This project creates a metal detector using an Adafruit CLUE with a few common components and an easy-to-make coil.

The program is written in CircuitPython for version 5.1.0 or later. The code also runs on the Circuit Playground Bluefruit (CPB) with the TFT Gizmo screen. The program can be used without a screen on the CPB in audio/light mode only.

Alligator clips to male jumpers can be used with or without the Adafruit Dragontail to connect the CLUE and the coil to the breadboard. The pictures feature alternate products.

This project was inspired by an old Ray Marston book featuring a metal detector project and the Detectorists BBC TV series.

sensors_clue-metal-detector-unstacked-1-2000x1500.jpg
An Adafruit CLUE with a simple circuit on a breadboard detecting a metallised sticker with a coil.

Parts

CLUE version

1 x Adafruit CLUE
Adafruit CLUE - nRF52840 Express with Bluetooth LE
1 x Adafruit DragonTail
Adafruit DragonTail for micro:bit - Fully Assembled (or use 3 Alligator Clip to Male Jumper Wires)
1 x 1k Resistor
Through-Hole Resistors - 1.0K ohm 5% 1/4W - Pack of 25 (1 needed)

Circuit Playground Bluefruit with TFT Gizmo version

1 x Circuit Playground Bluefruit (CPB)
Circuit Playground Bluefruit - Bluetooth Low Energy
1 x Circuit Playground TFT Gizmo (LCD Screen)
Circuit Playground TFT Gizmo - Bolt-on Display + Audio Amplifier
2 x STEMMA 3-Pin to Male Header Cable
STEMMA JST PH 3-Pin to Male Header Cable - 200mm

Circuit Playground Bluefruit only version

1 x Circuit Playground Bluefruit (CPB)
Circuit Playground Bluefruit - Bluetooth Low Energy
1 x 1k Resistor
Through-Hole Resistors - 1.0K ohm 5% 1/4W - Pack of 25 (1 needed)

Common

1 x USB 1m cable - A to Micro-B
USB cable - USB A to Micro-B - 3 foot long
1 x Half-size breadboard
Half-size breadboard
1 x Alligator Clip to Male Jumper Wires
Small Alligator Clip to Male Jumper Wire Bundle - 6 Pieces (2 needed for coil)
1 x Male/Male Jumper Wires
Premium Male/Male Jumper Wires - 40 x 3" (75mm)
1 x Signal Diode
1N4148 Signal Diode - 10 pack (1 needed)
1 x 0.1uF Capacitor
0.1uF ceramic capacitors - 10 pack (1 needed)
1 x 36ft (11m) Wire
Enameled Copper Magnet Wire – 11 meters / 0.1mm diameter (5-8m of most insulated wire will work fine)
1 x 3 x AAA Switched Battery Holder
3 x AAA Battery Holder with On/Off Switch and 2-Pin JST (if you want to be mobile!)
1 x AAA Batteries
Pack of 3

This guide was first published on May 13, 2020. It was last updated on May 13, 2020.

This page (Overview) was last updated on Aug 30, 2020.