For appointment and design, metal detectors are divided. How to choose a metal detector for search - reviews of specialists

Collecting metal collection with a metal detector is not only an interesting and exciting hobby. This is, above all, profitable occupation. Of course, luck is important in this matter, but the experienced seekers are confident that the most important thing is persistence and experience.

These metals are common:

• in the vicinity of settlements,
• near roads
• even in the forests.

But most of them are hidden from eyes, as it is underground. Just walking, you can choose a metal that others are not found on one or two thousand rubles.

And what can I say if you're lucky to stumble upon old expensive subjects or on the whole klad. This is quite often happening with those who use metal detectors.

This electronic device is able to determine the presence of metal on distance and point to this person with sound alerts.

To detect it is necessary to conduct an impact on it with radio waves Then get the "answer" in the form of a secondary signal.

The principle of operation of the metal detector to search for non-ferrous metal is the same for all such devices.

Dear apparatus from cheap different method of radiation radio wave and responding to the secondary signal-response. Different models and type of signalwho notifies the find.

Metal detector is able to clearly define what metal Located in the field of the coil: color or black. It is essential saves strength and time.

• air
• soil
• water
• tree and so on.

If something metallic falls in the field of the apparatus, it is formed on it eddy currents. They, in turn, weaken radiation from the coil. Metal detector catches this weakening and applies a signal.

Electric vortices fucking longer On non-ferrous metals, which is also catched by the device. Therefore, if you properly configure the metal detector, then you will be stumbled on the usual rusting moth, and on dear Lom. Colormet.

How to use

Main enemy efficient use of metal detector for collecting color scrap - impatience. At first, you will have to learn not only to hear the signals of the device, but also capture the shades. This is necessary for understanding the "language" of the device.

Sharp clear signal Specifies something small and well-preserved, for example, about a coin. Fuzzy signal which is interrupted - a metal object of irregular shape and, most likely rusty.

Depth Sliding the item will show the column on the device diagram. Properly exposed discriminator will show, with which metal we are dealing:

• black
• or color.

Test rules parameters Depend on the specific model, so carefully examine the instructions.

After reading the manual, you can go to practice:

1. Choose unpolluted area Earth.
2. We are convinced that soft soil.
3. To begin with, you need to work with discriminator. First listen to the soil without the subject. Since the metal detector reacts to minerals, we learn the degree of mineralization of soil by sound and exhibit filters that minimize this mineral impact.
4. During training Tonal sound It is advisable to reduce to get used to it. But during real searches, it is twisted to the limits of good hearing.
5. The coil is important to keep close to land, it is necessary to drive it smoothly and in different directions.
6. Coil should not move on the vertical arc - This is a common mistake. The coil above the surface should be in the same plane, that is, it is not necessary to lift it at the end of each movement.
7. Finding a subject, it is necessary to get to it from several sides, to understand where the signal from the metal disappears, and dig In the zone of the alleged location of the thing.

Views

Metal detectors are divided into several types. Some of them have an outdated design and is not released, although it is still used and sold.

By character of action

Based on the nature of the action, the devices can be divided into:

• dynamic;
• static.

By electronics

By using elements are divided into the following types:

• analog;
• microprocessor.

According to the technology

The following types of metal detectors used to search for color can be selected.

1. BFO. Designed for a long time. Leading manufacturers not issuedBut also used by search engines, it can be inexpensive to purchase it. In the simplest models there are only sound alert, there are also visual indications in others. The device compares the reference radiation and the frequency of the LC generator, which determines the black metal or color. At low cost, has a number of negative characteristics:
   • small working depth,
   • instability in work,
   • poor sensitivity and low returns on a wet and mineralized soil.
2. Tr. Also relates to early types of metal detectors. Metal determination occurs on the principle induction balance. It distinguishes the type of metal and is able to work at great depth. Poor functions or even does not work at all:
   • zamouranny
   • and a strong coherent soil.

   Rarely applied as independent technology for metal detectors. More often combined with VLF technology.

3. VLF. Most common, as it has a large functionality. Unmistakably capable of distinguishing the black metal from color, as well as non-ferrous metals. Uses:
   • very low radiation frequencies,
   • the principle of induction balance.

