How to increase the power of a metal detector with your own hands

During a long search, any user sooner or later has a question: how to increase the detection depth of a metal detector? This can be done using various techniques.

Before rushing to the instructions and advice of experienced treasure hunters, you need to try to use the natural features of the soil. Thus, the sensitivity of the metal detector increases:

• before a thunderstorm - the reason for this behavior of the device has not been studied; there is an assumption that the search depth increases due to increased humidity
• at night - most likely, the matter is a significant reduction in the level of electrical interference in the evening
• after rain – the ground after rain becomes looser, which allows electromagnetic radiation from the metal detector to penetrate deeper.

How to increase the power of a metal detector with your own hands

During a long search, any user sooner or later has a question: how to increase the detection depth of a metal detector? This can be done using various techniques.

Before rushing to the instructions and advice of experienced treasure hunters, you need to try to use the natural features of the soil. Thus, the sensitivity of the metal detector increases:

• before a thunderstorm - the reason for this behavior of the device has not been studied; there is an assumption that the search depth increases due to increased humidity
• at night - most likely, the matter is a significant reduction in the level of electrical interference in the evening
• after rain – the ground after rain becomes looser, which allows electromagnetic radiation from the metal detector to penetrate deeper.

Correctly setting up a metal detector is the key to a decent search depth

The settings of the device determine how productive it will work. The detection depth of beginners is much lower than that of experienced users, and all because of the inability to use the detector.

Carefully read the manufacturer's instructions, which accurately describe all settings. If you are the happy owner of a metal detector with ground balancing and electrical noise functions, turn them on. If the device is simple enough and does not have complex settings, you can limit the influence of interference yourself. To do this, choose the right search locations where there are no other metal detectors, power lines, and also do not forget to turn off your own electrical appliances (phone, tablet, radio, etc.).

Ground adjustment can be manual or automatic. If you have manual ground adjustment, you usually need to move the coil in front of the metal detector, while rotating the adjustment knob until the sound signal disappears. With automatic adjustment, everything is much simpler - the metal detector itself adjusts the device to changes in the ground, providing maximum sensitivity without false signals.

After you have dealt with the interference, proceed to adjust the sensitivity, increasing it to the maximum level. If a threshold tone is present, you can adjust its volume to maximum to better hear even small signals.

Particular attention should be paid to the battery indication level. You've probably noticed that as they gradually discharge, devices begin to work worse and malfunction. If your goal is to increase the search depth of your metal detector, then you need to install new batteries.

Metal detector made from a radio and calculator

As promised at the beginning of the article, we will tell you how to make a metal detector using a radio and a calculator. Let us immediately note that such a device is definitely not suitable for searching for metals even under a thin layer of earth. But you can try to use it as a detector of hidden wiring in walls. For such a device you will need:

1. Empty CD box.
2. A radio receiver capable of operating in the AM range.
3. Calculator.
4. Double-sided tape.

To make a metal detector, you need to do the following operations:

• stick double-sided tape on the inside of the CD box flaps;
• attach a radio receiver to one leaf;
• A calculator is attached to the second flap.

That's it, the metal detector is ready. All that remains is to configure it. To do this, both devices need to be turned on and the radio set to operate at the maximum frequency. Then, by changing the mutual inclination of the calculator and the receiver, it is necessary to ensure that only a slight noise background from the electromagnetic waves emitted by the calculator is heard from the radio speaker. This position needs to be fixed, and you can begin testing the device by bringing it to metal objects and recording the change in sound.

Using the correct search coil

By default, manufacturers most often equip metal detectors with mono coils, especially devices in the low price segment. Mono coils have an undeniable advantage: they work well on difficult soils and littered areas. In addition, mono coils distinguish between types of metals well.

In field conditions, when it is necessary to scan a large area, it is advisable to use large Double D coils. This way, it’s faster to explore the area, and the depth of the search increases. The larger the coil, the deeper it sees. You should also pay attention to the frequency of the sensor - at a low frequency you can achieve the greatest depth, and at a high frequency small objects are well detected.

Correct search behavior is the key to good depth

Why do novice treasure hunters lack the depth of their search? The reason most often lies in aggressive behavior. Sharp swings of the coil, jumping, or insufficient distance between the coil and the ground always lead to a loss of search efficiency.

