The same holds true for a lot of microcontroller designs including [rgco’s] clever metal detector ... Arduino can measure time, a coil and a resistor will create a delay proportional to the ...

Using the power of Arduino, Evan Kale has ingeniously transformed a weed wacker into an Arduino-powered metal detector ... which combines an LC circuit with a transistor amplifier for feedback ...

[vonPongrac] stumbled upon this handy guide, a free eBook on 50 555 Circuits, which contains many cool project ideas, including a simple metal detector ... one based on an Arduino.