The Terminator metal detector has occupied an honorable place in the ranks of home-made metal detectors for many years. Over the years, many improvements have been made, resulting in various modifications to this device. Let's consider a two-tone metal detector Terminator 3 (Fig. 1), operating on the principle of induction balance. In fact, it is an advanced metal detector Terminator 4. Its main features are: low power consumption, metal discrimination, non-ferrous metal mode, gold only mode and very good search depth characteristics, in comparison with semi-professional branded metal detectors. With a relatively small investment of money and time, anyone can assemble a Terminator 3 metal detector with their own hands, if they follow the detailed instructions in this article.
Making a circuit board
The circuit is assembled on a circuit board. Finding a board for a specific circuit on sale is problematic, so we will create it on our own. Below is the exact plan of action for successfully creating a circuit board:
- We print a drawing of the printed circuit board (Fig. 2).
The size of the scheme itself should be 104 × 66 mm, so when printing, we reduce the picture to the required size You can also download the circuit board and the program for its processing and printing from the link.
Cut off the extra edges, leaving 10 mm in stock on each side. We buy, corresponding to the size of the circuit, foil-clad textolite with a margin of 10 mm on all sides. We clean the textolite with sandpaper to a shine, while trying not to completely erase the copper layer;
- We overlay the diagram drawing on the textolite. We fix it with super glue or tape along the edges left in stock. Use a punch or a screw to mark future holes and peel off the circuit from the PCB. We drill holes according to the drawing of the circuit board. For drilling, a drill from 0.5 to 0.7 mm or a needle with a broken loop is suitable. With a hacksaw for metal, we trim the textolite to the desired size, you can also use other tools;
- Carefully, guided by the wiring diagram, we apply with varnish or a permanent track marker. We are waiting for complete drying;
- We carry out the persecution of the board. To do this, we need 3% hydrogen peroxide, citric acid and common salt. Pour 100 ml of hydrogen peroxide into a small dish. Add 30 g of citric acid and 5 g of salt. Stir until dissolved, then put textolite in the vessel. We are waiting for all the copper coating on the board to dissolve. To speed up the process, it is recommended to heat the solution and maintain its circulation by stirring or with air;
- After etching the board, remove the marker or varnish with acetone. We wash the board with water or alcohol to remove the remnants of the solution. We tin the resulting tracks with a small amount of solder, being careful not to solder the holes for the parts. The board is ready for mounting parts.
The manufacturing process can be viewed in the video attached below.
Assembling the circuit and selection of parts
The diagram of the metal detector is shown in Figure 3. Guided by it and the drawing of the circuit board, we assemble the board.
Parts marked with an asterisk on the diagram can be selected empirically to improve the performance of the device. But first, it is recommended to collect everything strictly according to the scheme, and experiment when you get to setting up the device.
A list of parts and comments to them are indicated in the table in Figure 4, and Figure 5 shows the pinout of microcircuits and transistors.
We start soldering by connecting the jumpers from the side of the radio components. For this we use a varnished or insulated wire of the smallest section. Jumpers are marked on the wiring diagram with simple thin lines.
From the side of the tracks, we solder smd parts - radioelements of miniature sizes and increased thermal resistance. They are highlighted in yellow. Then we solder the connectors for the microcircuits and the remaining parts. For elements of adjustment, switching on and off, changing the mode, batteries, sound and light indication - we bring out the wires to fix these parts on the case. Find suitable caps for adjusting resistors. We also bring out the connector for the sensor wire. A sample assembled board with connector, regulators and switches is shown in Figure 6.
Capacitor C2.3 and switch SA3 are assembled by surface mounting.
To check the performance of the assembled circuit, we connect a 9 V battery. When the device is turned on, the LED should light up and go out, as well as when it is turned off. When you touch the sensor connector, the sound of the metal detector should stop for a short period of time. At the maximum position of the sensitivity control, there should be a tonal sound, and at the minimum position, no. Do not forget to check all the control voltages on the circuit. To do this, turn on the constant voltage mode on the tester within 20 V. We apply the minus probe to the minus of the board, and measure the voltages at the points according to the circuit with the positive one.
The case is made from any plastic box of the required size and is fixed on the metal detector rod. You can use a housing from other metal detectors such as the M terminator or the Trio terminator. We sign buttons and controls in accordance with the functions performed.
With the successful creation of such a scheme, you will gain valuable experience that will be needed to assemble the most complex metal detector with your own hands.
Metal detector sensor (coil) accessories
An essential part of any metal detector is the sensor. It consists of coils in a housing, which search by transmitting and receiving a signal.
