Deep-type metal detectors are capable of detecting objects in the ground at a great distance. Modern modifications in stores are quite expensive. However, in this case, you can try to make a metal detector with your own hands. For this purpose, it is first recommended to familiarize yourself with the design of the standard modification.

Modification scheme

When assembling a metal detector with your own hands (the diagram is shown below), you need to remember that the main elements of the device are a damper on a microcontroller, a capacitor and a handle with a holder. The control unit in the devices consists of a set of resistors. Some modifications are made on drive modulators that operate at a frequency of 35 Hz. The racks themselves are made with narrow and wide plate-shaped plates.

Assembly instructions for a simple model

Assembling a metal detector with your own hands is quite simple. First of all, it is recommended to prepare a tube and attach a handle to it. High conductivity resistors will be required for installation. The operating frequency of the device depends on many factors. If we consider modifications based on diode capacitors, then they have high sensitivity.

The operating frequency of such metal detectors is about 30 Hz. Their maximum object detection distance is 25 mm. Modifications can operate on lithium batteries. Microcontrollers for assembly will need a polar filter. Many models fold on open-type sensors. It is also worth noting that experts do not recommend using high sensitivity filters. They greatly reduce the accuracy of detecting metal objects.

Model series "Pirate"

You can make a “Pirate” metal detector with your own hands only using a wired controller. However, first of all, a microprocessor is prepared for assembly. To connect it you will need Many experts recommend using grid capacitors with a capacity of 5 pF. Their conductivity should be maintained at 45 microns. Afterwards you can start soldering the control unit. The stand must be strong and support the weight of the plate. For 4 V models, it is not recommended to use plates with a diameter larger than 5.5 cm. System indicators do not need to be installed. After securing the unit, all that remains is to install the batteries.

Using reflex transistors

Making a metal detector with reflex transistors with your own hands is quite simple. First of all, experts recommend installing a microcontroller. In this case, capacitors are suitable of a three-channel type, and their conductivity should not exceed 55 microns. At 5 V they have a resistance of approximately 35 ohms. Resistors in modifications are mainly used of the contact type. They have negative polarity and cope well with electromagnetic vibrations. It is also worth noting that during assembly it is allowed to use the maximum width of the plate for such a modification is 5.5 cm.

Model with convection transistors: expert reviews

You can assemble a metal detector with your own hands only on the basis of a collector controller. In this case, capacitors are used at 30 microns. If you believe the reviews of experts, then it is better not to use powerful resistors. In this case, the maximum capacitance of the elements should be 40 pF. After installing the controller, it is worth working on the control unit.

These metal detectors receive good reviews for their reliable protection against wave interference. For this purpose, two diode-type filters are used. Modifications with display systems are very rare among homemade modifications. It is also worth noting that power supplies must operate at low voltage. This way the battery will last for a long time.

Using Chromatic Resistors

With your own hands? The model with chromatic resistors is quite simple to assemble, but it should be taken into account that capacitors for modifications can only be used on fuses. Experts also point out the incompatibility of resistors with pass filters. Before starting assembly, it is important to immediately prepare a tube for the model, which will be the handle. Then the block is installed. It is more advisable to select modifications at 4 microns, which operate at a frequency of 50 Hz. They have a low dispersion coefficient and high measurement accuracy. It is also worth noting that searchers of this class will be able to successfully work in conditions of high humidity.

Model with a pulse zener diode: assembly, reviews

Devices with pulsed zener diodes are distinguished by their high conductivity. If you believe the reviews of experts, then homemade modifications can work with objects of different sizes. If we talk about the parameters, their detection accuracy is approximately 89%. You should start assembling the device with a stand blank. Then the handle for the model is mounted.

The next step is to install the control unit. Then a controller is mounted, which runs on lithium batteries. After installing the unit, you can start soldering the capacitors. Their negative resistance should not exceed 45 ohms. Expert reviews indicate that modifications of this type can be made without filters. However, it is worth considering that the model will have serious problems with wave interference. In this case, the capacitor will suffer. As a result, the battery of models of this type quickly discharges.

Application of low frequency transceiver

Low-frequency transceivers in models significantly reduce the accuracy of the devices. However, it is worth noting that modifications of this type can successfully work with small objects. At the same time, they have a low self-discharge parameter. In order to assemble the modification yourself, it is recommended to use a wired controller. The transmitter is most often used with diodes. Thus, conductivity is ensured at around 45 microns with a sensitivity of 3 mV.

