How to make a mine detector at home. Go ahead and search for treasure! How to make a powerful metal detector at home with your own hands

This is what keeps a person from purchasing metal detectors, which cost a lot of money, but do not guarantee that anything will be found or not.

On the other hand, if you got such a device practically for nothing, then you wouldn’t have to walk through the forests in search of mythical treasures. Even on a personal plot, it is possible to dig up several meters of pipe or abandoned cable, which, when delivered to a collection point, can bring money. But, as you know, they are never superfluous.

In this case, you need to figure out whether it is possible to make a metal detector from a radio or disks with your own hands without the use of microcircuits, how complicated this process is and whether it requires any specific knowledge, whether the circuits of simple metal detectors are complex, what is required for this, and what is the algorithm for such work.

What is a metal detector

Such a device, homemade or made in a factory, is designed to search for any metal under a layer of soil, regardless of whether it is pieces of iron, copper or something even more valuable. Such devices are used not only by gold miners, but also by various archaeological groups, patriotic communities (in search of remains and objects left in the ground after the Second World War) and even sappers when demining territories.

The shapes, as well as the circuits of metal detectors, are different. This could be a disk mounted on a handle, or it could be some kind of microphone. The essence of this device this does not change - when any metal object is detected at a shallow depth, it emits a certain sound using a buzzer built into it, signaling the discovery.

Such devices operate on the basis of the physical law according to which electromagnetic induction operates. Its components are a transmitter, which, upon receiving a signal, sends it to a warning device (audio or visual), the signal receiver itself and a buzzer or screen. Electromagnetic waves are sent to the surface and reflected. If the transmitted signal returns unchanged, nothing happens in the circuit, but provided that any metal enters the signal transmission area, the returned wave turns out to be distorted and this is recorded by the transmitter, which gives an audio or visual alert.

Operating frequencies

A metal detector combines complex parameters that are sometimes mutually exclusive. For example, if you lower the frequency generated by the generator, you can achieve a greater search depth, but this will increase energy consumption, and also reduce sensitivity, as well as mobility due to the increase in the coil. But basically all the parameters, one way or another, are tied to the frequency of the generator, and therefore such devices are classified precisely according to the parameter of operating frequency ranges.

VLF

The circuit of a simple metal detector that operates in the range from approximately 100 to 500-600 Hertz is called ultra-low frequency. Such devices are amateur, with a power of no more than a hundred watts. Such devices are weak and it is almost impossible to recognize the signal without the use of computer processing.

LF

The next class of metal detectors is low-frequency. A little more powerful than the previous ones, the circuit is simple, they are resistant to interference, but the sensitivity is still quite low. With an energy consumption of more than 10 Watts, the possible search depth will be about 5 meters. Their inconvenience is also that, in addition to metal, they also react to large fragments of stone or concrete. The best signal is detected on ferrous metals, and therefore such a metal detector is also called a magnetic detector. They have low sensitivity to soil properties.

IF

Another classification is metal detectors of higher frequencies - several tens of kilohertz. They have less good noise immunity compared to LF. Convenient when performed using the pulse mode, which will be discussed a little later. The disadvantage of such devices is that with increased mineralization or in swampy areas, they completely stop receiving the changed signal, as a result of which they do not “see” metals.

HF

The most powerful metal detector, suitable for searching for precious metals, but at shallow depths. Not bad for finding gold items lost by vacationers in the sand on the beaches. The depth of penetration of the signal into the ground is no more than 80–90 cm. The results of the work depend on the power of the transmitter coil; they work with the result only on dry non-magnetic soil, which includes sand.

Pulsers

Such metal detectors are the best equipment in the line. They stand separately from other similar devices. The fact is that current flows to the coil in a pulsed mode. It is possible to set the pulse frequency in low ranges, and the duration, which determines the area of ​​the spectral composition, in high or high frequencies. Thus, a metal detector is obtained that combines best quality all categories of detectors, or a device that can be reconfigured, depending on the required parameters.

How to make a metal detector with your own hands?

