home Boiler room DIY metal detector diagram close-up. DIY metal detector: detailed instructions for assembling at home

DIY metal detector diagram close-up. DIY metal detector: detailed instructions for assembling at home

Finding artifacts underground is a fairly popular activity. For some, this is a profession, others are simply interested in archaeology. There are numerous groups of treasure hunters: both romantics and pragmatic treasure hunters. All these people are united by one passion: searching for metal objects hidden at various depths.

Just because you have an accurate map showing where the treasure is buried, or plans for fighting during the war, this does not guarantee success. You can shovel tons of soil, and the desired item will calmly lie a couple of meters from the active search site.

To search for gold and less valuable metals, you will need a metal detector that you can make yourself.

Important information: The use of such devices is not prohibited by law. However, there are penalties for the consequences of such a search regarding excavations, as well as the recovery of discovered objects.

We won’t go into details; that’s the topic of another article. Simply put: if you find a gold ring on the beach, or a handful of Soviet coins in the forest, there will be no problems associated with the use of electronic search tools.

But for recovered bronze spoons that are 100 years old or older, you can get a real sentence or a large fine.

Nevertheless, devices for searching for metal objects in the depths of the earth are freely sold, and those who want to save money can make a metal detector with their own hands at home.

Operating principle of the device

Unlike ground detectors, which work using waves of different frequencies or ultrasound, a metal detector (either factory-made or home-made) works with inductance.

The coil emits an electromagnetic field, which is then analyzed by the receiver. If any object that conducts electric current or has ferromagnetic properties is in the coverage area, the field format is distorted. More precisely, under the influence of the active field of the coil, the object forms its own. This event is recorded by the receiver, and an alert is generated: the instrument needle moves, a tone sounds, and indicator lights light up.

Knowing the operating method, you can calculate the electrical circuit and create a powerful metal detector with your own hands. The complexity of the design depends only on the availability of the element base and your desire. Let's look at several popular options for assembling a homemade metal detector:

The so-called "butterfly"

This nickname was received due to the characteristic shape of the platform on which the inductors are located.

The arrangement of the elements is related to the operating principle. The circuit is made in the form of two generators operating at the same frequency. When identical coils are connected to them, an induction balance is created. As soon as a foreign object with electrical conductivity gets into the electromagnetic field, the balance of the field is destroyed.

Generators are implemented on NE555 chips. The illustration shows a typical diagram of such a device.

The coil for the metal detector (there are two of them, in the diagram: L1 and L2) is made by hand from wire with a cross section of 0.5–0.7 mm². The ideal option is a transformer winding copper core in varnish insulation (removed from any unnecessary transformer). The characteristics do not have to be maintained with pinpoint precision, under one condition: the coils must be identical.

Approximate parameters: diameter 190 mm, each coil has exactly 30 turns. The assembled product must be monolithic. To do this, the turns are grabbed with a mounting thread and filled with transformer varnish. If this is not done, vibration of the turns will throw the circuit off balance.

Electrical diagram

There are two manufacturing options:

given the small number of elements, you can assemble it on a breadboard by connecting the legs of the parts using conductors;
For accuracy and reliability, it is better to etch the board according to the proposed drawing.

Any “snot-based” soldering can fail in the field, and you will be offended for wasting your time.

Just like a transistor metal detector, the NE555 device needs fine tuning before use. The diagram shows three variable resistors:

R1 is designed to adjust the frequency of the generator and achieve that same balance;
R2 coarsely adjusts sensitivity;
Using resistor R3, you can set the sensitivity with an accuracy of 1 cm.

Information: This scheme cannot discriminate against metals. The seeker only makes it clear that the object exists. And by the tone of the signal (based on your experience) you can determine the approximate volume and depth of the deposit.

The power supply is quite universal: 9–12 volts. You can select a battery from an uninterruptible power supply, or assemble a power supply from AAA batteries. A good option is 18650 batteries (they are also used for vaping).