Some experts recommend installing mesh filters, which increase the security of models. To increase conductivity, only transition type modules are used. The main disadvantage of such devices is considered to be controller burnout. If such a breakdown occurs, it is problematic to repair the metal detector yourself.

Using a High Frequency Transceiver

On high-frequency transceivers, you can assemble a simple metal detector with your own hands only on the basis of an adapter controller. Before installation, a stand for the plate is prepared as standard. The average conductivity of the controller is 40 microns. Many specialists do not use contact filters during assembly. They have high thermal losses and are capable of operating at 50 Hz. It is also worth noting that lithium batteries are used to assemble the metal detector, which recharge the control unit. The sensor itself in modifications is installed through a capacitor, the capacitance of which should not exceed 4 pF.

Model with longitudinal resonator

Devices with longitudinal resonators are often found on the market. They stand out among their competitors by their high accuracy in identifying objects, and at the same time they can work in high humidity. In order to assemble the model yourself, a stand is prepared, and a plate should be used with a diameter of at least 300 mm.

It is also worth noting that to assemble the device you will need a contact controller and one expander. Filters are used only on mesh lining. Many experts recommend installing diode capacitors that operate at a voltage of 14 V. First of all, they discharge little of the battery. It is also worth noting that they have good conductivity compared to field analogues.

Using selective filters

Making such a deep metal detector with your own hands is not easy. The main problem is that a regular capacitor cannot be installed in the device. It is also worth noting that the plate for modification is selected from 25 cm in size. In some cases, the racks are installed with an expander. Many experts advise starting assembly by installing the control unit. It must operate at a frequency of no more than 50 Hz. In this case, the conductivity depends on the controller used in the equipment.

Quite often it is selected with a lining to increase the security of the modification. However, such models often overheat and are not able to work with high accuracy. To solve this problem, it is recommended to use conventional adapters that are installed under the capacitor units. A do-it-yourself metal detector coil is made from a transceiver block.

Application of contactors

Contactors are installed in devices together with control units. Stands for modifications are used of short length, and plates are selected at 20 and 30 cm. Some experts say that devices should be assembled on impulse adapters. In this case, capacitors can be used with low capacitance.

It is also worth noting that after installing the control unit, it is worth soldering a filter that can operate at a voltage of 15 V. In this case, the model will maintain a conductivity of 13 microns. Transceivers are most often used on adapters. Before turning on the metal detector, the level of negative resistance is checked on the contactor. The specified parameter is on average 45 Ohms.

Have you decided to figure out how to create a metal detector and try to make your own experimental device to get acquainted with the principle of operation and to test your own strength, but you don’t know where to start? Let's figure it out together, because recreating simple electronic circuits, including metal detectors, with your own hands is not so difficult.

Metal detector allows you to find objects that have certain electrical and electromagnetic properties that distinguish them from their environment. Such objects include, for example, various metals in the ground. Metal detectors are used by inspection services, the military, geologists, builders and specialists in a number of other professions to find metal in the soil and more.

Nowadays, a metal detector is often used by ordinary people to search for scrap metal from ferrous metallurgy and find non-ferrous metals that make up various coins, jewelry and military paraphernalia: shell casings, tokens and much more. Also, a metal detector can help in searching for items lost due to negligence that are vital or have material or moral value (parts of mechanisms, keys, rings, jewelry, etc.).

The sensitivity of this device depends on the diameter of the search coil. The larger its diameter (from 30 cm), the less sensitivity to small objects, but increases in sensitivity to large, deep ones. Conversely, the smaller its diameter, the better the reaction to smaller objects. Industrial designs provide detailed instructions on the sensitivity and use of the various coils.

Metal detector signal for large and small coins

In a homemade device, the dependence of its sensitivity on the diameter of the coil is also preserved. But you need to remember that a homemade device will be far from professional equipment in its qualities due to various nuances of the physical processes occurring. In one phrase, the operating principle of a metal detector can be described as follows: the coil sends electromagnetic waves and simultaneously reacts to inductively induced currents in the metal, which generate their own magnetic field under the influence of the coil winding.

In reality, the physical processes are much more complex, and the search for treasures with professional equipment (with selectivity and separation) is not as simple as it might seem, and the abundance of debris in the soil can completely discourage digging when a high-quality device beeps every time. Therefore, the device given below cannot guarantee lucky finds of unimaginable treasures, but it will help you understand from your own experience the very principle of interaction between metal and the search coil of a metal detector.

