How to make a powerful home metal detector

If you like DIY and adventure, one of the best instruments you can have is a homemade metal detector. With it, you will not only have fun searching the countryside for “hidden treasures”, but also have fun setting up this device with your own hands and following a few simple steps. There are several methods to do this, although some propose to use an old radio that you do not use, but the results will not be as good.

This article proposes a more professional metal detector with higher power that allows you to detect smaller metal parts or those that are located at greater depth. This will avoid you to invest a significant amount of money in a metal detector, which can vary a lot in price. For example, you can find some very cheap ones that will give poor results for about 40 to 4800 euros on some professional products.

Method 1: home metal detector using a radio

radio am fm portable

It can be good for locating metals that are not too far away or even check if there are wires in the wall before drilling and get a good scare .

Materials needed

The materials are very cheap and you can find them at home:

  • Portable radio that supports AM frequencies. It can be any cheap radio that you can have at home without using or buying one. It doesn’t have to be much…
  • Cheap portable calculator, it is also not necessary to have peculiar characteristics.
  • , can be insulating or American. It is simply to join the devices.

Step by step construction

Once you have all the elements, the construction is very simple following these steps:

  1. The wave emitter used will be the calculator. When connected, it will emit waves that will collide with metal and make the radio set to AM sound different when you encounter metal. Therefore, you must glue both components together and in such a way that you can easily turn them on.
  2. Once they are put together, you must make sure that the radio is at full volume so that you can hear the oscillations well. If it detects any metal, the noise it will make will not be too loud, so it is better to do it in a quiet environment.
  3. You should make sure that when you connect the calculator there is interference on the radio. That’s why they should be very close together and well fixed with the adhesive tape. Try this by bringing a metal object close to you and seeing how the noise the radio makes is altered, that will be the same effect as when you track in the field.
  4. Finally, you can add a long stick attached to these two devices to search more comfortably without bending over, although if you are going to use it for walls you might prefer to leave it without a stick…

Method 2: home metal detector using Arduino

It’s a good option to go out into the wild and discover metal gold veins next to rivers, or just look for things that someone lost or buried there…

Its operation is simple. As you will have a capacitor and inductor in series, and when a metal approaches the inductor, and changing the magnetic permeability of the inductor core, causing a change of inductance and in turn a change of oscillation in the circuit. The oscillation before and after the inductor is out of phase with each other, as in a Colpitts oscillator. He will be in charge of generating a constant frequency so that the metals change it and an audible tone sounds.

The Arduino board will process the signal instead of using a second circuit to compensate for the oscillation. The Arduino board will store the fixed frequency and continuously compare the input frequency of the detector circuit with the stored frequency to see if there are variations (metal is detected).

Materials needed

It will use a Arduino UNO Rev 3 plate and a Colpitts oscillator and also:

  • Weed-whacker tool (the typical cutters) or you can make a case to house the circuit or print it with your 3D printer. This element is ideal because it has:
    • A trigger button that will be used to activate the speaker.
    • A side button to set the fixed frequency.
    • A battery compartment (3 AA batteries) with the on/off switch.
    • A speaker for playing the tones.
    • A motor with LEDs that will jump when something is detected.
    • A circular head where to place the wire coil for the circuit inductor.
  • A potentiometer to modify the tone sensitivity.
  • A coil made with 26 turns of 26 AWG wire around a 5.5″ diameter reel.
  • The circuit (explained in the following section) for which the original circuit of the trimmer has to be replaced by this one on a perforated plate or PCB.

Step by step construction

For its construction:

For more information about Arduino’s programming, you can download our free ebook.

  • First create the circuit with the Arduino board and the oscillator as shown in diagram 1.
  • Program the Arduino board with this code for the Arduino IDE. The code is in a well commented .ino in GitHub.
  • Replace the original weed-whacker circuit with the one you have created. It should look like in image 2.
  • Close the tool and connect the coil to the foot of this tool and connect it to the circuit as shown in image 3.

As a final clarification, say that if you set it with the lower sensitivity, it will be able to detect large metal objects like soda cans, mobile phones, work tools, etc., at a few centimeters depth. But if you set it to high sensitivity, it can even detect small metal objects like rings, screws or coins at the same depth. If you want, you can increase the area of the magnetic field of the inductor by increasing the current flow through it, that is, by increasing the input voltage of the oscillator or by increasing the number of turns of the coil wire .



Method 3: buy a metal detector


Metal detector

If you don’t want to create your own metal detector, you can buy one at Amazon or other specialized stores. Here are three of the recommended ones for three different prices, to suit all pockets:

  • Cheap detector: with you can search for old coins, metals and all kinds of buried metals for a small fee. Ideal for beginners who want something more than decent for their searches and that is of good quality. It allows you to adjust the sensitivity and depth, and the kit also includes other accessories such as a shovel, batteries and adjustable handle.
  • Medium detector: the is a quite professional metal detector but with a moderate price, ideal for amateurs with more experience or professional use. It can detect metals and also be placed on elećtrico. With 8 mode adjustment to modulate the sensitivity and depth you want to search.
  • Expensive detector: Minelab Equinox 600 EQX11 is one of the best professional metal detectors you can find on Amazon. It is compact, lightweight and waterproof. It can detect small metals even at a distance of 3 meters deep.
  • Wall detector: the allows to detect metal cables or pipes in the wall or underground to avoid digging or drilling in an inappropriate place at home. It is practical and works with a 9v battery. In addition, it will show the distance at which it is approximately on its LCD screen.

Now, whether you have chosen to create it on your own or have bought it, you can have fun going out into nature to discover metals underground. Maybe you’ll find something interesting!

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