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Dinsmore Instrument Company

Robert C Dinsmore

Kelvin Shih

Provided is a magnetomoter apparatus for measuring low-level magnetic fields. The magnetometer utilizes a coil-pair wound on cores of a high permeability material. These coils are driven to magnetic saturation by an energizing circuit, and develop a uniquely shaped distortion spike in their back emf having an amplitude which is directly related to the ambient magnetic field. The resulting back emf of the coils can be compared and processed to generate a measurement of the ambient magnetic field.

Mirror image differential induction amplitude magnetometer

Provided is a magnetomoter apparatus for measuring low-level magnetic fields. The magnetometer utilizes a coil pair wound on cores of a high permeability material. These coils are driven to magnetic saturation by an energizing circuit, and develop a uniquely shaped distortion spike in their back emf having an amplitude which is directly related to the ambient magnetic field. The resulting back emf of the coils can be compared and processed to generate a measurement of the ambient magnetic field.

The invention is a motion sensitive, battery operated compass utilizing Hall effect digital switches to sense the orientation of the compass in relation to the earth's magnetic field. A vibration sensing circuit serves to turn the compass on when it is in motion, and to turn the compass off when it is at rest. A chopper circuit is provided to interrupt the power supply at a predetermined frequency to conserve battery power. The Hall effect switches are mounted in a known relationship to a rotating magnet allowing selection and decoding of the sensor outputs to provide signals for the operation of an alpha numberic display.

Portable electronic compass

An electronic compass for vehicles such as automobiles comprising a float mechanism including a permanent magnet for following the earth's magnetic field and four Hall effect sensors for detecting magnet orientation at points corresponding to the cardinal compass points. The Hall effect sensors are connected to triggering circuits having overlapping thresholds so that two circumferentially adjacent sensors and sensor trigger circuits cooperate to indicate not only the corresponding cardinal compass points but also the secondary compass point intermediate the cardinal points. The sensor trigger circuitry is connected to a two-character multiple-segment display for indicating vehicle orientation at either one of the four cardinal compass points or one of the four secondary compass points intermediate successive cardinal points. Circuitry for compensating for variations in the earth's magnetic field caused by the vehicle comprises a pair of electromagnetic coils having perpendicular axes which perpendicularly intersect the axis of float rotation and variable resistors coupled to the coils for varying the magnetic compensation field generated by each coil independently of the other.

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Flint, MI, United States of America

Robert C Dinsmore