Do-it-yourself metal detector manufacturing schemes. Twisted pair coil for a metal detector How to make a quality search coil for a metal detector

You can buy for about 100-300 dollars. The price of metal detectors is strongly interconnected with their detection depth, not every metal detector can "see" coins at a depth of 15 cm. In addition, the presence of a metal type recognizer and interface type also greatly affects the cost of a metal detector, fashionable metal detectors are sometimes equipped with a display for convenient operation .

This article will consider an example of assembling a powerful metal detector called Pirat with your own hands. The device is able to catch coins underground at a depth of 20 cm. As for large objects, it is quite possible to work at a depth of 150 cm.

Video of working with a metal detector:

This metal detector received such a name due to the fact that it is a pulse, this is the designation of its first two letters (PI-impulse). Well, RA-T is consonant with the word radioskot - this is the name of the developers' site, where the homemade product was posted. According to the author, the Pirate is going to be very simple and fast, even basic skills in working with electronics are enough for this.

The disadvantage of such a device is that it does not have a discriminator, that is, it cannot recognize non-ferrous metals. So working with him on areas contaminated with various kinds of metals will not work.

Assembly materials and tools:
- microcircuit KR1006VI1 (or its foreign analogue NE555) - a transmitting node is built on it;
- transistor IRF740;
- K157UD2 microcircuit and VS547 transistor (the receiving unit is assembled on them);
- wire PEV 0.5 (for winding the coil);
- NPN type transistors;
- materials for creating the body and so on;
- electrical tape;
- soldering iron, wires, other tools.

The remaining radio components can be seen in the diagram.

You also need to find a suitable plastic box for mounting the electronic circuit. You will also need a plastic pipe to create a rod on which the coil is attached.

Metal detector assembly process:

Step one. We create a printed circuit board
The most difficult part of the device is, of course, the electronics, so it is advisable to start with it. First of all, you need to make a printed circuit board. In total there are several options for boards, depending on the radio elements used. There is a board for NE555, and there is a transistor board. All the necessary files for creating the board are in the article. You can also find other board options on the Internet.

Step two. We install electronic elements on the board
Now the board needs to be soldered, all electronic elements are installed exactly as in the diagram. In the picture on the left you can see the capacitors. These capacitors are film type and have high thermal stability. Thanks to this, the metal detector will work more stably. This is especially true if you use a metal detector in the fall, when it is already quite cold outside.

Step three. Power supply for metal detector
To power the device, you need a source from 9 to 12 V. It is important to note that the device is rather voracious in terms of energy consumption, and this is logical, because it is powerful. One krone battery is not enough for a long time, it is recommended to use 2-3 batteries at once, which are connected in parallel. You can also use one powerful battery (best rechargeable).

Step four. Assembling a coil for a metal detector
Due to the fact that this is a pulse metal detector, the accuracy of the coil assembly is not so important here. The optimal diameter is a mandrel of 1900-200 mm, in total you need to wind 25 turns. After the coil is wound, it must be carefully wrapped on top with electrical tape for insulation. To increase the detection depth of the coil, you need to wind it on a mandrel with a diameter of about 260-270 mm, and reduce the number of turns to 21-22. The wire is used with a diameter of 0.5 mm.

After the coil is wound, it must be installed on a rigid body, there should be no metal on it. Here you need to think a little and look for any case that is suitable in size. It is needed in order to protect the coil from shock while working with the device.

The leads from the coil are soldered to a stranded wire with a diameter of about 0.5-0.75 mm. It is best if these are two wires twisted together.

Step five. Setting up a metal detector
When assembling exactly according to the scheme, it is not necessary to adjust the metal detector, it already has maximum sensitivity. To fine-tune the metal detector, you need to turn the variable resistor R13, you need to achieve rare clicks in the speaker. If this is achieved only in the extreme positions of the resistor, then it is necessary to change the value of the resistor R12. The variable resistor should adjust the device for normal operation in the middle positions.

No one needs to explain what a metal detector is. This device is expensive, and some models are very decent.

