This type of design is designed to search for coins. The process of assembling it is completely simple. However, experience in assembling such a tool is still necessary. The Terminator is able to detect an object even if the target of capture is minimal.
First you need to prepare necessary equipment, namely:
- a multimeter that measures speed.
- LC meter
- Oscilloscope.
Next, you need to find a diagram broken down into nodes. Now you can make printed circuit board, into which jumpers, resistors, panels for microcircuits and other parts should be soldered in order. The next step is to clean the board with alcohol. It is definitely worth checking for defects. You can check whether the board is in working condition as follows:
- Turn on the power.
- Turn down the sensitivity control until no sound is heard from the speaker.
- Touch the sensor connector with your fingers.
- When turned on, the LED should blink and then go out.
If all actions occurred, then everything was done correctly. Now you can make a coil. It is necessary to prepare a winding enamel wire with a diameter of 0.4 mm, which must be folded in half. A circle is drawn on a sheet of plywood with a diameter of 200 mm and 100 mm. Now you need to drive nails in a circle, the distance between them should be 1 cm.
Next, you can move on to winding the turns. At 200 mm you should make 30 of them, and at 100 - 48. Then the first coil should be soaked in varnish; when it dries, you can wrap it with thread. The thread can be removed, and by soldering the middle, you get a solid winding of 60 turns. Afterwards, the coil must be wrapped with electrical tape quite tightly. And a 1 cm foil is placed on top, this will be a screen, and more electrical tape is wound on top of it. The ends should come out.
On the second coil it is also necessary to solder the middle. In order to start the generator, you need to connect the first coil to the board. The second coil should be wrapped with a wire of 20 turns, then we connect it to the board. Now you need to connect the oscilloscope minus to minus to the board, and the plus is connected to the coil. Be sure to look at what frequency it will be when you turn it on and remember it or write it down on paper.
Now the coils need to be placed in a special mold so that they can then be filled with resin. Next, the oscilloscope is connected to the board, with the negative pole, the amplitude should reach zero. The coils in the mold are filled with resin to approximately half the depth. When everything is ready, the metal discrimination scale is adjusted.
Parts list for the Terminator 3 metal detector
As parts for the trio metal detector you will need:
If you have these parts, you can assemble the Terminator Pro metal detector yourself.
Circuit diagram of a metal detector with metal discrimination
You can make a metal detector with metal discrimination yourself using the circuit for the Chance pulse device. The process of making a coil is quite simple.
The diagram itself can be found on the Internet. But still, experience in assembling such devices will be useful. Assembling the metal detector should begin with the board.
After the board is manufactured, the microcontroller needs to be flashed. And at the end of the work, we connect the metal detection device to the power supply.
DIY metal detector without microcircuits
Homemade equipment can be made without complex microcircuits, but using a simple transistor generator. The metal detector will be non-discriminatory. It will detect objects in the ground to a depth of 20 centimeters, and in dry sand - to a depth of 30 centimeters. In this device, the transmitting and receiving coils operate simultaneously.
Terminator 3 metal detector coil
To begin with, you should take winding enamel with a diameter of 0.4 mm. Fold it so that there are two ends and two beginnings. Next, you should wind from two reels at a time.
Now we need to make transmitting and receiving coils, for this we need to plywood sheet two circles are drawn 200 mm and 100 mm. Nails are driven in along these circles, the distance between them should be 1 cm. 30 turns of enamel wire are wound onto a large mandrel. Then you should apply varnish to the coil and wrap it with thread, then remove it from the winding and solder the middle. This creates one middle wire and two outer wires.
The resulting coil should be wrapped with electrical tape and a piece of foil should be placed on top, and foil again on top. The ends of the windings should go outside.
Now it’s time to move on to the receiving coil. 48 turns are already wound here. To start the generator, you need to connect the transmitting coil to the board. The middle wire is connected to the negative. And the middle terminal of the take-up coil is not used. The transmitting coil requires a compensating coil, on which 20 turns are wound.
We connect the oscilloscope to the board like this: a probe with a minus to the minus of the board, and a plus probe to the coil. Be sure to measure the frequency of the coils and write it down.
After connecting the coils according to the diagram, they must be placed in a special container and filled with resin. The oscilloscope now sets the division time (10 ms and 1 volt per cell). Now you should reduce the amplitude to zero. We wind the turns until the volt value reaches zero. We make a compensating loop at the coil, which will be outside.
The mold should be filled halfway with resin. When everything hardens, you need to connect the oscilloscope and bend the loop inward. Then twist it until the amplitude value becomes minimal. Afterwards, you need to glue the loop, check the balance, and now you can fill the second half of the container with resin. The reel is ready for use.
Metal detector coil repair
Before you begin the repair, you should prepare the following tools:
- Stationery knife;
- Incandescent lamp;
- A container for glue, preferably flat;
- Special or epoxy resin;
- Medium and fine sandpaper;
- Small spatula.
First of all, you need to dry the coil using an incandescent lamp. And use a utility knife to widen the cracks on it. Squeeze the glue onto a flat surface and mix with a spatula. Apply this substance to the coil. In places of cracks, you can apply more resin. Now you should wait until it all hardens thoroughly. And then sand it, using first medium and then fine sandpaper. This procedure will help smooth out all the unevenness. In this fairly simple way, you can revive the oldest coil from a metal detecting device.
Parameters of metal detectors depending on purpose and technical device
Metal detectors for amateurs are the simplest dynamic type devices. The search head of the device must constantly move; this is the only way the desired signal can appear. If you stop moving, the signal will disappear. Such simple detectors are convenient because they do not require complex settings and allow you to exclude medium soils. Disadvantages include its low sensitivity and frequent false alarms in difficult areas.
The scanning speed of the device is about 30 centimeters per second.
Mid-range devices have better sensitivity. In the factory configuration, this device comes with several search heads of different sizes. Setting up the detector will require certain skills. Mid-range metal detectors are capable of recognizing metals.
Computerized devices are already professional tool with liquid crystal screen and pointer indication. The memory of its processor is loaded with programs capable of recognizing and distinguishing a signal and classifying each detected object. Professionals independently program devices for search conditions, eliminating unwanted triggers.
Gold detecting tools work not only on coins and jewelry in the ground, but also on native metal. It is not suitable for searching for small particles such as sand. It does not recognize them, especially if the soil is highly mineralized.
Otherwise, these metal detectors are very sensitive and work great, for example, when searching for gold jewelry in the sand of the beach
Depth detectors are designed to search for objects located at impressive depths. They can detect metal at a depth of up to 6 meters, while other models “pierce” only up to 3. Such devices recognize voids and other internal soil anomalies. Depth detectors operate on two coils, one is parallel to the ground surface, the other is perpendicular.
Stationary detectors are frames installed at particularly important protected sites. They calculate any metal objects in the bags and pockets of people passing through the circuit.
What types of metal detectors can you make at home with your own hands?
Detectors are divided into 5 main types based on the principle of detecting the desired object.
Let's look at which metal detectors are suitable for making with your own hands at home:
| Type | Peculiarities | Is it suitable for making it yourself? |
|---|---|---|
| Reception and transmission | Works with two induction coils. If the desired object is absent, the signal does not pass into the receiving coil. | Yes |
| Induction | Combines the functions of both coils. The signal is constant, changing when detecting the metal. | No, as a rule, difficulties arise in isolating the effective signal. |
| Based on frequency meter | The design of the device includes an LC generator that changes the frequency when metal objects are detected. Has low sensitivity. | Yes |
| With Q meter | Has an LC generator signal analyzer. Does not work well at low temperatures. | Yes |
| Pulse | Based on the transmission of eddy pulse currents. The signal changes its character depending on the type of metal detected. | Yes |
And now more about how to make a simple metal detector with your own hands using the example of the “Pirate” design.
Homemade metal detector “Pirate”: diagram and detailed description of the assembly
If you are just thinking about how to make a homemade metal detector, do not try to take on complex models. Start with a simple but effective "Pirate". The name was invented by the author of the homemade product from a combination of Pi (pulse) and Ra-t (radioscope). The name stuck, but the simple and clear diagram the assembly was so loved by users that “Pirate” became one of the most popular homemade products in this area. Currently, there are already 4 modifications of the “Pirate” scheme. The metal detector is simply assembled with your own hands, without using any specific tools.