To detect a target at maximum depth, you need to work with a metal detector “with feeling, sensibly, and with precision.” Move the sensor slowly, bringing it as close to the ground as possible. Avoid superficial searching where the metal detector is not actually operated. This happens just with wide scales.

There are models with a fast response function; they are configured in such a way that the detector is able to pick up even the weakest signals during sudden movements. Of course, you can immediately buy such a metal detector and not think about the behavior, but it is at the very early stages of the search business that the correct feeling of searching is formed. To become a real professional, you will have to learn to search competently.

Headphones are a powerful tool in increasing search depth. The threshold tone makes it possible to determine by sound which object lies underground. Often, extraneous noises distract the digger, “leading” him away from the find. With headphones, you will be able to pick up even the weakest signals and will certainly not miss anything important.

Using various methods, you will very soon begin to feel your metal detector, and you will be able to achieve a really great search depth.

Along with discrimination, target detection depth is one of the most important indicators of a metal detector. It depends, first of all, on the device itself, the coil used and external factors, which will be discussed below. We will also consider how to increase the sensitivity of the device and whether it is generally worth focusing on this indicator.

How to increase search depth?

The most common and effective way to increase depth is to install a larger reel. This way you can increase the depth by more than 30%. But this method is only suitable for unlittered areas, otherwise a large coil simply will not “see” a coin next to a piece of an axe, for example. In such conditions, it is worth using a small coil - a “sniper”.

Here are other ways to increase search depth:

1. Correct setting of the operating frequency, if the device allows this.
2. Setting the maximum permissible sensitivity level. A sensitivity level that is too low will lead to a decrease in detection depth, and a sensitivity level that is too high will result in false alarms of the device.
3. Ground balancing, manual or automatic. The less soil mineralization affects the device, the better.
4. It’s worth trying to walk around with the device after a good rain or in dew. It may be possible to catch a deep signal. But it is better to do this after the snow melts or during prolonged autumn rains, when the ground gets wet to a decent depth. However, this should only be done on weakly mineralized soils, otherwise the effect may be the opposite.
5. Use of high-quality power sources. It doesn't matter whether it's batteries or rechargeable batteries.
6. It is worth avoiding various obstacles: try not to walk under power lines and near other diggers.

Conclusion

Most even entry-level devices are capable of detecting a coin at a depth of 15 to 40 cm. For example, the simplest Garrett ACE150 and Garrett ACE250 “see” a 5-kopeck coin of the USSR at a depth of up to 23 cm. But the semi-professional Garrett AT Pro is able to detect the same coin already at a depth of up to 37 cm. The numbers are average, of course. But is greater detection depth needed for coin-sized targets? In most cases, no. Firstly, you will quickly get tired if each of your holes is half a meter long. And secondly, most of the finds lie precisely at the detection depth of most instruments. There are exceptions, of course, but in this case it is enough to have a larger diameter coil.

When choosing a new device, it is better to focus on more important characteristics, such as discrimination. Although depth should not be discounted, in some situations it may be more important than the same discrimination, for example in areas with very little metal debris. Or on carved-out tracts, where the remaining finds are located at extreme depths. Choose a device, its coil and settings depending on the specific situation.

There are situations when you seem to completely knock out a place, but then, returning again, you find something again, and it seems that there is definitely something else there, but the depth is not enough, literally 5-7 cm. This is especially true when finishing off a plowed treasure or just at a promising place. I myself have a clearing with a diameter of no more than 50 meters, where I was able to find about 50 coppers of all eras. At the same time, the last coins were not given more than one per exit. There are probably still coins there, but the metal detector can no longer get them. What to do? There are several ways to increase target detection. So, how can you increase the detection depth of a metal detector:

Elementary methods : - set the sensitivity to maximum - do the “most manual” ground balance - turn on the all metals mode - dig with headphones or in complete silence late at night (for some metal detectors, the signal to a deep target can be very quiet) - remove the protection from the coil (especially if it's homemade)

Natural methods : - check the treasured place after heavy rain - try to dig before a thunderstorm (I use this method and sometimes it really helps) - dig late in the evening or at night (I don’t know why, but sensitivity increases)

Costly methods : - install a more powerful reel that gives an increase in depth (or borrow it for a while) - plow the desired area (as a rule, the costs of a tractor with a tractor driver are well compensated by the coins found)

Metal detector and its structure

Professional metal detector Garrett AT Pro for searching military trophies and coins

This model costs more than 32,000 rubles, and, of course, non-professionals will not be able to afford such a device. Therefore, we suggest studying the design of a metal detector in order to assemble a variation of such a device yourself. So, the simplest metal detector consists of the following elements.

