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Magnetic Materials Used in Communication

The magnetic materials used in early telephone apparatus were chiefly magnetic iron and silicon steel. Bundles of small iron wire early were used for cores. About 1915 cores of compressed powdered electrolytic iron were introduced.

diagram: magnetization curves
Figure 5. Magnetization curves for certain magnetic materials.

Silicon-steel laminations are used in cores for power-supply transformers and for similar purposes. They are also used in some audiofrequency equipment. Special alloys have been developed for the specific requirements of telephone equipment, and certain of these have found use in radio.

Last Update: 2011-05-14