| 摘要 |
To determine and/or monitor a predetermined contents level in a container, at the height of the level to be monitored a region of the container wall is defined by a ring or frame which is attached to the outer side of the container wall in such a manner that it is in oscillatory mechanical connection with said container wall. The region of the container wall enclosed by the ring or frame forms the diaphragm of a sensor which also comprises an electromechanical excitation transducer which when fed with an electrical voltage sets the defined diaphragm region into oscillations, and an electromechanical receiving transducer which converts the oscillations of the defined diaphragm region to an electrical AC voltage. An evaluating circuit connected to the receiving transducer serves to initiate display and/or switching operations in dependence upon the frequency, the phase or the amplitude of the AC voltage emitted by the receiving transducer.
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