home » Construction » Detailed instructions for assembling a metal detector with your own hands. How to make a simple metal detector with your own hands - step-by-step instructions Buy a homemade metal detector with discrimination

Detailed instructions for assembling a metal detector with your own hands. How to make a simple metal detector with your own hands - step-by-step instructions Buy a homemade metal detector with discrimination

Many radio amateurs dream of making a metal detector with their own hands. It can be used to detect metal objects in the ground at different depths. On the Internet you can find many photos of metal detector circuits that are simple to use. Any beginning radio amateur can make them.

Easy assembly

For example, let's take the circuit of a simple metal detector. It is of the pulse type, but due to the simplicity of its design it is not able to distinguish between types of metals. Therefore, it will not be possible to operate such a device in areas where objects made of non-ferrous metal are found.

How to assemble the device

To assemble a simple metal detector circuit with your own hands, you will need the following tools and parts:

Presence of KR1006VI1 microcircuit and IRF740 transistor;
Presence of K157UD2 microcircuit and VS547 transistor;
Copper conductor 0.5mm (PEV);
NPN transistor;
Housing, and various materials for it;
Solder, flux, soldering iron.

Other details are shown in the diagram. In order for the assembled circuit to be securely fastened, a plastic case should be prepared for it.

The bar can be made using a small diameter plastic tube. A metal detecting coil will be installed in its lower part.

Beginning of work

The circuit diagram of a metal detector using transistors is a common option for many models. Assembly begins with the manufacture of a printed circuit board. Next, all radio elements are mounted on it exactly as shown in the diagram.

To ensure stable operation of the device, film capacitors are used in the circuit. This will allow you to use it in cold weather without any problems.

Power type for device

The device can operate on a voltage of 9-12 V. Due to its sufficient power, energy is intensively consumed. It is recommended to install up to 3 batteries and connect them in a parallel circuit. You can use a small battery that has a charger. Thanks to its capacity, the metal detector will work longer.

Coil installation

There are different types and schemes for the manufacture of metal detectors, but in the pulsed version, inaccuracies are allowed in the installation of the coil. When making a mandrel, the winding should be up to 25 turns, and the diameter of the ring should be 1900-200mm.

All turns of the coil must be insulated with electrical tape. Reducing the number of turns to 22, and the mandrel diameter of 270 mm will allow you to detect objects at a deeper location. The wire cross-section on the coil is 0.5 mm.

When the winding is ready, it is attached to a durable housing with sufficient rigidity, on which there should be no metal parts. Otherwise, they are able to shield the magnetic field, and the operation of the metal detector will be disrupted. The body can be made of wood or plastic, but so that it can withstand various impacts that can damage the coil.

The leads on it should be soldered to a conductor of several cores. The best option is a two-core wire.

Installation of the non-ferrous metal detector circuit is a little more complicated, and high precision must be observed in the manufacture of the coil. The number of turns reaches 100pcs, and a vinyl tube is used as the core. Foil is wound on top of the winding, which forms an electrostatic screen.

Device setup

If the installation of the circuit is done exactly, then the metal detector will not need additional settings. Its sensitivity indicators will be maximum, but fine adjustment is possible through variable resistance R13. It must be performed until rare clicks begin in the headphones.

If the adjustment fails, then the resistances must be replaced with R12. When the resistor adjustment is in the middle, this will be considered normal.

An oscilloscope is suitable for checking the device. The frequency of transistor T2 is measured on it, and the pulse should last up to 150 ms. The optimal operating frequency is up to 150 Hz.

How to use the device

You should not rush and start working immediately after turning on the metal detector. It should stabilize, so you need to wait up to 20 seconds. After adjusting the resistor appropriately, you can start looking for metal.

Note!

Photo of the metal detector circuit

Note!

It was developed on the basis of the already known device "Terminator Pro". Its main advantage is high-quality discrimination, as well as low current consumption. Also, assembling the device will not be expensive, and it can work on any type of soil.

Here are brief characteristics of the device
According to the principle of operation, the metal detector is also pulse-balanced.
The operating frequency is 8-15 kHz.

As for the discrimination mode, it uses two-tone voice acting. When iron is detected, the device emits a low tone, and if non-ferrous metal is detected, the tone will be high.

The device is powered from a 9-12V source.

There is also the ability to adjust sensitivity and there is manual ground adjustment.

