Non-destructive material testing - using electromagnetic oscillations and voltage-frequency function display and comparing with reference function

摘要

The non-destructive material testing method is applicable where the dia. of the object or its distance from the test coil is unknown because of a lacquer or insulationg coating. When the tested object (R) is brought into the working zone of the coil (1) the effective voltage across the capacitor (3) in series with the coil is displayed on an oscilloscope (10) after passing through a rectifier and integrator circuit (11). The voltage is displayed against a frequency time base derived via a frequency-to-voltage converter (9). The function can also be compared with that produced when a body of known characteristics is introduced. The comparison is performed using a computer. (28pp Dwg.No.1) .