Abstract: An automatic eddy current inspection system for discrimination of defects in elongated parts made of conducting materials comprises an alternating current generator connected in series to an amplitude selector via a differential encircling eddy-current transducer and a detector. The amplitude selector has two selection levels. The system also comprises a signal analyzer with a controllable switch and the following counters: a counter for determining the length of long cracks; a minor defects counter; a major defects counter; and a counter for determining the length of tested parts. The outputs of the counters are connected to the inputs of a sorter having its outputs connected to quality grade indicators. The controllable switch of the signal analyzer has its control input connected to the output of the amplitude selector which corresponds to a higher selection level.

Abstract: The proposed eddy current converter for non-destructive testing of electrically conductive coating in holes of printed circuit boards comprises a cylindrical frame enveloped by an exciting winding and a measuring winding and inserted into a hole of a printed circuit board being tested. The coils of the exciting and measuring windings extend along the generatrices of the cylindrical frame.With the use of the proposed converter, the testing accuracy is independent of the parameters of respective contact areas of a hole being tested. The converter of the present invention is sensitive to the most undesired flaws like transversely extending cracks.