Tables for measuring the depth of detection by metal detectors. How to increase the search depth of a metal detector? Underwater metal detector practice and finds

The main groups of metal detectors (metal detectors) suitable for searching for coins, treasures, relics

According to the characteristics of metal detectors (metal detectors), which are suitable for searching for coins, treasures, relics, can be divided into several groups. Let's consider them according to the principle "From simple to complex".

Group 1. Simple ground metal detectors.

Price bar from 2500 to 10,000 rubles.

Peculiarities. Designed for beginners, have a small set of functions when searching.

Work principles. To detect a target, one or two frequencies are used, they include discrimination, less often - determining the depth of the target.

♦ small coins "flakes" (coins of the 15th-17th centuries) - 3-5 cm;

♦ large coins, for example, a nickel from the time of Catherine II - 15-20 cm;

♦ helmet, ax - 20-30 cm;

♦ manhole cover - 70 cm.

Group 2. Semi-professional metal detectors.

Price bar from 12,000 to 20,000 rubles.

Peculiarities. Designed for people with sufficient experience in search, have a fairly wide range of functions when searching.

Work principles. To detect a target, the use of multi-frequency radiation is provided, they have the ability to operate not only with sound, but also with visual information, i.e. visual information is displayed on the display, where you can see the VDI of the detected object:

♦ if VDI is in the positive zone (it has a “plus” value), then this means that the metal detector has detected a “non-ferrous” metal, and by the VDI value it is possible to determine with an accuracy of up to 70% which “non-ferrous” object is detected;

♦ if VDI is in the negative zone (has a value of “minus”), then this means that the metal detector has detected “ferrous” metal.

Copper and silver coins always give a VDI value close to the maximum values. On different metal detectors, the digital minimum and maximum VDI values ​​\u200b\u200bare different, for example, -10 to +100

or -30 to +50. That is why such devices can be classified as semi-professional.

Depth of detection(depending on soil type!):

♦ small coins "flakes" (coins of the 15th-17th centuries) - 5-15 cm;

♦ large coins, for example, a penny from the time of Catherine II - 25-30 cm;

♦ helmet, ax - 40-50 cm;

♦ manhole cover - 100-150 cm.

Group 3. Professional ground metal detectors.

Price bar - from 20,000 rubles.

Peculiarities. Designed for experienced searchers, have multi-voice discrimination, multi-frequency search range, many manual and automatic settings, i.e. a very wide range of functions when searching:

♦ it is possible to determine the presence of a “colored” object next to a “black” one with an accuracy of up to 80%, which makes it possible to more accurately search in places where there is a lot of household iron debris;

♦ when a signal is detected, visual, digital and audible signaling is used.

Analysis of these indications and makes it possible to determine:

♦ what is found;

♦ what is the depth of occurrence;

♦ What are the dimensions of the detected object.

Work principles. This is a search computer that

digital signal processing by the microprocessor is entirely used. It provides search and selection of all "colored" objects located in the investigated surface.

Detection depth (depending on the type of soil!):

♦ small coins "flakes" (coins of the 15th-17th centuries) - 15-25 cm;

♦ large coins, for example, a penny from the time of Catherine II - 30-45 cm;

♦ helmet, ax - 50-80 cm;

♦ manhole cover - 150-200 cm.

Group 4. Metal detectors for searching for gold nuggets.

Price bar - from 25,000 rubles.

Features Designed for experienced searchers, they have multi-voice discrimination, multi-frequency search range, many manual and automatic settings. Almost the entire range of such metal detectors can be classified as professional. They have the frequency to detect even the slightest gold content in any environment.

Gold has quite a characteristic VDI, but very similar to foil (both in sound and visual discrimination). It is very difficult to cut off the foil from gold or find a gold grain in the ground.

Gold metal detectors are designed to pick up the frequency of gold more than the frequencies of all other non-ferrous targets. At the same time, the indicators for finding other “colored” targets remain at a high level.

Group 5. Underwater metal detectors.

Price level - from 25,000 rubles.