   Forty influence filters are easily installed.

4. VLF / TR. Combines the two above-described technologies and principles of operation. High sensitivity. The more the coil, the deeper the device can "see". Settings can be set so that they are filled:
   • interference from garbage
   • background from the soil.
5. Pi. The principle of induction balance is combined with the work of the pulsating electromagnetic field. The most sensitive Type of metal detectors. It is characterized by the fact that no problems and errors are distinguished by the answer from:
   • highly mineralized soil,
   • salted medium.

   On the other hand, problems often arise with discrimination, that is, the device does not always recognize black and non-ferrous metal. It is usually purchased either for searching at the bottom of the sea, or if the metal type is not particularly important.

6. RF. Uses high frequencies to work. It is used if they want to find something big and pretty deeply. Depending on the soil type, the device is able to find a metal at depth up to nine meters. It is more often used by search engines, in whose area of \u200b\u200binterest includes:
   • cache
   • large pieces
   • taste and the like expensive things.

Additional functions

Simplest The metal detector will simply squeeze if you spend it with a coil over the buried piece of metal. It will give a signal regardless of whether you will find:

• old canning can,
• rusty iron prude
• or detail of color a few kilograms.

To distinguish The non-ferrous metal from black, appliances are equipped with a function discrimination.

This will save time, effort and will not lead to disappointment from the search process. If the search engine experienced, It can independently configure the parameters of discrimination. For newbies There are already set values.

Also a good machine has a function balancing According to the soil, which is designed for a specific:

• mineralization
• humidity,
• consistency of soil.

Good metal detectors are still very useful sometimes near additional features:

• settings for certain types of soil;
• screen backlight;
• sound regulator.

More functions are still available:

1. PIN-POINT mode.Allows the device to operate in static mode, which significantly improves the accuracy of determining the location of the metal subject. Also allows you to more effectively use the function of discrimination. The place where the metal object was found is called Pin-Point. Almost all metal detectors are dynamic, that is, you constantly have to move The coil over the earth to accurately find out the location of the subject. Using the PIN-POINT function, you can keep the coil in one place. The signal will depend on the proximity of the object: the closer - the louder. The peak signal will be when the object from the color will be directly under the metal detector. Since you don't need to move the device, you are more accurate to know where the metal is buried. This feature has one minus - the device will not be able to distinguish, black is metal or color. Therefore, it is necessary to include it when you in general mode have already found out the type of metal.
2. Setting sensitivity. Proper installation of this feature comes with experience. High level will help detect the object at greater depth. But at the same time the device becomes unstable to interference. This feature is used, pushing out the specific situation.
3. Threshold background. This sound is allowed constantly and depends primarily from the soil. It makes it clear that the device is functioning normally. This is useful if in this model no display. The hum also changes when switching to another type of soil, which is also important information for a hunter for scrap and treasures.
4. Adjusting from electrical. Neutralizes false signals created by power lines, repeaters included in engine engines and other emitters.
5. Tonal identification. Useful for models without display. Different sounds notify about different types of metal and object sizes.
6. Low charge indicator. Useful feature that will not give your metal detector to discholence ahead of time.

Review of models and prices

Metal detector market outlet Different ordinary (not for deep search) devices. In any store in the assortment there are many devices that differ from each other different Indicators:

• number available functions;
• the presence of good discrimination;
• cost.

If your plans are not included in the search for ancient coins or gold nuggets, you can buy models simpler. To detect the color of them enough.

Suitable metal detector for non-ferrous metals Price characterizes only indirectly. To search for color it makes no sense to acquire the device "with full minced" And pay for it the transcendent price. Most the main thing - Function discriminationthat will allow you to adjust the device in such a way that it does not react to the black metal unnecessary to us.

• silver;
• iron.

Iron can be simple ignore.

