REMOTE CONTROLLED LINE CONCENTRATOR 



265 



COUNT 

 INPUT 



lie 



STAGE NUMBER 

 3 



NOTE: 



LEADS A-0 TO A-4 

 ARE OUTPUT LEADS 

 OF RESPECTIVE STAGES 



1 I I \ r 



s 's 's 's 's 



Fig. 12 — Ring counter schematic. 



a bi-stable circuit per stage. The enabling gate for a stage is controlled 

 by the preceding stage allowing it to be set by an input advance pulse. 

 The output signal from a stage is fed back to the preceding stage to turn 

 it off. An additional diode is connected to the base of each stage for re- 

 setting when returning the counter to a fixed reference stage. 



A basic package of 5 ring counter stages is made up in the same frame- 

 work and with the same size plug as the flip-flop and amplifier packages, 

 see Fig. 2(b). A four stage ring counter is also used and is the same 

 package with the components for one stage omitted. The input and out- 

 put terminals of all stages are available on the plug terminals so that 

 the stages may be connected in any combination and form rings of more 

 than 5 stages. The reset lead is connected to all but the one stage which 

 is considered the first or normal stage. 



Other transistor circuits such as binary counters and square wave 

 generators are used in small quantity in the central office equipment. 

 They will not be described. 



