Measuring device with oscillation circuit including an exciting coil and tuned to a specific resonant frequency, for determining content of magnetizable substances in materials

摘要

A measuring device for determining the content of magnetizable substances, particularly ferrite and martensite, in a sample, the device including an exciting coil which preferably has an iron core, for producing a magnetic field to be applied to the sample, and further including an evaluation circuit and a display device for displaying measurement quantities proportional to the content of magnetizable substances in the sample. To improve measurement accuracy, the exciting coil is a part of a tuned resonant oscillation circuit. The inductance of the exciting coil can be changed by the magnetic field induced in the sample as a result of the applied magnetic field, whereby the change in inductance results in a change in the resonant frequency of the oscillation circuit. The measurement quantity fed to the display device is a quantity proportional to the content of magnetizable substances and corresponds to the change in at least one of the parameters of the oscillation circuit which change results when the resonant frequency is changed.