Radio amateurs are not those who want to save money and not purchase new equipment, but those who want to maximize all the existing parameters of a particular device. This statement also applies to those who are going to assemble metal detectors with their own hands. If a person has certain knowledge in the design of technology, they should be used to the fullest. This is much better than buying ready-made equipment for a lot of money at a time when the filling in it costs less than a third of the total amount. Based on the above, if you are one of the radio amateurs and are planning to assemble an underwater metal detector with your own hands, then we will help you do it right now.
An underwater metal detector is a special device that is designed to detect metal objects not only on the surface, but also in the water column. Thanks to such equipment, you have the opportunity to search for objects made of metals and alloys in the presence of poor visibility and strong noise.
The main difference between an underwater vehicle and a conventional detector is that the former has the ability to remain under water for a long period. When developing this equipment, one should take into account the fact that many search engines go almost up to their necks in water, so the depth of immersion is also of great importance. Such metal detectors can easily recognize fairly small objects such as earrings, chains and rings. After all, it’s them that underwater search engines are hunting for. When assembling equipment yourself, you can configure it to search mainly for non-ferrous metals. The above differences between an underwater metal detector and a standard ground detector should be taken into account during assembly.
In order to assemble a search coil that will have a diameter of 23 centimeters, you will need a PETV wire, the thickness of which is half a millimeter. You should have approximately 25 turns. Feel free to experiment with the wire and coil shape. For standard equipment approximately 20 meters should be used.
In order to make the rod and control unit, it is better to use plastic or stainless steel tubes. This is important because other metals tend to corrode when working underwater. Thanks to the use of plastic and stainless metal, you can significantly extend the service life of all equipment.
The frame should not be made too light so that the product does not float to the top, but also not too heavy, since otherwise it will sink to the bottom due to its heavy weight. Here it is best to take a closer look at your own feelings. The main task when choosing a material for the production of a rod is that it must be highly resistant to use in sea water and not be destroyed due to frequent exposure to an aggressive environment.
As an example, let's consider the construction of an underwater metal detector based on the Surfmaster PI 1.2 metal detector, which works great in both sea and fresh water, has excellent sensitivity for small objects made of non-ferrous metal and board sizes that allow it to be installed in a plastic pipe or tube from under the sealant.
In order to assemble the Surfmaster PI 1.2 underwater metal detector with your own hands, you will need the following tools:
soldering iron;
·PETV wires 0.5 mm;
·insulating tape;
· silicone sealant;
· scissors and knife and some others.
· printed circuit board
· set of electronic components
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Connect the power source. Ideally, you should use a powerful battery that can be recharged while you work, rather than regular batteries.
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Mount the finished board and battery in a small container that is hermetically sealed. It is necessary to bring the variable resistances out of this container, and all the resulting joints and cracks must be fixed with silicone sealant. The already prepared container must be installed on a pre-assembled rod.
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The coil should be wound. For these purposes, a regular jar with a volume of three liters is suitable. For the reel, you need to choose a housing that is made of plastic material that is not susceptible to water.
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The leads from the coil must be connected to a stranded wire.
Next, special attention should be paid to the issue of tightness, for which:
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all cracks formed must be filled with silicone sealant;
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it is better to use the most standard pipes, which are made of polypropylene, and the diameter can be chosen according to your preferences.
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To produce a rod, you can use an old fishing rod and ordinary adapters for plastic pipes.
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The tube left over from the sealant is perfect for assembling the control unit housing.
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Waterproof ports should be installed on all existing connectors.
Devices called metal detectors or metal detectors will help detect metal objects (ferromagnetic or non-magnetic) in a weakly conducting or neutral environment. The difference in these definitions lies in the functional purpose of the devices. Both a metal detector and a metal detector indicate the location of a metal object, but only the first device also has a function that allows you to recognize the type of metal. Such products are used for work purposes by archaeologists, geologists, builders, military personnel, and treasure hunters. They use expensive devices that are produced specifically for such purposes by Russian and foreign companies using different technologies. Industrial designs differ in their construction schemes, technical characteristics and the presence of additional options. This could be the depth, type of metal, shape of the object, etc. Is it possible to make a metal detector with your own hands at home? Fans of search work will get the answer to this question in this article.