Creating a device of this type does not present any great difficulties; you just need to be able to understand circuits and use a soldering iron. In this case, a simple circuit will be described using mainly a 555 chip (universal timer).

To familiarize yourself with the operation of such a timer, it is recommended to read the corresponding sheet with the parameters of this microcircuit (datasheet).

Required materials and tools:

1. 555 chip (universal timer);
2. 2 capacitors of 2.2 µF;
3. resistor=47 kOhm;
4. batteries = 9 V, wires for connections, cable for battery, switch;
5. circuit board;
6. copper wire=100 m (d=0.2 mm);
7. buzzer for sound signals (it can be replaced with a speaker with resistance = 8 ohms and capacitor = 10 μF);
8. wood glue and electrical tape;
9. cardboard;
10. pliers with which you can make a hole, tweezers;
11. solder in the form of a wire and a soldering iron;
12. ruler, sharp knife, compass, pencil;
13. glue used for hot gluing;
14. wires and breadboard.

Materials for making a simple metal detector

Metal detector circuit

You may come across various homemade metal detectors. They are freely available, you just need to enter “metal detector circuits” in the search bar. This one was taken in the same way from the Internet, but a buzzer was added instead of a speaker and a switch (for the battery).

Making a coil

For ease of calculation, you can use an online air coil calculator. Using it, you can calculate that for a coil with a diameter of 9 cm, 250 turns (turns) of varnished copper wire d = 0.2 mm are needed. The inductance of this coil will be approximately 10 MGn.

The smaller its d (diameter), the more revolutions will be needed (for a coil with a diameter of 7 cm, 290 revolutions are required).

Metal detector screen

Buying a ready-made one is not difficult. If you still decide to assemble it yourself, then before soldering the two ends of the wire you need to clean them using sandpaper. You must try to make all connections very carefully in order to exclude the influence of poor-quality installation on a homemade device, which will already respond to a lot of interference.

Assembled metal detector screen

Coil testing and PCB creation

In order not to spoil the working board, it is better to test this circuit on a breadboard.

Checking functionality on a breadboard

The next step is to make the circuit board. If you don’t know how, then it’s better to find a description on the Internet with video lessons.

Circuit board assembled

Testing

Basis for construction

The base for your simple metal detector can be made of any materials convenient for you (wood, plastic, etc.). In this case, cardboard served as the basis. It is easier to use.

First you need to make a sketch of the handle (3 parts), you can even do it without calculations. This handle will have to fit the battery, circuit board, switch and coil.

Metal detector handle made of cardboard

Cut out holes for the switch and battery. Glue the cardboard parts together using wood glue and leave to dry overnight (approximately 12 hours).

Cutting holes for batteries and wires
glue these parts together

After the glue has dried, you need to make a hole in the handle next to the switch so that the wires can pass through it freely. Finally, glue the spool to the cardboard handle using hot glue.

We place the battery and other parts on the handle

Assembly of parts and conclusion

When all the parts have been completed individually, all that remains is to assemble them. First you need to glue the switch to the handle using hot glue, insert the battery and then glue the circuit board.

Now it's time to connect all the components to each other and test the device you created. It will not be easy for a beginner to understand this manual, but if this is not your first time making a metal detector, you will quickly figure it out.

Assembled metal detector

This assembled metal detector is quite powerful for finding small objects at close distances and preferably indoors, in order to avoid problems. But it should be remembered that this homemade product will be very inferior in sensitivity, detection quality, separation and selectivity, resistance to interference to industrial equipment, and it is worth repeating it rather for the sake of sporting interest and familiarization with the principle of operation of a metal detector.

What happened eventually:

I offer for repetition a simple metal detector that I personally assembled recently and successfully operated. This metal detector operates on the transmit-receive principle. A multivibrator is used as a transmitter, and an audio amplifier is used as a receiver. The schematic diagram was published in Radio magazine.

MD receiver circuit - second option

Metal detector parameters

Operating frequency - about 2 kHz;
- detection depth of a coin with a diameter of 25 mm - 9 cm;
- iron sealing lid from a jar - 25 cm;
- aluminum sheet measuring 200x300 mm - 45 cm;
- sewer hatch - 60 cm.

The search coils connected to it must be exactly the same in size and winding data. They must be positioned so that in the absence of foreign metal objects there is practically no connection between them; examples of coils are shown in the figure.

