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Homemade metal detector Butterfly
Vladimir Andreevich from the city of Lviv sent a description of the original design of a simple metal detector. The design of the metal detector “Butterfly” with its own hands is easy to repeat at home, scarce and expensive parts do not apply.

Features of the metal detector “Butterfly”:

The air detection distance of the 5 cop of the USSR is 15 cm;
The air-opening distance of the rolling cover for preservation is 30 cm;
The air detection distance of the sewer hatch is 60 cm;
Automatic adjustment for the ground;
By the nature of the beep, you can determine the type of metal;
The maximum current of consumption is 15 mA;
ample opportunities to improve the metal detector.
How it works

The principle of operation is based on the property of two generators to synchronize their frequencies. Both generators are exactly the same in design, coils are located in the same plane, the distance between them is 10 cm. When a metal object enters the magnetic field of one of the coils, the synchronization is disrupted and a signal appears in the headphones.

Design and details

Most parts and materials can be borrowed from expired equipment, for example, for coils you can take a wire from a deflecting system, or loops of demagnetization of an old TV. There you can also find almost all the other details for the scheme.

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As a rod for a metal detector, the author uses a section of a metal-plastic water pipe one meter long and an external diameter of 26 mm. The handle from the handle of the bicycle is placed on top of the barbell.

The scheme is assembled by hinged installation and together with coils (the distance between the coils - 10 cm) is glued with oil varnish to the base, made of cellular polycarbonate or plywood thick - 8 mm, measuring 20 by 45 cm.

The diameter of the reels for the metal detector is about 20 cm. The diameter of the wire is 0.3-0.6 mm. 30 turns, from 10 turns - recusal. Be sure to mark the conclusions of the coils, then to solder properly. The coils should be exactly the same.

A rod and a node of maximum sensitivity are attached to the base. The wire with the headphone jack stretches out inside the barbell upstairs. The metal detector is turned on and off with a headphone jack. When the connector is inserted - the metal detector works, the connector is removed - the power is turned off.

As a power battery is used for a mobile phone, it is glued along with the whole scheme to the base. Power wires of generators and from the charging connector are glued to the battery contacts. The charger - from any mobile phone, the connector - any suitable.

The bar is attached to the base with plastic screws from adhesive tubes, and metal screws with lamb nuts can also be used.

The coils and scheme are covered with furniture or parquet oil varnish. After drying the varnish cover all the silicone.

Where to dig with a metal detector under the new law
To set up the metal detector during the search, a plastic nut and screw with a piece of ferrite or aluminum (you can take the frame from the inductive coil) are used. The thread is lubricated with a thick lubricant to smooth the rotation. The adjustment node is glued next to the coil.

Armrest for homemade metal detector

To make the armrest will need sections of a water pipe with an external diameter of 20 mm and a ventilation pipe with a diameter of 95 mm, two self-cutters, a piece of cloth and glue. The armrest tube is inserted into the metal detector tube.


The set-up is done before the varnish coils are filled, away from metal objects. We connect the headphones. It’s squeaking right away. If you don’t squeak, it’s a mistake in the scheme. Or, as is rare, the generators are synchronized. Take a piece of aluminum or a larger can. We bring to the coils alternately. Above one squeak is even higher, above the other falls silent. On the reel where it falls silent, bend inwards the last turn until it falls silent. On any coil on top we glue a tube with ferrit.

Working with the Metal detector “Butterfly”

We plug in the headphones, thus turning on the metal detector. Adjust the frequency to the brink of synchronization. It is desirable that the headphones were heard clicks, this is the maximum sensitivity. When searching, by dramatically changing the frequency of the signal, we determine the presence of a metal object in the ground.

If the object is found, iron, small size, the frequency will decrease until the signal is lost. If an object is made of colored metal, or iron with a large surface area, the frequency will increase. When searching for large items, adjust the frequency before the failure, so that the signal was not.