Having worked with the level of sensitivity, you can adjust the device in such a way that it does not have to dig the ground for the sake of foil from a cigarette pack or beer lid. All of the above functions are present in budget models that and recommended purchase

Popular models:

1. Inexpensive model that is perfect for a color of color. Its price is no higher than 12 thousand rubles. It is able to find volumetric metal objects at a depth of up to 40 cm. There is an indication of the battery charge.
2. Bounty Hunter Discovery 1100. A good choice for 9-11 thousand rubles. It has a slightly smaller power compared to the previous model. It will not respond to very small objects, focusing your attention on large metal pieces.
3. Garret Ace 150. The model is successful, but it will have to hunt for it a little, since it has recently been removed from production. But among private ads used the device meets often. New costs about 12,500 rubles. Great for color. There is even small objects at a depth of up to 30 cm, and large capable of finding deeper. From flaws - no battery charge indicator.
4. Garrett Asse 250. According to many search engines - the best solution for beginners. The device has five search modes, so you can set the settings automatically and unmistakably. The depth of detection is greater than that of previous search models - up to 60 cm. Comparatively light - 1.2 kg. But the price is a bit higher - it will cost an average of 23,000 rubles.
5. Minelab X-Terra 705. If you are more important than the result of the search, and not low cost, one of the best professional search metal detectors to search for non-ferrous metal is this model. She has four modes that set up the operator, + modes "All Metals" and "Iron Mascation". It has an advanced PIN-POINT target indicator, which not only exactly indicates the place, but also is able to determine the dimensions of the object. Seeking at a depth of 80 cm. It has a number of functions that significantly simplify the search for complex soils. There is a device about 33,000-38,000 rubles.

All models described have several search modes And they can react both to all metals and only on color what we need.

Extra accessories

There is plenty useful additions To the metal detector, which can be purchased immediately:

1. Additional batteries. It will be not good if you just enter the taste and start to find something, as the battery will immediately sit down, and there will be no spare.
2. Protective cover on the control module. Since the work will be carried out outdoors, on earth or sand, the control unit must be protected from dust and moisture.
3. Headphones. It can be both wired and not. And metal objects will be better audible, and the battery will sit so quickly.
4. Additional coils. With their help, it is better to choose the option of equipping the metal detector for a specific situation. True, they cost money.
5. Display backlight. A trifle, the presence of which will be very useful. First, you can work at dusk and even at night, which is especially relevant in the winter season. Secondly, such a backlight will help well in some situations, for example, in the forest in cloudy weather.
6. GPS module. The GPS satellite navigation device can be built into the metal detector. Scope is wide, you can:
   • see your geographic coordinates
   • write down search routes,
   • fix the places of finds.

   You can even conduct full-fledged navigation events and put the route "from point to point".

Do not forget to take with you Shovel.

How to make metal detector for non-ferrous metals with their own hands

If you have minimal radio Electronics SkillsYou know how to solder and understand the schemes, then make an elementary metal detector will not be much labor. Moreover, there are many schemes, how to do it.

Instruments, who are needed to create a home instrument:

1. Soldering iron and soldering supplies - rosin, and so on.
2. Screwdrivers, nippers, different sizes pliers.
3. Materials that are needed to create a printed circuit board.

Radioles are taken as the basis of the metal detector of the microcircuit K561L7.. Such a device will be able to distinguish the colometh from black, which we actually need. In the coil should be 90 Vitkov With diameter 230 mm.

Alone can be done different Metal detectors: Starting from highly sensitive models that act on distance up to 20-30 cm, to miniature, which will indicate the location of the wiring or other non-ferrous metal items at a distance multiple centimeters.

Detailed descriptions and schemes are fully posted on the site for radio amateur radio amateur.

The main thing is that This is possible And if you and the radio amateur itself, it is interesting.

On how to choose a metal detector, smoriate in the video:

Conclusion

Industing the collection of non-ferrous metal, without special technical training and tools do not earn a lot. On the contrary, having at hand (in the literal sense of the word) Metal detector with function discrimination, you can find truly large metal objects. And, if you're lucky, also a real treasure.

For conventional corop of non-ferrous metals no need to spend money on expensive models, Enough:

• buy simple apparatus,
• carefully read the instructions,
• pretty practice
• top patience
• and go hunting.