Design elements of a standard metal detector

The operating principle of such metal detectors is based on the transmission and reception of electromagnetic waves. The main elements of a device of this type are two coils: one is transmitting, and the second is receiving.

The principle of operation of the metal detector

The metal detector works like this: the magnetic field lines of the primary field (A) of red color pass through the metal object (B) and create a secondary field (green lines) in it. This secondary field is picked up by the receiver and the detector sends an audible signal to the operator. Based on the principle of operation of emitters, electronic devices of this type can be divided into:

1. Simple, working on the “receive-transmit” principle.
2. Induction.
3. Pulse.
4. Generating.

The cheapest devices belong to the first type.

The simplest metal detector will make you lose a couple of extra pounds. You'll be walking and digging a lot

An induction metal detector has one coil that sends and receives a signal simultaneously. But devices with pulse induction differ in that they generate a transmitter current, which turns on for a while and then turns off abruptly. The coil field generates pulsed eddy currents in the object, which are detected by analyzing the attenuation of the pulse induced in the receiver coil. This cycle repeats continuously, perhaps hundreds of thousands of times per second.

How to increase the detection depth of a metal detector

If your metal detector does not have enough detection depth, then you can increase it in several ways.

Method one. Make sure your metal detector is set up correctly. To do this, limit the influence of electromagnetic radiation as much as possible (turn off your mobile phone, move away from power lines, etc.). Then, do ground balancing - for each metal detector it has its own algorithm of actions. After which you can set the sensitivity of the device to maximum and, if there is a threshold tone, increase it too.

Many users of the popular Garrett 250 metal detector do not know that this device has automatic detuning from the influence of ground mineralization. It’s easy to do – you just need to place the coil in a clean place and turn on the metal detector. After this simple but necessary procedure, the detector will “see” deeper and “feel” more accurately.

It would not be superfluous to supply charged power supplies, because many devices (the same Garrett 250) are lost in the depths due to dead batteries.

How to increase the detection depth of a metal detector

Method two. Improve the search sensor of the metal detector. To do this, we will need to purchase it additionally. Of course, the new coil must be larger in diameter than the original one. For example, one of the popular ones at the moment is the Nel Tornado 12x13-inch reel. It gives up to twenty percent increase in target detection depth. Also, there are larger sensors on the market (fifteen inch) with an operating frequency of three kilohertz. It is this (low) frequency, combined with the size, that will give the maximum increase in depth to your metal detector.

Third way. Searching with a metal detector. In order to be able to detect a find as deeply as possible, you need to move slowly and move the search sensor above the ground. It is better to search with headphones and listen carefully to each signal. Such a search will be effective in an area that is not littered with various metal pieces.

By following these methods in various combinations, you can achieve the detection of a valuable find by a metal detector at maximum depth.

What parts can be replaced and with what?

Transistors : BC546 – ​​3 pcs or KT315. BC556 – 1 piece or KT361 Op amps :

LF353 – 1 piece or exchange for the more common TL072. LM358N – 2 pcs Digital chips: CD4011 – 1 pc CD4066 – 1 pc CD4013 – 1 pc Fixed resistors, power 0.125-0.25 W: 5.6K – 1 pc 430K – 1 pc 22K – 3 pcs 10K – 1 pc 390K – 1 pc 1K – 2 pcs 1.5K – 1pc 100K – 8pcs 220K – 1pc 130K – 2pcs 56K – 1pc 8.2K – 1pc Variable resistors: 100K – 1pc 330K – 1pc Non-polar capacitors: 1nF – 1pc 22nF – 3pcs (22000pF = 22nF = 0.022uF) 22 0nF – 1 piece 1uF – 2 pieces 47nF – 1 piece 10nF – 1 piece Electrolytic capacitors: 220 µF at 16V – 2 pieces

The speaker is miniature. Quartz resonator at 32768 Hz. Two ultra-bright LEDs of different colors.