Note! An electronic metal detector can detect coins at a depth of up to 0.5 m and large objects at a depth of up to 3.0 m.
The operating principle of a metal detector depends on the design type:
Induction devices contain a sensor. It contains a specially designed coil. It is excited by an alternating signal. If there is a metal object under the sensor, an electric signal appears. a signal that is recorded in a certain way.
A metal detector operating on beats records the difference in operating frequencies of 2 generators. One operates at a frequency that is known, the second has structural elements operating in a frequency-setting circuit. In the ground, walls, wood, etc., where there are no metal objects, the frequencies of the generators are the same; if present, they differ. These changes are recorded by appropriate means - by listening or digitally.
The principle of operation of devices operating in transmitting and receiving modes is to register a signal that is reflected from an object made of non-ferrous or ferrous metal. The device design has at least 2 coils, one of which operates in transmitting mode, the second in receiving mode. The signal arises from the transmitting coil, because it is affected by an alternating magnetic field. The best results are obtained by sensors whose coils are coplanar.
Frequency meter metal detectors are devices with built-in microprocessor technology. They are characterized by compact dimensions, and their sensitivity is an order of magnitude higher. They can estimate the frequency increment, which makes it possible to use such devices to recognize the type of metal.
Pulse metal detectors use a phenomenon called self-induction in a conductive object. It is customary to distinguish the following components in the design:
A switching device is necessary to separate the emitted and reflected signals according to such an indicator as time, i.e. For some time, a current pulse of a damped type is maintained, which is recorded.
You can assemble a metal detector at home using any of the above schemes. The main thing is to select all the necessary parts and components, without deviating from the parameters indicated in the diagram. It is very important to follow the technology of the work performed.
The operating principle of the simplest metal detectors is based on the properties of electromagnetic induction. The main technical characteristics of the product are:
In addition, the amount of electricity consumed and the time for which the electricity supply is calculated are taken into account. A simple metal detector is made with your own hands, taking into account all these factors.
Such a homemade metal detector with a 12 V power supply is manufactured according to the diagram shown in Fig. below.
Assembling a metal detector with your own hands is preceded by preparatory work: a list of necessary components is compiled. Then they are purchased in a retail chain or are found among the parts available to the radio amateur. Next, making a metal detector with your own hands will help the correct sequence of work performed. They are performed according to the following algorithm:
Board manufacturing stages:
The elements on the board are installed in the following order: microcircuit, amplifier, 2 SMD capacitors, MLT S2-23 type resistor, transistors and capacitors.
The coil is made on a Ø 200 m mandrel using PEV wire Ø 0.5 mm. The number of turns is 25. The speaker is taken from any portable radio.
The device is configured using potentiometers with a power of 10 and 100 kOhm.
A barbell for a metal detector can be made by using a crutch with an armrest or plastic or light metal pipes, giving them the required configuration. This is up to the manufacturer's taste. The device, which was assembled according to this scheme, will see objects at a depth of 1.0 m, if they are large, and coins up to 0.4 m.
The design of the metal detector may be different, it all depends on what the DIY enthusiast has on hand and what kind of result he wants to get.
The nuances of making a deep metal detector are presented in the video https://youtu.be/0WnD4UZCmcU.
How to make a metal detector to work underwater? The main difference from devices for working on land is the creation of a coil, which must be sealed, and when creating a circuit, it is necessary to take into account the specifics of the device’s operation under water. As a rule, such a do-it-yourself underwater metal detector is used to find small items made of non-ferrous metals (rings, earrings, pendants, chains, etc.) in water at different depths. Therefore, the product must be configured for gold or searching for other non-ferrous metals. And one more thing - during operation, the device is in water for a long time, so metal detectors are subject to increased requirements for the material from which the rod is made; it is also necessary to protect electronic components from exposure to water. On the Internet you can find diagrams of all 5 types of metal detectors and descriptions for them. It is not difficult to choose according to your liking or technical characteristics, as well as to make a metal detector at home. The main desire.
