Metal detectors get help from smartphones

[mircemk] This is quite a wizard when it comes to using cable coils in projects, especially when their application lies in easily made metal detectors. There are all sorts of ways to send signals through coiled wires to detect metallic objects on the ground and today [mircemk] Demonstrating a new method he is testing using a smartphone to detect frequency changes generated by a metal detector.

Like other metal detectors, it uses two coils of wire, including an oscillator circuit and some transistors. The unique part of this build, though, is how the detector warns the user about a piece of metal. There will usually be an audible alert due to the change in the frequency of the circuit in the presence of metal, but it instead uses a smartphone to analyze the frequency information. The circuit is delivered directly to the smartphone’s headphone jack and can be calibrated and used from within an Android app.

It can not only detect metals, but it can also distinguish between different types of metals. [mircemk] Note that since it was only for testing, it often needs to be calibrated and is not as sensitive as the others it has created in the past. Of course this build assumes that your phone still has a headphone jack, but we won’t dig for cans of worms for this feature. Instead, we’ll point that out [mircemk] Other builds have shown that no external hardware is required to uncover buried treasures.

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