If you cannot get imported microcircuits, here are domestic analogs: CD 4066 - K561KT3, CD4013 - 561TM2, CD4011 - 561LA7, LM358N - KR1040UD1. The LF353 microcircuit has no direct analogue, but feel free to install LM358N or better TL072, TL062. It is not at all necessary to install an operational amplifier - LF353, I simply increased the gain to U1A by replacing the resistor in the negative feedback circuit of 390 kOhm with 1 mOhm - the sensitivity increased significantly by 50 percent, although after this replacement the zero went away, I had to glue it to the coil in a certain place tape a piece of aluminum plate.

Soviet three kopecks can be sensed through the air at a distance of 25 centimeters, and this is with a 6-volt power supply, the current consumption without indication is 10 mA. And don’t forget about the sockets - the convenience and ease of setup will increase significantly. Transistors KT814, Kt815 - in the transmitting part of the metal detector, KT315 in the ULF. It is advisable to select transistors - 816 and 817 with the same gain. Replaceable with any corresponding structure and power. The metal detector generator has a special clock quartz at a frequency of 32768 Hz. This is the standard for absolutely all quartz resonators found in any electronic and electromechanical watches. Including wrist and cheap Chinese wall/table ones. Archives with a printed circuit board for the Volksturm SMD version and for the Volksturm+GEB (version with manual ground detuning).

Powerful DIY metal detector Pirat

This metal detector received this name due to the fact that it is pulsed, this is the designation of its first two letters (PI-pulse). Well, RA-T is consonant with the word radioskot - this is the name of the developers’ site where the homemade product was posted. According to the author, the Pirate is assembled very simply and quickly; even basic skills in working with electronics are enough for this.

The disadvantage of such a device is that it does not have a discriminator, that is, it cannot recognize non-ferrous metals. So it will not be possible to work with it in areas contaminated with various types of metals.

Materials and tools for assembly: - KR1006VI1 microcircuit (or its foreign analogue NE555) - the transmitting unit is built on it; — transistor IRF740; - K157UD2 microcircuit and BC547 transistor (the receiving unit is assembled on them); — wire PEV 0.5 (for winding the coil); — NPN type transistors; - materials for creating the body and so on; - electrical tape; - soldering iron, wires, other tools.

The remaining radio components can be seen in the diagram.

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

Metal detector assembly process:

Step one. Creating a printed circuit board

The most complex part of the device is, of course, the electronics, so it makes sense to start there. First of all, you need to make a printed circuit board. There are several board options, depending on the radio elements used. There is a board for NE555, and there is a board with transistors. All the necessary files to create the board are included in the article. You can also find other board options on the Internet.

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

The leads from the coil are soldered to a stranded wire with a diameter of about 0.5-0.75 mm. It is best if there are two wires twisted together. Step five. Setting up a metal detector

When assembling exactly according to the diagram, you do not need to adjust the metal detector; it already has maximum sensitivity. To fine-tune the metal detector, you need to twist the variable resistor R13, you need to achieve rare clicks in the speaker. If this can only be achieved in the extreme positions of the resistor, then it is necessary to change the value of resistor R12. The variable resistor should set the device to normal operation in the middle positions.

If you have an oscilloscope, you can use it to measure the frequency at the gate of transistor T2. The pulse duration should be 130-150 µs, and the normal operating frequency is 120-150 Hz.

Deep modernization of the “Pirate” metal detector.