To assemble a metal detector sensor, you will need the following set of accessories:
- Housing;
- Wire for connecting to the circuit. A shielded wire from an old audio equipment with 4 pins and 1 common shielded wire is suitable (Fig. 7);
- Varnished winding wire with a diameter of about 0.4 mm. You can find it on old picture tubes of TVs or computer monitors;
- Epoxy adhesive;
- Super glue;
- Insulating tape;
- Foil;
- Threads;
First of all, you need a housing for the sensor coils. For a high-quality metal detector, it is recommended to buy a ready-made ring-type housing. You can also make it yourself, but it will take a lot of time and a high degree of skill and ingenuity. In the purchased case, there will already be recesses for coils of the required diameter, an outlet for a wire and fasteners for a rod. The probe rod can be made from any sturdy stick, PVC pipe, or other dielectric material.
We wind the outer winding, hereinafter called TX. We select the diameter according to the body, about 20 cm. We wind the winding clockwise on a round object of the same diameter, for example, on cut foam. The winding is done with two folded wires in the amount of 30 turns. You should get 4 outputs, of which we connect 2 outputs of different wires from different sides. We fasten the sections of the winding tightly with threads and varnish. After drying, we insulate the winding with electrical tape and wrap it with foil on top. At the end of the winding, we do not connect the foil, leave a gap of 1-2 cm. Solder the wire to the foil and bring out the wire, and again wrap the TX coil with electrical tape.
The inner winding, called RX, is made in the same way, but with a diameter of 2 times smaller. The number of turns is 48. Just like in the TX coil, we connect two wires together.
The middle winding is called the compensation winding or CX. We wind 20 turns counterclockwise with a single wire, taking into account that it should fit into the groove with TX. We do not insulate or varnish this winding.
You should get three coils corresponding to Figure 8. The coils will be fastened after adjusting the sensor.
Adjustment and assembly of the metal detector
Below are detailed instructions for assembly and final adjustment of the coils. For this we need an oscilloscope. You can use a computer as an oscilloscope. There should be no metal objects near the metal detector. To configure, we will perform 2 steps.
The first step in tuning is to equalize the frequency of the coils:
We connect the TX winding according to the scheme. The wire from the shielded foil is connected to the common shielded contact of the connecting wire, and then to the minus of the board. We turn on the device. We attach the negative probe of the oscilloscope to the minus of the board, and the positive probe to one of the terminals of the coil. We measure and record the frequency.
In the same way, we connect the RX coil instead of TX and measure the frequency.
The RX coil frequency must be 100 Hz less than the TX frequency. The adjustment is carried out by connecting the 500 pF capacitors in parallel to the C1 capacitor. For example, the frequency of the TX and RX coils is 16500 and 15900 Hz, respectively. Therefore, we need to lower the generator frequency for the TX coil by 500 Hz. To do this, without disconnecting the RX coil, we connect additional capacitors until we reach the RX frequency of 15400 Hz. For convenience, in the circuit we align all the capacitors of the capacitors and replace them with a capacitor with the capacity of this amount.
The second step is balancing the coils:
We settle all the windings into the case and make the connection according to Figure 8. The connection of CX and RX is made with a margin for future adjustment. We connect the minus of the oscilloscope to the minus of the board, and the plus to the output of the capacitor C5 and the RX coil. We expose on the oscilloscope the time / division of 10 ms, and the volt / division of 1 V.
Tuning consists in reaching the minimum amplitude. You will have to constantly unsolder and solder the output of the CX coil in order to reduce the number of turns. As soon as we have reached the minimum amplitude, switch the volt / division regulator to the next lower value.
We repeat this until we reach the smallest amplitude value at the smallest volt / division.
After that, you can fill half of the circuit with epoxy glue, leaving the adjustment loop CX and RX free. After drying, we again check the amplitude with an oscilloscope and adjust it by moving the loop. Having chosen the optimal position of the loop, we try to fix it with super glue without moving it. And after one more check, completely fill the coil with epoxy glue (Fig. 9).
The assembled sensor can also be used on metal detectors: Terminator Pro, Terminator Trio and Terminator M, with proper and high-quality setup of the circuit.
Discrimination setup and preparation for work
To configure, turn on the SA2 switch to the non-ferrous metal only mode. The ferrite cut-off point should be in the region of 40-50 kOhm, so we set the R8 ground balance regulator to this range. If the cut-off point is in the range of 0 - 40 kOhm, we add capacitance to C2 in parallel, and if 50 - 100 kOhm, add capacitance to C1. Discrimination knob R7 should be equal to zero, so we unscrew it to its extreme position clockwise. We bring non-ferrous metal and ferrite to the metal detector. If two signals sound to ferrite, and one to non-ferrous metal, the windings are connected correctly, if vice versa, we swap the terminals of the TX coil.
With a decrease in the capacitance C1, a shift occurs to the foil, and with a decrease in the capacitance C2, to aluminum. We achieve the visibility of all metals from the table, the visibility of copper and ferrite clipping with a soil balance of 40-50 kOhm. We make additional adjustments with the capacitor C12.