Peculiarities. Designed for experienced searchers, they have multi-voice discrimination, multi-frequency search range, many manual and automatic settings. They have a sealed case, headphones. Visually, they do not give out information, only sound.

Work principles. The settings in such metal detectors are designed to take into account not only mineralization, but also the interference created by water, while the interference is different in fresh and salty sea water.

Usage area. Search at the bottom of the reservoir, on the beaches, in the coastal zone.

The depth of detection depends entirely on the search environment.

Group 6. Deep metal detectors.

Price bar - from 22,000 rubles.

Peculiarities. They are designed only to detect volumetric objects located at a depth and cannot find a coin that lies at a depth of several centimeters from the surface.

Features of work. They practically do not have discrimination, that is, when an object is found, it is necessary to dig it out in order to see what is found. This kind of metal detectors are usually used during excavations at the battlefields of the Second World War, where objects can be covered with earth more than 1.5-2 meters.

Detection depth (depending on the type of soil!):

♦ individual coins at a shallow depth - does not detect;

♦ treasure of coins - 1.5-2.5 m;

♦ large metammic objects - 3.5-5.5 m.

Depth coil. Garrett has created a deep special coil for the GTI 2500 universal metal detector. It is significantly inferior in size to the coils of deep metal detectors, but it makes it possible to use one metal detector for all kinds of searches.

Group 7. Pinpointers (metal detectors for pinpointing an object).

Price bar - from 12,000 rubles.

The name comes from the English words Pin Pointer (dotted pointer).

Features of work. A metal detector for detecting the exact, to the millimeter, location of an object. Such metal detectors do not have discrimination and are used to detect inside walls. Some search engines are used to detect small coins during excavations.

The main purpose of the pinpointer is to indicate the exact location of a metal object at a small search depth (up to 5 cm).

Of the factors that determine the depth of detection of an object, only the electromagnetic field and the electronic circuit that interprets the change in the field are functions of the device itself. Other factors depend on the object itself and on the environment.

First of all, the larger the object, the deeper it can be detected (but up to certain limits). For example, most modern devices can detect a silver fifty at a depth of 20-30 cm, while a beer can can be found at a depth of 40-60 cm. However, if the ground is highly mineralized, then the detection depth can be significantly reduced, especially for objects of small size . The humidity of the pound also affects. It usually increases the depth of detection, but not in all cases. Sometimes dry soil gives the best results.

The duration of the presence of objects in the ground also plays a role. So, copper and bronze coins that have lain in the ground for centuries and are covered with a crust of oxides can be found at a greater depth compared to modern coins. The fact is that copper oxides conduct electric current and, spreading around the coin, seem to increase its size. Corrosion of silver often produces sulphides, which reduce the depth of detection of such silver coins.

The shape of the object also affects the depth of detection. Objects with holes, such as a ring, can be found at greater depths than a coin of the same size. Difficult (in terms of detection) are very thin gold and silver chains. Of great importance is the orientation of the object in the ground. A coin standing on its edge can sometimes not be detected even at a depth of 10 cm. Fortunately for us, most coins lie flat.

The next important factor is the composition of the metal from which the object is made. Some metals have a fairly high electrical conductivity, but often in alloys they lose this property, and it becomes more difficult to find them. An example is an alloy of gold and silver. Both metals are good conductors, but electrum alloy (50% Au-50% Ag) is already a poor current conductor.

The level of discrimination that is used also affects the depth of detection. At low levels, the difference is not so noticeable, but with increasing discrimination, there is a significant loss of depth, especially for small objects and the use of static instruments. For dynamic metal detectors, the effect of discrimination on the detection depth is less pronounced

The level of sensitivity, of course, also affects the depth. As a rule, everyone wants to set the sensitivity knob to the maximum, however, with strong ground mineralization, this leads to false signals and unstable operation of the device. Therefore, at high sensitivity, the depth of detection may actually be noticeably lower than at lower sensitivity. In addition to poor ground, it is often necessary to reduce the sensitivity in case of various electrical interferences (power lines, powerful generators, radars, etc.). In these cases, often reducing the sensitivity will help increase the depth of object detection.