However, you can make a metal detector with your own hands at home. Moreover, you can not only save thousands of rubles on its acquisition, 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 instruction, we will show how you can assemble the simplest metal detector from improvised means with your own hands. We will need: an ordinary plastic CD box, a portable AM or AM / FM radio receiver, a calculator, a VELCRO-type contact tape (Velcro). So let's get started!

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

STEP 1. Removing the plastic insert from the sidybox

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

STEP 2.1. We measure approximately in the middle of the area on the back of the radio (highlighted in red)

STEP 2.2. Cut out 2 Velcro of the appropriate size, measured in step 2.1

Step 3 Fasten the radio. Attach one sticky side of Velcro to the back of the radio and a second to one of the inside sides of the CD case. Then attach the radio to the body of the plastic CD box with Velcro to Velcro.

Step 4 Clip the calculator. Repeat steps 2 and 3 with the calculator, but apply Velcro to the other side of the CD case. Then attach the calculator to that side of the box using the standard Velcro to Velcro method.

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 end of the AM band, but not to the radio station itself. Turn up the volume. You should hear only one interference.

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 hear only one interference!

Step 6 Roll up the CD box. Turn on the calculator. Start rolling the side of the calculator box towards the radio until you hear a loud beep. This beep signals to us that the radio has picked up an electromagnetic wave from the calculator's electrical circuit.

STEP 6. We turn 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 plastic box again so that 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 the loud sound again. This indicates the correct operation of our simplest metal detector.

Instructions for assembling a sensitive metal detector based on a two-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 metallic objects. The beat frequency between these two oscillator frequencies is in the audio range. As the detector passes over a metal object, you will hear this beat frequency change. Different types of 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 114.3 mm x 155.6 mm	1 PC.
Resistor 0.125W	1 PC.
Capacitor, 0.1μF	5 pieces.
Capacitor, 0.01μF	5 pieces.
Capacitor, electrolytic 220μF	2 pcs.
PEL 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.
9V battery binding connector	1 PC.
Potentiometer, 5 kOhm, audio taper, optional	1 PC.
Switch, single pole switching	1 PC.
Transistor, NPN, 2N3904	6 pcs.
Sensor wire (22 AWG or 0.3250 mm2)	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′ wooden 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 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. With the toner transfer method, you print a mirror image of the board design with a conventional laser printer, and then transfer the design onto the copper cladding with an iron. During the etching stage, the toner acts as a mask, keeping the copper tracks, while like the rest copper dissolves in chemical bath.

Step 2: Will fill 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 add two 220μF electrolytic capacitors.

Step 2.2. Add 2 electrolytic capacitors

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

Step 3.2. Add 5 0.01μF Capacitors

Step 3.3. Add 6 resistors 10 kOhm

Step 4: We continue to fill the electrical board with elements. Now we need to add one 2.2 mΩ resistor (red, red, green, gold) and two 39 kΩ resistors (orange, white, orange, gold). And then solder the last 1 kΩ 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 for 2 mΩ and two for 39 kΩ)

Step 4.2. Add 1 1 kΩ resistor (far right)

Step 4.3. Adding wires

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

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

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

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

Step 6: We make a receiving (search) coil. It is necessary to cut the spool holder from 6-7mm plywood. Using the same wire 0.4 mm in diameter, wind 10 turns around the groove. My reel has a diameter of 152mm. Using a 6-7 mm wooden peg, attach the handle to the holder. Do not use a metal bolt (or something 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 tune 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 counter for these purposes. Start by connecting the coil to 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 must 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 below 100kHz, my coil was 31mm long.

Metal detector on a transformer with Ш-shaped plates

The simplest metal detector circuit. 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 from water ingress. Turn on and 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 will change in the headphones.

A simple scheme on common elements. You need transistors of the K315B or K3102 series, resistors, capacitors, headphones, a battery. The ratings are shown in the diagram.

