| 摘要 |
A magnetic-inductive flowmeter is disclosed operating with an alternating field but supplied from a source of direct voltage. The inversion is executed with the aid of the excitation coils of the pickup as well as with the aid of a control circuit. In an advantageous embodiment, an oscillator circuit is formed with the aid of the excitation coils and a capacitor so that the power supplied by the source of direct voltage represents only a small portion of the apparent output of the excitation coil. Besides, the provision is made to keep the current through the control circuit and/or its amplitude, or the amplitude of the voltage at the excitation coil, at a constant value, so that the measuring signal is not subject to possible fluctuations of the direct voltage source.
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