ELECTRONICS IN TELEPHONE SWITCHING SYSTEMS 



1013 



ponents required in electronic telephone switching they are small and 

 when eciuipment using a multiplicity of printed wiring boards is assem- 

 bled it takes on the aspect of a three-dimensional arrangement of 

 components, with components mounted in depth as well as on the sur- 

 face. This is in contrast to electromechanical systems where all com- 

 ponents are generally mounted on a vertical surface. By using only one 

 or two common control circuits of a given type (due to high speed) and 



r^ 



4 





A' 

 B- 



■♦C 



WITH RELAYS 



AB=C 

 FUNCTION AND SYMBOL 



A 



_n_ 



B N * 



-TL 



TRANSMISSION TYPE 

 DIODE GATE 



DC COUPLED 

 DIODE GATE 



Fig. 23 — The "And" function. 



_rL 



-TL 



_n_ 



MAGNETIC CORE 

 "AND" GATE 



DC COUPLED 

 TRANSISTOR "AND" GATE 



Fig. 24 — Other "And" circuits. 