Based on the fact that the cost of such detectors is very high, it makes sense to look into the possibility of making a simple metal detector with your own hands at home. Homemade products require practically no costs, except, of course, a small amount of time.

Since the design of the metal detector is quite simple, to operate it you will need two disks (CD and DVD), headphones, a regular calculator, a 9-volt battery (“crown”), electrical tape and glue, and you assemble it practically on your knees.

So, detailed instructions for assembling a metal detector with your own hands.

To assemble a metal detector from disks, you need to adhere to the following algorithm of actions:

• The headphone plug is not required, so it is cut off and the wires are stripped to a length of about 1 cm.
• Each stripped wire is divided into two equal parts, one of which will go to the mirror part of the disk, and the second to the power element.
• Provided that the mirror surface of the disks is on both sides, one of the parts of the wire is attached to it separately using glue. If the discs are single-sided, then everything is simpler. The contact side is the writing side.
• The wires on the CDs and DVDs themselves are secured with electrical tape.
• When the calculator is turned on, it is secured with the same electrical tape between the disks, and the battery is secured to the surface of the DVD.

At this point the work is completed and the metal detector using improvised means is ready. As you can see, the process is completely uncomplicated and inexpensive, both financially and in time.

Of course, if you make a metal detector whose circuits are so simple, then its characteristics will not be comparable to professional devices, but you can find elementary structures in the ground with its help.

If you need a more powerful device than a simple metal detector, it can be made from an old radio.

Metal detector from radio

Using this method, you can make a detector that will be more powerful than a simple metal detector. To do this, you will need an empty CD case, a calculator, an AM radio, double-sided tape and electrical tape.

On the inside of the disc box, a radio is glued to double-sided tape, and on the other side - a calculator in the turned on state. The receiver is set to the highest frequency in the AM range, or the closest to it, at which there is no noise other than noise. extraneous sounds No.

You can attach any mop stick to the resulting structure. After this, all that remains is to configure the detector. To do this, you need to move the doors of the box apart or move until a sharp sound appears. After moving the doors apart, the same, barely noticeable sound is heard and the box is fixed in this position. After the work has been done, when approaching the metal, the same sound will be heard, but in a sharper sound range.

Of course, you cannot assemble a good metal detector with your own hands, but an acceptable one is quite possible.

Needed or not

Of course, if a person is not engaged in professional excavations, there is no point in purchasing such a device - it is simply throwing away a considerable amount of money. But for home use you can assemble a simple metal detector. Of course, it won’t help you find treasures buried in the bowels of the earth, but a simple metal detector with your own hands or from a radio is quite capable of determining the location of a metal frame behind a gypsum board wall or the location of hidden wiring in the concrete floors of houses, which is already important. Well, making a metal detector at home without the use of microcircuits using a phone (the description of the work is identical to assembling a metal detector with your own hands from disks or a radio, but a phone is used instead of a calculator) is not difficult.

Many people who want to find treasure or something valuable immediately go to the store in search of a good metal detector! In our article, we will tell you how to make a metal detector at home.

How to make a metal detector at home?

Let's start our assembly, what do we need:

1. Calculator;
2. Headphones;
3. CD and DVD disc;
4. Electrical tape;
5. 9V battery;
6. Glue;
7. Scissors.

Step #1. Cut off the headphone plug and expose the wires.

Step #2. Using glue, stick one bare wire to the CD. Just one drop of glue is enough. After that, secure the wire to the disk with electrical tape. Don't put electrical tape on top of the glue!

Step #3. We attach the second bare wire to the DVD disc in the same way.

Step #4. We take the battery and connect it with wires to two disks, where the headphones are attached. Secure the wires well so that they do not fall off.

Step #5. Take a calculator and place it in the middle of the CD. Tape it down with electrical tape.

Step #6. Place the DVD on top and secure the structure with electrical tape. Place the battery in the center of the DVD and secure it. Check that our metal detector is carefully glued together.

Your metal detector is ready! Pass it over metal objects and hear the sound in your headphones!

VIDEO. How to make a metal detector.

How to make a simple metal detector?

