please, can someone explain me how does this kit work? i thought metal detectors need AC to work, but this kit works with a 9V battery. so, how does the coil work? how can this kit detect metals without any V or I variation (sorry, i’m spanish and i have some troubles to write in english)? why does it have a diode (not the LED, but another one)? the LED is on without moving the metal, only because of its presence. there is a push button to close the circuit, but the LED stays on without pushing it repeatedly, only holding the button.
you can see the circuit in google easily if you don’t know how it is, i just tried.