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United States of America Patent
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-
Feb 12, 1991
Grant Date -
N/A
app pub date -
Apr 10, 1989
filing date -
Apr 8, 1988
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A housing contains a pick-up coil for detecting an external magnetic field; a power supply; a tone generator; and an electric circuit powered by said power supply and arranged to activate said tone generator in response to an output from said magnetic field pick-up including a piezoelectric material surrounded about its circumference by a thin layer of magnetostrictive material. Since the electrical output of the piezoelectric material is dependent on the stress imparted to it by the magnetostrictive material, and since the dimensional change in the magnetostrictive material is proportional to the magnetic field in the environment in which the magnetostrictive material is located, the electrical output of the piezoelectric material provides a measure of magnetic field strength.
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