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

A master oscillator with a frequency of 100 Hz is assembled on the first transistor, and a search oscillator with the same frequency is assembled on the second. As a search coil, I took an old plastic ladle with a diameter of 250 mm, cut it off and wound a copper wire with a cross section of 0.4 mm2 with 50 turns. I placed the assembled circuit in a small box, sealed it and fixed everything on the bar with adhesive tape.

Scheme 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, then 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 scheme on simple elements. You need a microcircuit, capacitors, resistors, headphones, power supply. It is advisable to first assemble the L2 coil, as shown in the photo:

A master oscillator with an L1 coil is assembled on one element of the microcircuit, and the L2 coil is used in the search oscillator circuit. When metal objects enter the sensitivity zone, the frequency of the search circuit changes and the sound in the headphones changes. With the knob of the capacitor C6, you can rebuild unnecessary noise. A 9V battery is used as a battery.

In conclusion, I can say that every person who is familiar with the basics of electrical engineering and has enough patience to complete the work that has been started can assemble the device.

Principle of operation

So, a metal detector is an electronic device, where there is a primary sensor and a secondary device. The role of the primary sensor is performed, as a rule, by a coil with a wound wire. The work of the metal detector is based on the principle of changing the electromagnetic field of the sensor with 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 signals us about the discovery of a metal object.

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

Metal detectors can be divided into several categories:

public devices;
middle class devices;
devices for professionals.

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

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

Photo: general view of a typical metal detector

All other devices should be classified as professional. They are equipped with a microprocessor, can work in dynamic and static modes. Allow to determine the composition of the metal (object) and the depth of its occurrence. 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 holding rod, an electronic control unit. The sensitivity of our device depends on its quality and size. The bar-holder is selected according to the height of the person so that it is convenient to work. All structural elements are fixed on it.

Metal detectors are used to search for metal in the soil at a certain depth. This device can be assembled independently at home, having at least minimal experience in this matter, or following the clear instructions of the instructions. The main thing is the desire and the availability of the necessary tools.

Do-it-yourself detailed instructions for the terminator 3 metal detector

This type of design is designed to search for coins. Its assembly process is quite simple. However, experience in assembling such a tool is still necessary. The Terminator is able to detect an item even if the target of capture is minimal.

First you need to prepare the necessary equipment, namely:

multimeter that measures speed.
LC meter.
Oscilloscope.

Next, you need to find a diagram with a breakdown into nodes. Now you can make a printed circuit board, into which jumpers, resistors, panels for microcircuits and other parts should be soldered in order. The next step is to flush the board with alcohol.. Be sure to check for defects. Whether the board is in working order can be checked as follows:

Turn on the power.
Unscrew the sensitivity control until no sound is heard in the speaker.
Touch the sensor connector with your fingers.
When turned on, the LED should flash and then turn off.

If all actions have taken place, then everything is done correctly. Now you can make a coil. It is necessary to prepare a winding enamel wire with a diameter of 0.4 mm, which must be folded in half. A circle is drawn on a sheet of plywood, having a diameter of 200 mm and 100 mm. Now you need to drive nails in a circle, the distance between them should be 1 cm.

Next, you can proceed to winding the turns. At 200 mm, you should make them 30, and at 100 - 48. Then the first coil must be impregnated with varnish, when it dries, you can wrap it with thread. The thread can be removed, and by soldering the middle, you get a whole winding of 60 turns. After the coil must be wrapped with electrical tape quite tightly. And a foil of 1 cm is superimposed on top, this will be a screen, another electrical tape is wound on top of it. The ends should come out.

On the second coil, it is also necessary to solder the middle. In order to start the generator, you need to connect the first coil to the board. The second coil should be wrapped with a wire of 20 turns, then we connect it to the board. Now you need to connect the oscilloscope minus to minus to the board, and the plus is connected to the coil. Be sure to look at what frequency will be when turned on and remember it or fix it on paper.

Now the coils must be put in a special form, then to fill them with resin. Next, the oscilloscope is connected to the board, with a negative pole, the amplitude should reach zero. Coils in the form are filled with resin to about half the depth. When everything is ready, the metal discrimination scale is adjusted.