The only drawback of this device is that the DIY metal detector does not have a scheme for working with metal discrimination. But for a novice treasure hunter this is unimportant.
In addition to the parts required for assembly, you will need a soldering iron, screwdriver, and insulating tape.
Parts for assembling a metal detector
To make the device you will need to purchase:
- ceramic capacitor - 1 nF;
- 2 film capacitors - 100 nF;
- electrolytic capacitors: 10 μF (16 V) – 2 pieces, 2200 μF (16 V) – 1 piece, 1 μF (16 V) – 2 pieces, 220 μF (16 V) – 1 piece;
- resistors - 7 pieces per 1; 1.6; 47; 62; 100; 120; 470 kOhm and 6 pieces for 10, 100, 150, 220, 470, 390 Ohm, 2 pieces for 2 Ohm;
- variable resistors - 3 pieces for 10 and 100 kOhm, 400 Ohm (1W);
- transistors – 3 pieces, VS557, IRF740, VS547;
- 2 diodes 1N148;
- 2 microcircuits: K157UD2 and NE555.
In addition to the listed details, stock up on headphones from the player
You will also need plastic pipe for the rod, 9V batteries or accumulators and PEV wire with a diameter of 0.8 mm.
For your information! Many people are interested in how to make a metal detector from a phone with their own hands. Some developers even offer programs that can be downloaded to your phone and used for this purpose. Serious radio enthusiasts can only advise you to use some spare parts - for example, a headphone input or a battery, perhaps a board to create a microcircuit.
DIY metal detector circuits
The simplest “Pirate” scheme looks like this.
The board can be placed in the body of a pocket receiver or any conveniently sized plastic box; even simple junction boxes from an electrician’s arsenal are suitable.
Important point! To get rid of possible interference when touching the device regulators, all variable resistor housings are connected to the negative side of the board.
If you want to take your experiments further, here is a diagram for making a gold-focused metal detector.
Schematic of the Terminator 4 metal detector with increased sensitivity
If you assembled the circuit correctly, the device will work properly. Possible problems with a microcircuit.
How to assemble a metal detector circuit board with your own hands
The metal detector circuit board circuit is quite simple. Conventionally, it can be divided into several blocks:
- search coil assembly;
- transistor sound amplifier;
- pulse generator;
- two-channel amplifier.
This is what it looks like.
The pulse generator is assembled on the NE555 timer. By selecting C1 and 2 and R2 and 3, the frequency is adjusted. The pulses obtained as a result of scanning are transmitted to transistor T1, and it transmits the signal to transistor T2. The audio frequency is amplified using the BC547 transistor to the collector, and headphones are connected.
For your information! You can make a metal detector with your own hands without microcircuits. On the Internet you will find many analog circuits using transistor oscillators. Such devices will detect metal at a depth of up to 20 centimeters in the ground and up to 30 centimeters in loose sand.
How to make a metal detector coil with your own hands
Coil – important detail device. It can be made from copper wire or twisted pair. More details in our master class.
Copper wire spool
| Illustration | Description of action |
|---|---|
 |
Copper wire with a diameter of 0.5 mm is suitable for the coil. |
 |
For winding, prepare a board with guides. The distance between the guides should be equal to the diameter of the base on which you will mount the reel. |
 |
Wind the wire around the perimeter of the fastenings in 20-30 turns. |
 |
Secure the winding with electrical tape in several places. |
 |
Remove the winding from the base and give it a round shape. |
 |
Choose a base that will hold its shape. This could be a plastic bucket lid or a wooden craft hoop. |
 |
Connect the circuit to the device and test its operation. |
 |
When assembled, a coil of wire may look like this. |
 |
To test the operation of the device, pass metal objects over the coil at different heights. |
Twisted pair coil
| Illustration | Description of action |
|---|---|
 |
Roll the wire into two coils as shown in the photo, leaving two ends of about 10 centimeters each. |
 |
Strip the winding and free the wires for connection. |
 |
Connect the wires as shown in the diagram. |
 |
For better contact solder the ends of the wires. |
 |
Test the coil in the same manner as a copper wire coil. |
Advice! If you want to make a more powerful DIY coil for your metal detector, give it an elliptical shape.
Detailed instructions for setting up a DIY metal detector “Pirate”
For final assembly of the device you will need a plastic pipe. The assembly diagram is simple. The sensitivity of the detector is adjusted using potentiometers. Achieve the result so that it recognizes a coin from a distance of 30 centimeters. He can “hear” large metal deposits a meter to one and a half meters away. “Pirate” does not recognize non-ferrous or ferrous metals underneath you, so you just have to dig, and it is possible that you will stumble upon an old trough, and not the desired treasure. But in this case, you can take it not by quality, but by quantity, because any metal can be taken to a recycling collection point.
It is possible that you will be lucky and all your efforts will not be in vain
What the assembled “Pirate” will look like is in the next video. It only remains to note that the construction kit for making this device can be purchased on the Internet. By the way, it comes with detailed instructions on how to make a metal detector yourself at home from kit parts.
Features of deep metal detectors
A deep metal detector is attractive because it can detect objects where other devices are powerless. A good deep metal detector, made by yourself, looks to a depth of 6 meters, and is not hindered by roots, voids or other obstacles. One caveat - with its help you can only detect large objects, and this is understandable, because for the sake of a couple of coins you will not dig a six-meter hole.
And again we return to the same universal model of the “Pirate” detector. It turns out that a deep-depth device can be made on its basis, and this is not at all difficult. The modification process is described in this video.
Instrumental search is simply enormously popular. Adults and children, amateurs and professionals are looking for it. They are looking for treasures, coins, lost things and buried scrap metal. The main search tool is a metal detector.
There are a great variety of different metal detectors to suit every taste and color. But for many people, buying a ready-made branded metal detector is simply financially expensive. And someone wants to assemble a metal detector with their own hands, and someone even builds their own small business on their assembly.
Homemade metal detectors
In this section of our website about homemade metal detectors, I will collect: the best metal detector circuits, their descriptions, programs and other data for making a metal detector with your own hands. There are no metal detector circuits from the USSR or circuits with two transistors here. Since such metal detectors are only suitable for visually demonstrating the principles of metal detection, but are not at all suitable for real use.
All metal detectors in this section will be quite technologically advanced. They will have good search characteristics. And a well-assembled homemade metal detector is not much inferior to its factory-made counterparts. Basically, various circuits of pulse metal detectors and circuits of metal detectors with metal discrimination are presented here.
But to make these metal detectors, you will need not only desire, but also certain skills and abilities. We tried to break down the diagrams of the given metal detectors by level of complexity.
In addition to the basic data required to assemble a metal detector, there will also be information about the required minimum level of knowledge and equipment for making a metal detector yourself.
To assemble a metal detector with your own hands, you will definitely need:
This list will include necessary tools, materials and equipment for self-assembly of all metal detectors without exception. For many schemes you will also need various additional equipment and materials, here are just the basics for all schemes.
- Soldering iron, solder, tin and other soldering supplies.
- Screwdrivers, pliers, wire cutters and other tools.
- Materials and skills for making a printed circuit board.
- Minimum experience and knowledge in electronics and electrical engineering as well.
- And also straight hands will be very useful when assembling a metal detector with your own hands.
Here you can find diagrams for self-assembly of the following models of metal detectors:
Design and principle of operation of the device
Metal detectors on the market operate on different principles. Many believe that they use the principle of pulse echo or radar. Their difference from locators lies in the fact that the transmitted and received signals act constantly and simultaneously; in addition, they operate at the same frequencies.
The principle of operation of the metal detector
Devices operating on the “receive-transmit” principle record the signal reflected (re-emitted) from a metal object. This signal appears due to the exposure of a metal object to an alternating magnetic field generated by the metal detector coils. That is, the design of devices of this type provides for the presence of two coils, the first is transmitting, the second is receiving.