After setting up the metal detector, terminator 3, enter the search area and turn on the metal detector with the SA1 switch. We bring the sensor closer and away from the ground. When giving signals, gradually unscrew the ground adjuster R8 counterclockwise, ensuring that there are no signals to the ground, and make sure that the copper is visible. It is advisable to mark the successful position of the regulator. By rotating the discrimination knob R7 counterclockwise, we cut out the metals we do not need. Cutting occurs alternately from the foil and further, according to the table in Figure 10. With the R29 sensitivity knob, you can increase the visibility range of metals and adjust false alarms. It is recommended to set the SA2 switch to the all metals mode, as it slightly increases the detection range. With the SA3 switch, you can turn on the mode - only gold, which works when the mode is turned on - all metals.
Since the price of non-ferrous metals and old coins can be very high, when searching in the right area, you can quickly recoup a homemade metal detector.
A metal detector, or metal detector (MD), is a device that finds metal-containing objects in a dielectric or low-conductive array. In civil society, many people acquire metal detectors. The Terminator 3 metal detector helps to detect various metal bodies in the ground, an array of enclosing structures of buildings and structures, in the depths of the ground and at the bottom of water bodies. A branded device is quite expensive. It is much more profitable to do it yourself MD Terminator 3.
Specifications MD Terminator-3
The MD Terminator-3 is a powerful metal detector capable of detecting metal objects at a great distance in the ground and under water. Also, the device can recognize metal in a monolith of various materials (concrete, brickwork, wood, etc.).
Technical characteristics determine the capabilities of the Terminator metal detector in the search for various metals, depending on their volume and depth. The main parameters of the device include such characteristics as:
- detection depth;
- discrimination;
- ground balance.
Detection depth
This parameter is the most important for the device. The high sensitivity of the metal detector determines the efficiency of its use. A device with a ø 240 mm spool is able to recognize the following objects at a maximum distance:
- modern coin in denomination of 5 rubles. - 240 mm;
- Catherine's five kopeck coin - 300 mm;
- army helmet - 800 mm.
Discrimination
This option allows you to distinguish between types of metal. In discrimination mode, the device can be tuned to certain groups of metals, cutting off the detection of other chemical elements. At the same time, the Terminator metal detector has an "All metals" mode setting.
Ground balance
Metal objects falling into the electromagnetic field emitted by the MD distort it. The control unit analyzes the changes and provides information in verbal form. In addition, the soil layer also introduces its own portion of distortion. The degree of imbalance depends on the mineralization of the soil. To cut off false pulses, the Ground Balance option is built into the metal detector. In MD Terminator 3 (MDT 3), ground balance is performed automatically.
Making MDT 3 with your own hands
Creating a metal detector with your own hands begins with its circuit. The schematic arrangement of radio components is most often copied on the Internet.
The plan for connecting parts into a single electrical system for the Terminator is shown in the figure below.
Making a circuit board
To assemble the control box of the metal detector, you will need to make a circuit board. By following the guide, you can quickly and accurately make an assembly site with your own hands.
Instructions for making the board:
- On the Internet, they select a picture of a printed circuit board
- A full-size drawing is printed on the printer.
- The paper is glued onto a piece of PCB.
- Around the perimeter of the picture, the textolite is cut with a hacksaw.
- An awl is used to mark the attachment points for radio components.
- The punctures are drilled with a mini drill.
- Carefully cut out all live areas with a scalpel or a suitable cutter.
- The paper is removed from the conductive branches and board areas.
- Bare areas are covered with paint.
- Remove the remaining pieces of paper. To do this, it is enough to wet it and wipe it off with a rag.
- The metallized surface is etched with a special solution for printed circuit boards.
- The board is finally cleaned with a napkin soaked in solvent.
Important! Following the instructions, you must be very careful. When cutting out the tracks, the parts of the metallized coating must not be separated from the board. Otherwise, the circuit will malfunction or fail altogether.
This completes the manufacture of the circuit board. Proceed to the installation of the control unit circuit MDT 3.
Assembling the circuit and selection of parts
Before proceeding with the assembly of the metal detector circuit, you need to select all the components of the circuit board. To do this, take a detailed list of parts of the MDT control unit 3 from the network.
The assembly begins with soldering the jumpers. SMD resistors, panels for microcircuits are soldered. Then the control wires and the rest of the radio components are soldered. For a variable resistor, it is better to use a multi-turn resistor.
At the end of the work, you need to make sure the quality of the soldering and the correct installation of the radio components. The MC 10 microcircuit is needed to indicate the battery charge level. It is quite expensive. At the discretion of the home technician, you can refuse to install the MC 10.
The finished circuit is inserted into the control unit housing. Plastic handles are put on the axis of the resistors and the switch. The block leads are connected to the coil (sensor) of the metal detector.
Component parts of the MDT 3 sensor
The metal detector sensor is a circle, along the perimeter of which there are two circuits of winding enameled wire ø 0.4 mm. The loops are the transmit TX and receive RX coils. As a bed for wires, an available dielectric material is used.
During balancing of the device, the coils are rotated in a circle relative to each other. At the end of the tuning, the turns of the radial conductors are tightly wrapped with threads. Then the coating is impregnated with varnish.
