Metal Detector (Simple LC Oscillator)

Circuit Diagram

How to Build It

1. Build an LC oscillator using the power inductor as the inductive element, in parallel with a ceramic capacitor.
2. Connect this assembly to a BC547 transistor's collector, with base bias through a resistor.
3. Connect a small feedback capacitor from the collector to the base, to sustain oscillation.
4. Connect the emitter to GND through a small resistor.
5. Power the circuit and use a nearby AM radio as a frequency detector — pass a metal object near the coil and listen for the static tone changing.

Bill of Materials