If the transmitter and receiver coils are positioned this way, the transmitter signal will not be heard in the receiver. When a metal object appears in the vicinity of this balanced system, under the influence of the alternating magnetic field of the transmitting coil, so-called eddy currents arise in it and, as a result, its own magnetic field, which induces an alternating EMF in the receiving coil.

The signal received by the receiver is converted by phones into sound. The metal detector circuit is really very simple, but despite this, it works quite well, and the sensitivity is not bad. The multivibrator of the transmitting unit can be assembled using other transistors of a similar structure.

The metal detector coils have a size of 200x100 mm and contain about 80 turns of 0.6-0.8 mm wire. To check the operation of the transmitter, connect headphones instead of the L1 coil and make sure that sound is heard in them when the power is turned on. Then, by connecting the coil in place, they control the current consumed by the transmitter - 5...8 mA.

The receiver is configured with the input closed. By selecting resistor R1 in the first stage and R3 in the second, a voltage equal to approximately half the supply voltage is set on the collectors of the transistors, respectively. Then, by selecting resistor R5, they ensure that the collector current of transistor VT3 becomes equal to 5...8 mA. After this, opening the input, connect the receiver coil L1 to it and, receiving the transmitter signal at a distance of about 1 m, make sure that the device is working.

Metal detector circuit

Today I would like to present to your attention a diagram of a metal detector, and everything related to it, what you see in the photograph. After all, it is sometimes so difficult to find the answer to a question in a search engine - Diagram of a good metal detector

In other words, the metal detector has a name Tesoro Eldorado

The metal detector can operate in both the search mode for all metals and background discrimination.

Technical characteristics of the metal detector.

Operating principle: induction balanced
-Operating frequency, kHz 8-10kHz
-Dynamic operating mode
-Precise detection mode (Pin-Point) is available in static mode
-Power supply, V 12
-There is a sensitivity level regulator
-There is a threshold tone control
-Ground adjustment is available (manual)

Detection depth in the air with a DD-250mm sensor In the ground, the device sees targets almost the same as in the air.
-coins 25mm - about 30cm
-gold ring - 25cm
-helmet 100-120cm
-maximum depth 150cm
-Consumption current:
-No sound approximately 30 mA

And the most important and intriguing thing is the diagram of the device itself

The picture is easily enlarged when you click on it

To assemble the metal detector you need the following parts:

So that you don’t have to spend a long time setting up the device, do the assembly and soldering carefully; the board should not contain any clamps.

For tinning boards, it is best to use rosin in alcohol; after tinning the tracks, do not forget to wipe the tracks with alcohol

Parts side board

We begin assembly soldering jumpers, then resistors, further sockets for microcircuits And all the rest. One more small recommendation, now regarding the manufacture of the device board. It is very desirable to have a tester that can measure the capacitance of capacitors. The fact is that the device These are two identical amplification channels, therefore the amplification through them should be as identical as possible, and for this it is advisable to select those parts that are repeated on each amplification stage so that they have the most identical parameters as measured by the tester (that is, what are the readings in a particular stage on one channel - the same readings on the same stage and in another channel)

Making a coil for a metal detector

Today I would like to talk about the manufacture of a sensor in a finished housing, so the photo is more than words.
We take the housing, attach the sealed wire in the right place and install the cable, ring the cable and mark the ends.
Next we wind the coils. The DD sensor is manufactured according to the same principle as for all balanced devices, so I will focus only on the required parameters.
TX – transmitting coil 100 turns 0.27 RX – receiving coil 106 turns 0.27 enameled winding wire.

After winding, the coils are tightly wrapped with thread and impregnated with varnish.

After drying, wrap tightly with electrical tape around the entire circumference. The top is shielded with foil; between the end and the beginning of the foil there should be a gap of 1 cm not covered by it, in order to avoid a short-circuited turn.

It is possible to shield the coil with graphite; to do this, mix graphite with nitro varnish 1:1 and cover the top with a uniform layer of tinned copper 0.4 wire wound on the coil (without gaps), connect the wire to the cable shield.

We put it into the case, connect it and roughly bring the coils into balance, there should be a double beep for the ferrite, a single beep for the coin, if it’s the other way around, then we swap the terminals of the receiving winding. Each of the coils is adjusted in frequency separately; there should be no metal objects nearby!!! The coils are tuned with an attachment for measuring resonance. We connect the attachment to the Eldorado board in parallel with the transmitting coil and measure the frequency, then with the RX coil and a selected capacitor we achieve a frequency 600 Hz higher than that obtained in TX.