Metal detector circuit
Devices of this class have the following advantages:
- simplicity of design;
- Great potential for detecting metallic materials.
At the same time, metal detectors of this class have certain disadvantages:
- metal detectors can be sensitive to the composition of the soil in which they search for metal objects.
- technological difficulties in the production of the product.
In other words, devices of this type must be configured with your own hands before work.
Other devices are sometimes called beat metal detectors. This name comes from the distant past, more precisely from the times when superheterodyne receivers were widely used. Beating is a phenomenon that becomes noticeable when two signals with similar frequencies and equal amplitudes are summed. The beat consists of pulsating the amplitude of the summed signal.
The signal pulsation frequency is equal to the difference in the frequencies of the summed signals. By passing such a signal through a rectifier, it is also called a detector, and the so-called difference frequency is isolated.
This scheme has been used for a long time, but nowadays it is not used. They were replaced by synchronous detectors, but the term remained in use.
A beat metal detector works using the following principle - it registers the difference in frequencies from two generator coils. One frequency is stable, the second contains an inductor.
The device is configured with your own hands so that the generated frequencies match or at least are close. As soon as metal enters the action zone, the set parameters change and the frequency changes. Frequency difference can be recorded different ways, ranging from headphones to digital methods.
Devices of this class are characterized by a simple sensor design and low sensitivity to the mineral composition of the soil.
But besides this, when operating them, it is necessary to take into account the fact that they have high energy consumption.
Typical design
The metal detector includes the following components:
- The coil is a box-type structure that houses the signal receiver and transmitter. Most often, the coil has an elliptical shape and polymers are used for its manufacture. A wire is connected to it connecting it to the control unit. This wire transmits the signal from the receiver to the control unit. The transmitter generates a signal when metal is detected, which is transmitted to the receiver. The coil is installed on the lower rod.
- The metal part on which the reel is fixed and its angle of inclination is adjusted is called the lower rod. Thanks to this solution, a more thorough examination of the surface occurs. There are models in which the lower part can adjust the height of the metal detector and provides a telescopic connection to the rod, which is called the middle one.
- The middle rod is the unit located between the lower and upper rods. Devices are attached to it that allow you to adjust the size of the device. On the market you can find models that consist of two rods.
- The top rod usually has a curved appearance. It resembles the letter S. This shape is considered optimal for attaching it to the hand. An armrest, a control unit and a handle are installed on it. The armrest and handle are made of polymer materials.
- The metal detector control unit is necessary to process the data received from the coil. After the signal is converted, it is sent to headphones or other display devices. In addition, the control unit is designed to regulate the operating mode of the device. The wire from the coil is connected using a quick release device.
Metal detector design
All devices included in the metal detector are waterproof.
It is this relative simplicity of design that allows you to make metal detectors with your own hands.
Types of metal detectors
There is a wide range of metal detectors on the market, used in many areas. Below is a list that shows some of the varieties of these devices:
Ground model 
Deep metal detector 
Underwater vehicle 
Security device 
Industrial metal detector
- Ground. These devices are designed to search for scrap metal with your own hands, jewelry, coins, etc.
- Deep. These devices are used to search for the above-mentioned metal products at great depths.
- Underwater. Devices of this type are designed to operate underwater. They can work at different depths.
- Metal detectors for searching for gold. These devices allow you to find gold and gold jewelry in any environment.
- Security devices. These devices are used to detect metal products on the human body and in luggage. Such devices are made in the form of arches and are installed at the entrance to places with large crowds of people, for example, at train stations, shopping centers etc.
- Industrial. This equipment is part of conveyor lines. Their main task is to detect metal in other substances. For example, in a mined sand-soil mixture.
- Army. The military uses such devices to detect mines, unexploded shells, bombs, etc. with their own hands. The military calls such devices mine detectors.
- Do-it-yourself devices are most often assembled by novice “treasure hunters”.
The use of modern materials allows us to design and manufacture devices with high accuracy in detecting metals in different environments. The use of microelectronics has made it possible to minimize their overall weight parameters. In addition, the simplicity of the electrical circuit allows minimal costs make a metal detector with your own hands.
Main settings
Like any technical device a metal detector has certain parameters that characterize their functional properties.
Detection depth
In the first place is the depth of metal detection. By the way, many companies producing such devices do not indicate the maximum depth at which their products can detect metal products. And if such a figure is indicated, then most likely this is data obtained during laboratory tests. That is, real field conditions differ significantly from laboratory (test) conditions.
This means that when doing real work with your own hands, the detection depth will be slightly less than indicated in the passport. Why is this happening? The fact is that the composition of the soil has a significant impact on the capabilities of the metal detector. In fact, it is one thing to search in river sand, and another in soil with a high iron content. Metal products, especially those that remain at depth for a long time, oxidize and change their properties, and this affects the ability to detect an object.
Metal detector detection depth
Most modern metal detectors can find metal objects at a depth of up to 2.5 m; special deep products can detect a product at a depth of up to 6 meters.
Operating frequency
The second parameter is the operating frequency. The thing is that low frequencies allow the metal detector to see to a fairly large depth, but they are not able to see small details. High frequencies allow you to notice small objects, but do not allow you to view the ground to great depths.
The simplest (budget) models operate at one frequency; models that fall into the middle price range use 2 or more frequencies. There are models that use 28 frequencies when searching.
Diagram of a deep metal detector
Deep metal detectors are used to search for metals at great depths. But it is worth noting that they are not cheap and therefore it is quite possible to assemble it yourself. But before you start making it, you need to understand how it works. typical diagram.
Scheme deep metal detector
The circuit of a deep metal detector is not the simplest and there are several options for its implementation. Before assembling it, you need to prepare the following set of parts and elements:
- capacitors different types– film, ceramic, etc.;
- resistors of different values;
- semiconductors - transistors and diodes.
Nominal parameters and quantity depend on the selected circuit diagram of the device. To assemble the above elements, you will need a soldering iron, a set of tools (screwdriver, pliers, wire cutters, etc.), and material for making the board.
Assembly process of a deep metal detector
The process of assembling a deep metal detector looks something like this. First, a control unit is assembled, the basis of which is a printed circuit board. It is made from textolite. Then the assembly diagram is transferred directly to the surface of the finished board. After the drawing is transferred, the board must be etched. To do this, use a solution that includes hydrogen peroxide, salt, and electrolyte.
After the board is etched, it is necessary to make holes in it to install the circuit components. After tinning the board. The most important stage is coming. Do-it-yourself installation and soldering of parts onto a prepared board.
To wind the coil with your own hands, use PEV brand wire with a diameter of 0.5 mm. The number of turns and the diameter of the coil depend on the selected circuit of the deep metal detector.
A metal detector is electronic device for searching and distinguishing metals, metal objects that can be hidden at different depths under a layer of sand, earth, in the walls of rooms and various structures.
Schematic diagrams of metal detectors made on transistors, microcircuits and microcontrollers are given. A factory-made metal detector is a fairly expensive device, so self-production a homemade metal detector can save quite a bit of money.
The circuits of modern metal detectors can be built according to different principles works, we list the most popular of them:
- Beat method (measuring changes in reference frequency);
- Induction balance at low frequencies;
- Induction balance on spaced coils;
- Pulse method.
Many novice radio amateurs and treasure hunters are wondering: how to make a metal detector yourself? It is advisable to start your acquaintance with assembling a simple metal detector circuit; this will allow you to understand the operation of such a device and gain first skills in searching for treasures and products made of multi-colored metals.
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The simplest and most practical way to make a deep metal detector with your own hands is to make a deep pulse metal detector. You can take an existing pulse metal detector as a basis, or make an electronic unit for a pulse metal detector, etc. How to make these metal detectors is already described on our website. And then you need to make a deep coil for it.
In this article we will look at methods for manufacturing depth coils for pulse metal detectors. Such coils can be used with Pirate, Clone, Tracker, Koschey and other pulse metal detectors.
But it should be taken into account that with the same dimensions of the depth frame, different metal detectors will result in different detection depths (with the Pirate the results will be the most modest, but best result show Koschey 5IG and Koschey 4IG (TrackerPI-G) since they have a separate deep firmware!