We will need:

1. Speaker;
2. PELSHO wire;
3. Electrical tape;
4. Foil from the electrolyte capacitor;
5. Tinned wire;
6. Capacitor;
7. Two LEDs.

Step #1. Let's make a housing for a metal detector. To do this, you can take a monitor case with a diameter of approximately 180mm.

After Step #1 Let's start making a coil for a metal detector.

We will wind the PELSHO wire 0.4-0.7 mm around a pan of suitable diameter. Then you need to carefully remove it and wrap it with electrical tape.

Step #2. Wrap the foil from the electrolyte capacitor over the electrical tape, and then wrap it again with electrical tape. For each winding we connect a capacitor of approximately 0.1 µF.

Step #3. Completely insulate the invention from moisture.

Step #4. Connect two LEDs to pin 7 of U2B. One for “plus”, the second for “minus”. Don't forget to attach the 470 ohm resistors. Try to choose the brightest LEDs so that they can be seen during the day.

Step #5. Take the speaker and connect it to our device.

The metal detector is ready! With its help you can discover many interesting things!

VIDEO. How to make a metal detector from a magnet?

Many people unreasonably believe that homemade metal detectors are inferior in many respects to branded samples produced at the factory.

But in fact, structures that are correctly assembled with your own hands sometimes turn out to be not only better, but also cheaper than “factory” competitors.

Worth knowing: most treasure hunters and local historians to save money cash, try to choose the cheapest options. As a result, they either assemble metal detectors themselves or purchase homemade custom devices.

Beginners, as well as people who do not understand electronics, are at first intimidated by the abundance of not only special terminology, but also various formulas and circuits. However, if you delve a little deeper, everything immediately becomes clear, even with the knowledge gained in school physics lessons.

Therefore, it is worth, first of all, to understand the principle of operation of a metal detector, what it is and how you can assemble it yourself at home.

How does it work

Operating principle of this device consists of using an electromagnetic field. It is created by the transmitter coil and after a collision with an object that conducts current (which is most metals), eddy currents are created that introduce distortion into the EPM of the coil.

In cases where the object is not electrically conductive, but has its own magnetic field, the interference it creates will also be captured due to shielding.

After this, changes in the electromagnetic field are sent directly to the control unit, which emits a special signal to notify that a person has been found. sound signal, and in more expensive models displays data on the display.

It is worth examining how such devices are created following the example of a “Pirate” type metal detector.

Metal detector "Pirate"

Making a printed circuit board with your own hands

First you need to create printed circuit board, where all the nodes of the metal detector will be located in the future. The best method is laser-iron technology or simply LUT.

To do this, it will be necessary to perform the manufacturing steps in the following sequence:

1. First, using only a laser printer, you need to print the corresponding diagram created through the Sprint-Layout program. It is best to use light weight photo paper for this.
2. We prepare the PCB workpiece, first sand it, and then clean it with a solution. It should have dimensions 84x31.
3. Now on top of the blank we place photo paper with the diagram on the front side on which it was printed. Cover with an A4 sheet and begin ironing with a hot iron in order to transfer the marking scheme to the textolite.
4. After fixing the circuit from the toner, we place it all in water, where we carefully remove the paper with our fingers.
5. Next, if there are smeared areas, we correct them using a regular needle.
6. Now the board needs to be placed in a solution of copper sulfate for several hours (ferric chloride can also be used).
7. The toner can be removed without any problems with any solvent, such as acetone.
8. We drill holes for later placement of structural elements (the drill must be very thin).
9. The last stage is to lay out the board tracks. To do this, a special solution “LTI-120” is smeared on the surface, which needs to be spread over the solder of the soldering iron.

Installing elements on the board

This stage of creating a metal detector consists of installing all the elements on the created board:

1. The main microcircuit is the domestic KR1006VI1 or its foreign analogue NE555. Please note that before installation, a jumper must be soldered underneath it.
2. Next, a two-channel amplifier K157UD2 is installed. You can buy it or take it from Soviet tape recorders.
3. After this, 2 SMD capacitors are mounted, as well as one resistor of the MLT C2-23 type.
4. Now you need to solder two transistors. One must be NPN structure, and the other PNP. It is advisable to use BC557 and BC547. However, analogues will also work. It is recommended to use IRF-740 or other options with similar characteristics as a field-effect transistor.
5. The capacitors are installed last. They should be taken with a minimum TKE indicator, which will increase the thermal stability of the entire structure.

