I'm looking for a simple short range metal detector.
I've looked everywhere and I can find only complex metal detectors circuits to find metal at several cms of distance, most over 60cm, they are an overkill for my purposes. What I want is a simple circuit to detect metal presence at no more than 1 cm of the search coil, I have an Attiny MCU available on the board where this should go, if that helps.
I was thinking into pulse the coil at some frequency, and measure the frequency at the other side of the coil. From what I've read, if I put a metal object near enough the inductance on the coil and the metal would make the frequency change at the receiver/measuring side. But i'm not sure how exactly implement that.