List of parts for metal detector terminator 3

As parts for the trio metal detector you will need:

If you have these details, you can assemble the terminator pro metal detector on your own.

Scheme of a metal detector with metal discrimination

Do-it-yourself metal detector with metal discrimination can be made using the scheme for the Chance impulse device. The process of making a coil is quite simple.

The diagram itself can be found on the Internet. But still, experience in assembling such devices will be useful. Assembling the metal detector should begin with the board.

After the board is made, it is necessary to flash the microcontroller. And at the end of the work, we connect the metal detection device to the power supply.

Homemade equipment can be made without complex microcircuits, but using a simple transistor generator. The metal detector will be without discrimination. He will detect objects in the ground 20 centimeters deep, and in dry sand - 30 centimeters. In this device, the transmitting and receiving coils work simultaneously.

Coil for metal detector terminator 3

To begin with, you should take the winding enamel, having a diameter of 0.4 mm. Fold it so that there are two ends and two beginnings. Next, it is worth winding from two coils at a time.

Now we need to make a transmitting and receiving coil, for this, two circles of 200 mm and 100 mm are drawn on a plywood sheet. Carnations are driven in according to these circles, the distance between them should be 1 cm. 30 turns are wound on a large mandrel with enamel wire. Then you should apply varnish to the coil and wrap it with a thread, then remove it from the winding and solder the middle. So you get one middle wire and two extreme wires.

The resulting coil should be wrapped with electrical tape and put on top of a piece of foil, and foil again on top. The ends of the windings must come out.

Now it's time to move on to the receiving coil. 48 turns are already wound here. To start the generator, you need to connect the transmitting coil to the board. The middle wire is connected to negative. And the receiving coil does not use the middle terminal. For the transmitting coil, a compensating coil is needed, on which 20 turns are wound.

We connect the oscilloscope to the board as follows: the probe with a minus to the minus of the board, and the positive probe to the coil. Be sure to measure the frequency of the coils and record it.

After connecting the coils according to the scheme, they must be placed in a special container and filled with resin. Now the oscilloscope is set to divide time (10 ms and 1 volt per cell). Now you should reduce the amplitude to zero. We wind the turns until the volt value reaches zero. We make a compensating loop at the coil, which will be outside.

Half of the mold should be spilled with resin. When everything hardens, you need to connect the oscilloscope and bend the loop inward. Then twist it until the amplitude value becomes minimal. After the loop must be glued, the balance checked, and now you can fill the second half of the container with resin. The coil is ready to go.

Before proceeding with the repair, you should prepare the following tools:

Stationery knife;
Incandescent lamp;
Container for glue, preferably flat;
Special or epoxy resin;
Medium and fine emery;
Small spatula.

First of all, you need to dry the coil with an incandescent lamp. And with the help of a clerical knife, expand the cracks on it. Squeeze the glue onto a flat surface and mix with a spatula. Apply this substance to the coil. In places of cracks, you can apply more resin. Now it's worth waiting until it all hardens thoroughly. And then process with emery, using medium first, and then fine. This procedure will help smooth out all the bumps. In such a fairly simple way, you can reanimate the oldest coil from a metal search device.

Circuit board for device terminator 3

A printed circuit board for this type of equipment can be made and configured independently. The circuit board for the terminator 3 is on the Internet. After it is found, you can begin to manufacture a printed circuit board. After that, jumpers, smd resistors and panels for microcircuits are soldered into it. Capacitors in the board must have high thermal stability.

DIY metal detector sensor

Before starting work, it is necessary to prepare a device that will accurately measure capacitance and inductance. Now you should take the body for the coil and make textolite inserts into the ears. Pieces of fabric are used for sealing. The upper surface of the ears should be sanded. The fabric must be impregnated with epoxy resin. When everything is dry, everything should be sanded and a pressure seal should be inserted, thus making the grounding. Next, you need to apply a special varnish Dragon.

Now windings are made, which are tied with threads. All windings are placed in a coil and capacitors are glued. Everything can be connected and configured. A body is required for pouring. Required: there should be no metal nearby. After pouring, the epoxy should be sanded and dried thoroughly. The sensor is suitable for terminator 3 and terminator 4 metal detectors, which are the most popular models of devices.

