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. And the main search tool is 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 some people want to assemble a metal detector with their own hands, and some even build their own small business on their assembly.
Homemade metal detectors
In this section of our website about homemade metal detectors, I will be collected: best schemes metal detectors, their descriptions, programs and other data for manufacturing DIY metal detector. 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. Mainly presented here various schemes pulse metal detectors And metal detector circuits with metal discrimination.
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 contain the necessary tools, materials and equipment for self-assembly 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:
 |
Principle of operation | I.B. |
| Metal discrimination | There is | |
| Maximum search depth | ||
| There is | ||
| Operating frequency | 4 - 17 kHz | |
| Difficulty level | Average | |
 |
Principle of operation | I.B. |
| Metal discrimination | There is | |
| Maximum search depth | 1-1.5 meters (Depends on the size of the coil) | |
| Programmable microcontrollers | There is | |
| Operating frequency | 4 - 16 kHz | |
| Difficulty level | Average | |
 |
Principle of operation | I.B. |
| Metal discrimination | There is | |
| Maximum search depth | 1 - 2 meters (Depends on the size of the coil) | |
| Programmable microcontrollers | There is | |
| Operating frequency | 4.5 - 19.5 kHz | |
| Difficulty level | High | |
I present to you the diagram and design a simple metal detector to make with your own hands
Fig.1. Schematic diagram metal detector
The circuit is based on two NE555 chips. There are transmitting (Tx) and receiving (Rx) coils, so the circuit can be divided into two parts. The left side is the generator rectangular pulses. The timing components R1, R2, C1 are selected so that the output frequency is about 700 Hz. This is the frequency of the audible range. The pulses are transmitted through current-limiting resistor R3.
Both coils are located in space in such a way that they together form a certain overlap zone and the system is in induction balance. In this case, there is zero voltage in the receiving coil and the right side of the circuit does not react in any way. If a metal object appears nearby, an imbalance occurs and an audible signal appears.
The signal from the receiving coil is amplified by transistor VT1 and fed to the input of the second microcircuit. A KT3102EM is used as a bipolar transistor VT1; it can be replaced with any similar one with a high gain. A voltage divider is formed using four resistors R5 - R8. Variable resistors are used to configure the metal detector. R6 is a trimmer and is adjusted after the mutual placement of the coils. And R7 and R8 are used for coarse and fine adjustments; they should be installed on the device body (provide easy access to them).
The sound signal is created thanks to the piezo emitter BA1, which can be taken from an unnecessary multimeter. But when testing the circuit, I liked the sound of the piezo emitter with a built-in oscillator. Despite the fact that the output DD2 is formed pulse signal it will not only signal well, but will also allow you to detect the slightest changes in sound when a metal object is detected.
Creating Reels
To wind the metal detector coils, you will need an enameled winding wire with a diameter of 0.3 mm. In my case, the maximum permissible diameter of 0.7 mm was used.
The optimal diameter for winding a coil is approximately 15-16 cm. You should select some round object (for example a bucket) to wind the coil around. But you can use the device. To do this, hammer nails into a clean wooden surface in a pre-drawn circle.
The inner diameter in my case is 15.5 cm. I wound 25 full turns. The number of turns can and should even be done more than mine, for example about 50 turns. The winding wire itself can be taken from unnecessary electric motors or power transformers.
When the coil is wound, carefully remove it from the device and wrap it with paper tape. As a result, you need to make two absolutely identical coils. Next, use a knife to scrape off the varnish and after cleaning, these ends need to be tinned.
Windings tend to bend and lose their correct geometry, so the coils need to be completely wrapped, for example, with paper tape. After this, they need to be flattened a little where they overlap each other. They are often made to look like the letter "D" as shown in the picture below.
It is convenient to use a sandwich panel as a base for search coils, which is used for slopes of plastic windows.
The board will be located at some distance from the search coils and it is not recommended to use ordinary wires. To connect the coils to the board, I used shielded wire, if I'm not mistaken from the microphone.
Shielded wire for connecting the coils to the board.
The central wire must be soldered to the beginning of the coil, and the other to the minus of the power supply as shown above.
For both coils, of course, the wires will be separate so that there is no interference.
Coil location and settings
Setting up the system begins before gluing the coils to the base.
We set the trimming resistor R6 to approximately 90 kOhm, and set the adjusting resistors R7 and R8 to the middle position. Now you need to move the coils. The device will produce sound in two positions. With wide and narrow overlap. I recommend fixing the coils at their narrow overlap as shown in the figure below (position 2). According to my observations, in position 2 the sensitivity is better and more accurate positioning occurs.