Modern metal detectors determine the object not by its volume (mass), but by the surface area facing the search coil. If you already have a metal detector, you can see for yourself by moving a large coin near the coil with its flat to the coil, and then edge to the coil. In the second case, the detection depth is almost two times less.

Thus, summarizing the above and taking into account other circumstances, the following factors influence the depth of detection of objects:

1. The degree and type of soil mineralization.

2. Soil moisture.

3. The size of the object.

4. The shape of the object.

5. The composition of the metal of the object.

6. Orientation of the object.

7. Type and degree of corrosion of the object.

8. The presence of electrical interference.

9. Type of metal detector.

10. Operating frequency of the metal detector.

11. Size and type of search coil

12. Level of discrimination.

13. Level of sensitivity.

14. The quality of the metal detector settings.

15. Battery status.

16. Operator experience.

17. Speed ​​of movement of the coil.

Special deep metal detectors can detect large objects at a depth of several meters, but they do not detect small objects the size of a coin.

Below are the approximate depths at which various objects can be detected in normal soil using modern metal detectors.

Car, tank - 4-6 m

Iron barrel 200 l - 2-4 m

Canister 20 l - 1.5-2 m

Soldier's helmet - 0.7-1.3 m

Rifle sleeve - 0.2-0.4 m

Perhaps the main two criteria by which a novice treasure hunter chooses a metal detector are the cost of the device and the depth of target detection. These are two important factors that directly depend on each other.

At the same time, you need to clearly understand that a cheap metal detector, by its nature, cannot have a large detection depth. It has a low cost, due to the fact that modern developments and achievements are not used in its production, but only old technologies of the 80s are used.

In the current situation, when instrumental search has become widespread, it is very problematic to find a worthy find with the help of a cheap metal detector. And every year this trend is getting worse. The more modern your metal detector, the greater the chance of success.

In a modern metal detector, the main thing is technologies that allow you to search deeper, more accurately recognize metals and ignore interference from the ground. Soil interference is the very cornerstone from which the depth of detection and sensitivity of the device are curled.

Soil interference or why the metal detector does not reach the center of the earth.

With a metal detector, we are looking for treasures and coins in the ground, which is replete with all sorts of interference that prevents the passage of an electromagnetic signal from the coil into the soil. These disturbances are collectively referred to as soil mineralization.

The less mineralized the soil, the higher the depth of detection. Light soils include chernozem, peat bogs, fresh sand. Highly mineralized soils - salty wet sand, soils with the inclusion of ceramics, burnt clay and bricks, with rusty remains of metal and oxides. Mountainous terrain, loam, clay, salty soils - all this should also be categorized as highly mineralized soil.

Today, the main struggle of metal detector manufacturers has unfolded in the field of technologies that compensate for soil interference, since this the only way increasing the depth and sensitivity of a modern metal detector.

Minelab can be considered the leader in technical solutions in the struggle for detection depth. Over the past few years, Australian scientists have developed and implemented dozens of unique technologies that we actively use now - VFLEX, FBS, BBS, SETA, DVT, AGT, AGT-C, SFT and a number of others, aimed mainly at filtering soil noise.

Choosing a metal detector according to the criterion "Price - quality"

Naturally, the cheaper the metal detector, the lower its detection depth, lower sensitivity, and extremely weak differentiation of metals. And yet, let's try to find a middle ground and choose a metal detector for your needs, based on the "price-quality" criterion.

A metal detector is cheaper than 10 thousand rubles.

Application: As fun, or to collect scrap metal.

Metal detectors from 16 to 25 thousand rubles.

Application: The first step in treasure hunting. Search for coins, treasures.

This group includes entry level metal detectors. They are intended mainly for those who seek to get acquainted with a new hobby for themselves - treasure hunting; or for those who choose a device according to the principle “there is little money, but they really want it. I’ll find a treasure, buy a cool metal detector.”

