A metal detector is a specific tool. Not every user may need this interesting device, but there are still plenty of people who want to purchase a metal detector or, as some call it, a metal detector. Of course, you can find and purchase a device for yourself, but why, if you can make it yourself with your own hands, according to the metal detector diagram below - Terminator 3.

On the Internet you can find a large number of diagrams and instructions for making a metal detector with your own hands, but below one of the most popular variations of home-made devices of this type will be presented.

This version of the metal detector is considered by many to be one of the most popular. The inventor of such a reliable device are Developers Yatogan and Radio destroyer- both users of the md4u.ru forum. On this forum, by the way, you can find a lot of interesting things for those who want to assemble their own metal detector.

It should be said a few words that the adjustment and assembly of this IB device will be very difficult for users who have not previously dealt with this. We can even say that it is almost impossible. This may scare readers, but in no case should you be scared.

You just need to carefully prepare for the assembly process, which can be done by visiting the well-known md4u.ru forum.

Depth of detection:

• Five Russian rubles - 22–24 cm;
• Pyatak Catherine - 27–30 cm;
• Helmet - approximately 80 cm;
• Beer can - up to a whole meter.

Depth calculated for chernozem with a sensor having 240 mm wire. By the way, we can say a few words about the discrimination of this metal detector. The fact is that while many such devices are able to locate a metal element at a certain depth, but cannot find out what kind of metal it is, Terminator-3 copes with this task. It can detect most metal objects at the ultimate detection depth.

Assembling the metal detector Terminator-3

To assemble and set up this device, you will need to use the following devices:

• multimeter;
• oscilloscope;
• LC meter;
• generator;
• frequency meter.

Of course, if you purchase the entire set of presented devices yourself, you will have to spend money. But you can try to create virtual measuring complex on the basis of an ordinary personal computer. On the Internet, by the way, you can find a fairly large number of programs for this purpose.

Metal detector scheme:

The Terminator-3 metal detector is one of the most popular devices of this type. In fact, it is a typical coin, which, having undergone some modifications, was able to detect gold, while ignoring other non-ferrous metals.

In addition, even though Terminator-3 is a coin, it is also able to search for scrap metal, for which you just have to enter a special “all metals” mode into the circuit, since the circuit is initially taken on which this mode is absent.

The execution of the circuit is carried out with a non-standard application of logic as an op-amp. Of course, there is a certain disadvantage, which is that unknown KU of the microcircuits themselves and the noise level is higher. You can apply domestic logic, but you have to put up with a larger spread of parameters. It is possible, however, to replace it with a domestic sound generator chip, without damage and without additional problems.

By the way, in terms of such indicators as the depth and accuracy of target identification, Terminator-3 is comparable to models of branded brands that are in the average price range. When compared with cheaper branded counterparts, the Terminator-3 overtakes them in all respects. But for it to be so, you should assemble the metal detector as it should, and not as it turns out.

Description of the setup of the metal detector Terminator-3

To begin with, you should pay attention to the nodes indicated in the diagram, since it is by them that you will have to navigate later. This will come in handy during the setup process. When connected to the oscillator transmitting coil (TX) it starts to generate current fluctuations. These oscillations come out in the form of a meander from the MC1 chip.

After that, you should move on to the receiving coil (RX), which also has a current induced by TX and creates a field. In this field, the coil should be balanced with TX. In other words, the RX field must be subtracted from the TX field. To do this, you need a compensation coil (CX). According to different sensors, it appears differently: in the “RING” CX sensor it is real, in the form of a coil, and in the DD CX sensor it is virtual. It should be connected so that the current in it runs in the opposite direction with respect to the receiving coil. By gradually unwinding from the compensation coil, balancing of TX and RX in current is achieved.

Balance reduction is controlled by an oscilloscope, which allows you to achieve a minimum amplitude at all positions of the knob in turn. When a certain point is reached, at which the amplitude begins to grow again, it begins act tuning loop, which is made from one of the ends of the compensation coil. Before this, be sure to tune TX and RX in frequency, while RX is made 100 Hz lower than TX. The coils are tuned to the desired frequency by connecting each of them in turn to the oscilloscope and the instrument's generator.