I’m sitting quietly, not bothering anyone, and then bam - a letter with an eccentric content arrives in my mail: - Dear author! Could you tell me how to improve the performance of the Pirate metal detector? When powered by a 9-volt battery, the sensitivity is not enough, but the current consumption is acceptable; when you switch to a 12-volt battery, the circuit’s performance becomes better, but you’ll get tired of constantly recharging it. The diagram is attached... Forget me! - I said, looking around, just in case, I went to my website, climbed there, crossed myself... There is nothing like metal detectors there! - Why on earth should I understand anything in this area? - I am writing to the author of the question. — Of course, about 100 years ago in magazines, I saw simple circuits of beat-based metal detectors, but nothing more. - No, this one is not beating - it’s pulsed, the guys from Radioskot developed it. There's just something there: a transmitter and a receiver. You feel like two fingers on the asphalt, but I don’t have enough knowledge and no one can really answer! Well, somehow,” I thought, “two fingers on the asphalt, this is not the process that I had dreamed about for so long since kindergarten,” and I wanted to send the intrusive questioner off in a gentle but decisive manner, but..., wandering around network and having studied the question, I discovered that this topic excites the minds of a fair number of radio amateurs. It turns out to be a popular topic! Yes, there are many more gold nuggets buried in the great expanses of our country,” I outlined the possible origins of such interest and decided to puzzle myself with this question. The result of the theoretical study of the topic was a page - a link to the page. And now we smoothly move on to “Pirate”.

It so happened that the “radio cattle guys” didn’t have to push themselves that hard. The first implementation of such a metal detector was found in the bourgeois magazine “Everyday Electronics August 1989”, and a very similar circuit “PI Metal Detector” was published on September 30, 2008 by S.V. Smith. So the only thing left for the lads to do was to throw out what they thought were unnecessary radio components. How much is extra - we’ll leave it up to them, it works, well, thank God!

Let's look at the operating principle of this metal detector. After the transmitter emits a short pulse of magnetic induction, a damped current pulse appears in the desired metal object and is maintained for some time (due to the phenomenon of self-induction), causing a time-delayed reflected signal. This reflected signal carries useful information about the object, which must be registered by the receiving part of the metal detector.

Fig.1

Figure 1 (left) shows the transmitting part of the “Pirate”. The pulse generator generates short current pulses arriving at a frequency of 150 Hz into the emitting coil, where they are converted into magnetic induction pulses. Since the emitting coil has a pronounced inductive nature, voltage surges across it can reach hundreds of volts. And since this coil is also a receiving coil, it is necessary to take care of limiting this voltage at the input of the receiving part of the recorder. For this purpose, a diode limiter D1-D2 is used. The right side of the figure shows diagrams of the voltage on the limiter in the absence of a metal object in the coil’s coverage area (blue color) and the presence of a piece of iron (red color). As you can see, there is an effect of pulse expansion due to re-emission of the target. The larger the metal object, or the closer it is to the search coil, the more pronounced the expansion effect will be, i.e. By calculating the difference between the durations of the red and blue pulses, one can judge the size and depth of the object.

Moreover, the main part of the device’s current consumption is precisely the process of pumping the energy coil necessary for sufficient radiation power. How can this consumption be reduced? Stupidly - reduce the pulse repetition rate. Let's think about why the frequency of these pulses was chosen in “Pirate” to be 150 Hz? Yes, it’s very simple - this frequency must be recorded by a speaker. The speaker is small, it will hardly reproduce this frequency, and if you lower it too much, it will be completely silent like a fish, and if not silent, then click slightly. Okay, forgot about the speaker! To what extent can this frequency be reduced? To values ​​that allow you to comfortably move the metal detector coil in space without losing the speed of target detection. It is clear to the hula hoop that lowering the frequency to 50Hz (or 50 spitting search impulses per second) will not have any negative effect on the speed of movement. But a threefold decrease in frequency will allow at least a threefold reduction in current consumption. Further reductions can be achieved by using digital signal processing via low-power CMOS chips.

Well, enough of this dull theory, it’s time to move on to the electrical circuit diagram!

Fig. 2 Scheme of a pulse metal detector

Figure 2 shows a diagram of the formation of a pulse, the duration of which is directly proportional to the power of the signal reflected from the metal object. The driver uses CMOS logic elements “2AND-NOT” with Schmitt triggers at the inputs. It is the presence of these triggers that allows microcircuits to avoid prolonged transient processes and ensures their own current consumption close to zero. The pulse frequency of the generator, as we have already agreed, is 50 Hz, the duration of the pump pulses is 150 μs (this value is optimal for the coil used in the metal detector). In the simplest version, the coil is wound on a 200 mm mandrel and contains about 30 turns of wire. Its shape and design can have different shapes; it is important that the resulting inductance is 300-330 μH. The beginning of the prohibition pulse coincides with the beginning of the transmitting pulse. The duration is regulated by variable resistor R2 and should be a value equal to the discharge time of the emitting coil. The DA1A operational amplifier amplifies the signal coming from the output of the diode limiter and makes its output shape closer to rectangular.