Good luck searching!

In contact with

Metal detectors and their types - this will be discussed in our cognitive article. Until at some time, in our country, they were known to the population only on military films, where sappers worked with these devices. Wars have passed, the economy fell into the dust, people were ruined, but they grew up like mushrooms of all kinds of myths about the treasures, starting with the treasures of Genghis Khant to the Kassa Kombka, and then to the Party Gold of the CPSU. Just the other day, the theme of the amber room began again, the cost of which is estimated by post-finish as 300 million euros. However, Amber metal detector is not found.

The principle of operation of the metal detector

Simply put - this is a special electronic device. The metal detector frame is a circuit emitting electrical fields. The field passes through the soil and "stupid" about any, for example, an iron object. On the surface of the item there are vortex electrical currents with a reverse vector, which weaken the total power of the field and are tracked with sensors. Thus, most of the scheme of the device consists of inductors, as well as a microcontroller that performs the service. In particular, when metal detected, the advanced metal detector is capable of:

• Distinguish the presence of black and non-ferrous metal;
• Approximately determine the shape and mass of the subject;
• In advance to report the depth of the subject;
• Sign up signal, sound and visual material on the display;
• Particularly expensive models can also inform the found coin and its characteristics at a depth of a third of meters.

It should be noted that it is almost impossible to develop a good device at home: it is not possible to configure it due to the presence of numerous magnetic fields. Fortunately, the cheapest devices today can be bought at a price of 100 dollars.

What needs metal detectors

Someone thinks that only black archaeologists and lovers enjoy the lost gold on the beaches use the devices. In fact, metal detectors are still used to demine the terrain from the time of war, to search for the accurate bookmark of engineering communications, to search for ordinary non-ferrous metal in scrap metal, to find lost things in the snow, etc. In any family, such a device will not be superfluous, especially in rural areas, and such a gift will be appropriate for any holiday.

Views

Views directly depend on their circuitry. In different models, various approaches to the formation of an electromagnetic field are used. Those who wish can read on their own, what is the BFO beagi method, the TR / VLF, high-frequency RF method, the PI pulsation induction method, etc. Actually, the difference in the price of simple and elite devices is already becoming a clear: much depends on the number of duplicate schemes in the design of the metal detector, in the equipment to filter false response, for accurate program modeling of findings.

In a nutshell, modern metal detector models can even work under water, search coins at a depth of up to 35-40 cm, and large metal objects at a depth to meter and more. In addition, devices can be divided into groups:

• Universal. Used for any purpose, "omnivores", but also the simplest and cheap;
• Didnote. Instruments with search frequency adjusted under the detection of exclusively nuggets from gold;
• Construction. Usually needed to search for pipes, wires. Such metal detectors are organized somewhat different than other induction devices;
• Security. The security framework and manual detectors were seen and felt all. There are stationary, wears, postal, etc.;
• Underwater. Used to search for various items at the bottom of the reservoirs. Hermetically closed, devices almost do not require configuration in operation;
• Deep. Only large items can look for, but at depths up to 6 meters underground.

All devices are divided into the following types:

• Elementary level devices;
• Semi-professional;
• Professional;
• Special. They are also diligent;
• Underwater. We have already written about them above. However, like deep, inspection, framework, etc.

Thus, species and types are somewhat mixed with a different approach, and it would be more correct to divide the instruments for simple species - the initial level, semi-professional, professional. Everything else can be included in the types of structures, opportunities and price. Simple devices allow you to search for metal items at depths to 10-20 (coins) or 60-70 cm (large items). Metals are not distinguished, output one type of signal. With them, you can most often find videos in YouTube. For beginners, it is enough, since even such a device costs up to $ 200. Characteristic example - Garrett ACE 250.

Semi-professional instruments

The price immediately begins from 500-1000 dollars. For this money, the device uses several operating frequencies, various types of signal output to the monitor determines the difference between black and non-ferrous metals. When working exclusively with silver and copper, the device very clearly differentiates them, therefore, for these materials, the metal detector can be called professional. He finds coins at a depth of 30 cm, larger items - from 0.5 to 1.5 m.