Butterfly setting

The principle of operation is described above, so let’s just look at the technology. We set all resistors to the middle position, and ensure that the synchronization of the generators is disrupted. To do this, we fold the coils in a figure eight and move them relative to each other until the squeaking turns into crackling. This is a synchronization failure.

We fix the rings and rotate the resistor R1 until a steady crackling sound appears at even intervals.

By bringing metal objects to the place where the coils overlap (this is the search point), achieve a steady squeak. The sensitivity is adjusted by resistor R2.

All that remains is adjustment with resistor R3, which is used rather to correct the voltage drop in the power source.

Mechanical part

A do-it-yourself metal detector rod is made from a lightweight plastic pipe or wood. The use of aluminum is undesirable as it will interfere with operation. The circuit and controls can be hidden in a sealed housing (for example, a junction box for wiring).

The butterfly finder is ready to go.

Pirate

Another popular pulse model for beginner treasure hunters is the “Pirate” metal detector. It is also easy to make with your own hands, detailed instructions in two versions:

It is advisable to bring the power supply closer to 12 volts, since the quality of operation depends on the voltage. Printed circuit boards have already been tested, both options are shown in the illustration.

The coil (in this case one) is made from the same 0.5 mm transformer wire. The optimal diameter is 20 mm, the number of turns is 25. Since we are making the “Pirate” metal detector with our own hands, the external design fades into the background. Any materials that you were ready to throw away will do.

It is better to make the handle detachable for ease of transportation. We remember that the use of metals is unacceptable.

Sensitivity is adjusted by two variable resistors in real time while searching. No fine tuning of the generator is required.

And if you manage to properly seal the case, you can start searching for “treasures” in the beach surf, and even at the bottom of the reservoir.

It is more difficult to make an underwater metal detector with your own hands, but it will give you an undeniable advantage over your competitors.

Improved performance

You can make a deep metal detector with your own hands from a ready-made “Pirate” without additional costs. There are two ways to do this:

Increasing the diameter of the inductor. At the same time, downward permeability increases significantly, but sensitivity to small objects decreases.
Reducing the number of coil turns while simultaneously adjusting the circuit. To do this, you will have to sacrifice one coil for experiments. We remove (and cut off) turn after turn until we see that the sensitivity begins to decrease. We remember the number of turns at maximum parameters, and make a new coil for this circuit. Then we change the resistor R7 to a variable one, with similar power parameters. After conducting several experiments with sensitivity, we fix the resistance and change the variable to a constant resistor.

The Pirate metal detector can be assembled using the popular Arduino controller.

It is more convenient to use such a device, but there will still be no metal discrimination.

Having figured out how to make a metal detector with your own hands for amateur tasks, we will briefly examine several serious models.

DIY metal detector Clone PI W

In essence, this is a cheaper version of the professional finder Clone PI-AVR, only instead of an LCD display, a line of LEDs is used. This is not as convenient, but still allows you to control the depth of artifacts.

The best option for the price is the CD4066 chip and ATmega8 microcontroller.

Of course, there is also a printed circuit board layout for this solution, only the control buttons are placed on a separate panel.

Programming ATmega8 is a topic for a separate article; if you have worked with such controllers, no difficulties will arise.

The powerful Clone PI W metal detector, made by yourself, allows you to find metal no more than a meter deep, although without discrimination.

Seeker "Chance"

A similar circuit on the ATmega8 controller is called “Chance”. The principle of operation is similar, only the possibility of screening out (partial discrimination) of ferrous metals has become possible.

A printed circuit board design has also been worked out, which can be successfully replaced with a classic “breadboard” for Arduino

DIY Terminator 3

If you need a homemade metal detector with metal discrimination, pay attention to this model. The scheme is quite complicated, but your efforts pay off with the coins you find, which may turn out to be gold.