Assembling Terminator 3
All components of the metal detector are placed on a rod no longer than 1.2 m. The length of the lever should not be comfortable. Particular attention must be paid to securely mounting the sensor disc.
The control unit with the battery is installed so that a person can simultaneously change the operating modes of the device and not interrupt the search process.
A horizontal handle is cut into the bar just above the block for easy grip with a hand. An elbow support can be cut out of a plastic pipe and fixed to a bar.
Note! An orthopedic crutch with an armrest is used as a guide bar. A sensor circle is attached at the bottom, a control unit with a battery is installed in the middle of the rod. Everything you need for a comfortable position of the operator's hand is already on the crutch.
Adjustment and preparation for work
In field tests, the sensor is brought closer and further away from the ground. When signals appear, turn the ground control knob to achieve silence. The discrimination knob cuts out unnecessary types of metals. The sensitivity of the device is adjusted to the required depth of recognition of the claim metal.
Discrimination setting
To adjust the discrimination of the metal detector, turn on the non-ferrous metal search mode. To cut off the ferrite point with a balance resistor, set a threshold in the region of 40-50 kOhm.
Discrimination knob is moved to zero position. Then the handle is turned clockwise until it stops. Ferrite and a piece of non-ferrous metal are alternately brought to the sensor. In the first case, two signals should sound, a single sound will be heard from the non-ferrous metal. If this is the case, then the sensor coils are connected correctly.
Then the visibility of all metals is adjusted. To do this, use the table below.
Metal Discrimination Table
| № | |
|---|---|
| 1 | Discrimination Inclusion Procedure |
| 2 | Gold products |
| 3 | Russian ruble coins |
| 4 | White coins of the USSR |
| 5 | Soviet coppers |
| 6 | Lead |
| 7 | Cartridge cases |
| 8 | Silver products |
| 9 | Dural plugs |
| 10 | Aluminum |
| 11 | Copper is not cut |
Checking the instrument board
The instrument board is tested using an oscilloscope. If it is not possible to check the metal detector circuit at home, then it is better to contact the nearest radio workshop. Within an hour, the wizard will test the device board and give recommendations on how to eliminate the identified deficiencies.
Battery discharge indication
Often there are cases when the operator, carried away by the search for "treasures", does not notice the discharge of the battery. To prevent this from happening, an MC 10 microcircuit is soldered into the device board. Its leads are connected to the power supply of the metal detector. The signal wires are soldered to the LED, which is embedded in the control unit panel of the MDT 3.
When the battery charge is lost, the LED starts blinking, then when the capacity drops by 80%, the lamp starts to light constantly. In this case, the battery is recharged.
Additional Information. Factory-made MDT 3 costs from 7 to 15 thousand rubles. In a home workshop, the manufacture of a metal detector of this model will cost a maximum of 3 thousand rubles.
Benefits
MD Terminator 3 compares favorably with its counterparts in its simplicity of design. A homemade device significantly saves financial costs.
disadvantages
There is no possibility to use AA batteries. There is no horn control. Lack of visual indication.
The first finds with the help of MDT 3 will bring a lot of positive emotions to the owner of the device. In the future, a metal detector can become a means of additional income.
Video
Easy to assemble and configure, along with enviable sensitivity. The device showed itself from the best side, discrimination at a high level - linearly removes the entire VDI scale, low current consumption of the device, cheapness and availability of parts, as well as the ability to work on heavy soils (it is very easy to rebuild from the ground), all this made (t3) excellent a surf tool for intermediate search engines. Make yourself such a device and you will see for yourself. The device board is checked and works with a bang.
Operating modes:
- dynamic search for all metals
- discrimination without threshold background
Specifications:
-The principle of operation is inductively balanced
-Working frequency, kHz 8-10kHz
-Mode of work is dynamic
-Accurate detection mode (Pin-Point) no
-Power supply, B 9-12
-Sensitivity level regulator is
-Threshold tone control is -Ground balance is (manual)
Detection depth by air with DD-250mm sensor
-coins 25mm
- about 35cm
-gold ring
- 30cm
- helmet 100-120cm
-maximum depth 150cm
-Current consumption: -Without sound about 35 ma
Metal detector circuit
The circuit almost does not require adjustment, but this is "almost" true if you assembled the board without using flux, but only rosin in alcohol. Also, the soldering should be neat - there should be no clamps or sticky, after assembly the board must be washed with alcohol.
Part side board
We start the assembly by soldering 16 jumpers, then gently solder SMD resistors, then sockets for microcircuits and everything else. It is better to take a multi-turn variable threshold regulator (more comfortable setting), but you can do with the usual one, in this case you need to twist it more accurately, twisted the device not stable, not screwed up and the chuyka fell a lot, otherwise you get used to it and the setting becomes not at all difficult.
Below is a photo of the board with resistors and the pinout of the components.
