38 



BELL SYSTEM TECHXIC.-IL JOURX.IL 



relay and the secondary relay in each case. In the one case, however, 

 rela\- £' operating when relay "D" operates gives positive release 

 of relay "E" instead of introducing an uncertain resistance in its 

 circuit. 



This circuit embodies se\eral features which are not common in 

 relay systems. The operation of relay E' is dependent on the \alues 



Current In A.C.Signaling Relay 



AA Current in Winding 

 BB' - through Contoct 



Fig. 27— Curve showing signal impulses in a.c. signaling relay 



A.\', current in winding 



BB\ current through contact 



, J,} JliAdjustirnnl 

 K 115C»cll!« 



Adiustmeirt 



pi fli tOiAmpereTurrw 



-^WWrfAWi gt: Direct Current \^ 



Fig. 2f^— Circuit for a make contact l.^.i cycle relay 



selected for resistancc-s K' and R- and for condenser A'. These \alues 

 must he such that the current in the relay winding is maintained 

 during the opening of the contact of relay "D" by means of the dis- 

 charge current from the condenser. On the other hand A' and R- 

 must be proportioned to limit the arcing of the contact of "D" at 