In this price category, two models of the X-Terra 305 metal detector by Minelab worth 26,900 rubles stand out with their characteristics. and a Whites Treasure Master metal detector worth 23,170 rubles. Maximum detection depth 80-100 cm. Important features:

Detuning from soil interference,

Detuning from electrical interference,

8 and 12 band discriminator,

Polyphony,

tonal background,

The XT305 model uses two detection frequencies - 7.5 kHz, and a high frequency - 18.75 kHz - a unique digital VFLEX technology, the essence of which is the rejection of noisy and noise-immune analog signal transmission circuit, and the transition to a modern digital computer technology. This new development allowed to improve the quality of metal recognition, increase the depth of target detection and sensitivity.

Killer ASI 250, so they called the new one Treasure Master by Whites. By technical specifications it is much superior to the ACE250, but the price is not inferior to it. The price of ACE 250 is 21,000 rubles, and Treasure Master is 23,000 rubles.

All these technical innovations put X-Terra 305 and Treasure Master metal detectors, though not expensive, into a series of professional serious devices.

Metal detectors from 30 to 50 thousand rubles.

Application: a serious metal detector for treasure hunters.

In this price category, high-tech metal detectors are presented, which are used for professional work. The maximum detection depth of such metal detectors is more than a meter. A good discriminator allows you to distinguish between types of metals and not waste time extracting iron targets.

The X-Terra 705 metal detector is the most popular among treasure hunters. The price-quality ratio allowed it to become the most popular metal detector. At a low cost - 45,990 rubles, the X-Terra 705 has three detection frequencies of 3 kHz, 7.5 kHz and 18.75 kHz, which contributes to the maximum possibilities for detecting both large and very small objects. VFLEX digital technology has made it possible to increase sensitivity and search in the presence of electrical interference, even near power lines. This is a versatile model with a wide range of action, which can successfully search for treasures, coins, jewelry lost on the beach, as well as gold nuggets in mines and mountain streams. A special GEO program allows you to find gold particles smaller than a match head. Treasure hunters use GEO mode to collect treasures and search for small silver coin- scales. No other metal detector in this class has such features as the X-Terra 705.

Standing out in this category is the new Whites Treasure Pro metal detector with automatic ground balancing (AutoTrac® (Tracking) function), waterproof control box and waterproof coil. The peculiarity of this model is that with it you can search under the water. The cost is 31,590 rubles.

Metal detectors from 45 thousand rubles and more.

Application: The choice of professional treasure hunters.

These are professional metal detectors with modern technical solutions that allow you to find objects at the maximum depth available to modern technologies.

The most popular metal detectors in the treasure hunting community, as one would expect, have the most advanced technical solutions and know-how, on which the detection depth, sensitivity, and discrimination quality depend. For example, models: Explorer, E-Trac and modern CTX 3030. These metal detectors are unique developments of Australian scientists, which have no analogues in the world, and use not only information about the conductivity of the metal, but also its inductance to determine the type of target. In addition, they use 28 search frequencies to detect a target, and not just one, like conventional metal detectors. A multi-frequency metal detector in the process of searching examines a target in the ground with a whole range of frequencies, obtaining the maximum amount of information about the object, and thereby allowing you to more accurately determine the type of metal and most effectively compensate for soil interference. These unique metal detectors are able to work steadily both on clay soil and on a salty sea beach, among broken bricks and clay shards.

A good single-frequency model is the XP DEUS model with good sensitivity to small objects, a wireless coil and an original control unit. This model is worth paying attention to.

Note to treasure hunter

What is the frequency of detection of a metal detector and what depends on it? Single-frequency metal detectors, depending on the frequency, are purposefully tuned to large or small search targets. The high frequency of 18 kHz allows you to capture small items 1-2 mm in size. However, the high-frequency signal attenuates faster in the soil, so the depth of detection of objects is somewhat less. low frequency 3 kHz detects small objects worse, but electromagnetic waves penetrate deeper into the soil, respectively, the depth of detection of objects is higher. The lower the operating frequency, the deeper the detector can locate the target. Multi-frequency metal detectors with 28 detection frequencies from 1.5 to 100 kHz search both at high and low frequencies, allowing you to combine best qualities low-frequency machines and deep low-frequency. Working with a metal detector that uses multi-frequency technology is essentially the same as using several single-frequency metal detectors at the same time with different characteristics at the same time.