The board is ready to be inserted into the case. The MC10 microcircuit and its strapping can be omitted, it is a low battery indicator, it is expensive.
Making a coil
The DD sensor is manufactured according to the same principle as for all balancers, so I will focus only on the required parameters.
TX is the transmitting coil and RX is the receiving coil. number of turns: 30 turns with a wire folded in half wire diameter: 0.4 enameled winding And the transmitting and receiving coils are wound with a double wire (that is, there should be 4 ends of the wire), we determine the arms of the windings with the tester and connect the beginning of one arm with the end of the other, it turns out the middle lead of the coil.
The middle output of TX is connected to the minus of the board (without this, the generator will not start), the middle output of RX is only needed for frequency tuning, after tuning in frequency (resonance) it is isolated and the receiving coil turns into a regular one (without output). The receiving room for tuning is connected instead of the transmitting one and is adjusted to 100Hz-150Hz below the transmitting one. Balancing is carried out by shifting the coils (like on wedding rings) relative to each other. The balance should be within 20-30mv but not higher than 100mv. After winding, the spools are tightly wound with threads, soaked in varnish.
After drying, they are tightly wrapped with electrical tape around the entire circumference. From above it is shielded with foil, between the end and the beginning of the foil there should be a gap of 1 cm uncovered by it, in order to avoid a short-circuited loop. Each of the coils is tuned in frequency separately, there should be no metal objects nearby !!! The coil can be screened with graphite, for this we mix graphite with nitro varnish 1: 1 and cover it with a uniform layer on top of a tinned copper 0.4 wire wound on a coil (without gaps), connect the wire to the body.
Another small recommendation, now regarding the manufacture of the device board. It is highly desirable to have a tester that can measure the capacitance of capacitors. The fact is that the device has two identical amplification channels, therefore, the amplification along them should go as much as possible the same, 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 indications in a specific cascade on one channel - the same indications on the same cascade and in another channel), and it is also desirable to select the C1 and C2 contour conduits with the same indications on the tester, this will greatly facilitate your device setup.
On my seal, instead of C1.1 and C1.2 (contour conductors TX), only one conductor (C1) is placed, the frequency at which the entire device will operate will depend on its capacity, therefore it is not necessary to be tied exactly to the denomination of the conductor that is indicated on scheme. For example, I put C1 on TX with a capacity of 100nf, and C2 on RX put 100nf + 3.3nf, and at the same time I get the operating frequency of the device 10.5KHz. But you can put other ratings (that is, increase or decrease the frequency of the device, within reasonable limits, of course). The device can operate from 7KHz to 20KHz. The lower the frequency, the deeper it will take the target, but at the same time it will be worse discriminating for some targets, and vice versa, the higher the frequency, the less depth, but better discriminating against some targets (such as gold, for example). Therefore, I think that it is better to choose, as they say, the "golden mean" - this is approximately 10KHz - 14KHz.
Begin the correct assembly of the board by checking the correct power supply to all nodes. Take the circuit and the tester, turn on the power on the board, and referring to the diagram, walk the tester through all the points of the nodes where power should be supplied. Where there should be 4 volts, it means there should be 4 volts (well, plus / minus a few millivolts), and so on at all points.
The second point: - Also concerns the check of the assembly, unscrew the feeling knob to the maximum and turn on the board power - the speaker should emit a continuous sound, when the feeling knob is unscrewed in the direction of decreasing, the sound should disappear. If so, then the board has been collected correctly. Then we set all the knobs to zero (that is: the B / G knob - the ferrite is not cut out, and the discrimination knob - not a single color is cut, the switch is in the "color only" mode), set C5 to start with 4n7, held the ferrite over the coil if there is a double beep, then everything is fine, if a single beep, then the ends were transferred to TX in places), connected the oscilloscope probe to the C5 output and move the coils to achieve the minimum amplitude. So the device works, on which TX or RX coil to solder additional capacitors when setting up the reaction to metals! If ferrite is visible over the entire range of R8, then on RX, if ferrite is not visible over the entire range of R8, then on TX. The foil from the chocolate is on one the end of the scale, copper at the other end. This is what you should be guided by.
Here, for a reference point, the entire VDI scale, with the position of the discrim knob at a minimum, the device should see all non-ferrous metals, when winding the discrim, all metals should be cut out in order to copper, less should not be cut, if the device works like this, then it is configured correctly
Metal detector Terminator 3
For a long period of time, this unit is one of the best among home-made devices for finding metal. Over the years, this device has been modernized more than once, resulting in new modifications of the metal detector. With this device, you can only find gold or non-ferrous metals - this will already depend on the selected setting. Making a Terminator 3 metal detector with your own hands will not pose any difficulties at all, but for this you need to follow the instructions below.