CX frequency adjustment is not required. A situation is formed in which the balance is disturbed if a metal object appears under the sensor, causing current to flow in RX, which from there enters the preamplifier, where it is then amplified and fed into a sync detector (SD), which, in turn, detects the phases of the incoming signal and outputs everything to the amplifying channels. Everything is amplified in them and then it gets to the MC8 comporator, whose task is to compare the signal levels in the channels, after which the comporator gives permission to the sound generator to work.

In principle, almost all balancers work this way, however, with slight differences. The differences, in many respects, relate to the nuances with detuning the metal detector from the ground. In Terminator-3, the detuning is phase.

Checking the device board after final soldering:

In order to check the metal detector board after soldering all the elements of the circuit, a series of procedures should be carried out to determine whether the circuit was soldered correctly.

To do this, follow these steps:

A few words should be said about the low battery indicator. It looks like this: the metal detector starts to give frequent signals at regular intervals. In this case, the diode should burn constantly, and the sensitivity drops sharply.

All frequency settings of the metal detector should be made with the same cable with which the device will be subsequently used. After the user has made all the necessary frequency settings, in no case should he change the cable length.

Above is a picture that describes the sensitivity of the device. Some data is given about several materials that can be detected by this metal detector.

Conclusion

In principle, assembling such a metal detector does not seem to be a very difficult task. Yes, it may require effort, time and money, but there are a number of advantages that a user who has assembled this metal detector gets as a bonus.

The Terminator 3 is a very strong device when compared to branded metal detector models, and given that it can be made by hand, this makes it even prettier and preferable.

Of course, it will be much more difficult for the user to assemble such a device if he does not have the proper experience. But there are always manuals and instructions for beginner radio amateurs who can find a lot of interesting information there for further work with electronics.

Metal detector Terminator 3

For a long period, this unit has been one of the best among homemade metal search devices. Over the years, this device has been modernized more than once, as a result of which new modifications of the metal detector have appeared. 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 cause any difficulties at all, but for this you need to follow the instructions below.

Circuit Terminator 3

Terminator 3 parts list

How to make a DIY Terminator 3 PCB

The circuit of the future device is assembled 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 image 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 textolite that will match the size of the board. It should also have a margin of 10 millimeters on all sides. Textolite must be cleaned with sandpaper to a shine.

2. Overlay the image of the circuit on the textolite, fix it with any durable material (good adhesive tape or superglue) along the edges that were left. Next, you should mark with a screw or a core those places where any holes are located, after which you should peel off the printout from the textolite. These holes must be drilled in full respect of the image on the circuit board. For drilling, 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 hacksaw or other tool.

3. Very carefully, focusing on the wiring diagram, apply with a varnish or a permanent track marker and wait until they are completely dry.

4.At this stage, the board is baited. To this end, it is necessary to mix 10 milliliters of a 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 the copper coating is completely dissolved on the board. In order for the above process to accelerate, you should slightly heat this solution, stirring constantly.

5.After the etching is completed, it is necessary to remove the applied strips with acetone. Next, wash the board from the remnants of the solution with water. You can use alcohol for this purpose. The tracks must be tinned with solder carefully so that the holes for the parts are not soldered.
The board made in this way is ready for installation of parts.

Assembling the circuit and preparing the necessary parts

Based on the scheme of the Terminator 3 metal detector and the drawing of the circuit board, it is possible to start collecting the board.

