EDDY-CURRENT FLAW DETECTOR Russian patent published in 1994 - IPC

FIELD: nondestructive testing; eddy-current testing of conducting objects. SUBSTANCE: eddy-current flaw detector has eddy-current converter, series-connected controlled self-excited oscillator whose oscillatory circuit includes eddy-current converter, amplitude detector and threshold device, indicator, connected in series pulse generator, first control switch, first pulse counter, first D/A converter and analog adder which contains also series-connected second controlled switch, second pulse counter, and second D/A converter, and indication unit provided with mode switch whose one pair of inputs is connected to reset inputs of pulse counters and serves for alternate connection of them with reset input of indication unit connected with output of mode switch and input of second controlled switch is connected to output of pulse generator by means of frequency detector whose input is connected to output of controlled self-excited oscillator by means of connected in series amplifier-compensator of amplitude variation whose input is connected to output of amplitude detector, and analog switch whose output is connected with reset input of second pulse counter, and control input with output of threshold device, as well as potentiometer, whose inputs are connected to output of frequency detector and to output of amplifier-compensator of amplitude variation, and comparator whose inputs are connected, respectively, outputs of potentiometer and second D/A converter. Output of comparator is connected with control input of second controlled switch and input of indicator. Second pair of inputs of mode switch is connected to outputs of controlled switches and serves for their alternate connection to counter input of indication unit. EFFECT: higher confidence of testing. 4 dwg