After selecting the resonance, we assemble the coil together and check whether the device sees the entire VDI scale from aluminum foil to copper; if the device does not see the entire scale, then we select the capacitance of the resonant capacitor in the RX circuit in steps of 0.5-1 nf in one direction or another, and in addition the moment when the device will see foil and copper at a minimum of discrimination, and when the discrimination is turned up, the entire scale will be cut out in turn.

We finally reduce the coils to zero, fixing everything with hot glue. Next, to lighten the coil, we glue the voids with pieces of polystyrene foam, the foam sits on the hot glue, otherwise it will float up after filling the coil.

Pour the first layer of epoxy, without adding to the top 2-3mm

Fill in the second layer of resin with color. An aniline dye is a good choice for dyeing fabric; the powder comes in different colors and costs a penny. The dye must first be mixed with the hardener, then the hardener must be added to the resin; the dye will not dissolve in the resin immediately.

To assemble the board correctly, start by checking the correct power supply to all components.

Take the circuit and the tester, turn on the power on the board, and, checking the circuit, go through the tester at all points on the nodes where power should be supplied.
When the discrimination knob is set to minimum, the device should see all non-ferrous metals

, when screwing the discrim, they should be cut out

all metals in order up to copper should not be cut out if the deviceit works this way, which means it is configured correctly. The discrimination scale needs to be selected so that it fits completely into a full turn of the discrimination knob, this is done by selecting c10. When the capacity decreases, the scale stretches and vice versa.

Even the most serious and respectable citizens feel a slight excitement when they hear the word “treasure”. We literally walk through treasures, of which there are immeasurably many in our land.

But how can you look under the soil layer to know exactly where to dig?

Professional treasure hunters use expensive equipment, the purchase of which can pay for itself after one successful find. Archaeologists, builders, geologists, members of exploration societies use equipment provided by the organization in which they work.

But what about novice treasure hunters on a budget? You can make a metal detector at home with your own hands.

To understand the subject, consider the design and operating principle of the device

Popular metal detectors operate using the properties of electromagnetic induction. Main components:

• transmitter – generator of electromagnetic oscillations
• transmitting coil, receiving coil (in some models the coils are combined for compactness)
• electromagnetic wave receiver
• decoder that separates the useful signal from the general background
• signaling device (indicator).

The generator, using a transmitting coil, creates an electromagnetic field (EMF) around it with specified characteristics. The receiver scans the environment and compares field performance with reference values. If there are no changes, nothing happens in the circuit.

• When any conductor (any metal) enters the field of action, the basic EMF induces Foucault currents in it. These eddy currents create the object's own electromagnetic field. The receiver detects the distortion of the basic EMF and gives a signal to the indicator (audio or visual alert).
• If the object being examined is not metallic, but has ferromagnetic properties, it will shield the underlying EMF, also causing distortion.

Important! There is a misconception that the soil in which searches are carried out should not be electrically conductive.

This is wrong. The main thing is that the electromagnetic or ferromagnetic properties of the environment and the search objects are different from each other.

That is, against the background of certain characteristics of the EMF generated by the search environment, the field of individual objects will stand out.

Types of metal detectors

Understanding the features of different circuits will help not only to choose a ready-made detector. If you decide to build a metal detector for coins with your own hands, you do not need to install a detector for water pipes or fittings in concrete.

You should initially know what the device is for, since universal metal detectors are expensive, both when purchased and when assembled yourself. In addition, a narrow-profile device is more compact and lightweight.

Main settings

1. Search depth. Determines the penetrating power for standard primers: below this band the coil will not respond to artifacts.
2. Coverage area: the wider it is, the less time it will take to “comb through”. True, selectivity and sensitivity are reduced.
3. Selectivity: selecting the required object from a variety of objects. For example, when searching for gold jewelry on the beach, your device will not respond to steel hairpins or coins.
4. Sensitivity: the higher it is, the more likely it is to find small objects. True, the coil reacts to various debris, such as nails or hairpins.
5. Noise immunity. The detector sensor is affected by many extraneous factors: thunderstorms, power lines, mobile phones, etc. It is necessary to filter them out.
6. Autonomy: this means both energy consumption and battery charge reserve.
7. Discrimination is the ability to distinguish artifacts by type. Let's look at this parameter in more detail.