Institut Dr. Friedrich Forster, Prufgeratebau

Alfons Kalisch

Friedrich M Forster

A magneto-inductive materials tester has probes which, when brought into contact with the material, produce an electrical signal corresponding to properties of the material desired to be tested. Apparatus for evaluating this test signal has at least one device for producing a compensation voltage to eliminate residual or drift error voltages that may be superimposed on the test signal. The compensating device includes a counting pulse generator, at least one pulse counter connected to the generator at least temporarily, and a digital/analog converter connected to the pulse counter output to provide the desired compensation voltage.

Magnetic or magneto-inductive materials tester with improved processing

The described tube testing apparatus indicates whether a defect is either external or internal, enabling a quantitative classification of defects and an analog representation on location of the defect in the tube wall. The ratio of the signal levels of a defect is taken as a threshold in two different circuit channels. For tubes of a given wall thickness, the ratio of the defect signal levels resulting in the two channels is a fixed number which is a function of the location of a defect in the tube wall causing a defect signal. Uninfluenced test signal voltages from the first channel are available for further evaluation and are applied to voltage discriminators having various threshold voltages. Since the signal levels for external and internal defects are different, this may be effected separately for external and internal defects, offering the possibility for defect classification adapted to the respective requirements, for example, into large, medium or small external defects, or large, medium or small internal defects.

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Reutlingen, Germany

Alfons Kalisch