Note: The hardest thing will be to get the K157UD2 amplifier out of this circuit. The reason is that it is already an old chip. That is why you can try to find similar modern options with similar parameters.

Creation homemade coil made on a frame with a diameter of 20 cm. The total number of turns should be approximately 25 pieces. This indicator is based on the fact that PEV wire is used, which has a diameter of 0.5 mm.

However, there is a certain peculiarity. The total number of turns can be changed up or down. To find the most best option, you need to take a coin and check in which case there will be the greatest distance to “catch” it.

Other elements

A signal speaker can be used taken from a portable radio. It is important that it has a resistance of 8 ohms (Chinese options can be used).

To carry out the adjustment, you will need two potentiometer models of different power: the first is 10 kOhm, and the second is 100 kOhm. To minimize the influence of interference (it will be difficult to eliminate it completely), it is recommended to use a shielded wire that will connect the circuit and the coil. The metal detector's power source must be at least 12 V.

When the entire structure has been tested for functionality, it is necessary to make a frame for the future metal detector. However, here we can only give some recommendations, because everyone will create it from the items at hand:

• to make the bar more convenient, it is worth purchasing 5 meters of ordinary PVC pipe (which are used in plumbing), as well as several jumpers. It is worth installing a special palm rest at its upper end to make it more comfortable to hold. For the board, you can find any box of the appropriate size that needs to be mounted on the rod;
• To power the system, you can use a battery from a regular screwdriver. Its advantages are low weight and high capacity;
• When creating the body and structure, keep in mind that there should not be any unnecessary metal elements in them. The reason is that they significantly distort the resulting electromagnetic field of the future device.

Checking the metal detector

First of all, you need to adjust the sensitivity using potentiometers. The threshold will be a uniform, but not very frequent, crackling.

So, he will have to “find” a five-ruble coin from a distance of approximately 30 cm, but if the coin is the size of a Soviet ruble, then from about 40 cm. He will “see” large and voluminous metal from a distance of more than a meter.

Such a device will not be able to search for small objects at significant depths. In addition, he will not be able to distinguish between the size and type of metal found. That is why, while searching for coins, you may come across ordinary nails.

This model homemade metal detector Suitable for people who are just starting to master the basics of treasure hunting or do not have the necessary funds to purchase an expensive device.

Their this video You will learn how to make a homemade metal detector:

The number of treasure hunters is growing steadily. And although everything has long been dug up, there are still enthusiasts who want to try their luck and go on another search for gold, antiques or coins. This is not strange, because the procedure itself has a unique atmosphere and gives each participant a lot of unforgettable emotions. It is enough to charge the batteries, drive away from the city, make the first couple of swings of the coil and wait for the sound signal about the find. That's the secret Have a good mood every treasure hunter.

Currently, there is a large selection of instruments for detecting metals. It’s easy to find models on sale that cost less than a hundred dollars. But besides this, there are also expensive products that sell for over $1,000. Does it make sense for a beginner to buy such an expensive device? Of course not. The more expensive the device, the more difficult it is to set up. Naturally, a novice digger will not be able to understand all the possibilities of such an invention without having the appropriate experience and minimal skills. Or maybe try to make a simple metal detector with your own hands? After all, this is a completely doable procedure and anyone can do it.

How to make a metal detector with your own hands

Before you make a simple metal detector at home, you should understand principle of its operation.

A metal detector (metal detector, metal scanner, etc.) is a special device for quickly identifying metal objects underground. There are several types of such inventions available on the market, each with different characteristics and capabilities. To a large extent, the key differences lie in detection depth and ease of use. Naturally, the deeper the device “sees,” the more expensive it will cost.