Well, now about the main thing, about the detection depth of the metal detector. The device is capable of detecting coins with a diameter of 25 mm at a distance of 35 cm in the air. A golden ring can be caught at a distance of 30 cm. The device detects a helmet at a distance of about 1 meter. The maximum detection depth is 150 cm. As for consumption, without sound it is about 35 mA.

Materials and tools for assembly:
- mini drill (the author has a homemade one from a motor);
- wire for winding the coil;
- four-core shielded cable;
- soldering iron with solder;
- materials for the manufacture of the case;
- printed circuit board;
- all the necessary radio components and their ratings can be seen in the photo of the diagram.

Metal detector manufacturing process:

Step one. Board manufacturing
The board is made by etching. Next, you can drill holes, their diameter is 0.8 mm. For these purposes, the author uses a small motor with a drill installed.

Step two. Board assembly
Assembly must begin by soldering the jumpers. After this, you can install panels under the microcircuits and solder other elements. For quality assembly, it is very important to have a tester that can measure the capacitance of capacitors. Since the device uses two identical amplification channels, the gain along them should be as close as possible to the same value, that is, be the same. Both channels of the same cascade must have the same readings when measured by the tester.

You can see what the already assembled circuit looks like in the photo. The author did not install a unit that determines the degree of battery discharge.

After assembly, the board must be checked with a tester. You need to connect power to it and check all strategically important inputs and outputs. Everywhere the power supply must be exactly the same as in the diagram.

Step three. Assembling the coil
The DD sensor is assembled according to the same principle as for all similar balancers. The transmitting coil is designated by the letters TX, and the receiving coil by RX. In total, you need to make 30 turns of wire folded in half. The wire used is enameled, with a diameter of 0.4 mm. Both the receiving and transmitting coils are formed by double wires, resulting in four wires at the output. Next, the tester needs to determine the arms of the windings and connect the beginning of one arm to the end of the other, as a result, the middle terminal of the coil is formed.

To fix the coil after winding, you need to wrap it well with thread and then soak it with varnish. After the varnish has dried, the coils are wrapped with electrical tape.

Subsequently, a screen of foil is made on top; between the beginning and the end you need to make a gap of about 1 mm to avoid a short-circuited turn.

The middle TX pin must be connected to the board ground, otherwise the generator will not start. As for the average RX output, it is needed for frequency adjustment. After adjusting the resonance, it needs to be insulated and the receiving coil turns into a regular one, that is, without a lead. As for the receiving coil, it is connected instead of the transmitting coil and set to 100-150 Hz lower than the transmitting coil. Each coil must be configured separately; when tuning, there should be no metal objects near the coil.

To balance, the coils are shifted, as can be seen in the photo. The balance should be within 20-30 mV, but not more than 100 mV.

The operating frequencies of the device range from 7 kHz to 20 kHz. The lower the frequency, the deeper the device will go, but at low frequencies the discrimination becomes worse. Conversely, the higher the frequency, the better the discrimination, but the smaller the detection depth. The golden mean can be considered a frequency of 10-14 kHz.

To connect the coil, a four-core shielded wire is used. the screen is connected to the body, two wires go to the transmitting coil and two to the receiving coil.

Among amateur radio designs, developments that help detect metal objects hidden in the ground are of particular interest. Especially if the latter are small in size, lie at a considerable depth and are also non-ferromagnetic.

Quite a few good electrical diagrams of such devices, called metal detectors by analogy with well-known military developments, and descriptions of fully functional designs have been published in various technical
Publications, but they are often designed for trained, experienced home-made workers who have a good material base and scarce parts.

But even a beginner can easily repeat and make the design we propose. Moreover, it will be quite possible to purchase the necessary parts (including a 1 MHz quartz resonator). Well, the sensitivity of the assembled metal detector... It can be judged at least by the fact that with the help of the proposed device it is easy to find, for example, a copper coin with a diameter of 20 mm and a thickness of 1.5 mm at a depth of 0.9 m.

Operating principle

It is based on a comparison of two frequencies. One of them is reference, and the other is variable. Moreover, its deviations depend on the appearance of metal objects in the field of the highly sensitive search coil. In modern metal detectors, to which the design under consideration can quite rightly be included, the reference generator operates at a frequency that is an order of magnitude different from that which appears in the field of the search coil. In our case, the reference generator (see the circuit diagram) is implemented on two logic elements ZI-NOT integrated DD2. Its frequency is stabilized and determined by a quartz resonator ZQ1 (1 MHz). The generator with varying frequency is made on the first two elements of the IC DD1. The oscillatory circuit here is formed by the search coil L1, capacitors C2 and SZ, as well as a varicap VD1. And to adjust to a frequency of 100 kHz, use potentiometer R2, which sets the required voltage to the varicap VD1.