The video at https://youtu.be/XGVeqdTYVzk shows in detail the manufacture of an underwater metal detector, as well as the nuances of its configuration.
What the board with components looks like can be clearly seen in Fig. below.
The manufacturing steps are the same as for the device for working on land, but only the control unit board is placed in the housing, which is additionally treated with silicone sealant. For these purposes, you can use a tube from the sealant itself or another hermetically sealing device.
A homemade metal detector using transistors or using other elements is not difficult to make. To do this, you just need basic knowledge in the field of electrical engineering and electronics, the ability to work with your hands and use the tools necessary to perform specific work, including instrumentation. You can even create not only the simplest device, but also a powerful metal detector. Detailed instructions that are replete with the Internet will help you do everything yourself - from the board to the design. It all depends on the desire and money that a lover of creativity wants to spend on his brainchild.
The dream of finding treasure is increasingly being replaced in our time by a more realistic program of searching for precious metals in a natural or artificial environment.
In modern conditions it is very important to find and extract valuable materials, who turned out to be among the waste, or in another uncontrolled environment.
Equipment is an important component of such search technology.
The search and extraction of gold and valuable metals from waste, garbage, in the natural environment is part of the recycling strategy, a technology for the effective processing of used materials, including.
Searching for them in the ground or in masses of industrial and other waste not only requires the use of equipment, but also stimulates its improvement. Are being created devices of different levels and specializations. There is interest in such equipment among amateurs and enthusiasts of searching for valuable metals.
A metal detector is the most important tool for manually searching for metals in a chaotic natural or artificial environment.
Using such a device, you can search not only for silver, but also for silver and other precious metals.
Device principle any metal detector based on electromagnetic effects.
Here's how typical metal detecting technology works:
A large number of metal detector models operate precisely on this principle.
Technical differences in such equipment make it possible to obtain more complete information about the fact of detecting a metal object, for example:
There is a lot of information on the Internet about metal detectors of varying complexity and design. There you can also refresh your memory about the theory of the electromagnetic field, studied at school.
The simplest, primitive metal detectors (usually these are homemade designs for searching for gold, silver and other metals by amateur enthusiasts) assembled from ready-made devices and products operating using electromagnetic effects.
Many are familiar with the primitive, but quite workable circuit of a metal detector, in which an electromagnetic field creates a pulse element of a conventional calculator.
Reaction generated field on detected metal objects picks up the simplest household radio. The signal about such a find is audible, quite distinct and understandable.
More complex amateur and professional metal detecting devices retain the logical basis of the technology in the form of three components:
Devices of different levels of complexity and functional potential can be divided into groups. Classification based on professionalism and user specializations – one of the generally recognized:
The distribution of search equipment is such that many devices of this type can be purchased at gardening and country supply stores.
A device for searching and detecting metal is needed not only for recycling, but also for searching for artifacts and treasures. Numerous security systems for everyone well-known frames - one of the technology versions metal search. The settings of these frames are focused on searching for weapons and similar dangerous objects.
A very important node metal detecting equipment – reel or frame. This is most often a winding of a special configuration, the task of which is to form an electromagnetic field and capture its reaction to the detection of a metal body foreign to the search environment.
In most designs the coil is placed on a long rod– a handle to move it near the search area.
For amateur production of reels, frames of the most popular types are sold. The easiest way to make such a purchase is in an online store.
Many lovers make the coil frames yourself. This is done for reasons of cost savings or in the hope of obtaining a better-quality instrument of the author's design.
For this, improvised means are used– plastic products, plywood and even filling the assembled winding with construction foam.
