MAGNETIC MATERIALS IN TELEPHONE SYSTEM 



453 



losses due to the shunting effect of ringers across the Hne, especially 

 in the case of party lines. 



The third application of polarized structures is in certain relays for 

 composite ringing, duplex telegraph, and special selecting circuits. 

 Various materials are used in such relays, depending upon the sensi- 



DIAPHRAGM 



AIR GAPS- 



POLE PIECES- 



-POLARIZING- 

 MAGNETS 



Fig. 6 — Magnetic circuit of the new telephone receiver. 



tivity required, so that no general statement can be made as to needs 

 in this field. The problems encountered are essentially similar to 

 those met in the receiver and ringer, for which numerous materials are 

 available. 