The principle of operation is based on the use of the law of magnetic attraction of objects. The device generates a magnetic field and sends it to a specific area underground. If there is any object with metallic properties there, a signal is displayed from it and returns back, notifying the treasure hunter of the find.

To build a high-frequency instrument you need to assemble high quality command block. It is used as a laptop or radio with a maximum AM frequency. First make sure that the wave is “clean” and there are no radio stations on it.

The next step involves creating a search head, which is easy to make from a thin sheet of plywood. We cut out two circles with a diameter of 15 and 10 centimeters and secure them tightly together.

Then you need to cut sticks out of wood to position the rings parallel to each other. It is necessary to wrap the plate with enameled copper wire, making 10-15 turns. After this, the fake can be attached directly to the block itself. We launch the highest frequency. If the procedure is successful, you will hear a low tone. For clearer playback, it is better to use an external speaker or headphones. Installing a metal detector according to these instructions is very simple. In addition, on the Internet you can download training videos and diagrams for performing the action.

DIY metal detector: diagram

Finding circuits for a simple metal detector with discrimination support is very simple. To make a device, you need to stock up:

For making a coil with a diameter of 90 millimeters, need to be wrapped copper wire circles from cardboard, making 250 turns. If we are talking about a coil with a diameter of 70 mm, then here you will have to make 290 turns. As a result, it will be possible to obtain 10 mH.

After you assemble the circuit, you need to make sure it works. After this, you can begin manufacturing the printed circuit board, where all other elements of the metal detector will be installed.

The next step involves preparing the handle. It can be made from cardboard by cutting out three identical blanks in the shape of a boomerang. It is necessary to cut holes in the handle for the batteries, after which three separate ones can often be fixed together with glue. You should also cut out a space for the on/off button. After attaching the circuit, battery and switch, the coil can be completed.

DIY metal detector made from DVDs

You can make a simple metal detector with your own hands using two CDs and a DVD. The instructions are particularly simple and do not require the use of additional diagrams or complex instructions. All that is required for production is:

Calculator. It doesn’t matter what type of device you get your hands on. You can take the most simple and cheap model;

1. Headphones;
2. Battery "Krona";
3. Glue and a roll of electrical tape;

Sequencing when creating a metal detector from DVDs:

• Take the headphones and cut off the plug.
• Then you need to strip 10 centimeters of insulating wire and divide it into two to get two pairs of wires;
• After this, you should attach one wire from a pair to the disk. If you are using a single-sided disc, you need to attach it to the writing side;
• We fix the wires with electrical tape, and connect the rest of the “bare” part to the battery, to the plus and minus contacts.
• At the next stage, you need to carefully insulate the exposed cable;
• We tightly attach a previously turned on and charged calculator to the surface of the CD;
• Then you need to place it on it DVD disc, and at the final stage wrap the structure with electrical tape;
• At the final stage, it is necessary to fix the Krona battery on the surface of the disk;

That's all, the circuit of the simplest but very effective metal detector is ready. All that remains is to test it in real conditions and make sure that everything works without failures. Of course, you won’t be able to search for coins at a depth of half a meter with such a device, but still, for home use it will do just fine.

DIY metal detector “Pirate”

Among homemade metal detectors, it is especially in demand. option called "Pirate". The Pirate is a pulse metal detector that is built on a simple and available scheme. The design uses several small elements and a small coil. If you equip the device with a coil with a diameter of 280 mm, then it will be able to “see” coins at a depth of up to 20 centimeters. The device will find large metal objects even at a depth of one and a half meters.

The name “Pirate” (PIRAT) comes from the developers of the scheme - PI - denotes the principle of operation, and RAT - is an abbreviation for “Radio Scott” - the developers’ site.

The homemade Pirate device is not capable of discriminating between metals. But to search for large objects It will do just fine. Such a device is especially valued among novice metal detectors. Everything is determined by ease of use and good search results. You can find diagrams and buy components for creating a “Pirate” at any market or in a store of parts for radios and other radio equipment. To manufacture such a device it is not necessary to have high level preparation.

