Eddy current flaw detector using a pair of parallel resonant circuits and a negative resistance in parallel with each circuit
 When a negative resistance is connected in parallel to a parallel resonance circuit composed of coil and condenser for detecting flaws and other defects of a travelling metal material, the detecting system is capable of improving sensitivity for detecting said flaws and lowering the required degree of amplification of the following amplifier, consequently reducing influence depending upon unbalance of a bridge circuit. At the same time, the simplifying of the power source of said system may be easily realized. 
Nippon Kokan Kabushiki Kaisha
G G
G01V G01N
inventional inventional
Seigo Toshihiro
Ando Mori