Feature application of many frequencies and special programs.

Depth of detection

The depth of detection of metal detectors depends on the size of the target: the larger the object, the deeper it can be detected by the metal detector. For example, the average detection depth of modern professional metal detectors with a standard 10” coil reaches 30-40 centimeters for single coins, about a meter for a treasure the size of an army helmet, and up to 1.5 meters for a larger object. You can increase the detection depth by installing a larger diameter coil, for example - 15 or 18”. That allows you to increase the search depth by 30-35%. At the same time, it should be taken into account that such an increase in the detection depth is possible only when using multi-frequency metal detectors. For inexpensive single-frequency models, the increase in detection depth will be no more than 10-20%, due to increased soil interference with the diameter of the coil. A priori, single-frequency metal detectors cope less effectively with soil mineralization than multi-frequency ones.

Finally

When choosing a metal detector, try not to save money. These are one-time costs that are justified only at a certain level. Remember, treasures and coins are not mushrooms, and will not grow again "after a rain on Thursday." Saving 10,000 rubles, you risk missing expensive coin or a treasure, which is incomparably higher in value than the money saved. Treasure hunting is becoming a mass hobby, and if you don't find your treasure, someone else with a better metal detector will find it tomorrow.

Metal detector detection depth chart

To enlarge the graph, click on the picture.

Underwater metal detector practice and finds.

An underwater metal detector is a special topic. The choice of such devices is not great, but I will talk about one of them, as I know its features well. The main advantage of this metal detector over others is the ability to work in any water, fresh or salty.

Why do treasure hunters need headphones

Metal detector X-Terra 705 video instructions for use

Metal detector X-Terra 305 video instructions for use

Let's talk together on such an interesting topic as the depth of detection. In almost 90% of cases, novice searchers, when purchasing their first metal detector, ask: how deeply does it determine the target. In the minds of many, there was a strong belief that the deeper the “electronic beam” of a metal detector penetrates into the ground, the more finds will be able to pick up. Is this true, and where is the catch?

Let's start with the fact that most of the finds are at a depth not exceeding 15-25 centimeters. And it is at this depth that most metal detectors work, from the simplest models to more advanced ones. If we are talking about searching in the fields, then regular plowing pulls coins, crosses and buttons to the surface, with repeated plowing, the whole thing again turns out to be under a layer of earth. And so every year.

The main part of forest losses is also located in the upper layer of the earth. No, of course, sometimes there are cases when someone specially hid something and buried it to a meter deep. But, if you naively believe to find a gold coin, then even from 50 centimeters it is hardly possible to detect it, especially if it lies on the edge.

So it turns out that marketing statements about the maximum sensitivity of a metal detector (by 1-2 meters) are beautiful words that caress the ears of beginners. And interestingly, no cheating.

For example, a sewer manhole or a rusty hood, even a simple metal detector will calmly see both 50 cm and from a meter depth. But, first of all, decide for yourself what you are going to look for: single coins or voluminous shmurdyak, which lies at depths of at least 1-1.5 meters.

What kind of metal detector sees targets deeper

In the second case, depth matters, and special deep metal detectors have been developed for these purposes, which react only to large metal, ignoring small targets. In all other situations, it remains to choose one of the numerous metal detectors, the main task of which is to search for coins and other small metal objects.

But, choosing a metal detector among the second category, a person again faces a problem. Some metal detectors see really deeper than others. For example, some metal detectors see 5 kopecks of the USSR at a maximum depth of 17 centimeters, while others sniff out this coin already from 25-30 centimeters. The difference in the price of these devices can be enormous, differ at times. From here you must answer a number of important questions for yourself:

1. Is metal detecting a hobby or a job for you?
2. How much are you willing to pay for a metal detector
3. Where is it planned to search most often (forest, beach, cultivated or abandoned field, old villages, and so on)
4. How often do you plan to search

These are the main questions that will help you choose your metal detector. So, if your place of search is arable fields, then deep-wells are not really needed here. Of course, you will miss a number of coins, you won’t pick up something, but put most of it in your habarnitsa. Here it is much more important to deal with your device, to delve into the discrimination system, to understand the sound of the device, and so on.