Metal detector terminator 3: reviews

Many consider this model of the device popular. The positive qualities are:

Finding non-ferrous metal objects.
No false positives.

And as negative features, they distinguish:

Rusty iron detects rather poorly.
You can lose some of the finds.

The search depth of the device is higher than that of other similar models. Basically it is 30 centimeters on the example of a coin.

Sokha 3 metal detector: diagram and description

The metal detector has an operating frequency of 5 to 17 kHz. Its power supply is 12 volts. The ground balance is manual.

The circuit of this device is not quite simple, since it contains two microcontrollers. The diagram can be found on the Internet. The device itself has good characteristics. However, due to the lack of detailed assembly information, difficulties may arise in the manufacture of the apparatus.

A device that allows you to search for metal objects located in a neutral environment, for example, soil, due to their conductivity is called a metal detector (metal detector). This device allows you to find metal objects in various environments, including in the human body.

Largely due to the development of microelectronics, metal detectors, which are produced by many enterprises around the world, have high reliability and small overall weight characteristics.

Not so long ago, such devices could most often be seen with sappers, but now they are used by rescuers, treasure hunters, public utilities workers when searching for pipes, cables, etc. Moreover, many "treasure hunters" use metal detectors that they assemble with their own hands .

The design and principle of operation of the device

Metal detectors on the market operate on different principles. Many believe that they use the principle of pulsed echo or radar. Their difference from locators lies in the fact that the transmitted and received signals operate constantly and simultaneously, in addition, they operate at the same frequencies.

Devices operating on the principle of "reception-transmission" register the signal reflected (re-radiated) from a metal object. This signal appears due to the impact on a metal object of an alternating magnetic field, which is generated by the metal detector coils. That is, the design of devices of this type provides for the presence of two coils, the first is transmitting, the second is receiving.

Devices of this class have the following advantages:

simplicity of design;
great ability to detect metallic materials.

At the same time, metal detectors of this class have certain disadvantages:

metal detectors can be sensitive to the composition of the soil in which they search for metal objects.
technological difficulties in the production of the product.

In other words, devices of this type must be configured by hand before operation.

Other devices are sometimes referred to as a beat detector. This name comes from the distant past, more precisely from the time when superheterodyne receivers were widely used. Beating is a phenomenon that becomes noticeable when two signals with close frequencies and equal amplitudes are summed. The beating consists in pulsing the amplitude of the summed signal.

The pulse frequency of the signal is equal to the difference in the frequencies of the summed signals. By passing such a signal through a rectifier, it is also called a detector, the so-called difference frequency is isolated.

Such a scheme was used for a long time, but today, it is not used. They were replaced by synchronous detectors, but the term remained in use.

The beat metal detector works using the following principle - it registers the frequency difference from two generator coils. One frequency is stable, the second contains an inductor.

The device is set up by hand so that the generated frequencies match or at least are close. As soon as metal enters the coverage area, the set parameters change and the frequency changes. The frequency difference can be recorded in many ways, ranging from headphones to digital methods.

Devices of this class are characterized by a simple sensor design, low sensitivity to the mineral composition of the soil.

But besides this, during their operation it is necessary to take into account the fact that they have high energy consumption.

Typical design

The structure of the metal detector includes the following components:

The coil is a box-type design, it houses the receiver and transmitter of the signal. Most often, the coil has an elliptical shape and polymers are used for its manufacture. A wire is connected to it, connecting it to the control unit. This wire transmits the signal from the receiver to the control unit. The transmitter generates a signal when metal is detected, which is transmitted to the receiver. The coil is installed on the lower rod.
The metal part on which the coil is fixed and its angle of inclination is adjusted is called the lower rod. Thanks to this solution, a more thorough examination of the surface occurs. There are models in which the lower part can adjust the height of the metal detector and provides a telescopic connection with the rod, which is called the middle one.
The middle shaft is the node located between the lower and upper shafts. Fixing devices are fixed on it, allowing you to adjust the size of the device. on the market you can find models that consist of two rods.
The top bar is usually curved. It resembles the letter S. This form is considered optimal for fixing it on the hand. An armrest, a control unit and a handle are installed on it. The armrest and handle are made of polymeric materials.
The metal detector control unit is required to process the data received from the coil. After the signal is converted, it is sent to headphones or other means of indication. In addition, the control unit is designed to adjust the operating mode of the device. The wire from the coil is connected using a quick-release device.