The search operator or treasure hunter strives to find the most effective technique for working with a metal detector, choosing the desired operating modes of the electronics and the correct techniques for manipulating the coil.
The logical element of a metal detector is an electronic circuit. She performs many functions:
It is best if anyone who wants to assemble an electronic circuit has knowledge of amateur radio or electronic technology. Such a master can not only assemble the required circuit, but also change and improve the design.
Many electronic devices are quite simple, Even a beginner can assemble them. The resulting device will be operational without configuration if the assembler exactly followed the recommendations of the developer of such a circuit.
One of the most popular models of metal detectors designed for homemade amateur production is the “Pirate”.
This name, containing abbreviated details of its device and the developers' website, wittily reflects the romance of searching for precious metals.
Here the main advantages of this model:
The electronic circuit of this model does not require programming. In "Pirate" details available to everyone are used, a correctly assembled circuit is fully operational.
The design and layout of the “Pirate” metal detector is traditional for equipment of this kind. It is a rod, at the lower end of which there is a coil, and in the upper part – electronic unit with battery.
The location of the electronic unit should leave room for comfortable holding of the rod by hand.
Some craftsmen prefer that the sound signal from the device is supplied not by a speaker, but by headphones. In this case, the headphone cable departs from the electronic unit.
The technology of operation of the device is pulsed. This allows us to provide very good sensitivity indicators for this class of equipment. Below is a diagram of an electronic unit on microcircuits. 
A similar circuit can be assembled using transistors instead of microcircuits. This version may require additional settings, available only to experienced radio technicians. This is why the transistor circuit is used less frequently.
In addition to the details and precision indicated on the circuit diagram of the electronic unit, for assembly metal detector for gold and other metals you will need to prepare some materials and blanks:
It is best to make a printed circuit board for assembling an electronic circuit based on designs presented on the Internet.
Below is one of these samples, suitable for assembling electronics on microcircuits.
The manufacture of the board is carried out by amateurs of homemade electronics, and even then not all of them. Most people who want to create a metal detector themselves prefer to buy such a part.
To assemble the coil you will need a frame or frame, does not contain metal elements. An amateur craftsman can make such a frame from plywood, plastic, or select similar parameters from ready-made plastic products, for example, dishes. The frame can be purchased ready-made or made independently
Recommended coil parameters– 25 turns of enamel wire with a diameter of 0.5 mm on a mandrel with a diameter of 190-200 mm. An increase in diameter by 30% will lead to an increase in the sensitivity of the device, provided that the number of turns is reduced to 20-21.
The plastic frame for the coil is one of the most common metal detector parts on sale.
The technology for manipulating the coil is such that this very fragile unit can suffer from impacts from uneven ground, stones, and sharp objects. To avoid this the coil on the frame is covered from below with a plastic plate. This plate not only protects the reel, but also ensures that it glides through tall grass. The search becomes more intense.
To successfully assemble a metal detector It is best to follow this procedure:
Although the order of assembly is not fundamental. For those who manufacture a device for constant long-term work in the field of searching for non-ferrous metals and subsequent recycling (processing for reuse), ease of use is an important factor.
In this case, elaboration of the shape of the bar and the layout of the main elements of the apparatus becomes a key factor. Thus, a serious design phase appears in the creation of the device.
It is best to perform this stage of work using life-size modeling. Such modeling can be done using wooden parts of suitable shape, for example:
Having made sure that the assembled model of the device will be sufficiently functional and convenient, you can begin the final assembly. Ready-made device, usually, does not require configuration, it is completely ready to work. You can start searching for metal by choosing the desired level of sensitivity and the correct tactics for manipulating the coil.
Assemblers who need to assemble their apparatus as quickly as possible can use ready-made sets of parts.
Purchasing such a kit allows you to significantly simplify the production of “Pirate”. There is one of the proposals.