A diagram of the unit can be found on the World Wide Web, as well as a list of necessary parts. In the diagram, some elements can be indicated by "asterisks" and they can be selected through experiments so that the resulting device is improved. But for the first assembly, you must strictly adhere 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 components. For this purpose, it is necessary to use a varnished or insulated wire with a small cross section.
Near the tracks, the smallest elements should be soldered, after that it is necessary to solder the panels intended for microcircuits and other elements that are available. The wires necessary to fix the control and regulation panels on the metal detector, mode changes, power sources, light / sound indicator must be removed. It is also necessary to find caps for adjustment resistors. At the last stage, you need to bring out the connector that will be needed for the sensor wires.
To check if everything works, you will need to connect a 9V battery. If the connection was correct, the LED will turn on and off. 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 carefully check all available control voltages that are in the circuit. For this purpose, it is necessary to enable 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 instrument rod. Buttons and controls will need to be signed, according to the functionality that is assigned to them.
Making a coil for Terminator 3
An important component of all metal detectors are search sensors. In this case, it consists of two coils located in the housing. It is due to their use that metal objects will be found.
To assemble a search coil for a Terminator 3 metal detector, the following parts are needed:
·epoxy adhesive;
adhesive tape;
·foil;
lacquer;
threads.

· frame ;

a special wire for connecting the circuit and the sensor;

winding wire PETV, having a section size of 0.4 mm;

The first task is to make a coil housing for the sensor. It is better to purchase a factory case, or molded from ABS plastic, rather than try to make 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 notch for the coils has the right size. The rod can be made from any material with dielectric properties.
Next, you need to wind the windings. The diameter value should be chosen based on the body - 20 centimeters. They need to be wound on a product that has a round shape, which has a similar diameter. Winding must be done clockwise. Thirty turns should be done. Get four conclusions. All winding sections will need to be connected as tightly as possible with threads and varnished. At the end of drying, you need to wrap the turns using electrical tape, after which the process should be completed by wrapping with foil. You do not need to close the foil circle, you need to leave 1 cm without it. Wires will need to be attached to the foil and brought out. After completing all the steps, 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 that. It is necessary to make a winding of forty-eight turns. Also, as in the previous time, two wires should be connected to the external winding.
To wind the middle coil, you need to make twenty turns in a counterclockwise direction. You should take into account the fact that it will need to be placed in the groove, next to the coil of the outer winding. CX does not need to be further varnished and insulated.
At the end of the work, you will have three coils available.

Setting up the metal detector Terminator 3

In order to assemble a metal detector, you need to use a device called an oscilloscope. An important role is played by the complete absence of metal objects with this device. To set up the Terminator 3 metal detector, you will need to perform the following steps:
1. equalize the frequency of the coils;
2. balance coils.
Initially, a coil with an external winding is connected. Next, turn on the device. The minus probe should be attached to the minus located on the board, and the plus probe to one of the terminals located on the coil. The next step is to measure the frequency. Similar manipulations should also be carried out with an external coil. Its frequency should be 100 Hz less than the same data on TX.
The next step is to lay 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 reach its minimum amplitude. For this reason, it is necessary to solder the output 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. Similar actions should be repeated until the smallest amplitude is reached.
Now it is possible to fill part of the existing circuit with epoxy, but note that the adjustment loop CX and RX must be left free.

How to prepare Terminator 3 for work

In order to make the adjustment, you should set the switch to the mode that allows you to determine metals. The ground balance regulator will need to be set to 40-50 kOhm. 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 the ferrite will be the appearance of two signals, and to the metal there will be only one, then you did everything right.

Terminator 3 is an IB metal detector with discrimination and very good performance! The main thing is that it is not difficult to set up and does not contain microcontrollers. The reduced scheme shows the main blocks of the device.

1. Power supply. I advise you to check its performance before installing the chips. When assembling the device without installed microcircuits and without coils, turn on the metal detector for verification. Do not forget about the current, if it is very small and the voltages correspond to 6 and 4 volts, then you can go further! 2. Sound generator. I advise you to put the ms3 chip first and turn on the power - you will hear a tone that will delight you when a metal detector detects a target. The tone can be changed by selecting c13 and resistors p14-15 3. RF generator. The main block that creates a radiated magnetic field that will be received reflected from the target. 4. Receiving amplifier. From the name, the functionality and importance of this node is clear. 5. Synchronizer. The key on the chip 4066. 6. