. 



T 



TO ALL TRUNK LINES 

 + 30V 



A/vV 



U 



j^Wv- 



-65V 



T 



I 

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CONCENTRATOR 



TRUNK 

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Fig. 20 — Crosspoint closure check. 