Let's start with the mechanical designs of the depth frames for a metal detector.
The deep frames are small in size and installed on a rod like a regular reel, but there are restrictions on weight and dimensions. Therefore, this design is suitable for frames with a diameter of up to 60-70cm. The large frame becomes too heavy and is no longer comfortable to carry this way.
Depth coil frame for metal detector made from plastic pipes, without the use of metal elements. You choose a pipe depending on the way you will connect it, and depending on the size of your frame, so that the pipe provides sufficient structural rigidity!
Small coils are usually made non-separable in the shape of a ring or square.
Here are some photos of such frames:
For large frames, the non-demountable design is already inconvenient for transportation, and it is already difficult to carry such a frame on a rod. The most common solution for large frames, this is a collapsible square frame with an overhead search loop or a loop passed inside the pipe frame.
In this case, the frame frame is made of plastic pipes, and the search coil is wound with stranded wire in insulation! THE WIRE MUST BE MULTI-CORE, since when disassembling and transporting the deep coil, the wire will bend and the single-core wire may eventually break!
Such frames are usually worn by two people:
But there are design options for a deep metal detector for self-carrying:
Here are a few more design options for deep metal detectors and their coils:
Winding the depth frame
Table of the number of turns for depth frames various sizes and their maximum detection depth with PIRAT and Koschey 5I metal detectors:
| 40*40cm | 60*60cm | 90*90cm | 120*120cm | 150*150cm | |
| Number of turns | 19 | 16 | 13 | 11 | 10 |
| Detection range helmets with MD PIRATE | 0.8m | 0.9m | 1m | 1.1m | 1.25m |
| Maximum range PIRATE | 1.7m | 2.3m | 2.6m | 3m | 3.5m |
| Detection range helmets with a metal detector Koschey 5IG | 1m | 1.2m | 1.25m | 1.5m | 1.6m |
| Maximum range detecting with a metal detector Koschey 5IG | 2.3m | 3m | 3.5m | 4m | 5m |
It is advisable, after winding the frame, to tighten the turns together with electrical tape or tape; this will reduce the interturn capacity and make the loop stronger. The wire from the frame to the electronic unit can be made from the same wire with which the frame is wound, twisting it in increments of 1 turn per 1 cm. And then crimp it with heat-shrink tubing or wrap it with electrical tape.
This is how you can easily make a depth frame for a pulse metal detector, and get a full-fledged depth metal detector that is not inferior in depth to branded metal detectors.
DIY deep metal detector: diagram, instructions and reviews
Deep-type metal detectors are capable of detecting objects in the ground at a great distance. Modern modifications in stores are quite expensive. However, in this case, you can try to make a metal detector with your own hands. For this purpose, it is first recommended to familiarize yourself with the design of the standard modification.
Modification scheme
When assembling a metal detector with your own hands (the diagram is shown below), you need to remember that the main elements of the device are a damper on a microcontroller, a capacitor and a handle with a holder. The control unit in the devices consists of a set of resistors. Some modifications are made on drive modulators that operate at a frequency of 35 Hz. The racks themselves are made with narrow and wide plate-shaped plates.
Assembly instructions for a simple model
Assembling a metal detector with your own hands is quite simple. First of all, it is recommended to prepare a tube and attach a handle to it. To install the control unit, high conductivity resistors will be required. The operating frequency of the device depends on many factors. If we consider modifications based on diode capacitors, then they have high sensitivity.
The operating frequency of such metal detectors is about 30 Hz. Their maximum object detection distance is 25 mm. Modifications can operate on lithium batteries. Microcontrollers for assembly will need a polar filter. Many models fold on open-type sensors. It is also worth noting that experts do not recommend using high sensitivity filters. They greatly reduce the accuracy of detecting metal objects.
Model of the “Pirate” series
You can make a “Pirate” metal detector with your own hands only using a wired controller. However, first of all, a microprocessor is prepared for assembly. To connect it you will need blowtorch. Many experts recommend using 5 pF grid capacitors. Their conductivity should be maintained at 45 microns. After installing the capacitors, you can begin soldering the control unit. The stand must be strong and support the weight of the plate. For 4 V models, it is not recommended to use plates with a diameter larger than 5.5 cm. System indicators do not need to be installed. After securing the unit, all that remains is to install the batteries.
Using reflex transistors
Making a metal detector with reflex transistors with your own hands is quite simple. First of all, experts recommend installing a microcontroller. In this case, capacitors are suitable of a three-channel type, and their conductivity should not exceed 55 microns. At 5 V they have a resistance of approximately 35 ohms. Resistors in modifications are mainly used of the contact type. They have negative polarity and cope well with electromagnetic vibrations. It is also worth noting that lithium batteries can be used during assembly. The maximum width of the plate for this modification is 5.5 cm.
Model with convection transistors: expert reviews
You can assemble a metal detector with your own hands only on the basis of a collector controller. In this case, capacitors are used at 30 microns. If you believe the reviews of experts, then it is better not to use powerful resistors. In this case, the maximum capacitance of the elements should be 40 pF. After installing the controller, it is worth working on the control unit.
These metal detectors receive good feedback behind reliable protection from wave interference. For this purpose, two diode-type filters are used. Modifications with display systems are very rare among homemade modifications. It is also worth noting that power supplies must operate at low voltage. This way the battery will last for a long time.
Using Chromatic Resistors
How to make a metal detector with your own hands? The model with chromatic resistors is quite simple to assemble, but it should be taken into account that capacitors for modifications can only be used on fuses. Experts also point out the incompatibility of resistors with pass filters. Before starting assembly, it is important to immediately prepare a tube for the model, which will be the handle. Then the block is installed. It is more advisable to select modifications at 4 microns, which operate at a frequency of 50 Hz. They have a low dispersion coefficient and high measurement accuracy. It is also worth noting that searchers of this class will be able to successfully work in conditions of high humidity.
Model with a pulse zener diode: assembly, reviews
Devices with pulsed zener diodes are distinguished by their high conductivity. If you believe the reviews of experts, then homemade modifications can work with objects of different sizes. If we talk about the parameters, their detection accuracy is approximately 89%. You should start assembling the device with a stand blank. Then the handle for the model is mounted.
The next step is to install the control unit. Then a controller is mounted, which runs on lithium batteries. After installing the unit, you can start soldering the capacitors. Their negative resistance should not exceed 45 ohms. Expert reviews indicate that modifications of this type can be made without filters. However, it is worth considering that the model will have serious problems with wave interference. In this case, the capacitor will suffer. As a result, the battery of models of this type quickly discharges.
Application of low frequency transceiver
Low-frequency transceivers in models significantly reduce the accuracy of the devices. However, it is worth noting that modifications of this type can successfully work with objects small size. At the same time, they have a low self-discharge parameter. In order to assemble the modification yourself, it is recommended to use a wired controller. The transmitter is most often used with diodes. Thus, conductivity is ensured at around 45 microns with a sensitivity of 3 mV.
Some experts recommend installing mesh filters, which increase the security of models. To increase conductivity, only transition type modules are used. The main disadvantage of such devices is considered to be controller burnout. If such a breakdown occurs, it is problematic to repair the metal detector yourself.
Using a High Frequency Transceiver
On high-frequency transceivers, you can assemble a simple metal detector with your own hands only on the basis of an adapter controller. Before installation, a stand for the plate is prepared as standard. The average conductivity of the controller is 40 microns. Many specialists do not use contact filters during assembly. They have high thermal losses and are capable of operating at 50 Hz. It is also worth noting that lithium batteries are used to assemble the metal detector, which recharge the control unit. The sensor itself in modifications is installed through a capacitor, the capacitance of which should not exceed 4 pF.
Model with longitudinal resonator
Devices with longitudinal resonators are often found on the market. They stand out among their competitors with their high accuracy of identifying objects, and at the same time they can work in high humidity. In order to assemble the model yourself, a stand is prepared, and a plate should be used with a diameter of at least 300 mm.
