Design and Implementation of a Low Cost VLF Metal Detector with Metal-Type Discrimination Capabilities

Land mine detectors, security metal doors that we all go through in buildings and airports, as well as metal mining detectors are just examples of metal detector use in our daily lives. In this paper we present a cost efficient, low complexity very low frequency (VLF) handheld reconfigurable metal detector (MD) design and implementation that has the capability of discriminating between various metal types. A concentric coil consisting of an outer transmitter coil, an inner receiver coil and a feedback coil. The coils operate in the 5.5 KHz frequency range. An amplitude and phase detection circuits were designed to detect and distinguish between metal types. The detection algorithm was implemented using a PIC microcontroller. The results from the actual implemented metal detector are shown and discussed for 3 types of metals: Iron, Copper, and Aluminum at various distances. The MD can detect metals about 16 cm below its coils.