All devices included in the metal detector are waterproof.

This is the relative simplicity of the design and allows you to make metal detectors with your own hands.

Varieties of metal detectors

The market offers a wide range of metal detectors used in many areas. Below is a list that shows some of the varieties of these devices:

Most modern metal detectors can find metal objects at a depth of up to 2.5 m, special deep products can detect a product at a depth of up to 6 meters.

Operating frequency

The second parameter is the frequency of operation. The thing is that low frequencies allow the metal detector to see to a fairly large depth, but they are not able to see small details. High frequencies allow you to notice small objects, but do not allow viewing the ground to a great depth.

The simplest (budget) models operate at one frequency, models that are classified as average price levels use 2 or more frequencies in operation. There are models that use 28 frequencies when searching.

Modern metal detectors are equipped with such a function as metal discrimination. It allows you to distinguish the type of material located at depth. At the same time, when ferrous metal is detected, one sound will sound in the searcher's headphones, and another when non-ferrous metal is detected.

Such devices are referred to as pulse-balanced. They use frequencies from 8 to 15 kHz in their work. Batteries of 9 - 12 V are used as a source.

Devices of this class are able to detect a gold object at a depth of several tens of centimeters, and ferrous metal products at a depth of about 1 meter or more.

But, of course, these parameters depend on the device model.

How to assemble a homemade metal detector with your own hands

There are many models of devices on the market for searching for metal in the ground, walls, etc. Despite its external complexity, making a metal detector with your own hands is not so difficult and almost anyone can do it. As noted above, any metal detector consists of the following key components - a coil, a decoder and a power supply signaling device.

To assemble such a metal detector with your own hands, you need the following set of elements:

controller;
resonator;
capacitors of various types, including film ones;
resistors;
sound emitter;
Voltage regulator.

The simplest do-it-yourself metal detector

The metal detector circuit is not complicated, and you can find it either in the vastness of the global network, or in specialized literature. Above is a list of radio elements that are useful for assembling a metal detector with your own hands at home. A simple metal detector can be assembled with your own hands using a soldering iron or another available method. The main thing at the same time, the parts should not touch the body of the device. To ensure the operation of the assembled metal detector, power supplies of 9-12 volts are used.

To wind the coil, a wire with a cross-sectional diameter of 0.3 mm is used, of course, this will depend on the selected circuit. By the way, the wound coil must be protected from the effects of extraneous radiation. To do this, it is screened with your own hands using ordinary food foil.

To flash the controller, special programs are used, which can also be found on the Internet.

Metal detector without chips

If a novice "treasure hunter" has no desire to get involved with microcircuits, there are schemes without them.

There are simpler circuits based on the use of traditional transistors. Such a device can find metal at a depth of several tens of centimeters.

Deep metal detectors are used to search for metals at great depths. But it is worth noting that they are not cheap and therefore it is quite possible to assemble it with your own hands. But before you start making it, you need to understand how a typical circuit works.

The scheme of a deep metal detector is not the simplest and there are several options for its execution. Before assembling it, it is necessary to prepare the following set of parts and elements:

capacitors of various types - film, ceramic, etc .;
resistors of different ratings;
semiconductors - transistors and diodes.

Nominal parameters, quantity depend on the selected circuit diagram of the device. To assemble the above elements, you will need a soldering iron, a set of tools (screwdriver, pliers, wire cutters, etc.), material for making the board.

The process of assembling a deep metal detector is approximately as follows. First, a control unit is assembled, the basis of which is a printed circuit board. It is made from textolite. Then the assembly scheme is transferred directly to the surface of the finished board. After the drawing has been transferred, the board must be etched. To do this, use a solution that includes hydrogen peroxide, salt, electrolyte.