The peculiarity of the “Terminator” is the separation of the receiving and transmitting coils. A 200 mm ring is made to emit the signal. 30 turns of wire are laid for it, then it is cut, as a result we get 2 half-coils with a total capacity of 60 turns (see diagram).

The receiving coil is located inside, 48 turns with a diameter of 100 mm.

The adjustment is made using an oscilloscope; after achieving optimal amplitude results, the windings are fixed in the housing by pouring epoxy resin.

Then an experimental hands-on adjustment of the discrimination switch is performed. For this, real objects made of various metals are used, and their type is marked on the mode switch (after verification).

Radio amateurs are working on an improved version of Terminator 4, but there is no practical copy yet.

Simple metal detectors from ready-made electrical appliances

Bottom line

Regardless of the complexity of the design, making a homemade metal detector will require a lot of time and effort from you. Therefore, out of curiosity, such devices are not made. But for professional use, this is an excellent alternative to factory copies.

Video on the topic

This simple metal detector can be repeated even by beginner radio amateurs. It does not contain microcontrollers, expensive or scarce parts - its basis is a simple K561LE5 microcircuit, which is often used in various Soviet equipment. You can do it at home with only a multimeter. The diagram of a simple metal detector is shown in the figure:

It has replaceable coils with a diameter of 25 to 30 cm, which allows, depending on the necessary search conditions, to detect small and large metal objects.

The operating principle is traditional for devices of this class - the metal detector has a reference generator with a frequency of 100 kHz and a metal-sensitive generator based on the DD1.2 element and one of the remote inductors connected to the generator. Headphones are connected to the mixer output.

To obtain greater sound volume, you can add a simple ULF and a small speaker. The metal detector is powered by a 9-volt Krona battery. Microcircuits in the device can be used K561LA7 or K564LE5. Resistors MLT-0.125, variable - any small size. Capacitor c3 is a tuning capacitor, from any Chinese receiver. The search winding must contain the following number of turns:

For a coil with a diameter of 25 mm - 150 turns of wire PEV-1 0.1;

For a coil with a diameter of 75 mm - 80 turns PEV-1 0.2;

For a coil with a diameter of 200 mm - 50 turns PEV-1 0.3.

After making one of the coils, we connect it to the circuit. By moving the resistor and variable capacitor C3 we achieve low-pitched sound in the headphones.

When the coil approaches the metal, the sound in the headphones should change in tone - thus determining the presence of a metal object in the search area. As a body I used a plastic box of suitable sizes.

Discuss the article MAKING A METAL DETECTOR AT HOME

Every person has his own hobby. Embroidery, weaving, hunting and fishing are the most favorite activities of people after work and during leisure. Many people get not only pleasure from this hobby, but also income. Various battle reconstructions and other archaeological works are popular at this time. This is not just work, it is a tribute to the fallen warriors from the modern generation. A metal detector will be an excellent assistant in this matter. But it is very expensive for beginner search engines to buy. How to choose it or make it yourself, later in the article.

Operating principle and details to know how to make a metal detector with your own hands

The entire operation of metal detectors depends on changes in the inductance of the coil, which is intended for searching. The description and operating diagram of such a coil is publicly available to anyone.

When any metal object enters the magnetic field of this coil, its inductance affects the frequency of operation of the generator itself to search for objects.

Afterwards there is a comparison of the frequency obtained from the object being taken into account and the reference frequency. The comparison is made using a part called a mixer. The result is converted into a signal that the user hears. A very simple and accessible way for a tool to “tell” a person that something interesting has been found or, conversely, there is nothing here.

What you need to make a metal detector:

Several chips, such as IC1 and IC2;
A powerful transistor, for example, you can use VT1-KT315;
Resistors;
Capacitors;
Coils;
Headphones;
Connectors for headphones and batteries;
Batteries.

You can also add elements such as power buttons and various wires. You also need a printed circuit board; you can make it yourself, at home, using an iron and a laser printer. The board can be created using programs that are designed for this, but when printing, it is worth positioning it in a mirror image. You need to print as densely as possible, on glossy paper. The drawing should not be exposed to dust or leave your fingerprints on it.