Professional devices

Prices start from 1000 dollars and indefinitely. In additions, polychast generators of electromagnetic fields are used. The instrument settings allow you to detect a separate copper coin among the silver bucket at a depth to half a meter, and large items are determined at a depth of up to two meters. Sophisticated models can still draw the contour of the object found, estimate its weight, chemical composition with precisely defined electromagnetic permeability tables.

POST Views: 6 347

Metal detectors are several types:

1. Initial-level detectors to search for ground
2. Semi-professional
3. Professional primer detectors.
4. Special devices for the detection of gold nuggets
5. Metal detectors for searching under water.
6. Deep Metal Detectors
7. Framework devices (arched), stationary metal detectors
8. Hand metal detector for inspection
9. Pinpo channels (devices for accurate object detection)

Ground-level ground metal dealers

The cost of such devices varies in the range of $ 100-500. Popularity is mostly popular with beginner seekers, since it is easy to use, have a minimum set of functions for search. To search for goals, one, sometimes two frequencies is used. They have a function of discrimination, in some devices there is a definition of the depth of the object. The available depth of metal detectors of this species is small, depends on the properties of the soil: minor coins 15-17 centuries. ("Scalys) - 3-5 cm, coins with a nominal five kopecks of Catherine II - 15-20 cm, objects with an ax - 20-30 cm, the lid from the hatch can be found at a depth of 70 cm.

There are masters who collect metal detectors themselves according to the schemes from books. However, the quality of such devices is not too high. At home, it is almost impossible to rebuild the metal detector from all sorts of electromagnetic influence, even having a special equipment at hand. The background from metal objects located around forms a variety of interference. As a result, when used in the field where there is no interfering background, such a metal detector begins to work incorrectly.

Alone, of course, you can make it possible to make the easiest metal detector with the sound indicator. However, due to its devices, a large piece of ferrous metal will give the same signal as "color" items. Disrupt the device from this interference without having a gadograph is extremely difficult.

The leader among initial level devices is due to a democratic price. Good quality and indicators (as well as the possibilities of upgrading coils).

Semi-professional metal detectors

There are such devices about $ 500-800. These metalpeakers will use search engines with experience. The work of the metal detectors of this species is based on the use of several working frequencies at once. Such devices provide sound and visual information. Visual data is shown on the display where you can see the VDI subject found. If the VDI value is in the zone positive, that is, it goes with the "+" sign, then the device found from the non-ferrous metal, if the value is "-", then the found object from ferrous metal. Based on the value of VDI, with 70% probability, it is possible to find out which item from the non-ferrous metal is found.

Copper, and always silver coins create a VDI value close to the maximum mark. In metal detectors of different firms, the maximum and minimum values \u200b\u200bof VDI are different. There are devices with a scale -10 - +10, and there is a scale -30- + 50, etc. With this, these instruments are considered professional. The maximum possible depth of efficient operation of such devices: "Scales" - 5-15 cm, five kopecks of Catherine II - 25-30 cm, the items with an ax - 40-50 cm, covers from the hatch - 100-150 cm.

P roffessionalmetal detectors

Such instruments can cost from $ 800 and up to several thousand. The high price of such metal detectors is explained by the fact that these devices are multifunction and designed for professional treasures. The devices of this type of multi-voiced discrimination, multiple frequencies for search are used, there is a whole set of manual, as well as automatic settings. Professional metal detectors can reveal under the ground "color" item located next to the "black" with a probability of about 80%. This greatly simplifies the search in the territories highly contaminated with metal garbage. If the target is detected, professional metal detectors issue a visual, digital and beep. After analyzing the received data, an experienced search engine can immediately determine what detected the device at what depth is the object, its dimensions.

In professional metal detectors, the signal is processed by a microprocessor.
Professional experience workers use complex multifunctional devices that can detect all the "color" items on the territory under study. The depth of detecting devices of this type: flakes - 15-25 cm, coins with a nominal five kopecks of Catherine II - 30-45 cm, the items with an ax - 50-80 cm, covers from the hatch can be found at a depth of 150-200 cm.

