22 BELL SYSTEM TECHNICAL JOURNAL 



able relay. Its time constant, however, is influenced by the electrical 

 constants of the loop with which it is associated; so that the length 

 of the loop effects the speed at which the armature operates and releases 

 and thus causes the relay to introduce some pulse distortion. 



An Accurately Adjusiahle 1-lat Type Relay 



In order to decrease this distortion a new punched-type relay was 

 designed which reproduces dial pulses with much greater accuracy. 

 It will be seen from the picture of this relay shown in Fig. 15 that 

 the armature is light, that the air gaps can be adjusted closely and 

 with great precision, and that the reduction in the inertia of the 

 armature was obtained by changing the position of the supporting 



Fig. 1S^"L" type imlsing relay 



reed hinge. The core of this relay is of small cross section, so that a 

 condition of magnetic saturation is obtained with small current 

 values. With maximum flux on long loops, the increa.se in current 

 as the length of the substation loop decreases produces very little 

 change in the total flux. Also, changes in the armature air gap as 

 the armature approaches the core do not reduce the reluctance of 

 the magnetic circuit approciabK", so that the armature oix-rates and 

 releases with little time \ari.itioii irres|)i'cti\'e ot changes in the elec- 

 trical constants ol the loop. 



The slow-release relay, in Fig. 14, is a round-core relax' with a reed 

 hinge armature, similar in general construction to the cutoff relay 

 prexiously described in connection with the early manual system. It is 

 pro\'ided with a cojiper .sleeve on the core which acts as a short circuited 

 secondary transformer winding ot \er\- low resistance. 



