JPS5780555A - Disposing method of eddy-current detecting signal - Google Patents

Abstract

PURPOSE:To remove turbulent signals with almost the same frequency component as that of crack information by inputting the difference signals from a part of the signals from an eddy-current detector which are integrated and exchanged to the direct current component instead of phase detected to the distinguishing circuit. CONSTITUTION:Signals from an eddy-current detector amplified at an amplifying circuit 1 are inputted to adding circuits 5 and 9 via buffer circuits 2 and 6 integrating circuits 4 and 8. On the other hand, a part of the output signals from the amplifying circuit 1 is partly applied to one end of potentiometer 13 via an inverting circuit 12, and partly to the other end of the meter 13 via a buffer circuit 10 and an amplifying circuit 11. The mid-point terminal is inputted to an integrating circuit 14 of the potentiometer 13. Output signals of the integrating circuit 14 are inputted to the adding circuits 5 and 9, and added to the input signals from the integrating circuits 4 and 8 respectively, and inputted to a discriminating circuit 15. By this kind of structure, turbulent signals negate each other, and even the turbulent components of almost the same frequency as the cranck component can be removed.