From the magnitude of the electrical resistance of the coil with the wire depends on the attenuation time of this electrical pulse. The complete absence of resistance, or opposite the very high value will make the pulse fluctuate. It looks like throwing a rubber ball on a very hard surface, on which he bounces many times before calming finally. With a sufficient electrical resistance, the attenuation time of the impulse is shortened and the reflected impulse "smoothes". This is similar to throwing the rubber ball in the pillow. The coil of the detector with pulse induction says that it is critically plugged when the reflected impulse quickly fades up to zero without hesitation. Excessive or insufficient suppression will make instability to work and mask signals from well-conductive metals such as gold and reduce detection depth. When the metal object is close to the search coil, it poins some part of the pulse energy, which leads to tightening the damping process of this pulse to zero. The change in the width of the reflected pulse is measured and signals the presence of a metal object. In order to highlight the signal of such an object, we must measure the part of the pulse where it falls to zero (tail). At the inlet of the coil receiver, there is a resistor and a limiting diode scheme, which clip the input pulse voltage to 1 volt in order not to overload the input of the circuit. The signal in the receiver consists of a pulse from the transmitter and the reflected impulse. Usually the receiver amplification is 60 decibels. This means that the area where the reflected signal falls to zero can be increased 1000 times.

Gate scheme.
The reinforced signal from the receiver enters the circuit, measuring the voltage drop to zero. The reflected pulse is converted into a sequence of pulses. When the metal object is approaching the coil, the shape of the transmitter pulse will not change, but the reflected impulse will become a little longer. The increase in the duration of the "tail" of the pulse is only a few millionth fractions of a second (microsecond) sufficient to determine the presence of a metal under the coil. The impulses (gates) are superimposed on this reflected pulse, synchronized with the start of the transmitter pulse, and the output of the electronic circuit turns out a series of gates, the number of which is proportional to the length of the "tail" of the pulse. The most sensitive impulse is located as close as possible by the end of the tail where the voltage is completely close to zero. This is usually a temporary area of \u200b\u200babout 20 microseconds after turning off the transmitter and the beginning of the reflected impulse. Unfortunately, this is also the area where the operation of a metal detector with pulsed induction becomes unstable. For this reason, most models of metal detectors with pulsed induction continue to produce gating pulses of another 30-40 microseconds after complete attenuation of the reflected impulse.

Integrator.
Next, the stroved signal must be converted to DC voltage. This is done by the circuit - an integrator that averages the pulse sequence and converts them to the appropriate voltage, which increases when the object is close to the frame and decreases when the object is removed. The voltage is further enhanced and controls the audio control circuit.
The period of time during which the integrator collects incoming gates is called integrator time constant - (PVI). It determines how quickly the metal detector reacts to a metal object. Long-term PVI (order of seconds) has an advantage in reducing noise and simplify the setting of the detector, but it requires a very slow movement of the search coil, since the object can be missed by quick movement. A short PVI (about the tenths of a second) is faster reacting to the goal, which allows you to quickly move the coil, but the noise immunity and stability of work deteriorate.

Discrimination (recognition).
The metal detector with impulse induction is not capable of the same degree of discrimination as the SNC devices. Due to the measurement of an increasing period of time between the end of the transmitter pulse and a point in which the reflected pulse is absorbed to zero (delay time), objects consisting of certain metals can be filtered. In the first place for this characteristic there is an aluminum foil, then minor nickel coins, buttons and gold. Some coins can be calculated on a very long pulse tail, but iron is thus not determined.
A lot of attempts have been made to create a metal detector with a pulsed induction, capable of determining the iron, but all these attempts had a very limited success. Although iron and gives a long "tail", silver and copper have the same characteristics. Such a long delay does not affect the determination of the depth of the occurrence. The content of minerals in the soil will also extend the reflected impulse, changing the point in which the object is determined or rejected. If the integrator time constant is configured so that the gold ring is not determined in the air, the same ring can "light up" in the soil saturated with the salts. Thus, the soil saturated with salts changes everything to the delay time and the electoral ability of a metal detector with pulsed induction.