In the end, we can say with confidence that it is quite possible to assemble a metal detector with your own hands at home. To do this, you should study the detailed instructions and understand the manufacturing diagram. It is important to understand that homemade devices not suitable for more serious searches, for example, coins or small antiques. This is due to the small range. In any case, making a metal detector with your own hands will allow you to create a very good device that will be suitable for acquiring the initial skills of a real treasure hunter.

There is no need to explain to anyone what a metal detector is. This device is expensive, and some models cost quite a lot.

However, you can make a metal detector with your own hands at home. Moreover, you can not only save thousands of rubles on its purchase, but also enrich yourself by finding a treasure. Let's talk about the device itself and try to figure out what's in it and how.

Step-by-step instructions for assembling a simple metal detector

In this detailed instructions We will show you how you can assemble a simple metal detector with your own hands from available materials. We will need: a regular plastic CD box, a portable AM ​​or AM/FM radio, a calculator, VELCRO type contact tape (Velcro). So let's get started!

Step 1. Disassemble the CD box body. Carefully disassemble the plastic CD case body, removing the insert that holds the disc in place.

STEP 1. Removing the plastic insert from the sidebox

Step 2. Cut 2 strips of Velcro. Measure out the area at the center back of your radio. Then cut 2 pieces of Velcro the same size.

STEP 2.1. Measure approximately in the middle the area on the back of the radio (highlighted in red)
STEP 2.2. Cut out 2 Velcro strips of the appropriate size measured in step 2.1

Step 3. Secure the radio. Place one piece of Velcro on the sticky side back radio and a second one on one of the inside sides of the CD case. Then attach the radio to the body of the plastic CD case using Velcro to Velcro.

Step 4. Secure the calculator. Repeat steps 2 and 3 with the calculator, but apply the Velcro to the other side of the CD case. Then secure the calculator to this side of the box standard method"Velcro to Velcro."

Step 5. Setting the radio band. Turn on the radio and make sure it is tuned to the AM band. Now tune it to the AM end of the band, but not to the radio station itself. Turn up the volume. You should only hear static.

Clue:

If there is a radio station that is at the very end of the AM band, then try to get as close to it as possible. In this case, you should only hear interference!

Step 6. Roll up the CD box. Turn on the calculator. Start folding the side of the calculator box toward the radio until you hear a loud beep. This beep tells us that the radio has picked up an electromagnetic wave from electrical diagram calculator.

STEP 6. Fold the sides of the CD box towards each other until a characteristic loud signal is heard

Step 7 Bring the assembled device to a metal object. Open the flaps of the plastic box again until the sound we heard in step 6 is barely audible. Then start moving the box with your radio and calculator close to the metal object and you will hear a loud sound again. This indicates the correct operation of our simplest metal detector.

Instructions for assembling a sensitive metal detector based on a dual-circuit oscillator circuit

Operating principle:

In this project we will build a metal detector based on a double oscillator circuit. One oscillator is fixed and the other varies depending on the proximity of metal objects. The beat frequency between these two oscillator frequencies is in the audio range. When the detector passes over a metal object, you will hear a change in this beat frequency. Various types metals will cause a positive or negative shift, raising or lowering the audio frequency.

We will need materials and electrical components:

Copper Multilayer PCB Single Sided 114.3mm x 155.6mm	1 PC.
Resistor 0.125 W	1 PC.
Capacitor, 0.1μF	5 pieces.
Capacitor, 0.01μF	5 pieces.
Capacitor, electrolytic 220μF	2 pcs.
PEL type winding wire (26 AWG or 0.4 mm in diameter)	1 unit
Audio jack, 1/8′, mono, panel mount, optional	1 PC.
Headphones, 1/8′ plug, mono or stereo	1 PC.
Battery, 9 V	1 PC.
Connector for binding 9V battery	1 PC.
Potentiometer, 5 kOhm, audio taper, optional	1 PC.
Switch, single pole	1 PC.
Transistor, NPN, 2N3904	6 pcs.
Wire for connecting the sensor (22 AWG or cross-section - 0.3250 mm 2)	1 unit
Wired speaker 4′	1 PC.
Speaker, small 8 ohm	1 PC.
Locknut, brass, 1/2′	1 PC.
Threaded PVC pipe connector (1/2′ hole)	1 PC.
1/4′ wood dowel	1 PC.
3/4′ wooden dowel	1 PC.
1/2′ wooden dowel	1 PC.
Epoxy resin	1 PC.
1/4′ plywood	1 PC.
Wood glue	1 PC.

