Planet Arduino

For an easy DIY metal detector setup, look no further than this project by creator “rgco.” 

The handheld device uses a 20-60 turn coil of 26AWG enameled wire, connected across an Arduino Uno or Nano’s pins 8 and 10. A series of pulses is continuously sent out by pin 10, which are delayed in reaching pin 8 according to the inductance across the coil. As this coil approaches other metallic objects, the effective inductance changes, thus varying the delay in the signal reaching pin 10.

This effect is sensed by the Arduino, outputting chirps on a buzzer as audio feedback when metal is nearby. To convert it into a practical device, the Nano configuration is stuffed into a Tic Tac container, with the coil held at a distance with two skewer sticks.

With an Arduino, 10m of wire and a 100 Ohm resistor you can build a metal detector in 10 minutes! It is based on sound physics and works for a large range of coil sizes and shapes. The sensitivity is not enough for treasure-hunting, but it can be made into a small hand-held device that is very useful indoors to check for the presence of metals. It will help you find nails inside wood or heating pipes in the wall, and to check the composition of tools and furniture. The method can also be used to integrate as a sensor, integrated with more elaborate projects.

While using a metal detector to find valuable jewelry, and less valuable aluminum cans, can be interesting, the more accurately you can pinpoint the “treasure,” the easier it is. For excellent accuracy while maintaining a wide sensing field, Maker “TechKiwiGadgets” built a detector with not one, but four sets of sensing coils, all controlled using an Arduino Mega.

The device generates and senses a magnetic pulse from each set of coils, which is modified if there is a metallic object present. In search mode, the four signals are combined into a single display, and once an object is located, the four sensors can be shown in a split-screen. You can then dig where, and only where, it’s needed, minimizing work and your environmental impact!

Want to create your own? Check out TechKiwiGadgets’ Instructables page for more details and see a demo of it below!

Evan Kale is back with another hack. This time, the YouTuber decided to convert a weed wacker-like toy into a metal detector with the help of an Arduino Uno.

As Kale explains, the project is based on a Colpitts Oscillator, which combines an LC circuit with a transistor amplifier for feedback. The frequency of oscillation is somewhere in the 100KHz range, which cannot be heard by humans. Enter the Arduino. When the trigger is pressed, an Arduino program translates the oscillation into an audible tone that is played out of the speaker. When the oscillation exceeds a certain threshold, it also emits a celebratory light show because… why not?

Kale walks through his entire build—along with the science of it all and how it works—in the video below. The schematics can be found on Imgur.