Terminator 3 schematic
Terminator 3 parts list
How to make a Terminator 3 circuit board with your own hands
The assembly of the circuit of the future device is made on a printed circuit board, you can make it yourself at home, for this you need:
1. Print the image of the board on glossy paper, it is necessary to "fit" the picture to the required size during printing. After printing, you need to get rid of the extra edges, but so that 10 millimeters remain in stock on each side. Next, you need to purchase a foil-clad textolite, which will correspond to the size of the board. It should also have a margin of 10 millimeters on all sides. The textolite must be cleaned with "sandpaper" to shine.
2. Apply the image of the circuit to the textolite, fix it with any durable material (good scotch tape or superglue) along the edges that were left. Next, you should mark with a screw or core the places where any holes are located, after which you should peel off the printout from the PCB. These holes must be drilled in full respect of the illustration on the circuit board. For drilling, you should use a drill that has an appropriate diameter of 0.5 - 0.7 millimeters for resistors and 0.9 for power transistors, wires. Next, you need to reduce the textolite to the required size. For these purposes, you can use a metal hacksaw or other tool.
3. Very carefully, referring to the installation diagram, apply with varnish or permanent track marker and wait until they are completely dry.
4. At this stage, the board is baited. For this purpose, it is necessary to mix 10 milliliters of 3% peroxide solution, 30 grams of citric acid and 5 grams of kitchen salt in a container, and stir everything until the ingredients are completely dissolved. Next, textolite should be placed in a tank with the resulting liquid. Then you have to wait until complete dissolution of the copper coating on the board occurs. In order for the above process to accelerate, this solution should be slightly warmed up, stirring constantly.
5.After etching is complete, it is necessary to remove the applied strips with acetone. Next, you need to wash the board from the remnants of the solution with water. You can use alcohol for this purpose. The tracks need to be tinned with solder carefully so that the holes for the parts are not sealed.
The board made in this way is ready for the installation of parts.
Assembling the circuit and preparing the necessary parts
Based on the circuit of the Terminator 3 metal detector and the drawing of the circuit board, it is possible to start collecting the board.
The assembly diagram can be found on the World Wide Web, as well as a list of required parts. On the diagram, some elements can be designated with "asterisks" and you can select them through experiments so that the resulting device turns out to be improved. But for the first assembly, you must adhere strictly to this scheme. Experiments can be continued at the stage of setting up the metal detector.
It is necessary to start soldering the parts by first connecting the jumpers that are located near the radio parts. For this purpose, it is necessary to use a varnished or insulated wire with a small cross section.
The smallest elements must be soldered near the tracks, after which it is necessary to solder the sockets intended for microcircuits and other elements that are available. The wires required to secure the regulation and control panels to the metal detector, mode changes, power supplies, light / sound indicator should be brought out. It is also necessary to find the caps for the adjustment resistors. In the last step, you need to remove the connector that will be needed for the sensor wires.
To check if everything is working, you will need to connect a 9V battery. If the connection was correct, the LED will light up and go out. The same should happen when the device is turned off. If you touch the connector where the sensor is supposed to be installed, the sound will disappear for a while.
It is also necessary to make a thorough check of all available control voltages that are in the circuit. For this purpose, it is necessary to turn on a mode that assumes a constant voltage, which should be 20V. With a probe with a plus, it is necessary to measure the existing voltage that is available at the points of this circuit, and the negative probe must be applied to the minus.
For the manufacture of the case, a plastic box of the required size is used. It must be attached to the rod of the instrument. Buttons and controls will need to be signed in accordance with the functionality that is assigned to them.
Making a coil for Terminator 3
Search sensors are an important component of all metal detectors. In this case, it consists of two coils located in the housing. It is due to their use that metal objects will be located.
To assemble a search coil for a Terminator 3 metal detector, you need the following parts:
·epoxy adhesive;
· Adhesive tape;
·foil;
· Varnish;
· Threads.
· body;
· A special wire to connect the circuit and the sensor;
· PETV winding wire having a cross-sectional size of 0.4 mm;
The first task is to make a coil body for the sensor. It is better to purchase a factory case, or molded from ABS plastic, rather than try to produce it yourself. You can also do it yourself, but it will take a lot of time and work. The advantages of the purchased housing are that the recess for the coils is of the correct size. The bar can be made of any material with dielectric properties.
Next, you need to wind the windings. The size of the diameter should be selected based on the case - 20 centimeters. They need to be wound on a round product that has a similar diameter. Winding should be done clockwise. Thirty turns should be done. There are four conclusions. All winding sections will need to be connected as tightly as possible with threads and varnished. At the end of the filler, you need to wrap the turns using electrical tape, after which the process should be completed by wrapping it with foil. You do not need to close the foil circle, you need to leave 1 cm without it. You will need to attach and lead wires to the foil. After completing all actions, the TX coil should be rewound with electrical tape.
The second coil will need to be created in a similar way, but the diameter should be half the size. It is necessary to make a winding with forty-eight turns. Also, as in the previous time, you should connect two wires with an external winding.
To produce the winding of the middle coil, you need to make twenty turns counterclockwise. It should be borne in mind that it will need to be placed in a groove, next to the coil of the outer winding. CX does not need to be varnished and insulated.