We will need tools:

So let's get started!

Step 1: Make a PCB. To do this, download the board design. Then print it out and etch it onto the copper board using the toner to board transfer method. Using the toner transfer method, you print mirror image board design using conventional laser printer, and then transfer the design onto the copper cladding using an iron. During the etching stage, the toner acts as a mask, preserving the copper traces while like the rest copper dissolves in chemical bath.

Step 2: Fills the board with transistors and electrolytic capacitors . Start by soldering 6 NPN transistors. Pay attention to the orientation of the collector, emitter and base legs of the transistors. The base leg (B) is almost always in the middle. Next we add two 220μF electrolytic capacitors.

Step 2.2. Add 2 electrolytic capacitors

Step 3: Fill the board with polyester capacitors and resistors. Now you need to add 5 polyester capacitors with a capacity of 0.1μF in the places shown below. Next, add 5 capacitors with a capacity of 0.01μF. These capacitors are not polarized and can be soldered onto the board with their legs in any direction. Next, add 6 10 kOhm resistors (brown, black, orange, gold).

Step 3.2. Add 5 capacitors with a capacity of 0.01μF
Step 3.3. Add 6 10 kOhm resistors

Step 4: We continue to fill the electrical board with elements. Now you need to add one 2.2 mOhm resistor (red, red, green, gold) and two 39 kOhm resistors (orange, white, orange, gold). And then solder in the last 1 kOhm resistor (brown, black, red, gold). Next, add pairs of wires for power (red/black), audio output (green/green), reference coil (black/black), and detector coil (yellow/yellow).

Step 4.1. Add 3 resistors (one 2 mOhm and two 39 kOhm)
Step 4.2. Add 1 1 kOhm resistor (far right)
Step 4.3. Adding wires

Step 5: We wind the turns onto the reel. The next step is to wind turns on 2 coils, which are part of the LC generator circuit. The first is the reference coil. I used 0.4mm diameter wire for this. Cut a piece of dowel (about 13mm in diameter and 50mm in length).

Drill three holes in the dowel to allow the wires to pass through: one lengthwise through the middle of the dowel, and two perpendicularly at each end.

Slowly and carefully wrap as many turns of wire as you can around the dowel in one layer. Leave 3-4mm of bare wood at each end. Resist the temptation to "twist" the wire - this is the most intuitive way to wind, but this is the wrong way. You must rotate the dowel and pull the wire behind you. This way he will wrap the wire around himself.

Pull each end of the wire through the perpendicular holes in the dowel, and then one of them through the longitudinal hole. Secure the wire with tape once you're done. Finally, use sandpaper to remove the coating on the two open ends of the coil.

Step 6: We make a receiving (search) coil. It is necessary to cut the spool holder from 6-7 mm plywood. Using the same 0.4mm diameter wire, wind 10 turns around the slot. My reel has a diameter of 152 mm. Using a 6-7 mm wooden peg, attach the handle to the holder. Do not use a metal bolt (or anything similar) for this - otherwise the metal detector will constantly detect treasure for you. Again, using sandpaper, remove the coating on the ends of the wire.

Step 6.1. Cut out the spool holder
Step 6.2 We wind 10 turns around the groove with a wire 0.4 mm in diameter

Step 7: Setting up the reference coil. Now we need to adjust the frequency of the reference coil in our circuit to 100 kHz. For this I used an oscilloscope. You can also use a multimeter with a frequency meter for these purposes. Start by connecting the coil into the circuit. Next, turn on the power. Connect the probe from an oscilloscope or multimeter to both ends of the coil and measure its frequency. It should be less than 100 kHz. You can, if necessary, shorten the coil - this will reduce its inductance and increase the frequency. Then new and new dimensions. Once I got the frequency under 100kHz, my coil was 31mm long.