After this you need to glue it well to the base. I did this using hot glue. But if you wish, you can make recesses in the base for the coils and fill them with epoxy.
After the glue has hardened, you need to adjust the settings again. We do not touch R7 and R8 for now, they are set in the middle position and resistor R6 needs to achieve a position in which the sound emitter crackles a little and, so to speak, is in a borderline position between silence and squeaking (on the verge of breakdown). In the future, when using the metal detector, you will only need to adjust the position of R7 and R8. This is due to the fact that the device is not ideal, the coils are not shielded, and the settings will deteriorate if the battery voltage is lost.
Revision option
If desired, you can make additional modifications to the coils - shielding from external electromagnetic fields ("Faraday shield"). This is done after the initial covering of the windings, which was described earlier (with paper tape or electrical tape). Then you need to take long strips of aluminum foil and wrap the coils. This is not done completely, but leaves a gap of about 1-2 cm at the point where the wires exit. The foil is connected to the end coil and connects to the power supply minus. After this, the coil is covered with electrical tape.
I didn't do this because I was afraid of losing sensitivity.
Metal detector design
After soldering the components, it is advisable to remove the remaining flux and rosin from the surface of the board, because they can adversely affect the operation of the circuit.
I decided to place the board in a metal box, and to avoid short circuits with solder joints, the bottom of the case was covered with electrical tape. Later I will most likely choose a plastic case.
Always pay attention to the rigidity of the cables, because... It would be a shame if something comes off during use.
The circuit will be powered by a crown battery. The scheme has low power consumption, but it’s still better to install an alkaline battery, it will ensure the device operates for several “cops”.
The handle was made of a metal-plastic water pipe, and closer to the base it was continued with plastic tubes so that the coils did not react to the metal-plastic handle itself. The design turned out to be quite light. The shielded wires were laid with electrical tape. I installed the box with the metal detector board higher so that the adjusting resistor was at hand.
Advice
Every time before using a metal detector, you should use a variable resistor to make the emitter quickly crackle. The faster the crack, the greater the sensitivity.
First find
Experiment: I buried a coin with a diameter of 2.5 cm in the ground at a depth of 25 cm. When scanning, the coils were at a distance of 5 cm from the ground. At the same time, the metal detector emitted a distinct signal. I assume that large metal objects will “ring” deeper.
In any case I need certain time to get used to the metal detector and after some searching, draw the final results of its capabilities.
This article has a video that shows the process of creating a metal detector and its testing.
List of radioelements
| Designation | Type | Denomination | Quantity | Note | Shop | My notepad |
|---|---|---|---|---|---|---|
| DD1, DD2 | Programmable timer and oscillator | NE555 | 2 | To notepad | ||
| VT1 | Bipolar transistor | KT3102EM | 1 | To notepad | ||
| R1 | Resistor | 1 kOhm | 1 | To notepad | ||
| R2 | Resistor | 100 kOhm | 1 | To notepad | ||
| R3 | Resistor | 470 - 680 Ohm | 1 | To notepad | ||
| R4 | Resistor | 2 - 2.2 MOhm | 1 | To notepad | ||
| R5 | Resistor | 10 kOhm | 1 | To notepad | ||
| R6 | Trimmer resistor | 100 kOhm | 1 | To notepad | ||
| R7 | Variable resistor | 100 - 500 kOhm | 1 | Rough tuning |
Many people who want to find treasure or something valuable immediately go to the store in search of a good metal detector! In our article, we will tell you how to make a metal detector at home.
How to make a metal detector at home?
Let's start our assembly, what do we need:
1. Calculator;
2. Headphones;
3. CD and DVD disc;
4. Electrical tape;
5. 9V battery;
6. Glue;
7. Scissors.
Step #1. Cut off the headphone plug and expose the wires.
Step #2. Using glue, stick one bare wire to the CD. Just one drop of glue is enough. After that, secure the wire to the disk with electrical tape. Don't put electrical tape on top of the glue!
Step #3. We attach the second bare wire to the DVD disc in the same way.
Step #4. We take the battery and connect it with wires to two disks, where the headphones are attached. Secure the wires well so that they do not fall off.
Step #5. Take a calculator and place it in the middle of the CD. Tape it down with electrical tape.
Step #6. Place the DVD on top and secure the structure with electrical tape. Place the battery in the center DVD disc and secure it. Check that our metal detector is carefully glued together.
Your metal detector is ready! Pass it over metal objects and hear the sound in your headphones!
