How to make a powerful homemade metal detector

If you like DIY and adventure, one of the best instruments you can have is a home metal detector. With it, you will not only have fun scouring the countryside in search of "hidden treasures", but also have fun assembling this device with your own hands and following a few simple steps. To do this, there are several methods to do it, although some propose to use an old radio that you do not use, but the results obtained will not be so good.

This article proposes a more professional metal detector with greater power that allows you to detect smaller or deeper metal parts. That will save you from investing a significant amount of money in a metal detector, which can vary greatly in price. For example, you can find some very cheap and that will give poor results for around € 40 to € 4800 in some professional products.

Method 1: homemade metal detector using a radio

portable am fm radio

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

Necessary materials

Each filtering bag materials are very cheap and you can find them at home:

  • No products found. battery powered that supports AM frequencies. Can be any radio cheap of which you can have at home without using or acquiring one. It doesn't have to be a big deal ...
  • No products found., it is not necessary that it have peculiar characteristics either.
  • No products found., it can be insulating or American. It is simply to link the devices.
  • A long stick, such as a mop, broom, an unused selfie stick, a pole, or if you prefer, a adjustable stick in length of those used by painters.
  • Others: if you prefer to adjust it for your needs, you can equip it with a padded handle, or whatever you need.

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 it is connected, it will emit waves that will collide with the metal and will make the radio set to AM sound differently when you find some metal. Therefore, you must paste both components together and in such a way that you can turn them on easily.
  2. Once put together, you need to make sure that the radio is on full volume so you can hear the oscillations well. If it detects any metal, the noise it will make will not be too loud, so it is best to do it in a quiet environment.
  3. You make sure that when you plug in the calculator there is interference on the radio. That is why they must be very close together and well fixed with the adhesive tape. Try this by bringing a metal object closer and seeing how the noise the radio makes is altered, that will be the same effect that occurs when you scan 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 may prefer to leave it without a stick ...

Method 2: homemade metal detector using Arduino

Es a good option to go out into nature and discovering metallic veins of gold next to rivers, or simply looking for things that someone lost or buried there ...

Su operation is simple. How are you going to 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 in inductance and in turn a change in oscillation in the circuit. The oscillation before and after the inductor is 180º 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.

La arduino board it will take care of processing 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).

Necessary materials

A plate is to be used Arduino UNO Rev 3 and a Colpitts oscillator plus:

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

Step-by-step construction

For its construction:

For more information on Arduino programming, you can download our free ebook.

  1. Create the circuit with the board first Arduino and the oscillator As can be seen in diagram 1.
  2. Program the Arduino board with this code for Arduino IDE. You have the code in a well-commented .ino on GitHub.
  3. Replace the original circuit of the weed-whacker you created by. It should look like image 2.
  4. Close the tool and connect coil at the bottom of this tool and connect it to the circuit as seen in image 3.

As a final clarification, say that if you configure it with the sensibility lower, it will be able to detect large metal objects such as soda cans, cell phones, work tools, etc., within a few centimeters of depth. But if you set it to high sensitivity, it can detect small metal objects like rings, screws or coins at the same depth. If you want, you can increase the area of ​​the inductor's magnetic field by increasing the current flow through it, that is, increasing the input voltage of the oscillator or 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 on amazon or other specialized stores. Here are three of the recommended ones for three different prices, to adapt it to all pockets:

  • Cheap detector: With No products found. You can search for old coins, metals, and all kinds of buried metals for a small fee. Ideal for beginning hobbyists 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 an adjustable handle.
  • Middle detector: The No products found. It is a fairly professional but moderately priced metal detector, ideal for more experienced hobbyists or professional use. It can detect metals and also electrical wiring. With 8-mode adjustment to modulate the sensitivity and depth at which you want to search.
  • Expensive detector: No products found. It is one of the best professional metal detectors that you can find on Amazon. It is compact, lightweight and submersible. It can detect small metals even at a distance of 3 meters deep.
  • Wall detector: The No products found. Allows you to detect cables or metal 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. Also, it will show your approximate distance on your LCD screen.

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

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  1.   Rene Santiago Batista Aja said

    My great-great-grandfather was the owner of large coffee plantations for slaves and according to family tradition he left a huge treasure buried in one of his estates. I am sure that if the story is true, it is still twice since he buried it. I need a powerful metal detector .but I don't have the resources to opt for it. If it were something easy to build, it would be very useful, but of good scope.