Users of the “Pirate” metal detector who have skills in amateur radio modify the design of this device. That's just several directions such improvements:
A simple, inexpensive and reliable metal detector “Pirate” works properly in a variety of conditions.
Cheapness, basic advantage self-production of any products, relevant for a metal detector. Here are some others dignity for a homemade device:
Like any amateur-made device, a metal detector not without some drawbacks.
Here are the features of the “Pirate” model that users note:
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, accompanying knowledge and, of course, Good luck.
The video provides a detailed guide to making and assembling the Pirate metal detector with your own hands:
When the metal detector is ready, you can begin work. You need to be aware that not even the most advanced apparatus will allow you to find only golden hidden objects.
A metal detector will help you find valuable metal, and it is very likely that it will be gold. It is best if the future metal and gold seeker has a realistic understanding of search techniques.
Many features of the operation of finished equipment are very important for those who develop and assemble their own models. You need to have an idea of the technology in advance with such equipment - this is precisely the basis of its high-quality design.
The success of finding gold increases with experience. Here most important elements such experience:
Properly assembled and debugged equipment will always help in the search for gold, and this valuable metal will definitely be found.
In contact with
The report was kindly provided by Valery Andreev, Novorossiysk
I had the idea of an underwater metal detector for a long time, but there was no worthy example to test it at sea. And finally PI was in my hands. Having tested it in the most severe tests on land, I realized that this is what I need. The device gave an unambiguous response to the target and had good sensitivity. Having been inspired by the idea of testing it under water, I made a trial version within one day. I used a plastic bottle as a body. I cut it in half, inserted the battery and PI directly into the case. Through the hole in the plug I brought the cable out to the reel. The part of the bottle closer to the neck was filled with epoxy compound to seal the cable that goes to the sensor. A piece of cut polyethylene pipe was inserted into the middle part of the bottle for rigidity. The joint was wrapped with a rubber medical bandage. I used reed switches located inside the bottle as a switch and reset button. He controlled them using small magnets. Sensitivity was set to maximum once. A standard piezoelectric element was used as a sound indicator. I had to keep the bottle near my ear all the time. The coil was wrapped with fiberglass and epoxy. Thus, I had in my hands the first most primitive underwater metal detector, but it worked, and I was proud :-). During my first dives, my joy knew no bounds. I found the harpoon of the underwater gun that I had lost five years ago. The device behaved the same as on land, only sensitivity decreased. I dived with it for several days until the battery died. Subsequently, he made a thorough device. The body was based on a piece of stainless pipe. I welded one end, and welded a flange with a groove for a rubber sealing ring on the other. A plexiglass disk is attached to the flange with eight bolts through a clamping ring that follows the shape of the flange. Practice has shown that sound through the housing is only audible to a depth of two meters. I had to make an underwater earphone. The case was made of plexiglass, with the same piezoelectric element placed inside. You can hear it up to 15 meters, I haven’t experienced it deeper. For reliability and to check the tightness, I also put the case under excess pressure through a car nipple attached to the front panel. There is also a sealed socket for charging the battery on the front panel. After experimenting with reels, I came to the conclusion that a spiral reel is better suited for the underwater version. It was made from single-core wire in vinyl insulation. I glued a circle with a diameter of 7 cm, cut out of cardboard, onto a flat surface, secured the end of the bare wire on it, covered it with a piece of glass on top and wound the entire coil in a spiral. Then I turned on a kilowatt light bulb above the glass for a few minutes. The coils fused together and the coil no longer fell apart. Then, using the method described above, I covered it with layers of glass tape and epoxy. This coil detects both small and large objects well.
The only thing I want to say is that rumors about jewelry at the bottom of the sea are greatly exaggerated. Apparently for advertising purposes, selling devices. From statistics carried out not only by me, one product made of despicable metal ends up in a bucket of copper coins :-). It should also be noted that one big advantage of underwater search compared to land search is that there are few onlookers, especially in winter and spring-autumn periods.