Adjusting from the Earth.
Definition from the Earth is very critical for SNC devices, but not for metal detectors with impulse induction. On average, the soil does not spare any significant amount of energy from the search coil and usually does not give any signal. Soil will not mask the signal from the object and even on the contrary, the soil mineralization slightly lengthens the signal in proportion to the increase in the depth of the object. In relation to MD with impulse induction, the term "automatic detuning from the Earth" is often used (Automatic Ground Balance), they usually do not react to excessive soil mineralization, do not require an external adjustment for different types of soil. An exception is one of the most unpleasant components of the soil - magnetite (Fe3O4), or magnetic iron oxide. It causes overloading of the input coils of the SCH type detectors, strongly reducing their sensitivity, the metal detectors with pulse induction will work, but can show false goals if you bring the coil too close to the ground. You can minimize this harmful effect, extending the delay time between the end of the transmitter pulse and the beginning of the gating. Configuring this time constant can be disturbed from the interference caused by the mineralization of the soil.

Automatic and manual adjustment.
Most of the metal detectors with pulse induction have manual setting. This means that the operator must turn the setup until the click or itching sound in the headphones is heard. If the soil in the search area varies from and to neutral sand or from dry soil to sea water, in this case the adjustment is necessary. If this is not done, you can lose in the depths of detection and skip some objects. Manual setting is very difficult when using a short time integrator time (PVI). Therefore, many manual adjustment devices have a long PVI and require slow moving the search coil.
There are no problems using MD with pulse induction for underwater search, since the search coil is not moved quickly. When used in the surf band, the coil will be, it will be in water, then under water, and under such conditions, the use of manual adjustment devices can be very disappointed, because they will have to continuously adjust the trigger threshold. Some operators in this case immediately set up the device just below the trigger threshold. But this can lead to a decrease in detection depth, when the soil characteristics change.
Automatic configuration (SAT-SELF adjusting threshold) gives a significant advantage in searching to and over salty water or on the soil with a high salt content. It allows you to use the detector on the maximum sensitivity without constant adjustment. This improves the stability of work, noise immunity and allows you to use a greater gain. MD with pulse induction does not emit strong negative signals as SNC devices. Therefore, they are not excavated by pits with minerals. You must continuously move the coil of the metal detector equipped with the auto-adjustment system, if you stop the coil, the setting is knocked down or the device stops reacting.

Audio control.
Schemes of sound alarm systems with pulse induction are disintegrated into two categories: with a changing frequency and changing volume. Schemes with a variable frequency, built on the basis of a voltage controlled generator, are good for registration of small items, since the change in frequency is easier to catch on a rumor than change in volume, especially with a small volume level, especially for instruments with manual adjustment of the threshold. However, the sound like a fire siren quickly tires, and some people are not able to distinguish high tones. One of the good options is a mechanical vibration that was originally used for underwater vehicles. Such a device makes sounds and vibration that increases to buzz when the object is detected. Signals of such a mechanical device are easy to recognize and they do not muffle the air supply system.
Many people prefer a more traditional sound tone with increasing volume, not frequencies. Such sound control systems work well in devices, with a rapid movement of the frame, those in devices with automatic adjustment, and they sound like instruments with SNC.

Conclusions on MD with impulse induction.
These are specialized tools. They are little suitable for searching coins in urban conditions, since they cannot filter the iron and ferro-containing garbage. They can be used for archaeological searches in the countryside, where there is no iron garbage in large quantities, the search for gold nuggets and to search at the maximum depth in extreme conditions, such as the coast of the seas or the place where the land is strongly mineralized. Such metal detectors show excellent results in such conditions and in general are comparable to SNC devices, especially by their abilities to be removed from such soils and "punch" them to maximize depth.

Modern metal detector is a highly specialized device designed for non-contact discovery of metal and products from it by trapping the secondary signals with radio waves. When the device is turned on, an electromagnetic field is created in a certain range, distributed to the environment: land, stone, water, wood, air. On metals that fall into the metal dealer coil area, vortex currents appear under the influence of the electromagnetic field, creating their own secondary fields that distort the configuration and signals of the main field, which is rapidly captured by the device. The metal detector electronic device processes information and signals about finding metal.