Fig.1. Schematic diagram of a highly sensitive homemade metal detector.

Logic elements DD1.3 and DD2.3, operating on mixer DD1.4, are used as signal buffer amplifiers. The indicator is a high-impedance BF1 telephone capsule. And capacitor C10 is used as a shunt for the high-frequency component coming from the mixer.

The configuration of the printed circuit board is shown in the corresponding illustration. And the layout of radio elements on the side opposite the printed conductors is shown here in a different color.

Fig.2. Printed circuit board of a homemade metal detector, indicating the locations of the elements.

The metal detector is powered by a 9 V DC source. And since high stabilization is not necessary here, a Krona type battery is used. Capacitors C8 and C9 work successfully as a filter.

The search coil requires special precision and attention during manufacture. It is wound on a vinyl tube with an outer diameter of 15 mm and an inner diameter of 10 mm, bent in the shape of a circle 0 200 mm. The coil contains 100 turns of PEV-0.27 wire. Once the winding is complete, it is wrapped in aluminum foil to create an electrostatic shield (reduce the effect of capacitance between the coil and ground). It is important to prevent electrical contact between the winding wire and the sharp edges of the foil. In particular, “wrapping obliquely” will help here. And to protect the aluminum coating itself from mechanical damage, the coil is additionally wrapped with insulating bandage tape.

The diameter of the coil may be different. But the smaller it is, the higher the sensitivity of the entire device becomes, but the search area for hidden metal objects narrows. When the diameter of the coil increases, the opposite effect is observed.

Work with a metal detector as follows. Having placed the search coil in close proximity to the surface of the earth, adjust the generator with potentiometer R2. And in such a way that the sound in the telephone capsule cannot be heard. When the coil moves above the surface of the earth (almost close to the latter), the treasured place is found - by the appearance of sound in the telephone capsule.

When using the device discussed above to find objects hidden in the ground that are of archaeological and national cultural value, prior permission is required from the relevant authorities.

Attention!!! The information contained on this page has been added from unverified sources and may be out of date and contain errors. Therefore, it is provided for informational purposes only.

N. Kochetov, based on materials from “Mlad Constructor”

Today, there are many different ideas on the Internet that allow you to make a metal detector with your own hands at home. Some of them require certain skills in working with electrical appliances, soldering and understanding of simple electrical circuits, while some do not require any knowledge in these areas to create. However, there are many non-working, fake methods floating around the Internet, captivating with their simplicity and accessibility. It is very easy for an inexperienced person to fall for the bait of deceivers - to spend time and effort on making a device that is obviously not working and lose all interest in it. But don’t be discouraged, then readers of “” will be provided with an interesting and really working scheme for creating a homemade metal detector!

Idea No. 1 – Discs in action!

Surely you have already seen or heard that you can make the simplest metal detector yourself using a CD and DVD disc, as shown in the photo. The scheme is quite simple and does not require any professional tools or skills.

This instruction is the most popular due to the availability of the necessary components and the ease of assembly; you just need to connect a couple of wires and the crown together and the device is ready. At the same time, the characteristics of this device are attributed to be quite good - it finds a coin at a distance of 25-30 cm, which is quite enough for searching for coins and treasures. However, unfortunately, this instruction is fake.

The fact is that the metal detector itself is a rather complex device; its operation is based on several physical phenomena at once. Therefore, a calculator and a pair of disks cannot even remotely replicate its operating principle, no matter what the creators of such instructions claim, who sometimes write that they even find treasures with the help of such homemade products.

It is very easy to understand that you are being deceived even without knowledge of the laws of physics. The wires from the headphones that need to be attached to the disk do not actually contact it in any way, since the copper is under a layer of varnish insulation, which must be removed by firing and labor-intensive cleaning of carbon deposits; of course, none of the authors of the instructions does this in their devices . Consequently, the headphones are simply not connected to any circuit, and there can be no talk of any work, much less metal detecting.

A real metal detector operates on the basis of an induction balance; its design must have at least one coil of copper wire. When a metal object enters the field of the coil, its characteristics or the received signal, depending on the design, change. These changes are recorded and amplified by the circuit, and also displayed in a form understandable to humans, usually by means of sound signals.