VIDEO. How to make a metal detector.
How to make a simple metal detector?
We will need:
1. Speaker;
2. PELSHO wire;
3. Electrical tape;
4. Foil from the electrolyte capacitor;
5. Tinned wire;
6. Capacitor;
7. Two LEDs.
Step #1. Let's make a housing for a metal detector. To do this, you can take a monitor case with a diameter of approximately 180mm.
After Step #1 Let's start making a coil for a metal detector.
We will wind the PELSHO wire 0.4-0.7 mm around a pan of suitable diameter. Then you need to carefully remove it and wrap it with electrical tape.
Step #2. Wrap the foil from the electrolyte capacitor over the electrical tape, and then wrap it again with electrical tape. For each winding we connect a capacitor of approximately 0.1 µF.
Step #3. Completely insulate the invention from moisture.
Step #4. Connect two LEDs to pin 7 of U2B. One for “plus”, the second for “minus”. Don't forget to attach the 470 ohm resistors. Try to choose the brightest LEDs so that they can be seen during the day.
Step #5. Take the speaker and connect it to our device.
The metal detector is ready! With its help you can discover many interesting things!
VIDEO. How to make a metal detector from a magnet?
Not so often, but losses still happen in our lives. For example, we went into the forest to pick mushrooms and berries and dropped the keys. It will not be so easy to find them in the grass under the leaves. Don’t despair: a homemade metal detector, which we will make with our own hands, will help us. So I decided to collect my first metal detector. Nowadays, few people decide to make a metal detector. Homemade devices were popular twenty to twenty-five years ago, when there was simply nowhere to buy them.
Modern metal detectors from manufacturers such as Garrett, Fisher and many others have high sensitivity, metal discrimination, and some even have a hodograph. They are able to adjust the ground balance, tune out electrical interference. Thanks to this, the detection depth of a modern coin metal detector reaches 40 cm.
I chose a scheme that was not very complicated, so that it could be repeated at home. The principle of operation is based on the difference in the beat of two frequencies, which we will pick up by ear. The device is assembled on two microcircuits, contains a minimum of parts, and at the same time has quartz frequency stabilization, thanks to which the device operates stably.
Metal detector circuit on microcircuits
The scheme is very simple. It can easily be repeated at home. It is built on two 176 series microcircuits. The reference oscillator is made on La9 and stabilized by quartz at 1 MHz. Unfortunately, I didn’t have this, I had to set it to 1.6 MHz.
The tunable generator is assembled on the K176la7 microcircuit. To achieve zero beats, varicap D1 will help, the capacity of which varies depending on the position of the variable resistor R2 slider. The basis of the oscillatory circuit is the search coil L1, when it approaches a metal object, the inductance changes, as a result of which the frequency of the tunable generator changes, which is what we hear in headphones.
I use regular headphones from a player, the emitters of which are connected in series in order to put less load on the output stage of the microcircuit:
If the volume turns out to be too much, you can introduce a volume regulator into the circuit:
Details of a homemade metal detector:
- Microcircuits; K176LA7, K176LA9
- Quartz resonator; 1 MHz
- Varicap; D901E
- Resistors; 150k-3pcs., 30k-1pc.
- Variable resistance resistor; 10k-1pcs.
- Electrolytic capacitor; 50 microfarads/15 volts
- Capacitors; 0.047-2pcs., 100-4pcs., 0.022, 4700, 390
Most of the parts are located on printed circuit board:
I placed the entire device in an ordinary soap dish, shielding it from interference with aluminum foil, which I connected to a common wire:
Since there is no place on the printed circuit board for quartz, it is located separately. For convenience, I removed the headphone jack and frequency control from the end of the soap dish:
The entire metal detector unit was placed on a piece of ski pole using two clamps:
The most important part remains: making the search coil.
Metal detector coil
The sensitivity of the device and resistance to false alarms, the so-called fontons, will depend on the quality of the coil's manufacturing. I would like to immediately note that the depth of detection of an object directly depends on the size of the coil. So, the larger the diameter, the deeper the device will be able to detect the target, but the size of this target should also be larger, for example, a sewer manhole (the metal detector simply will not see a small object with a large coil). Conversely, a small-diameter coil can detect a small object, but not very deep (for example, a small coin or ring).