It is also worth noting that to assemble the device you will need a contact controller and one expander. Filters are used only on mesh lining. Many experts recommend installing diode capacitors that operate at a voltage of 14 V. First of all, they discharge little of the battery. It is also worth noting that they have good conductivity compared to field analogues.
Using selective filters
Making such a deep metal detector with your own hands is not easy. The main problem is that a regular capacitor cannot be installed in the device. It is also worth noting that the plate for modification is selected from 25 cm in size. In some cases, the racks are installed with an expander. Many experts advise starting assembly by installing the control unit. It must operate at a frequency of no more than 50 Hz. In this case, the conductivity depends on the controller used in the equipment.
Quite often it is selected with a lining to increase the security of the modification. However, such models often overheat and are not able to work with high accuracy. To solve this problem, it is recommended to use conventional adapters that are installed under capacitor units. A do-it-yourself metal detector coil is made from a transceiver block.
Application of contactors
Contactors are installed in devices together with control units. Stands for modifications are used of short length, and plates are selected at 20 and 30 cm. Some experts say that devices should be assembled on impulse adapters. In this case, capacitors can be used with low capacitance.
It is also worth noting that after installing the control unit, it is worth soldering a filter that can operate at a voltage of 15 V. In this case, the model will maintain a conductivity of 13 microns. Transceivers are most often used on adapters. Before turning on the metal detector, the level of negative resistance is checked on the contactor. The specified parameter is on average 45 Ohms.
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Metal detector circuit
Tesoro Eldorado
-Dynamic operating mode
-Power supply, V 12
-coins 25mm – about 30cm
-gold ring – 25cm
-helmet 100-120cm
-maximum depth 150cm
-Consumption current:
-No sound approximately 30 mA
Parts side board
We begin assembly And all the rest. The fact is that the device
radiostroi.ru
| The recently published metal detector circuit has aroused great interest among radio amateurs. And this is not surprising, because in terms of technical characteristics that metal detector was not inferior to many industrial devices mid-price level, and in its ease of assembly and configuration it surpassed them.
Over the course of several months, the metal detector circuit was repeated many times by many radio amateurs, even not very experienced ones, and almost always left the most positive reviews about it on the forum. In some cases, of course, problems arose with the setup, which raised many questions and long discussions at the conference, so it was decided to systematize all the information on this metal detector and post it here, along with the updated diagram.
The schematic diagram of the metal detector is in the archive in the form of the sPlan file. As can be seen from the diagram, the input stage on the LM358 has undergone some changes, it has become possible to change the signal phase with a button, an LED indicator of the response from a target in the ground has been added, which allows you to visually identify non-ferrous iron, and one transistor has been added to the ULF. Now you can safely install an ordinary small-sized 8-ohm speaker there. It is recommended to use it for sound emission, since headphones will interfere with making your way through the bushes, and the ZP-shka is too quiet for searching on the banks of noisy rivers and seas.
Everyone makes a metal detector body out of whatever they have at hand. The main thing is that it is strong enough, waterproof and preferably made of metal. Additional shielding will not be superfluous at all, because the metal detector contains very sensitive op-amps. At the back there are two tulips for connecting search coils with high-quality shielded wire.
The metal detector is powered by 12V, but it is quite acceptable to reduce it to 8. When choosing a power source, keep in mind that you will have to walk with it outdoors all day, so the battery should last 10 hours. In the author’s version, naturally with slightly worse sensitivity, the device worked even from two old lithium-ion batteries from mobile phone. The current consumption of the metal detector is about 50 mA, so in some cases you can install a 9-volt power supply, but such power will be enough for 2 hours of operation, no more.
To charge the batteries, a socket is provided, to which power is supplied from the charger or, in the simplest case, from the power supply through a resistor. Be sure to install a volume control, because sometimes you will have to search in an atmosphere of secrecy (behind enemy lines), guided only by the LEDs. On the other side of the front panel there is a Trash control - threshold. It is used to set the moment when the metal detector stops beeping on its own, and the sound appears only when there is metal within sight of the search coil. A lot has been written about making a metal detector coil; I’ll just add some recent information. We start by making a template for winding.
Any suitable material (fibreboard, plywood, plexiglass, plastic, etc.) is made from 5 mm plywood. We process the edges of the finished template and cover it with tape so that the template does not stick to the reel. We clamp the finished template with the axle in a vice and wind 80 turns of wire onto it, impregnating every 20 turns with tsaponlac. You can impregnate with epoxy at your own peril and risk; on many forums they write that batches of resin with different electrical conductivity come across, which affects the parameters of the coil not in better side. After drying, we disassemble the template, remove the coil and “tighten” its “waist” with fum tape. I consider the use of electrical tape inappropriate since electrical tape has a sticky side and can displace the turns - tsaponlak is not epoxy.
Next, we shield it with foil (I use lavsan foil taken from an RG-6U antenna cable, a piece 2 meters long is enough for 2 coils), then we wrap it with tinned wire, and on top with electrical tape or fum tape. As a result, we obtain coils that are absolutely identical in parameters, geometry and quality factor, which is important for a balanced metal detector, since balanced coils are very critical to the geometry of the coils. Then we set the coils to resonance and begin to reduce to “0”. It should be remembered that for this model, reduction to absolute “0” is undesirable - discrimination will disappear, so an imbalance of 0.2-0.6 millivolts is enough, although the detection depth will decrease by a couple of centimeters. Having brought the coils together, we fix them together with cyanoacrylate and threads, and dry them. Now we begin to manufacture the sensor housing.
The most optimal and cheapest, in my opinion, is a sensor made from ceiling tiles. We make a template, cut the blanks and glue the body. I don’t recommend making the cheeks of the reel seat from plexiglass - it’s very fragile, it’s better to use fiberglass, or even better - plastic inserts that railway workers put under the rail on the sleeper (just don’t let the train derail). The result is quite decent, lightweight and cheap to manufacture metal detector search sensors.
As supporting tubes, you can use a telescopic painting rod, cut to the right size. A sliding handle from a Chinese mop or a Chinese three-legged landing net for fishing will also work. A lot has also been said about setting up contours. Let's give the floor to the forum guests: I turned on the search coil for transmission as a series oscillatory circuit, and for reception as a parallel oscillatory circuit. I set up the transmitting coil first, connected the assembled sensor structure to the metal detector, an oscilloscope parallel to the coil, and selected capacitors based on the maximum amplitude. After this, I connected the oscilloscope to the receiving coil and selected the capacitors for RX based on the maximum amplitude. Setting the circuits to resonance takes several minutes if you have an oscilloscope. Further reduction to zero. It’s easier to solder a switch (sensitive voltmeter) to the output of the 1st stage and overlap the coils by about 1cm and move them apart. And the arrow will show the zero point. It can be quite accurate and not easy to catch right away. But it is there. If it still doesn’t work, try turning one of the coils over.
The metal detector circuit can and should be checked first without coils. To do this, let’s mentally break it down into blocks, which we set up and launch separately: Bipolar voltage former on U6A - makes from 12V + -6V. Of course, not all possible questions are covered here, so please check. Additional information on setting up a metal detector on the forum. And I just have to thank Elektrodych for a good description of the coil design, slavake for drawing a new diagram, and all the other forum participants for showing interest in the metal detector. Metal detector forum Discuss the article METAL DETECTOR DIAGRAM |
radioskot.ru
Diagram of a good metal detector with your own hands
Metal detector circuit
Today I would like to present to your attention a diagram of a metal detector, and everything related to it, what you see in the photograph. After all, it is sometimes so difficult to find the answer to a question in a search engine - Diagram of a good metal detector
In other words, the metal detector has a name Tesoro Eldorado
The metal detector can operate in both the search mode for all metals and background discrimination.
Technical characteristics of the metal detector.
Operating principle: induction balanced
-Operating frequency, kHz 8-10kHz
-Dynamic operating mode
-Precise detection mode (Pin-Point) is available in static mode
-Power supply, V 12
-There is a sensitivity level regulator
-There is a threshold tone control
-Ground adjustment is available (manual)
Detection depth in the air with a DD-250mm sensor In the ground, the device sees targets almost the same as in the air.