After the board is etched, holes must be made in it to install the circuit components. After the board has been tinned. The most important step is coming. Do-it-yourself installation and soldering of parts on a prepared board.

To wind the coil with your own hands, use a wire of the PEV brand with a diameter of 0.5 mm. The number of turns and the diameter of the coil depend on the chosen scheme of the deep metal detector.

A little about smartphones

There is an opinion that it is quite possible to make a metal detector from a smartphone. This is not true! Yes, there are applications that install under the Android OS.

But in fact, after installing such an application, he will really be able to find metal objects, but only pre-magnetized ones. He will not be able to search and, moreover, discriminate against metals.

Meaningless names for an uninitiated person: a butterfly, an ellipse, a "sniper" - always attract the attention of a seeker for valuable metals. Coils of metal detectors can completely ruin a trip to the excavations or give their owner positive emotions and valuable finds.

The coil is a periscope, only all observations take place underground. Each metal detector has its own standard coil, and for a beginner digger it is enough for the first time. But then, to get the best search result, you will need to have several types of different coils in your arsenal.

search coils

There is no universal metal detector coil. For each particular exit point, a special device is needed for the search to be successful. You should always remember that a considerable number of treasure hunters walk in the same areas as you, and it becomes difficult to find a secluded place. What is needed is a coil that can spot what the competition has failed to find. When choosing it, consider:

the location of the place where the search will be performed;
probable finds;
the presence of garbage;
soil mineralization.

Large metal detector coils covering a wide area in places with a lot of debris will not bring pleasure in the search. And with small "snipers" it is convenient to work in such a place. The search coil criteria are:

size - small, medium, large;
shape type - butterfly, ellipse, circle;
frequency (the number of waves that are sent into the ground to find metal) - high for finding small targets, low for large ones.

What coil to buy?

The acquisition of a coil, as well as the metal detector itself, is a responsible matter. The generic models that come with a metal detector are great to start with, but later on you will need variations of them to work in different areas. It is necessary to determine the location of the search in order to select the appropriate size and shape of the coil.

Ideally, you should have several different ones in order to always be in full readiness, since it is possible to change several search locations in a day. It is not necessary to replace an outdated detector with a new one; it is cheaper to purchase a coil for it. It is safer to buy a product of the same brand as the metal detector, or from a partner manufacturer recommended by the supplier. When buying, do not forget to pay attention to warranty service.

Garrett ACE 250 metal detector

This metal detector is the undisputed leader in the Russian market. The device has a reliable circuit, high-quality performance, an excellent combination of price and search characteristics. He showed himself perfectly among a wide range of search engines. The detector is produced by the American company Garrett, which is the leading company. The following additional features distinguish it from the previously released :

Pinpointer. It gives the most accurate information about finding the find underground. And this helps to avoid digging large pits and save time and effort.
Wide scale of discrimination. The metal detector contains 12 sectors independent of each other to determine the metal. Depending on the algorithms, they receive information about the shape, material, conductivity of the object. For comparison: the previous detector Garrett ACE 150 contained only 5 sectors. This means that each signal of the new device is more informative.

The principle of operation of a simple metal detector Garrett ACE 250 allows anyone who does not have any experience to quickly learn how to use it and enjoy the hobby. It is this detector, as the easiest to use, that has gained great popularity among search engines.

Description of the device Garrett ACE 250

The device is manufactured using modern technologies, similar to those used in more expensive models. It is easy to set up and manage, has high sensitivity, quickly responds to the target. The Garrett metal detector has the ability to search in the "all metals" and "discrimination" modes, which allows you to select the type of metal you want (silver, copper, gold), rather than tearing garbage out of iron. The weight of the device is slightly more than a kilogram, it lies comfortably in the hand, and it is convenient to work with it. The metal detector contains the following modes:

any metals;
only jewelry;
relics;
all coins;
custom.