Therefore, I first wound a medium-sized reel, so to speak, a universal one. Looking ahead, I want to say that the metal detector was designed for all occasions, that is, the coils should be of different diameters and they can be changed. To quickly change the coil, I installed a connector on the rod that I pulled out of an old tube TV:
I attached the mating part of the connector to the coil:
As a frame for the future reel, I used a plastic bucket that I bought at a hardware store. The diameter of the bucket should be approximately 200 mm. Part of the handle and bottom should be cut off from the bucket so that a plastic rim remains, on which 50 turns of PELSHO wire with a diameter of 0.27 millimeters should be wound. The connector should be attached to the part of the remaining handle. We insulate the resulting coil using electrical tape in one layer. Then we need to shield this coil from interference. To do this, we need aluminum foil in the form of a strip, which we will wrap on top so that the ends of the resulting screen do not close and the distance between them is approximately 20 millimeters. The resulting screen should be connected to a common wire. I also wrapped it with electrical tape on top. Of course, you can soak it all with epoxy glue, but I left it that way.
After testing a large coil, I realized that I needed to make a small one, the so-called sniper, to make it easier to detect small objects.
The finished coils look like this:
Setting up a finished metal detector
Before you start setting up your metal detector, you need to make sure that there are no metal objects near the search coil. The setup consists of selecting the capacitance of capacitor C2 in order to obtain the maximum level of beats that we hear in headphones, since there are many harmonics in the signal (we need to highlight the strongest one). In this case, the slider of the variable resistor R2 should be as close to the middle as possible:
I made the rod from two parts, the tubes were selected in such a way that they fit into each other very tightly, so I didn’t have to come up with a special fastening for these tubes. An armrest and handle were also made to make it easier to wire above the ground. As practice has shown, this is very convenient: the hand does not get tired at all. When disassembled, the metal detector turned out to be very compact and literally fits into a bag:
The appearance of the finished device looks like this:
In conclusion, I would like to say that this metal detector is not suitable for people who are going to work in the old way. Since it doesn't discriminate against metals, you'll have to dig for everything. You will most likely be very disappointed. But for those who like to collect scrap metal this device will be of help. And just as entertainment for children.
Devices capable of detecting metal objects in weakly conducting environments are called metal detectors, or metal detectors. They can be used to search for ferrous and non-ferrous metals. A homemade metal detector for coins is capable of detecting small items at a distance of 10 to 50 cm, and larger metals from 0.5 to 3 m.
The use of metal detectors has been known since ancient times, and a large increase in their production occurred at the end of the 60s. Thanks to progress and a variety of schemes, any novice radio amateur can make a metal detector with his own hands, without resorting to extensive knowledge in electronics. The main advantage of homemade metal detectors is low costs.
Let's assemble a simple metal detector that operates on two frequency generators - a beat metal detector. At the same frequency, the generators are synchronized, but when one of the metal coils enters the field, the frequency in one of the generators changes. As a result, the circuit reproduces the sound of the difference in frequencies of two generators in the dynamics.
Tools and materials for the device
To make a homemade metal detector, you need to divide the process into three stages - creating a design, implementing a circuit, and assembling it into a single whole. We will describe an approximate list of tools and materials that may be needed for these purposes. Further on in the article, we will explain in more detail: what a metal detector for gold can be assembled from, and what kind of material is best to use. Let's start by preparing a tool for beginning diggers. To work you will need:
- Cutters for working with wires and parts;
- Knife;
- Saw for plastic. In extreme cases, you can use a knife or a regular saw;
- Soldering iron;
- Screwdriver Set.
Necessary materials:
- Insulating tape;
- Soldering kit. You can just use rosin and solder;
- Glue;
- Parts and board for the circuit;
- Wire for coil;
- A piece of plastic and a plastic pipe;
- Fasteners.
Preparing parts
Described here detailed instructions about choosing and searching for parts.
First, you need to decide on the material and fastening of the components of the metal detector and find the necessary components.
As a barbell, you can use a crutch with an armrest, a fishing rod, a pipe made of cross-linked polyethylene or polyvinyl chloride (Fig. 2).
The coils and circuitry will be placed underneath on a stand attached to the rod. So it is important to consider the rigidity of the bar and its material. It is better to give preference to dielectrics, i.e. non-conductive electricity– plastic, wood and more. It is necessary to make a handle to make it comfortable to hold the metal detector being manufactured. In the case of a crutch, it is not needed, but in another case, you can attach either a bicycle handlebar or another homemade structure.
The stand for the circuit and coils can be made from ordinary plastic. It is easy to trim and weighs little. You will need one bottom sheet, since access to the coils is required to adjust the device. To reduce vibration of the circuit with coils, it is advisable to choose stronger plastic.