At the end of the work, you will have three coils available.
Setting up a metal detector Terminator 3
In order to assemble a metal detector, you must use a device called an oscilloscope. An important role is played by the complete absence of metal objects with this device. To configure the Terminator 3 metal detector, you will need to do the following:
1.
equalize the frequency of the coils;
2.
balance the coils.
Initially, a coil with an external winding is connected. Next, you should turn on the device. The minus probe should be applied to the minus located on the board, and the plus probe to one of the terminals located on the coil. Next, you should measure the frequency. Similar manipulations should be carried out with the external coil as well. Its frequency should be 100 Hz less than the same data on TX.
The next step is to put all the windings in one case. Next, you need to connect both coils with a margin. It is necessary to connect the minus of the oscilloscope to the minus located on the board, and the plus to the output of the capacitor C5 and RX. The time on the oscilloscope must be set to 10 ms, and the voltage must be set to 1V.
When setting up the metal detector, terminator 3 must be reached to the minimum amplitude. For this reason, it is necessary to solder the lead of the middle coil in order to reduce the existing number of turns. When the desired results have been achieved, it is necessary to switch the regulator to the lowest value. This should be repeated until the smallest amplitude is reached.
It is now possible to fill part of the existing circuit with epoxy glue, but note that the adjusting loop CX and RX must be left free.
How to get Terminator 3 ready for work
In order to make the setting, set the switch to the mode that allows you to determine the metals. The ground balance regulator will need to be set to the 40-50 kΩ column. Discrimination will need to be set to zero. Next, you will need to bring an object made of non-ferrous metal and ferrite to the Terminator 3 metal detector. If the reaction to ferrite is the appearance of two signals, and there is only one to the metal, then you did everything right.
A metal detector is a very specific and unusual tool that may not be needed by every person. Despite its uniqueness, a metal detector is a dream of many people. Most are trying to purchase such equipment, but you can do it yourself. Detailed instructions for the "Terminator 3" metal detector and a diagram are offered by many specialized forums. Look for this information in this article as well.
Metal detector "Terminator 3"
This model of a metal detector is considered by many to be one of the most popular. The developers of the device are users of one of the forums on the Internet.
It should be noted right away that it will be very difficult to assemble a metal detector with your own hands according to detailed instructions for those who have never been interested in such things and have never used such equipment. It will be really difficult to do such work, but you should not be intimidated by this: it is enough to carefully prepare for the process and collect all the necessary parts and elements.
Detection depth
A metal detector can search for coins and other objects at different depths:
- Five rubles - 22-24 cm.
- Catherine's penny - 27-30 cm.
- The helmet is about 80 cm.
- Beer can - a meter or more.
All given parameters are calculated for sensors with 240 mm wire and chernozem soil. Separately, it is worth mentioning the discrimination of the Terminator 3 metal detector by many users, which is completely unfair: unlike their counterparts, which can only determine the depth of an object, this model determines the metal from which the object is made.
Assembling the metal detector
To assemble and configure the metal detector, you will need the following equipment:
- Oscilloscope.
- Multimeter.
- Generator.
- LC meter.
- Frequency meter.
When buying all of the above set for a metal detector, you will have to pay a tidy sum. In order to save money, many users prefer to limit themselves to a virtual measuring complex based on a personal computer. You can find suitable software designed for such purposes on the Internet.
Metal detector circuit
By its design, the Terminator 3 metal detector is a standard coin changer that has undergone some changes that allowed it to detect gold and ignore other non-ferrous metals. When using a scheme with a special "all metals" mode, the device can search for any scrap metal. The standard scheme allows you to search for coins with a metal detector, nothing more.
The non-standard use of logic as an op-amp is the basis of the metal detector circuit. The disadvantages of this are unnecessary noise and unknown CU of all microcircuits. Of course, it is possible to use domestic logic to create a device, but this threatens with too large a scatter of parameters. It is possible to reduce the damage and avoid additional problems by replacing the sound microcircuit with a domestic analogue.
Metal detector cost
The price of the Terminator metal detector is in the middle range. Compared with similar devices in the same category, "Terminator 3" bypasses them in such parameters as the accuracy of object identification and search depth. Cheaper analogs are significantly inferior to "Terminator 3" in all respects.
Setting up a metal detector
On the diagram of the metal detector, certain nodes are marked, which are taken into account, since during further assembly you will have to focus on them. This may also be needed when setting up your metal detector.
The surge of current oscillations by the generator is carried out after connecting the transmitting coil to it. Such vibrations come out of the MC1 microcircuit in the form of a meander.
The current induced by the TX and creating the field is transmitted through the receiving coil. According to the formed field, the search coil is balanced with TX: in other words, the RX field is subtracted from the TX field. For this purpose, a compensation coil CX is used. Depending on the sensors, its representation changes: in the case of the DD CX sensor, the coil is virtual, in the “RING” CX sensor - real. It is connected in such a way that the direction of current flow in it is opposite to the receiving coil. Equilibration of RX and TX is achieved by unwinding from the compensation reel.
