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Curated by: Huygens Optics (81 videos)
In this video I discuss the principle of a VLF- type induction balanced metal detector (Garrett AT pro), in particular how the discrimination between different metals works. I do this by looking at the emitted and received signals of a test coil, so not by opening up the detector. 00:00 General Intro 00:34 Need for discrimination / ID in metal detection 03:19 Test setup 03:55 Principle of double D coil explained 08:29 ID and phase shift for different metals (para- and diamagnetism) It turns out that the detector measures the phase delay between the emission and reception coil. The reception coil shows this delay because of changes in the inductance which are introduced by the conductivity and intrinsic magnetic properties of metal objects in the vicinity.