Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Frequency of cyclic current or voltage
Patent
1975-12-23
1976-11-30
Krawczewicz, Stanley T.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Frequency of cyclic current or voltage
324 37, 324 40, G01R 3300
Patent
active
039952118
ABSTRACT:
The detector comprises a reference AC signal generator with one terminal grounded, a feedback amplifier having one input connected to receive the reference AC signal; a feedback network coupled to the output of the feedback amplifier, the other input of the feedback amplifier, and the grounded terminal so as to supply a feedback voltage between the grounded terminal and the other input of the feedback amplifier; and a detector for detecting the output of the feedback amplifier. The feedback network includes two serially connected detection coils spaced in the direction of movement of a metallic member to be detected to vary their impedances in accordance with the variation in the electric or magnetic characteristic of the metallic member. Further, the pair of detection coils are arranged such that when the homogeneous portions of the metallic member pass by these coils they provide a substantially constant feedback ratio whereas when a portion having electric or magnetic characteristic different from those of the homogeneous portions passes between the detection coils, the inversion between a larger feedback ratio than the constant value and a smaller feedback ratio than the constant value is obtained, thereby detecting the position of the portion to be detected.
REFERENCES:
patent: 3867689 (1975-02-01), Mori et al.
patent: 3939403 (1976-02-01), Stassart
patent: 3946307 (1976-03-01), Mori et al.
Ando Seigo
Watanabe Katsujiro
Yamada Takeo
Krawczewicz Stanley T.
Nippon Kokan Kabushiki Kaisha
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