Metal detector on a transformer with W-shaped plates

The most simplest scheme metal detector. We will need: a transformer with W-shaped plates, a 4.5 V battery, a resistor, a transistor, a capacitor, headphones. Leave only the W-shaped plates in the transformer. Wind 1000 turns of the first winding, and after the first 500 turns, make a tap with PEL-0.1 wire. Wind the second winding 200 turns with PEL-0.2 wire.

Attach the transformer to the end of the rod. Seal it against water. Turn it on and bring it close to the ground. Since the magnetic circuit is not closed, when approaching the metal, the parameters of our circuit will change, and the tone of the signal in the headphones will change.

A simple circuit based on common elements. You need transistors of the K315B or K3102 series, resistors, capacitors, headphones, and a battery. The values ​​are shown in the diagram.

Video: How to properly make a metal detector with your own hands

The first transistor contains a master oscillator with a frequency of 100 Hz, and the second transistor contains a search oscillator with the same frequency. As search coil took an old plastic bucket with a diameter of 250 mm, cut it and wound it copper wire with a cross section of 0.4 mm2 and a quantity of 50 turns. Assembled circuit placed it in a small box, sealed it and secured everything to the rod with tape.

Circuit with two generators of the same frequency. There is no signal in standby mode. If a metal object appears in the field of the coil, the frequency of one of the generators changes and sound appears in the headphones. The device is quite versatile and has good sensitivity.

A simple circuit based on simple elements. You need a microcircuit, capacitors, resistors, headphones, and a power source. It is advisable to first assemble coil L2, as shown in the photo:

A master oscillator with coil L1 is assembled on one element of the microcircuit, and coil L2 is used in the search generator circuit. When metal objects enter the sensitivity zone, the frequency of the search circuit changes and the sound in the headphones changes. Using the handle of capacitor C6 you can tune out excess noise. A 9V battery is used as a battery.

In conclusion, I can say that anyone who is familiar with the basics of electrical engineering and has enough patience to complete the job can assemble the device.

Principle of operation

So, a metal detector is electronic device, where there is a primary sensor and a secondary device. The role of the primary sensor is usually performed by a coil with a wound wire. The operation of the metal detector is based on the principle of changing the electromagnetic field of the sensor by any metal object.

The electromagnetic field created by the metal detector sensor causes eddy currents in such objects. These currents cause their own electromagnetic field, which changes the field created by our device. The secondary device of the metal detector registers these signals and notifies us that a metal object has been found.

The simplest metal detectors change the sound of the alarm when the desired object is detected. More modern and expensive samples are equipped with a microprocessor and a liquid crystal display. The most advanced companies equip their models with two sensors, which allows them to search more efficiently.

Metal detectors can be divided into several categories:

• public devices;
• mid-range devices;
• devices for professionals.

The first category includes the cheapest models with a minimal set of functions, but their price is very attractive. The most popular brands in Russia: IMPERIAL - 500A, FISHER 1212-X, CLASSIC I SL. Devices in this segment use a “receiver-transmitter” circuit operating at ultra-low frequencies and require constant movement of the search sensor.

The second category, these are more expensive units, have several replaceable sensors and several control knobs. Can work in different modes. The most common models: FISHER 1225-X, FISHER 1235-X, GOLDEN SABER II, CLASSIC III SL.

Photo: general form typical metal detector

All other devices should be classified as professional. They are equipped with a microprocessor and can operate in dynamic and static modes. Allows you to determine the composition of the metal (object) and the depth of its occurrence. The settings can be automatic, or you can adjust them manually.

To assemble a homemade metal detector, you need to prepare several items in advance: a sensor (a coil with a wound wire), a holder rod, an electronic control unit. The sensitivity of our device depends on its quality and size. The holder bar is selected according to the person’s height so that it is convenient to work. All structural elements are fixed to it.