36 



DELL SYSTEM TECHXICAL JOURNAL 



increases the time for Ihe building up of the magnetic force neces- 

 sary to move the armature from the normal position. It also in- 

 creases the time for such a reduction in the magnetic force as will 

 permit the armature to release. 



The slow release feature is further secured l)\" oniiuing the sioj) 

 pins which are usualK' proxidwl between the armature and the jiole 



Fig. 25 — Sectional view 



162 type relay, 



iperating relay 



piece. This lends to delay the decline in tlux through the magnetic 

 circuit when the current is interrupted. Fig. 2.") illustrates diagram- 

 matically the structure of these relays. 



Ri-:i,.\vs or- the Composite Ringer 



A somewhat similar use of rela\s is to be seen in the com[)osite 

 ringer circuit mentioned al)o\e. Tin- reluN' circuit ol such a ringer 

 is shown in l'"ig. 2(), in simpliheil form. This circuil is designed to 

 recei\-e 20-cycle signals from the switchboard and transmit oul on 

 the line signals of a higher frequency and to recci\e the higher fre- 

 quency impulses and in tiirn transmit 20 cycles to the switchboard. 

 In this case, the 20-cyclc relay "A" does not meet the requirement 

 for high impedance since protection to the telephone circuit is af- 

 forded by coil " C." \ single core is therefore satisfactory and a 

 positive make-contact relay is used. In this case, the cliii'f recjuire- 

 ment is that relay " B" should be slow in operating. 