Video instructions for assembling a metal detector from disks

Idea No. 2 – Metal detector according to the “Pirate” scheme

This is a scheme that has been tested by many DIYers and allows you to achieve good results. It contains two microcircuits, so you will have to make a small printed circuit board or assemble the device on a breadboard. But don’t be alarmed, anyone can make this option if they put in the necessary effort. Below is an electronic circuit diagram of the device and a printed circuit board for it.

The coil is made of enameled copper wire with a diameter of 0.5 mm. Winding should be done on a frame with a diameter of 200-260 mm, the number of turns from 21 to 25. For reliability, it is better to install the coil in a protective plastic casing, which can then be attached to a handle made of PVC pipes.

After assembling the metal detector, it must be checked. The procedure for use is as follows: turn on the device away from metal objects for about 30 seconds so that its operation is more stable, then rotate the variable resistor knob for coarse and fine adjustment, you need to achieve rare clicks. When metal enters the action area, you will hear a characteristic sound.

Below is a detailed video assembly instruction, which clearly shows all the stages of creating a homemade metal detector.

Metal detectors or metal detectors are a diverse family of measuring instruments, the operation of which is based on differences in the electromagnetic radiation of objects.

Using a metal detector

Professional highly sensitive metal detectors are used in the daily work of various inspection points; they are used to conduct search and investigative activities of police and rescue services.

A huge army of amateur treasure hunters around the world practice long and leisurely hikes with metal detectors. Sometimes such entertainment brings income and even fame.

Nowadays, an industry of detector (recognition) devices has already been established for all occasions, differing not only in operating principles, but also in a wide range of prices and technical characteristics.

Simple magnetic detectors

The operating principle of the simplest metal detector is based on electromagnetic induction - the device contains an electromagnetic coil, which, due to oscillations and distortions of its field, detects nearby electrically conductive and ferrous-magnetic materials, creating an audio or visual signal.

The first experience of assembling a metal detector at home can be the beginning of a serious hobby: new design solutions and even inventions in this field of applied radio electronics are not excluded even at the amateur level.

The diagram shows the structure of a simple low-frequency magnetic detector.

Hundreds of different designs are used in the production of metal detectors. In order to implement one of them yourself, you will need to make a printed circuit board with your own hands, purchase the necessary coils, transistors, resistors, capacitors, etc., and assemble the device.

Metal detector made from improvised means

Another option is to assemble a metal detector from available materials; it is more suitable for humanists and novice technicians with a passion for finding treasures and lost artifacts.

During operation of such a homemade device, electromagnetic waves emitted by the calculator are caught on the AM band of the receiver.

An indicator of the location of an object in this device is the rotation of the electromagnetic field during re-emission, which changes the parameters of the sound signal. A photo of such a do-it-yourself metal detector can be found on the Internet and at the end of our material.

To use such a prefabricated version, you do not need a detailed diagram or assembly instructions, but compliance with certain requirements for the two main components of a homemade detector, namely a properly working calculator and a radio receiver.

Both devices must be from the cheapest category, the receiver must have an AM band and a magnetic antenna, and the calculator must emit pulsed radio interference during operation.

To work on the model, you will also need a suitable sized plastic box with an opening lid, like a book, which will become the body of the finder.

An old CD box is ideal for these purposes. To attach the parts you will need double-sided tape.

Metal detector assembly

Securing the instruments inside the case: a strip of tape is attached to the back of the instruments, then the calculator is placed at the base of the box, the receiver is on the inside of the lid.
Setting up the receiver: you need to turn on the receiver at maximum volume and select the upper position of the AM range, free from radio broadcasts and interference.
Adjusting the calculator: when the calculator is turned on, the receiver should respond with a sharp noise, hum or wheezing; if this does not happen, you need to adjust the range.
Fixing the position: we begin to smoothly close the box until the sound disappears or becomes more uniform and fix the box doors in this position, using a cube of foam plastic, rubber bands, etc.
The metal detector is ready. If there is a product with electromagnetic radiation nearby, the receiver will sound an alarm.

By combining elements of other radio devices in a simple detector, you can observe the operating principle of metal detectors in action and enjoy your first search expedition.

Note!

Such a detector, assembled at home, can be tested to search for coins or metal construction debris lying in the surface layer of the earth in almost any area, on any open ground.