New Genre Metal Detector

A reader commented this morning on a CCO (Coil-Coupled Operation) metal detector I put on this blog: see New Metal Detector. I had quite forgotten about it. In 2005, I invented CCO as an entirely new genre of metal detectors -- or so said Elektor. I was already familiar with a TCO, which is a transformer-coupled oscillator. This is governed by theory which, even in its full complexity, has no interest in outside influences on the inductance of the coils. But I stepped outside of straight TCO theory, to discover the new principle, CCO. OBSERVATION: When publishing metal detectors, I have usually obtained my own best result, then reduced it by 10% for publication. With the design above, I claimed that one could find an old English penny at 150 mm. Someone wrote about a related design of mine (it's in the comments): "Detected old Victorian penny at 180 mm." One advantage of CCO is easy set-up compared to IB (Induction Balance).