-coins 25mm – about 30cm
-gold ring – 25cm
-helmet 100-120cm
-maximum depth 150cm
-Consumption current:
-No sound approximately 30 mA
And the most important and intriguing thing is the diagram of the device itself
The picture is easily enlarged when you click on it
To assemble the metal detector you need the following parts:
So that you don’t have to spend a long time setting up the device, do the assembly and soldering carefully; the board should not contain any clamps.
For tinning boards, it is best to use rosin in alcohol; after tinning the tracks, do not forget to wipe the tracks with alcohol
Parts side board
We begin assembly soldering jumpers, then resistors, further sockets for microcircuits And all the rest. One more small recommendation, now regarding the manufacture of the device board. It is very desirable to have a tester that can measure the capacitance of capacitors. The fact is that the device These are two identical amplification channels, therefore the amplification through them should be as identical as possible, and for this it is advisable to select those parts that are repeated on each amplification stage so that they have the most identical parameters as measured by the tester (that is, what are the readings in a particular stage on one channel - the same readings on the same stage and in another channel)
Making a coil for a metal detector
Today I would like to talk about the manufacture of a sensor in a finished housing, so the photo is more than words.
We take the housing, attach the sealed wire in the right place and install the cable, ring the cable and mark the ends.
Next we wind the coils. The DD sensor is manufactured according to the same principle as for all balancers, so I will focus only on the required parameters.
TX – transmitting coil 100 turns 0.27 RX – receiving coil 106 turns 0.27 enameled winding wire.
After winding, the coils are tightly wrapped with thread and impregnated with varnish.
After drying, wrap tightly with electrical tape around the entire circumference. The top is shielded with foil; between the end and the beginning of the foil there should be a gap of 1 cm not covered by it, in order to avoid a short-circuited turn.
It is possible to shield the coil with graphite; to do this, mix graphite with nitro varnish 1:1 and cover the top with a uniform layer of tinned copper 0.4 wire wound on the coil (without gaps), connect the wire to the cable shield.
We put it into the case, connect it and roughly bring the coils into balance, there should be a double beep for the ferrite, a single beep for the coin, if it’s the other way around, then we swap the terminals of the receiving winding. Each of the coils is adjusted in frequency separately; there should be no metal objects nearby!!! The coils are tuned with an attachment for measuring resonance. We connect the attachment to the Eldorado board in parallel with the transmitting coil and measure the frequency, then with the RX coil and a selected capacitor we achieve a frequency 600 Hz higher than that obtained in TX.
After selecting the resonance, we assemble the coil together and check whether the device sees the entire VDI scale from aluminum foil to copper; if the device does not see the entire scale, then we select the capacitance of the resonant capacitor in the RX circuit in steps of 0.5-1 nf to one or another side, before that the moment when the device will see foil and copper at a minimum of discrimination, and when the discrimination is turned up, the entire scale will be cut out in turn.
We finally reduce the coils to zero, fixing everything with hot glue. Next, to lighten the coil, we glue the voids with pieces of polystyrene foam, the foam sits on the hot glue, otherwise it will float up after filling the coil.
Pour the first layer of epoxy, without adding to the top 2-3mm
Fill in the second layer of resin with color. An aniline dye is well suited as a color for dyeing fabric, powder can be different colors and costs pennies. The dye must first be mixed with the hardener, then the hardener must be added to the resin; the dye will not dissolve immediately in the resin.
Start by checking whether the board is assembled correctly correct delivery power supply to all nodes.
Take the circuit and the tester, turn on the power on the board, and, checking the circuit, go through the tester at all points on the nodes where power should be supplied.
When the discrimination knob is set to minimum, the device should see all non-ferrous metals
When screwing the discrim, they should be cut out
All metals in order up to copper should not be cut out, if the device works like this, then it is configured correctly. The discrimination scale must be selected so that it completely fits into a full turn of the discrimination knob, this is done by selecting c10. When the capacity decreases, the scale stretches and vice versa.
In conclusion, I want to say about the cable, it has 4 wires in a common screen, two wires to the transmitting coil and two to the receiving coil, the screen to the housing.
There are also diagrams of metal detectors on our website.
radiostroi.ru
Highly sensitive metal detector for non-ferrous metals - diagram » Useful homemade products
Among amateur radio designs, developments that help detect metal objects hidden in the ground are of particular interest. Especially if the latter are small in size, lie at a considerable depth and are also non-ferromagnetic.
Quite a few good electrical diagrams of such devices, called metal detectors by analogy with well-known military developments, and descriptions of fully functional designs have been published in various technical
Publications, but they are often designed for trained, experienced home-made workers who have a good material base and scarce parts.
But even a beginner can easily repeat and make the design we propose. Moreover, it will be quite possible to purchase the necessary parts (including a 1 MHz quartz resonator). Well, the sensitivity of the assembled metal detector... It can be judged at least by the fact that with the help of the proposed device it is easy to find, for example, a copper coin with a diameter of 20 mm and a thickness of 1.5 mm at a depth of 0.9 m.
Operating principle
It is based on a comparison of two frequencies. One of them is reference, and the other is variable. Moreover, its deviations depend on the appearance of metal objects in the field of the highly sensitive search coil. In modern metal detectors, to which the design under consideration can quite rightly be included, the reference generator operates at a frequency that is an order of magnitude different from that which appears in the field of the search coil. In our case, the reference generator (see the circuit diagram) is implemented on two logic elements ZI-NOT integrated DD2. Its frequency is stabilized and determined by a quartz resonator ZQ1 (1 MHz). The generator with varying frequency is made on the first two elements of the IC DD1. The oscillatory circuit here is formed by the search coil L1, capacitors C2 and SZ, as well as a varicap VD1. And to adjust to a frequency of 100 kHz, use potentiometer R2, which sets the required voltage to the varicap VD1.
Fig.1. Schematic diagram of a highly sensitive homemade metal detector.
Logic elements DD1.3 and DD2.3, operating on mixer DD1.4, are used as signal buffer amplifiers. The indicator is a high-impedance BF1 telephone capsule. And capacitor C10 is used as a shunt for the high-frequency component coming from the mixer.
The configuration of the printed circuit board is shown in the corresponding illustration. And the layout of radio elements on the side opposite the printed conductors is shown here in a different color.
Fig.2. Printed circuit board of a homemade metal detector, indicating the locations of the elements.
The metal detector is powered by a 9 V DC source. And since high stabilization is not necessary here, a Krona type battery is used. Capacitors C8 and C9 work successfully as a filter.
The search coil requires special precision and attention during manufacture. It is wound on a vinyl tube with an outer diameter of 15 mm and an inner diameter of 10 mm, bent in the shape of a circle 0 200 mm. The coil contains 100 turns of PEV-0.27 wire. Once the winding is complete, it is wrapped in aluminum foil to create an electrostatic shield (reduce the effect of capacitance between the coil and ground). It is important to prevent electrical contact between the winding wire and the sharp edges of the foil. In particular, “wrapping obliquely” will help here. And to protect the aluminum coating itself from mechanical damage, the coil is additionally wrapped with insulating bandage tape.
The diameter of the coil may be different. But the smaller it is, the higher the sensitivity of the entire device becomes, but the search area for hidden metal objects narrows. When the diameter of the coil increases, the opposite effect is observed.
Work with a metal detector as follows. Having placed the search coil in close proximity to the surface of the earth, adjust the generator with potentiometer R2. And in such a way that the sound in the telephone capsule cannot be heard. When the coil moves above the surface of the earth (almost close to the latter), the treasured place is found - by the appearance of sound in the telephone capsule.
When using the device discussed above to find objects hidden in the ground that are of archaeological and national cultural value, prior permission is required from the relevant authorities.
Attention!!! The information contained on this page has been added from unverified sources and may be out of date and contain errors. Therefore, it is provided for informational purposes only.
N. Kochetov, based on materials from “Mlad Constructor”
www.freeseller.ru
schemes and varieties / Do it yourself / Collective blog
It is generally accepted that homemade items and designs are inferior in all respects to their branded counterparts. Allegedly, with the help of a metal detector, assembled with your own hands from improvised means, you can only find scrap metal. However, as practice shows (in the form of regularly held treasure hunting competitions), many home-made devices are not only quite competitive, but also superior to purchased “rivals” in most characteristics. However, the knowledge and experience of the master play an important role in this matter. Therefore, if you do not already have either one or the other, we will tell you where to start.
General information about metal detectors
Before we talk about assembling a metal detector yourself, it would be nice to have an idea of what it is and how it functions.
Design
Depending on the type of assembly and the parts used, metal detectors are conventionally divided into 5 types (which will be discussed below), however, in structural assembly Most detectors have similar features:
- A magnetization coil (search coil) is a part consisting of several rings, the main task of which is to “feel” metals located underground. The sensitivity of a metal detector directly depends on the size of the coil and/or the power of the circuit installed in it.
- The control unit is the “heart” of the device. Responsible for its operation and consists, as a rule, of a microprocessor, speaker and battery.
- Holder with armrest (lower rod + upper rod) – a device for connecting the control unit to the coil. In most cases, it consists of 2 parts and is selected according to the person’s height (so that you don’t have to constantly bend over).
- The coil cable is a part whose main task is to organize the interaction between the coil and the control unit.
General view of the metal detector
Principle of operation
The operation of any metal detector is based on the principle of magnetic attraction. The moment the coil comes into close proximity to a metal object, sharp fluctuation magnetic waves, which, in turn, causes a sound signal.
Depending on the assembly, the metal detector can operate either at low frequencies or at high frequencies. In the first case, it will be able to find large objects buried to a depth of 4 m, but will ignore small objects lying almost on the surface. In the second case, it’s the other way around: small things located at a depth of 1 - 1.5 m will be detected immediately, while a large object will go unnoticed. Therefore, before you start assembling a metal detector, clearly decide for what purpose you need it.
Type varieties
Depending on the device and type of signal reception/transmission, metal detectors can be divided into 5 types:
- "Reception and transmission." This type of metal detector has 2 inductance coils built into it – transmitting and receiving. Moreover, they are placed so that when the device is in a “quiet state,” the signal from the transmitting coil does not reach the receiving coil, and when a metal object is detected, it is amplified by it and supplied to the power supply.
- Induction. It combines the functions of 2 coils (receiving and transmitting) in one, which makes it difficult to isolate the reflected signal during self-assembly.
- Frequency meter. It operates on the basis of an LC generator, the frequency of which changes as the circuit approaches the location of the metal. Low sensitivity is compensated by the simplicity and accessibility of assembly.
- Quality meter. Analyzes the oscillatory circuit of an LC generator, the quality factor of which becomes lower the closer the metal detector is to the target. Easy to assemble, however, characterized by low temperature stability.
- Pulse. When a metal detector enters the area where a metal object is located, eddy pulse currents are excited, and a signal (in the form of pulses) from the coil to the sensor is transmitted periodically. The shape and duration of the signal directly depend on the size and conductive properties of the detected object.
Assembling a metal detector from improvised means
There are a huge number of options for assembling a metal detector. They all vary quite a lot in the complexity of the circuits, ease of assembly, materials used, etc. They can be found as complicated versions:
Diagram of a metal detector operating on the principle of the difference in the beat frequencies of 2 generators
And accessible to everyone:
Circuit diagram of a metal detector operating on 3 transistors
Below we will look at the simplest version of the metal detector, which even a beginner can implement.
Initial scheme for work
Frame
In order not to stop to rest every 10 - 15 minutes, select light and durable metal to make the barbell. Be sure to take into account your height so that the finished device does not turn out too long or too short. Those who do not have the opportunity to make a barbell themselves often replace it with PVC pipes, mop handles, or a regular crutch with a ready-made armrest.
A regular crutch is ideal for a holder
Search coil
Let's start by creating a device for winding a coil (the values below are for a coil with a diameter of 16 cm). We take a board measuring 18x18 cm, cambric and nails. We draw a circle on the board equal to the diameter of the coil, and drive at least 16 nails along its contour so that they protrude from the board by about 2 cm. We “bite off” the heads of the nails and put cambrics on them. We wrap the device with 80 turns of copper wire, after which we tighten the resulting coil with strong threads and impregnate it with epoxy resin.
Coil ring after winding
Leaving the leads up to 4 cm long, wrap the coil with electrical tape and shield it with foil. Don't forget to leave a gap in the terminal area.
We tin a piece of copper wire up to 1.25 m long, and then tightly wrap it around the coil around the entire screen (leaving a 12 cm lead). Then we wrap the coil with electrical tape again, cut out the tin contact pad and solder it to the coil terminal.
Final result
Control block
To assemble it we will need:
- The battery is 9 volt;
- Chip;
- 8 ohm microspeaker;
- Amplifier transistor 250+.
All these parts can be found in a regular transistor type radio. We make or select a ready-made housing for the control unit (for example, a box for piston rings) and install the assembled parts.
Control unit - inside view
We connect the board and the coil using a two-core shielded wire, solder the cable screen to the coil terminal and to the common bus located on the board. We insulate the terminals. We fix the cable on the rod with electrical tape, and the coil with self-tapping screws.
We carry out a control check and adjust the frequencies. Ready.
In 1989, an Australian was able to find a gold nugget shaped like a boot, the length of which reached 12 inches. In 2008, “Cortez’s boot” (that’s the name the find was given) “went under the hammer” for $1.5 million. Agree, a good way to replenish family budget. Don't be afraid to experiment, and then perhaps you will be the next lucky one?
"Boot of Cortez"
44kw.com
DIY metal detector: detailed instructions on how to make
Finding artifacts underground is a fairly popular activity. For some, this is a profession, others are simply interested in archaeology. There are numerous groups of treasure hunters: both romantics and pragmatic treasure hunters. All these people are united by one passion: searching for metal objects hidden at various depths.
Just because you have an accurate map showing where the treasure is buried, or plans for fighting during the war, this does not guarantee success. You can shovel tons of soil, and the desired item will calmly lie a couple of meters from the active search site.
To search for gold and less valuable metals, you will need a metal detector that you can make yourself.
Important information: The use of such devices is not prohibited by law. However, there are penalties for the consequences of such a search regarding excavations, as well as the recovery of discovered objects.
We won’t go into details; that’s the topic of another article. Simply put: if you find Golden ring on the beach, or a handful of Soviet coins in the forest - there will be no problems associated with the use of electronic search tools.
But for recovered bronze spoons that are 100 years old or older, you can get a real sentence or a large fine.
Nevertheless, devices for searching for metal objects in the depths of the earth are freely sold, and those who want to save money can make a metal detector with their own hands at home.
How the device works
Unlike ground detectors, which work using waves of different frequencies or ultrasound, a metal detector (either factory-made or home-made) works with inductance.
The coil emits an electromagnetic field, which is then analyzed by the receiver. If any object that conducts electric current or has ferromagnetic properties is in the coverage area, the field format is distorted. More precisely, under the influence of the active field of the coil, the object forms its own. This event is recorded by the receiver, and an alert is generated: the instrument needle moves, a tone sounds, and indicator lights light up.
Knowing the operating method, you can calculate the electrical circuit and create a powerful metal detector with your own hands. The complexity of the design depends only on the availability of the element base and your desire. Let's look at several popular options for assembling a homemade metal detector:
The so-called "butterfly"
This nickname was received due to the characteristic shape of the platform on which the inductors are located.
The arrangement of the elements is related to the operating principle. The circuit is made in the form of two generators operating at the same frequency. When identical coils are connected to them, an induction balance is created. As soon as a foreign object with electrical conductivity gets into the electromagnetic field, the balance of the field is destroyed.
Generators are implemented on NE555 chips. The illustration shows a typical diagram of such a device.
The coil for the metal detector (there are two of them, in the diagram: L1 and L2) is made by hand from wire with a cross section of 0.5–0.7 mm². The ideal option is a transformer winding copper core in varnish insulation (removed from any unnecessary transformer). The characteristics do not have to be maintained with pinpoint precision, under one condition: the coils must be identical.
