MAGNETIC MATERIALS IN TELEPHONE SYSTEM 



459 



A further type of inductance is the impulse coil used in harmonic 

 generators.^'' The cores of these coils should be saturated over most 

 of the magnetizing cycle, and reverse very quickly and completely 

 just as the magnetizing force passes through zero. This implies use 

 of material having a high permeability, and a high resistivity, such as 

 4-79 Mo-permalloy. 



Fig. 10 — Large and small coils used in the telephone system. 



4c. Transformers 



With transformers, the inductance and losses of the individual coils 

 can be analyzed as simple inductances, for which the considerations of 



" E. Peterson, J. M. Manley & L. R. Wrathall, Elec. Engg. 56, 995 (1937). 



