| 摘要 |
PROBLEM TO BE SOLVED: To provide an electromagnetic flow meter in which a high stability is obtained by removing influences of drifts, etc., and the measuring accuracy is improved. SOLUTION: A detection tube 1 has a pair of electrodes 3a, 3b facing each other, and electromagnetic coils 4a, 4b are provided facing crosswise to the electrodes 3a, 3b and excited to measure a voltage generated in a fluid flowing in the tube 1 through the electrodes 3a, 3b. A differential amplifier circuit 17 amplifies the measured signal and inputs it to a zero point correcting circuit 31 through a high-pass filter 19, this correcting circuit 31 compensates the phase such that a low-pass filter picks up a lower frequency component than the exciting frequency of the exciter circuit 5 and a phase shifter delays a main signal by a time delaying in passing the low-pass filter, and a subtractor subtracts the output signal of the low-pass filter from the output signal of the phase shifter, thereby correcting a d-c variation of a detected signal.
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