Approximate parameters: diameter 190 mm, each coil has exactly 30 turns. The assembled product must be monolithic. To do this, the turns are grabbed with a mounting thread and filled with transformer varnish. If this is not done, vibration of the turns will throw the circuit off balance.
Electrical diagram
There are two manufacturing options:
- given the small number of elements, you can assemble it on a breadboard by connecting the legs of the parts using conductors;
- For accuracy and reliability, it is better to etch the board according to the proposed drawing.
Any soldering “on the snot” can fail in field conditions, and you will be offended for wasting your time.
Just like a transistor metal detector, the NE555 device needs fine tuning before use. The diagram shows three variable resistors:
- R1 is designed to adjust the frequency of the generator and achieve that same balance;
- R2 coarsely adjusts sensitivity;
- Using resistor R3, you can set the sensitivity with an accuracy of 1 cm.
Information: This scheme cannot discriminate against metals. The seeker only makes it clear that the object exists. And by the tone of the signal (based on your experience) you can determine the approximate volume and depth of the deposit.
The power supply is quite universal: 9–12 volts. You can select the battery from the source uninterruptible power supply, or assemble a power supply from AAA batteries. A good option is 18650 batteries (they are also used for vaping).
Butterfly setting
The principle of operation is described above, so let’s just look at the technology. We set all resistors to the middle position, and ensure that the synchronization of the generators is disrupted. To do this, we fold the coils in a figure eight and move them relative to each other until the squeaking turns into crackling. This is a synchronization failure.
We fix the rings and rotate the resistor R1 until a steady crackling sound appears at even intervals.
By bringing metal objects to the place where the coils overlap (this is the search point), achieve a steady squeak. The sensitivity is adjusted by resistor R2.
All that remains is adjustment with resistor R3, which is used rather to correct the voltage drop in the power source.
Mechanical part
A do-it-yourself metal detector rod is made from a lightweight plastic pipe or wood. The use of aluminum is undesirable as it will interfere with operation. The circuit and controls can be hidden in a sealed housing (for example, a junction box for wiring).
The butterfly finder is ready to go.
Pirate
Another popular pulse model for beginner treasure hunters is the “Pirate” metal detector. It is also easy to make with your own hands, detailed instructions in two versions:
- On the same NE555 chip. This is a classic generator that starts working when metal appears in the coil’s coverage area. No adjustments are required, just a squeak will be heard in the speaker.
- A metal detector assembled with transistors works on the same principle. Actually, the circuit is similar, only NE555 is replaced by a transistor generator with KT315.
It is advisable to bring the power supply closer to 12 volts, since the quality of operation depends on the voltage. Printed circuit boards have already been tested, both options are shown in the illustration.
The coil (in this case one) is made from the same 0.5 mm transformer wire. The optimal diameter is 20 mm, the number of turns is 25. Since we are making the “Pirate” metal detector with our own hands, the external design fades into the background. Any materials that you were ready to throw away will do.
It is better to make the handle detachable for ease of transportation. We remember that the use of metals is unacceptable.
Sensitivity is adjusted by two variable resistors in real time while searching. No fine tuning of the generator is required.
And if you manage to properly seal the case, you can start searching for “treasures” in the beach surf, and even at the bottom of the reservoir.
It is more difficult to make an underwater metal detector with your own hands, but it will give you an undeniable advantage over your competitors.
Improved performance
You can make a deep metal detector with your own hands from a ready-made “Pirate” without additional costs. There are two ways to do this:
- Increasing the diameter of the inductor. At the same time, downward permeability increases significantly, but sensitivity to small objects decreases.
- Reducing the number of coil turns while simultaneously adjusting the circuit. To do this, you will have to sacrifice one coil for experiments. We remove (and cut off) turn after turn until we see that the sensitivity begins to decrease. We remember the number of turns at maximum parameters, and make a new coil for this circuit. Then we change the resistor R7 to a variable one, with similar power parameters. After conducting several experiments with sensitivity, we fix the resistance and change the variable to a constant resistor.
The Pirate metal detector can be assembled using the popular Arduino controller.
It is more convenient to use such a device, but there will still be no metal discrimination.
Having figured out how to make a metal detector with your own hands for amateur tasks, we will briefly examine several serious models.
DIY metal detector Clone PI W
In essence, this is a cheaper version of the professional finder Clone PI-AVR, only instead of an LCD display, a line of LEDs is used. This is not as convenient, but still allows you to control the depth of artifacts.
The best option for the price is the CD4066 chip and ATmega8 microcontroller.
Of course, there is also a printed circuit board layout for this solution, only the control buttons are placed on a separate panel.
Programming ATmega8 is a topic for a separate article; if you have worked with such controllers, no difficulties will arise.
The powerful Clone PI W metal detector, made by yourself, allows you to find metal no more than a meter deep, although without discrimination.
Seeker "Chance"
A similar circuit on the ATmega8 controller is called “Chance”. The principle of operation is similar, only the possibility of screening out (partial discrimination) of ferrous metals has become possible.
A printed circuit board design has also been worked out, which can be successfully replaced with a classic “breadboard” for Arduino
DIY Terminator 3
If you need a homemade metal detector with metal discrimination, pay attention to this model. The scheme is quite complicated, but your efforts pay off with the coins you find, which may turn out to be gold.
The peculiarity of the “Terminator” is the separation of the receiving and transmitting coils. A 200 mm ring is made to emit the signal. 30 turns of wire are laid for it, then it is cut, as a result we get 2 half-coils with a total capacity of 60 turns (see diagram).
The receiving coil is located inside, 48 turns with a diameter of 100 mm.
The adjustment is made using an oscilloscope; after achieving optimal amplitude results, the windings are fixed in the housing by pouring epoxy resin.
Then an experimental hands-on adjustment of the discrimination switch is performed. For this purpose, real objects from various metals, and their type is marked on the mode switch (after checking).
Radio amateurs are working on an improved version of Terminator 4, but there is no practical copy yet.
Simple metal detectors from ready-made electrical appliances
Bottom line
Regardless of the complexity of the design, making a homemade metal detector will require a lot of time and effort from you. Therefore, out of curiosity, such devices are not made. But for professional use, this is an excellent alternative to factory copies.
You can buy it for about 100-300 dollars. The price of metal detectors is strongly related to their detection depth; not every metal detector can “see” coins at a depth of 15 cm. In addition, the cost of a metal detector is also greatly affected by the presence of a metal type recognizer and the type of interface; fashionable metal detectors are sometimes equipped with a display for convenient operation .
This article will look at an example of do-it-yourself assembly. powerful metal detector called Pirate. The device is capable of catching coins underground at a depth of 20 cm. As for large objects, it is quite possible to work at a depth of 150 cm.
Video of working with a metal detector:
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 you won’t be able to work with it in areas contaminated with various types of metals.
Materials and tools for assembly:
- microcircuit KR1006VI1 (or its foreign analogue NE555) - the transmitting node 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.
Step two. Install electronic elements for a fee
Now the board needs to be soldered, all electronic elements are installed exactly as in the diagram. In the picture on the left you can see the capacitors. These capacitors are film capacitors and have high thermal stability. Thanks to this, the metal detector will work more stably. This is especially true if you use a metal detector in the fall, when it is sometimes quite cold outside.
Step three. Power supply for metal detector
To power the device, you need a source from 9 to 12 V. It is important to note that the device is quite voracious in terms of energy consumption, and this is logical, because it is also powerful. One Krona battery will not last long here; it is recommended to use 2-3 batteries at once, which are connected in parallel. You can also use one powerful battery (best rechargeable).
Step four. Assembling a coil for a metal detector
Due to the fact that this is a pulse metal detector, the accuracy of the coil assembly is not so important here. The optimal diameter of the mandrel is 1900-200 mm; a total of 25 turns need to be wound. After the coil is wound, it needs to be thoroughly wrapped on top with electrical tape for insulation. To increase the detection depth of the coil, you need to wind it on a mandrel with a diameter of about 260-270 mm, and reduce the number of turns to 21-22. In this case, a wire with a diameter of 0.5 mm is used.
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. For more fine tuning metal detector, you need to twist the variable resistor R13, you need to achieve rare clicks in the dynamics. 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.