The scheme for making the board is clear: a printer and then an iron. An iron is used to perform an ironing procedure to print the ink with the circuit board diagram from the paper onto the PCB. But the rest of the elements for the metal detector can be obtained from an old cell phone, radio, radio, by disassembling a calculator and electric kettles. You can collect a lot of devices around the house. But it’s more difficult to get a mini-mine detector or, even better, a gold digger from all this material.

Step-by-step instruction:

Disassemble the plastic case of one disc box and remove all unnecessary items that help secure the discs in it.
Using adhesive tape, mark a spot in the center of the radio body and stick the Velcro there.
We place the radio in the box. You need to attach the radio inside the box.
Attach the calculator to the other inside of the box in a similar manner.
Tune the radio to a special band: AM. When the volume is increased, only noise should be heard.

When you detect the latest radio station on the range, you need to “get” to it as close as possible. But the interference should not disappear. After all this, roll up the box with its contents.

Tools and detailed instructions for making a DIY Butterfly metal detector

If you buy a metal detector ready-made, then you need to take into account 2 important factors: price and depth of detection of objects. If a metal detector is unreasonably cheap, then it will not work well in detection.

Another novelty in the world of treasure hunting is a metal detector with the ability to distinguish between metals.

But, if it is not possible to buy a metal detector or your hands simply grow out of the right place, then you can make it yourself at home. The Butterfly type of metal detector involves the synchronization of several coils; in appearance it resembles a butterfly.

What parts are needed to assemble such a metal detector:

Transistors: 2 pieces, KTZ15;
Capacitors type 1000 pF – 2 pieces;
Capacitors type 10000 pF - 2 pieces;
Headphones for stereo broadcasting;
Mobile device battery;
Soldering iron and material for the case with wires.

This device works in water and has a very reliable battery life - 20 or 30 hours. The product works with any type of soil. The sound is fed into the headphones, and the type of metal is determined by its type.

Popular schemes: how to make a metal detector at home

A homemade metal detector is useful not only in a hobby, when searching for precious treasures, but also for searching, for example, for a missing earring or key. Detailed instructions for assembling such a device will help you find your loss in an instant. There are a lot of schemes for assembling a metal detector from improvised materials; the materials can be found in almost any home, but understanding the operating principle and assembly diagram is more difficult. But even here you can understand everything if you really want to.

Simple fun with metal detecting can develop into great adventures and discoveries. A good metal detector will help increase interest in history, archeology and simply searching for various relics. But not everyone can take it, then amateurs collect it on their own.

Popular metal detectors:

Pirate. This metal detector has excellent sensitivity and is quite accurate. For example, it detects a small coin from 1961 at a depth of up to 50 cm. It can be additionally enhanced with various features.
Koschey. A metal detector, which is sold disassembled on an industrial scale, is a construction kit for users.
Clone. It has great sensitivity and light circuitry.

It’s not worth taking on a complex scheme at first; it’s better to start with a simple model. These metal detectors are the simplest. They are collected independently. A homemade metal detector is a very convenient thing for excavations and treasure hunting.

What is a homemade metal detector

A tool for searching for various objects made of gold and non-ferrous metals is called a metal detector. You can assemble it not only from improvised means, you can use your imagination and come up with a tool with any desired abilities. Such a product can be rewarded with good parameters that will be useful for various jobs.

When searching for various materials, a deep researcher will be an excellent assistant and will save the user from digging in an “empty” place.

The metal detector has a first sensor and a second device. The first sensor is a coil wrapped in wire. When a metal object is detected, the field changes and becomes different from what it was before. The second device registers changes in the electromagnetic field and informs the user about the finding. Therefore, when designing and assembling a metal detector with your own hands, it is worth considering the alarm capability of your user. Metal detectors come in different models or brands: Krot-M, Spektr, Kasper. It’s not at all difficult to assemble the best similar device yourself.