For a better understanding of the operation of the circuit, I will provide voltage diagrams at various points.

Fig. 3 Pulse metal detector voltage diagrams

I think no further explanation of the shaper’s operation is required.

As a matter of fact, now all we have to do is measure the duration of the output pulse and record it using any method convenient for the user. This can also be done conveniently using purely digital means.

Fig.4 Pulse duration meters

Figure 4 shows two options for a pulse duration meter: the first with LED indication, the second with duration registration using a changing audio frequency. Both devices are based on the CD4017 (K561IE8) chip, which is a decimal counter with a decoder. The decoder works in such a way that it provides a logical one at only one output at any time, which is extremely useful for reducing the power consumption of the circuit when operating on LED matrices. How does it all work?

When a positive differential of the measured signal (input pulse) arrives at the input of the device, a generator built on IC1.1 is started, the output pulses of which, with a frequency specified by the R1-C1 chain, are supplied to the clock input of the counter IC2. The counter begins to do its immediate job - counting. At the end of the measured signal, its level becomes zero, the generator stops and so does the counter, indicating the number of counted pulses as “one” at the corresponding output. The more the counter manages to count by this moment, the longer the duration of the signal arriving at the input. Elements IC1.2 and IC1.3 are designed to stop the counter at the moment the “one” appears on the last digit in order to prevent its subsequent restart. Variable resistor R1, which regulates the frequency of the generator, is also responsible for the sensitivity of the metal detector: the higher the frequency, the higher the sensitivity.

So, we sorted this out, throw out the LEDs, connect the generator to the meter (Fig. 4 on the right). The generator is made on IC3.1, IC3.2, T1 and is a device whose frequency is generated by the control current. The control current, in turn, depends on the values ​​of resistors R4-R11 connected to the corresponding outputs of the meter. With the values ​​indicated in the diagram, the minimum frequency corresponding to the shortest duration of the input pulse will be about 500 Hz, the maximum, corresponding to the longest duration: ≈ ​​1 kHz. The remaining resistors should be selected from a grid of intermediate values. In the process of increasing the frequency of the generator, there is a simultaneous increase in the volume in the sound emitter, associated with a decrease in the duty cycle of the output pulses (approaching their shape to a meander).

To maintain high stability of the metal detector, all logic elements must be powered with a stabilized voltage taken from the integrated stabilizer VR1 (Fig. 2). In fact, for the classic “Pirate” such a stabilizer would also be quite useful!

How to increase the search depth of a metal detector?

Hi all! Today I will tell you how to increase the search depth without interfering with the metal detector circuit and without replacing it with a more advanced one. I will not consider these options, since if you tamper with the device circuit unqualifiedly, it can easily be damaged and then you will forget about the problem for a while, and opening the unit will completely void the warranty. And even if everything goes well and the MD breaks under warranty, it will not be repaired for free. And certainly not everyone can just pick up and buy a new device. They are not cheap!

Surely, if you are the owner of an inexpensive metal detector with a small mono coil, you have asked yourself this question. And in this article I will try to answer this question. And so, let's go!

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Device setup

Correct device settings are the key to successful digging. Correctly selected sensitivity in accordance with the litteriness of the place. If you are walking through a plowed village, especially on the site of houses, then you should turn down the sensitivity, but if the place is clean, then feel free to turn it up to the maximum. Cooler devices already have much more settings. This is the task - to select the optimal parameters for the location of the cop. If you set everything to automatic, then, of course, the search efficiency and depth will be less.

I experimented with an Explorer SE with an 8 inch coil. I walked around the field with full sensitivity and there were even phantoms while searching. But when I turned on autosensitivity, the phantoms immediately disappeared. I moved a coin in front of the coil - the detection depth decreased sharply.