First of all, before purchasing this complex, functional apparatus, it is necessary to determine the following number of issues:

• The main goals and objectives that will have to solve the metal detector
• Type of device
• Price category

Tip! The difference between expensive and cheaper models consists only in radiation radiation, the ability of capturing and processing secondary signals. More expensive devices have a higher degree of metal detection before it is retrieved, they can immediately identify the depth of its occurrence and other additional information.

Main species and features of metal detectors

On the scope of application, functional purpose and load level, all modern metal detectors are divided into the following types:

Universal devices. They are intended to search for small objects (coins, nuggets and jewelry) in the ground at a depth of 50 cm and large finds at a depth of 1.5 m.

Specialized devices. Each type of device is designed to carry out highly specialized work, has its own constructive features and functional intended, on which all specialized metal detectors are divided into:

• depth
• underwater
• pERSONAL
• construction
• security devices

Universal devices

The most popular metal detector group is universal devices, which, depending on the set of functions and cost, are divided into the following groups:

For beginners . The instruments of this class are designed to solve simple tasks. These are dynamic variants of TR / VLF models, i.e. Metal detectors requiring continuous movement of the head. The dynamic principle of operation of these devices provides the following advantages:

• Automatic detuning from the "average" soil
• Easy to use according to the principle "included and went"
• High reliability associated with the simplicity of the device

Disadvantages of metal detectors for beginners:

• Low sensitivity
• Not accuracy of the localization of the object
• Reduced sensitivity or false responses when working on "complex soils".

Middle class. Configured to static and dynamic mode. They have high sensitivity and excellent resolution. Completed with multiple search heads of replaceable type and different diameter. The number of control functions can reach 8. Therefore, the setting and work with such a device requires certain skills and time.

Computerized. You can decide on the nature of the find with the help of a powerful built-in microprocessor. Equipped with a convenient and multifunctional liquid crystal screen (or direction indicator) and a minimum number of touch keys for programs.

The main characteristics of specialized metal detectors

Deep devices

The depth metal detector search method differs from other devices in the following features:

• The scanning of the soil is carried out by non-oscillatory movements of the head, but by carrying out the metal detector parallel to the soil, with the coating of the search strip equal to the width of the coil (25 cm).
• This type of metal detectors cannot be checked in the premises due to reflection from the walls and household appliances of electromagnetic waves
• The devices of this type work well above the surface of the Earth, however, the search in the dug trenches, pits, grottoes, the caves are hampered by complex signals.
• Depth devices do not react to small items located at a small depth, and do not distinguish metals.

Underwater devices

They can withstand immersion at a significant depth (about 90 m), in fresh or salty water.

Tip! For periodic immersion on a small depth (shallow water), almost all types of metal detectors described above are suitable. However, only a specialized device must be used to continuously work in aquatic environment and immersion.

Personal devices

This type of metal detectors is mainly designed to search for gold. Modified impulse type devices have been widely popular, which make it possible to perfectly search for the smallest gold products on the beaches and shallow water.

Construction Communication devices

These special metal detectors designed to solve certain tasks whose execution is impossible through traditional instruments. Apply to search for cable, pipelines and other underground communications. This group includes iron search devices that differ from induction metal detectors. Special instruments include magnetometers to search for iron.

Security Devices

Security devices are divided into manual inspection devices, stationary detectors and instruments for checking mail.

• Manual inspection devices are designed to search for hidden in luggage or under the clothing of weapons and various prohibited items.
• Stationary detectors - arched-type devices installed in input or passing zones for passing visitors with simultaneous control of hidden metal.
• Mail detectors - Conveyor-type automatic devices designed to search for unresolved attachments and parts of explosives in letters and parcels.

Today to buy a metal detector of any destination is not a problem. Many experts advise to acquire the device of famous brands, arguing that in the future it will be easier to work with the device according to the instructions and it is easier to choose components and spare parts. In the ranking of the most popular models of metal detectors, the following brands: Aka, Garrett, Minelab, Fisher and Whites.