For easy use;
Higher class;
For professionals.

By a simple metal detector, users mean very cheap models, a little better than home-made ones or even at the same level. Masterful assembly allows you to assemble a product of higher quality. Higher-end products have replaceable sensors. And devices for professionals already have a more advanced microcircuit. With its help, you can determine not only the type of metal, but also the depth at which it is located. Such a metal detector has a higher speed of identifying an object and many other useful qualities.

Do-it-yourself metal detector: what are the operating frequencies?

It is important to remember that the metal detector should emit a uniform hum during operation, and when metal is detected, it should change the frequency of the sound and give clear signals to the user. Many people don't like the buzzing in their ears while searching, so they set the beat to zero.

All the time before detection, the finder will not make a sound, but when an object is detected, the metal detector will emit a squeak, and it will intensify as it approaches it.

Each property of a metal detection product is associated with all elements. If you lower the frequency for greater penetration, you can increase battery consumption. All metal detectors were initially classified by frequency. All parameters of the product, one way or another, are related to it and depend on it.

What are the frequencies of metal detectors:

VLF or ultra-low frequency;
LF or low frequency;
IF or high frequency;
RF or Radio Frequency.

All these frequencies are broken down from the first hundreds of Hz to tens of kHz, and then there will be metal detectors looking for gold. They already operate on radio frequencies. With this device you can find a lost ring on the beach or in other non-magnetic soil.

Metal detector circuit for DIY assembly from a phone

A device for detecting metal in the ground can not only be cheap to purchase, but also bring a lot of benefits in the future. For example, when identifying a treasure or an important find. Using a special magnet, you can determine what is located at a certain depth, a metal object or an ordinary piece of stone.

You can assemble a metal detector at home, independently or using improvised materials. In order to find iron, you need: a box of computer disks, a portable radio, a calculator, and Velcro tape. All of these items will be acceptable for assembling a simple type metal detector at home.

Necessary parts and elements: 555th model (see markings on top of the chip) or an element on the timer, resistor, capacitors, board, batteries, various switches and battery cables, buzzers and electrical tape, and cardboard will also come in handy.

Scheme for assembling a metal detector from a phone:

Find the diagram. After studying it, you can add or exclude certain elements.
Make a reel. If it is not possible to make it yourself, then it is worth purchasing it. Then test. In order not to damage the board, the coil is tested only on a breadboard.
After successful testing, assemble the finished board.
Assemble the cardboard case. Here, as fantasy will tell you, the main thing is to be comfortable for him.
Glue all the elements to the cardboard body and arrange them in the desired order.

Fasten all the elements and test the resulting metal detector. For connection, use glue that is suitable for hot fixing parts and materials.

It’s very easy to assemble a metal detector using your phone; all you need is one wish. In order to fully understand this issue, it is necessary to study the relevant literature, but the approximate course of events can be recorded.

DIY metal detector (video)

This metal detector can be used at home to detect missing items in the pile of a carpet or in a sofa. On the street, such a product will be useless and will not justify itself.

A metal detector is a device that can be used to find metal objects underground. There are many types and varieties of this device. The main differences are in scanning depth and ease of use. The deeper a metal detector “sees,” the more expensive its cost.

The principle of its operation is based on the magnetic attraction of objects. The device generates a magnetic field that you direct into the ground. As soon as an object is encountered, the field is reflected from it and returns back. In this case, a signal about the find is issued.

Now we will tell you how to make a metal detector with your own hands.

Show all

How to make a high-frequency metal detector with your own hands?

First, assemble the command block. You can use a laptop or radio for this.

Tune the radio to the AM frequency, as high as possible. Make sure there is no radio station operating on this frequency.

Now you need to make a search head. To do this, cut out two circles using a thin plywood sheet as the material. One should have a diameter of fifteen centimeters, the other approximately ten, so that they can fit into each other.