Yes, and detuning from the ground also makes a difference. Reduces the influence of the soil and thereby increases the depth by several centimeters. In my opinion, it’s better to use automatic adjustment here - when the device itself monitors changes in the ground and performs balancing itself.

Well, if you are searching near power lines or underground communication lines, and if you have a non-entry-level metal detector, use electrical noise rejection.

And of course, study the instructions for your metal detector and video instructions in order to master your metal detector perfectly.

Types of MI by purpose

DIY surge protector

In accordance with their intended purpose, MI is divided into the following types:

1. Soil models designed for underground surveys in the upper layers of soil. Devices in this category are the most common among metal detectors and treasure hunters who can assemble a metal detector with their own hands at home. The simplest homemade product has low accuracy and does not always distinguish between different types of metals. Professional instruments can detect small grains of gold, ignoring other metals.
2. Depth models designed to detect targets at a depth of up to 6 meters. However, they can only “see” large objects with an area of ​​over 400 square meters. see. Deep devices are in demand by engineering services as route finders, by geologists as specialized georadars for searching for native gold, etc.
3. Underwater metal detecting devices operating underwater. They are subject to increased requirements for the tightness of the search system. The operating conditions of underwater MI in sea and fresh water differ significantly. Underwater detectors use only sound indication.

We recommend reading: Types of batteries: detailed classification of batteries by size, composition and other parameters
Please note! Underwater MI can be used on the surface in the mode of a conventional ground metal detector. Searchers only need to adjust the length of the rod and the position of the stop to make it more convenient to use the device.

1. Special metal detectors:

• security devices for detecting metal products in luggage, clothing or on a person’s body during inspection;
• industrial metal detectors as part of conveyor lines, signaling the presence of metals in products;
• military devices, collectively called mine detectors;
• detectors tuned exclusively to gold objects.

Metal detector coil

Most metal detectors for beginners are equipped with small mono coils. They are well suited for searching in littered areas, picking out interesting targets among the rubbish. And the discrimination of such reels is better.

But they are not suitable for deep search. Nowadays, almost all places are knocked out. A lot has already been pulled out near the surface, but at the depths there are still some good coins and other objects of interest to us. And in order to take them, you need to buy additional coils of larger diameter - rudders. With them, the depth of the device, compared to standard coils, noticeably increases. But in trash cans, such coils choke, catching several colored and black targets at once. But in clean places there is beauty!

Frequency. At a low frequency you can squeeze out the greatest depth on medium and large coins, and at a high frequency on small things like money - half coins or scales.

And of course, the reel should not malfunction and be in excellent technical condition.

Homemade metal detector - pros and cons

Cheapness, the basic advantage of making any products yourself, is relevant for a metal detector. Here are some other advantages of a homemade device:

• best match to search technology for beginners;
• the ability to create a device with a completely individual shape, design and configuration;
• the pleasure of making an effective, efficient device yourself.

Like any device made by an amateur, a metal detector is not without some drawbacks.

Here are the features of the “Pirate” model that users note:

• high battery consumption;
• lack of discrimination, that is, precise sensitivity to ferrous, non-ferrous and precious metals;
• limited sensitivity compared to expensive models.

Despite its shortcomings, the Pirate model is very popular. This is explained by the simplicity of homemade production and the high performance of an inexpensive device.

Recycling experts believe that the discrimination capabilities of a metal detector are not of great importance. All metals found are so valuable that recycling them is always justified. Focusing on finding gold requires not only equipment, but also considerable experience, related knowledge and, of course, luck.

Correct wiring

The depth of the search coil also depends on how the search coil is positioned. If the coil is high above the ground, then feel free to subtract this distance from the search depth. This is especially pronounced in the spring, when searching through last year’s compacted grass. But some, without noticing this, lift the coil themselves high.

Also, the coil should always be parallel to the ground plane. But many people neglect this, especially at the ends of each wire. Consider that the depth at the edges is also lost, and with it the finds.

Natural factors

The detection depth is also influenced by natural factors that are independent of us and the instruments. Wet soil conducts electromagnetic waves much better than dry soil, which means that after rain the depth will be greater than during drought.

They say that before a thunderstorm, a metal detector seems to get a second wind and begins to see a little deeper. I don't know the reason for this.

That's all. Write in the comments about your ways to increase search depth!