| 摘要 |
A reflection type probe for an eddy current testing instrument comprises a ferromagnetic core 2, 3 and a driver coil system 8 and a pick-up coil system 9 mounted on the core, the core having four limbs 4 to 7 each with a free end. One of the coil systems 9 is wound on the four limbs with its turn equally distributed between the four limbs and the other coil system 8 is wound on a core part remote from the turns of the coil system 9 and which interconnects the core limbs at least in pairs. Advantageously the coil system which is wound on the limbs 4 to 7 is the pick-up coil system. A detector coil section of the pick-up coil system can then have its turns equally distributed between one pair of limbs and a balancing coil section having its turns equally distributed between the other pair of limbs. In further development of this arrangement, the opposed winding of the two coil sections can be readily achieved by "Figure of 8" windings around pairs of the limbs, one half of each "Figure of 8" forming a turn of the detector coil section and the other half forming a turn of the balancing coil section.
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