Now cut out the sticks from wood so that the rings are parallel to each other.

Using enameled copper wire a quarter of a millimeter thick, make fifteen turns from the plates.

Now you can attach the craft to the block itself.

Take a pole and attach a head to the lower end, and a radio detector to the upper end.

Turn on the frequency. If you did everything correctly, a quiet sound will be heard. To hear it better, you can connect headphones.

How to make a metal detector with your own hands? Easy way

You will need:

Timer chip 555 (SE555/NE555);
Resistor forty-seven kilo-ohms;
Two 2.2 microfarad capacitors;
Battery "Krona" nine volts;
Buzzer;
Copper wire 0.2 millimeters in diameter;
Wires;
Scotch;
A piece of cardboard;
Glue.

Electrical diagram

Making a coil

To make a coil with your own hands with a diameter of ninety millimeters, you need to wind two hundred and fifty turns of copper wire, and for a coil with a diameter of seventy millimeters - two hundred and ninety turns. After these manipulations we get 10 mH.

The frames for the coils can be made of cardboard and the wire is wound on them.

Testing the circuit

Assemble the parts on the circuit board and check how it works.

If everything works as it should, you make a printed circuit board on which you assemble all the parts.

Making a handle for the device

You can make it yourself using cardboard for the base. From it you cut out three identical parts in the shape of a boomerang, and make a hole in them for the battery. Then glue all three parts together. Dry and cut out a place for the switch. Attach the circuit, connect the battery, switch and glue the coil.

Checking the resulting metal detector

What you will need:

Any discs, but double-sided ones are better, so the device will be more sensitive.
Headphones.
Calculator without solar panels.
The battery is 9 volt, you can use the crown.
Glue.
Insulating tape.

Cut off the headphone plug and strip off the insulation at the ends. Expose the wires by ten millimeters.

Divide the stripped wires into two parts, you get four wires.

Take one end of the wire from different headphones and glue it to the writing sides of both discs.

Using electrical tape, secure the wires to the drives.

Connect the two bare ends of the wires that remain to the plus and minus of the battery and also secure with electrical tape.

Turn on the calculator and attach it to the top of one of the disks.

Place the second disk on the calculator and fasten the disks with electrical tape.

Again, use electrical tape to attach the battery to the disk.

Ready! You can test it.

Metal detector at home

To get started, stock up on an empty computer disk box.

Take a small radio and attach it with the back wall to one of the doors of the box.

You also attach a working calculator without solar panels to the other door with its back.

Now set up the device. Turn on the radio and switch it to the AM reception range. Make sure there is no broadcast on this frequency. If it is on, adjust the dial until there is complete silence on the air. When you turn the receiver volume up to maximum, you should only hear noise.

The time has come to check the functionality of the device. To do this, slowly and slowly close the box. At some point there will be a loud sound. This means that the radio picked up the magnetic waves emitted by the calculator.

Now open the box so that the sound is not loud. Hold the box in this position, bring it to a metal object, and you will hear the same loud sound. This means that the device is working.

This is such a simple device that it is better to use it to find lost metal products at home. It is possible in nature, but there you need a more advanced device.

Simple and reliable metal detector

Electrical diagram

In order to make such a device, you will first need a vinyl plastic tube, the outer diameter of which is one and a half centimeters, and the inner diameter is one centimeter. It needs to be twisted into a ring twenty-five centimeters in diameter. This will serve as the base of the search coil (indicated in the diagram as L1). Do not forget to provide an exit hole; a stick will be inserted into it for holding.

Wrap the coil a hundred times with PELSHO wire with a diameter of 02.7, wrap aluminum foil in the form of a tape along the top, it will serve as a screen for the device. It is important that you remember to leave a small gap in the screen so that the L1 coil does not become shorted.

The device is powered by a battery or battery. You can control the frequency and sound of the signal using headphones.

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 iron-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.