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KF5JRV > TECH 29.09.16 13:20l 37 Lines 2045 Bytes #999 (0) @ WW
BID : 2692_KF5JRV
Read: GUEST
Subj: Ferrites
Path: IW8PGT<IZ3LSV<IW0QNL<ED1ZAC<GB7CIP<N0KFQ<KF5JRV
Sent: 160929/1115Z 2692@KF5JRV.#NWAR.AR.USA.NA BPQK6.0.13
History of Ferrite
The history of ferrites (magnetic oxides) began centuries before the birth of
Christ with the discovery of stones that would attract iron. The most plentiful
deposits of these stones were found in the district of Magnesia in Asia Minor,
hence the mineral’s name became magnetite (Fe3O4).
Much later, the first application of magnetite was as ‘Lodestones’ used by
early navigators to locate magnetic North. In 1600 William Gilbert published
De Magnete, the first scientific study of magnetism. In 1819 Hans Christian
Oersted observed that an electric current in a wire affected a magnetic compass
needle. With further contributions by Faraday, Maxwell, Hertz and many others,
the new science of electromagnetism developed.
Naturally occurring magnetite is a weak ‘hard’ ferrite. ‘Hard’ ferrites possess
a magnetism which is essentially permanent. In time, man-made ‘hard’ ferrites
with superior properties were developed but producing an analogous ‘soft’ magnetic
material in the laboratory proved elusive.
During the 1930’s research on ‘soft’ ferrites continued, primarily in Japan and
the Netherlands. However, it was not until 1945 that J. L. Snoek of the Phillips
Research Laboratories in the Netherlands succeeded in producing a ‘soft’ ferrite
for commercial applications. Originally manufactured in a few select shapes and
sizes, primarily for inductor and antenna applications, ‘soft’ ferrite has
proliferated into countless sizes and shapes for a multitude of uses. Ferrites
are used predominately in three areas of electronics: low level applications,
power applications, and Electro-Magnetic Interference (EMI) suppression.
The breadth of application of ferrites in electronic circuitry continues to grow.
The wide range of possible geometries, the continuing improvements in material
characteristics and their relative cost-effectiveness make ferrite components
the choice for both conventional and innovative applications.
73 Scott kf5jrv
KF5JRV @ KF5JRV.#NWAR.AR.USA.NA
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