Using the modes of a simple metal detector, the user can quickly and conveniently search for certain objects, filtering out unnecessary signals. In addition, the operator can specify his own mode of operation.

Types of coils

The metal detector coil has two loops:

Transmitting - produces an electromagnetic field.
Host - monitors field changes. The field begins to deform when a metal object gets under the coil. The resulting distortions allow the operator to start searching for the object.

Coils are of the following types:

Concentric. The loops (receiving and transmitting) are spaced as far apart as possible. As a result of this, a symmetrical field is created, which makes it possible to better separate the finds that lie side by side in one posting. The field has the shape of a cone. The concentric coil of the metal detector is designed for the entire set of existing finds. They are affected by increased soil mineralization.
Mono. It is used on a pulse metal detector. The receiving and transmitting loops are located side by side. It has the same properties as the concentric.
Imaging. A feature of this reel is an additional receiving loop. This allows the detector to identify the find most accurately.
D.D. The coil is used to search for non-ferrous metals. It has good sensitivity to small finds. The coil field is shaped like a flat bucket, which ensures the same visibility at different depths. Unaffected by high mineralization of the soil.

Coil shape

Metal detector coils differ in shape by:

Ellipsoid. They well separate the targets located nearby. Ellipse-shaped pinpoint coils are more accurate, and they allow you to search for objects in dirty areas.
Round. These coils allow you to determine the subject at a greater depth than the ellipsoid.

Do-it-yourself metal detector coil

Making a coil yourself is not difficult, since it does not require great precision in manufacturing.

A mandrel is required to wind the coil. To do this, take a board and draw a circle or the Latin letter D on its surface. Small carnations are stuffed around the perimeter of the figure.
For the transmitting coil, take a small length of copper wire, the diameter of which is 0.45-0.6 mm, and wind the mandrel 25 times. The receiving coil for is made in the same way, only copper wire is taken with a diameter of 0.2 mm.
Tie the coils with a thread every one and a half centimeters and remove from the mandrel.
Impregnate the coils using epoxy resin or varnish.
Dry the product well during the day.
Wrap the coils with electrical tape or FUM tape.
Make shielding products by wrapping them with thin foil.
Wrap a wire without insulation on top of the foil, preferably tinned to improve electrical conductivity.
The body of the metal detector coil can be made of foam or expanded polystyrene. For strength, its outer and inner surfaces are reinforced.
Make the grooves of the coil using a cutter. The depth of the grooves should be such that after they are immersed from above, it will be possible to fill the coils with epoxy.

So, the homemade coil for the metal detector is ready and placed in the case.

Quick fix coil

Sometimes, unsuccessfully waving the device, you can hit the coil on a stone or tree roots. The metal detector starts to “scream”, and a chip appears on the coil. Such a defect must be filled with epoxy resin, and the detector will still work properly. Experienced searchers advise buying epoxy resin in the form of a pencil or two syringes in a hardware store and always carry it with you. If a chip appears, fill it with glue and continue the search after a few hours. Most importantly, you need to wait a certain time for the resin to harden. It is best to repair the metal detector coil in the evening, and in the morning wrap the chipped area with electrical tape for additional protection, and you can work.

Superglue can be used for a faster repair. It freezes much faster. In a backpack, a treasure hunter should always have a tube of superglue, strips from a bicycle tube (several pieces) and a medical tourniquet. Having noticed a chip, you need to carefully remove the dirt from it, drip a few drops of glue, after two minutes tighten this place tightly with a tourniquet, capturing the undamaged places of the coil, and stick the camera strip on the same glue. This, of course, is a temporary repair, but it allows you to use the metal detector for another two days. At home, the coil can be repaired more carefully. To keep the product in good condition, you can buy a protection for the metal detector coil or make it yourself from improvised means, for example, wrap it with electrical tape or a thick cloth, attach the bottom of a plastic bucket to the outer surface.

Conclusion

You should not rush to change a metal detector if it is not technically outdated yet, has several detection frequencies and is tuned to the ground.

Minor additions will make it possible to increase its sensitivity and depth of detection of objects.

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