After preparing the rod and stand, you need to connect them. You can use fasteners, but do not forget that for the circuit to work properly, you should not bring metal products closer than 30 cm. Therefore, we use good glue, for example, liquid nails. You can use other materials - it all depends on your abilities in plumbing and carpentry.
The wire for the coils must be insulated. Suitable enameled copper wire with a diameter of 0.5 - 0.7 mm grade PEV or PEL. The wire length is about 100 meters. An oil-based varnish is suitable for fixing parts.
The parts can be mounted using a hinged method on PCB or cardboard. For beginning radio amateurs, in specialized stores you can buy processed textolite from the factory or material with holes for parts. You can also make a board yourself from solid unprocessed PCB. To do this, you need to mark the location of the contacts of the radio components on the diagram, then separate the sections of the textolite with a knife and tin the pads and tracks (Fig. 3). We cut off the excess part of the PCB with a plastic saw.
To assemble a working metal detector, radio components can be found at home in old radio equipment, but it is advisable to purchase them in a store. Identical parts must be completely identical and preferably from the same batch. Table 1 provides a list necessary details and comments, the implementation of which will lead you to assembling a high-quality metal detector.
After finding all the necessary parts, you can easily assemble the metal detector at home.
Assembling the device
Having considered the list of necessary materials and parts, we will answer in detail how to assemble a metal detector from them with your own hands.
To wind the coils, we use any round object with a diameter of 20–25 cm. The number of turns is 30. We bring out one end of the wire and wind it 10 turns, after which, without breaking it, we bring out the second end. We continue winding another 20 turns and bring out the third end. We make the wire leads with a margin of 10 to 20 cm. Remove the resulting winding from the object and wrap it tightly with electrical tape, leaving three wire leads (Fig. 5).
We perform the second coil in a similar way. For the greatest success, we make the coils as identically as possible, with a mirror image.
Let's start assembling the radio components. We arrange the parts on the board and carry out soldering according to the diagram in Figure 4. When using cardboard or material with holes, we connect the parts with insulated wires of any cross-section. When using prepared PCB, we perform soldering to the finished tracks. The circuit can be placed in a wooden or plastic box.
Solder the coil leads according to the diagram. We solder and bring out two wires with a connector for the battery.
We prepare a stand for the circuit and coils. We select the dimensions taking into account that the distance between the coils must be at least 10 cm, since the circuit and the attached rod must fit between them.
To properly secure the coils, temporarily attach the headphones to the circuit and insert the battery. By slightly moving the coils, we achieve silence in the headphones with single clicks or the highest possible, barely audible sound. We try to bring metal to one of the coils, if we hear significant changes, this indicates the functionality of the metal detector. We fix the coils and the board in this position. If possible, it is better to glue them immediately and then cover them with oil varnish.
For headphones, we make two holes in the rod - bottom and top. Using wire cutters, electrical tape and a soldering iron, we extend the headphone wire to the required length - from the circuit to the human ear area. You need to take growth into account right away. We stretch the wire inside the rod and solder it to the circuit.
We cut off the excess stand and attach the bar to it in a way convenient for you.
Adjustment
The most accurate setting is the absence of clicks in the headphones, and the presence of a barely audible high-frequency squeak.
Adjustment is carried out in three ways:
- We bring the metal one by one to the coils. On the coil where the noise has stopped, we bring the last turn inside the coil ring.
- You can use small pieces of aluminum. We bring them to the coils and achieve silence or single clicks. Secure with glue.
- We attach a tube to the coil and insert a ferrite rod through it. Having achieved the desired result, we fix the rod in this position. Watch the video below, which demonstrates how to make a homemade regulator for tuning using this method.
With good hearing and experience, you can use the manufactured metal detector as a simple metal detector with discrimination, that is, with recognition of types of metal.
Modernization
If you have figured out how to make the simplest metal detector with your own hands, you can proceed with a small modernization without microcircuits in Figure 9. The list of parts is collected in Table 2.
IN new scheme an RC circuit has been added, consisting of a resistor and a capacitor. It will allow you to achieve increased sensitivity.
Variable resistors have been added to adjust the circuit without touching the coils. This will seal the sensitive unit of the metal detector in a durable box that protects it from shock.
Instead of headphones, you can use a speaker with a capacitor to increase the volume slightly.
In this scheme, the coils are placed one on top of the other, as shown in Figure 10. Before fixing the coils, we adjust them by moving them.
When turned on, we set the variable resistors to the same position and by rotating we achieve precise adjustment. After that, all that remains is to take a metal detector and go in search of nuggets or metals. Tested in practice - if you search on any Russian beach, you can find gold and silver.
