Portable Metal Detector

Metal detectors are fascinating devices used for detecting hidden metal objects underground or inside materials. In this DIY guide, you will learn how to build a simple , low cost ,portable metal detector using common electronic components and a 9V battery. This project is perfect for beginners, students, hobbyists, or school assignments.

1 × 9V battery

1 × toggle ON/OFF switch

1 × LED indicator

1 × buzzer

1 × preset

Resistors

Transistors

Capacitors

Copper coil (40 turns of copper wire)

PCB board

The coil is the heart of the metal detector.

1.Take enamel-coated copper wire.

2.Wrap a total of 40 turns around a circular object (like a bottle, bowl, or PVC pipe).

3.Crucially, after wrapping the 20th turn (half of the total 40 turns), create a center tap by carefully stripping a small amount of insulation from the wire at that point or by forming a small loop you can later strip and connect.

4.Continue wrapping the remaining 20 turns.

5.Keep the coil tight and even.

6.Secure the coil with tape to maintain its shape.

7.You will now have three connection points:

The Start end of the wire.

The Center Tap (at the 20th turn).

The End of the wire.

8.These three ends (Start, Center Tap, and End) are necessary for connecting the coil to the PCB.

On your PCB, solder the following:

1. Resistors
2. Capacitors
3. A transistor
4. Preset (to adjust sensitivity)
5. Buzzer
6. LED

Connect the 9V battery snap to the terminal block.

Connect the toggle switch in series with the battery to control power.

Test the circuit by switching it ON.

Place the PCB board inside the plastic project box.

Fix the coil to the underside of the box using tape.

Drill small holes for:

1. LED
2. Buzzer sound
3. Switch

Close the box and secure with screws.

Turn the preset slowly using a small screwdriver.

Move metal objects near the coil.

Adjust until buzzer/LED respond clearly.

Try scanning different objects:

1. Coins
2. Keys
3. Nails
4. Aluminium foil
5. Steel pieces

When metal gets close:

1. The buzzer beeps
2. The LED light up