The oscilloscope controls the roll-off of the balance, due to which the minimum amplitude is set in all positions of the knob. One end of the compensation coil is used to make a tuning loop, which is activated after the amplitude reaches a certain point, at which it begins to grow again. TX and RX must be pre-tuned in frequency, while TX must be 100 Hz higher than RX. You can tune all the coils to the desired frequency by connecting them to the generator of the Terminator 3 metal detector and an oscilloscope.
You do not need to adjust the CX frequency. When a metal object appears under the sensor, the balance is disturbed, which provokes the flow of current into the RX, which is then fed to the preamplifier and synchrodetector, which fixes the phases of the incoming signal and outputs them to the amplifying channels. In the latter, all the obtained parameters are amplified and fed to the MC8 comparator, which compares the received signal levels and activates the sound generator.
The principle of operation of almost all metal detectors is similar to each other, with the exception of some nuances. In most cases, they affect the ground balance of the instrument. In the case of the "Terminator M" metal detector, phase detuning.
Checking the instrument board
After soldering all the details of the circuit, the printed circuit boards of the metal detector are checked. This is done in order to check the quality of the circuit splicing and its performance.
The check is done as follows:
- The printed circuit board of the metal detector is thoroughly washed from the traces of flux left after soldering. It is advisable to remove all residues, since in the future they can cause breakdowns and malfunctions.
- The board is powered on without activating the sensor.
- The sensitivity knob is unscrewed until a stable sound signal appears from the speaker.
- To interrupt the speaker signal, just touch the sensor connector with your finger. An interruption in the emitted sound signal when touched indicates that the metal detector board has been correctly soldered.
- After turning on the power, the LED always blinks and goes out. When the power is turned off, the diode lights up and gradually fades.
Battery discharge indication
When the battery is discharged, the metal detector beeps at regular intervals. This is accompanied by a continuous burning of the LED and a sharp decrease in the sensitivity of the sensors.
The frequency settings of the metal detector are made using the cable with which the device will be used in the future. The cable length remains unchanged after making all the necessary frequency adjustments.
Metal detector "Terminator Trio"
"Terminator Trio" is a two-tone metal detector, equipped with a DD coil measuring 250 x 300 mm. Equipped with four adjustment modes - "Sensitivity", "Volume", "Discrimination" and "Ground Balance" - and a switch between common and non-ferrous metals.
Benefits
The advantage of the "Terminator Trio" metal detector is the confident detection of non-ferrous metal objects. The device finds non-ferrous metal in 85% of all detections, the remaining 15% are in iron and rusty objects.
Another plus is the absence of false positives. Many analogs react to the edges of dug holes, grass stalks or small wires, which "Terminator Trio" does not sin.
disadvantages
The only drawback of the metal detector is the poor detection of rusty iron. In almost all situations when the device gives a dirty signal, that is, mixing black with an admixture of colored or, conversely, colored with an admixture of black, there is a rusty metal object.
Of course, this drawback can be simply ignored, but there is a possibility that some of the finds will be lost due to an incorrect signal. Distinguishing between a clean color signal and a dirty signal is possible only when gaining experience with a metal detector.
Search depth
The reviews left by users on "Terminator" indicate that the maximum search depth of a metal detector exceeds that of another model - "Asi 250" with a standard coil. Despite such assurances, in practice it turns out that according to this criterion "Terminator" is equal to "Ace". When searching in the air for 50 Ukrainian kopecks, the detection depth is 32 centimeters, while the search on the ground for the same coin is limited to 26-28 centimeters with reduced sensitivity. Basically, a metal detector allows you to detect objects at a depth of no more than a shovel bayonet, which, however, can be a very good indicator for such a device.
The Terminator Trio metal detector cannot be classified as a device that can start searching immediately after being turned on. The cost of the device is several times less than the cost of the new ACE 250 model, but the Terminator is more suitable for those seekers who want to try their hand at instrument search.
Outcomes
Collecting is not that difficult. This will require certain financial and time costs, but at the same time the user who has assembled a metal detector on their own will receive certain advantages as a bonus.
"Terminator 3" is a rather powerful device in comparison with similar branded metal detectors. Given the fact that you can assemble it with your own hands with the possibility of saving money, it is more affordable, profitable and attractive for users.
Correctly assembling and setting up a metal detector in the absence of the necessary experience is quite difficult. Novice radio amateurs in specialized forums are provided with detailed instructions and manuals that will allow them to carry out all the work correctly and without errors, which is very important when working with electronics.
The advantage of the Terminator 3 metal detector and subsequent models is the possibility of self-assembly of the device and an affordable price. You can find the necessary schemes on the Internet at specialized forums of specialists professionally engaged in the search for metal objects. The creators of the device are always ready to help with advice to those who plan to assemble a metal detector on their own.
