576 



BELL SYSTEM TECHNICAL JOURNAL 



4-WIRE VOICE- 

 FREQUENCY 

 PATCH BAY 

 I 



xl 



PADS FOR 

 BUILT-UP - 

 CONNECTIONS 



4-WIRE 



TERMINATING 



CIRCUIT 



TO TOLL 

 SWITCH- 

 BOARD 



TOLL 



LINE 

 RELAY 

 CIRCUIT 



SWITCH- 

 ING PAD 



TO 2-WIRE LINE OR 

 TOLL SWITCHBOARD 



PRIMARY 

 TEST BOARD 



4-WIRE 

 LINE 



D-C COM- 

 POSITE 

 SET 



RE- 

 PEATING 

 COILS 



RE- 

 PEATER 



(2-WIRE 



TERMINATION) 



TYPE C 



CARRIER 



TELEPHONE 



CHANNELS 



CARRIER 

 TERMI- 

 NATING 

 CIRCUIT 



4-WIRE 



TERMINATING 



CIRCUIT 



-X ^ 



■*> 



C4-WIRE 

 TERMINATION) 



h-X— X- 



r-x- 



VOICE- 

 FREQUENCY 

 CARRIER 

 TELEGRAPH 

 TERMINAL 



RE- 

 PEATER 



1 PAD \ - 



1 PAD | - 



■^ K- 



TYPE J OR K 

 CARRIER CHANNEL 

 ^ ^ 



■ | pad[ ->< 

 - | pad| -k 



-K — H- 



H 



)C X 



X X 



fT 



X X 



X X 



X X 



-X — X- 



n 



Fig. 14 — Schematic showing the various circuit arrangements on the office side voice 



frequency patching bay. 