What can be done to increase depth

On the other hand, if your goal is to search in the forests, where there are many old roads, near the village, you have heard many legends that people in your area were digging something, and you know that the area has already been explored by people with metal detectors and all the cream has already removed - you can take a closer look and the device is more expensive, which sees deeper. There is another option, take a simpler device, and then, if everything goes well, expand its capabilities with a more powerful search coil. As they say, there are many options.

Many search engines of our time, in our opinion, have really “hit” the settings of various programs, delve into the intricacies of discrimination, and so on. There is a truth that was voiced by one of the comrades that the best discriminator of all ages is an ordinary spade, a faithful hard worker.

Indeed, even the most modern discrim is sometimes mistaken, which means that you can interpret the signal in a wrong way, skip it. It is clear that by digging all the signals you quickly get exhausted, but only in this way does experience, understanding of the process, understanding of the device come. In general, supplementing the words of the “wise comrade”, let’s say this: “ Learn to hear and listen to the sound of your device, it will tell you a lot if you find a common language with it". And all these discrepancies, advanced settings are good, but believe me, they are not the most important thing.

Selecting a search location

Well, the last thing that has already been said hundreds of times is the place where you plan to search. Usually we say this to beginners: “If the place is chosen correctly, and there is something under the coil, it will make itself felt. If, in your hands who sees on the "meter", and the place is empty - you will have to enjoy the singing of birds and the rustle of leaves.

So it turns out that the race for depth is not always justified, much more important is a more meaningful and high-quality . Although, to be honest, you always want to have a metal detector in your hands, the functionality of which inspires confidence. But this understanding does not come immediately, you need to approach this, gain experience. So, getting out for a ride once or twice a year, it is somehow strange to purchase a device at the price of a used car, although ..., to each his own.

When I had Chinese in my hands, I came up with a check for him. I was wondering what is the real depth of detection of a coin in the ground with this detector. Then I decided to conduct the following experiment.

I took a standard coin - 5 late Soviet kopecks. He took out a whole pyramidal piece from the ground 25 centimeters high. At the bottom of the hole formed at the same time, he laid flat a coin. Then I thought about it and decided that sticking it into the wall would not be a bad decision. Therefore, 5 kopecks. stuck at a depth of 25 cm in dense soil. Then he returned the pyramidal piecelandin place.

What did he do? I brought the experiment as close as possible to the natural conditions in which there are thousands of coins we dig.

But, in order to determine the quality of the search for the metal detector under test, I took mine. Since these devices belong to the same class () and have DD coils of almost the same diameter, it will be interesting to see the reaction to one coin from two different (according to the manufacturer) detectors. This, in my opinion, will enable us to fully appreciate the quality of the definition of a penny in the ground by the Ground.

I filmed this entire test, so my reader has the opportunity to see it right now.

And so: I took the 400th Ground, built in the same place, and with a sensitivity of 7, in the “all metals” mode, I began to search for the just hidden coin. The readings of the device were thrown either in color or in black - it was not digging. Then I increased the sensitivity to the maximum. And the MX400 began to respond to everything.

I summarize. Ground EFX MX 400 5 kopecks of the USSR at a depth of a quarter of a meter voices it not dug signal.

Then I tried with my B-5 to find the buried coin. The device voiced the tested target in the same way as the Ground - now in black, then in color. Not digging. The only thing: the “bird” worked more stable than the four hundredth one - it didn’t phantom for everything indiscriminately.

Outcome.

Ground MX 400 sees not a small coin (5 kopecks) at a depth of 25 centimeters, but not a dug signal. Yes, it shows that the target is deep and if the digger does not yawn to look at this parameter, then he may decide to dig such a target.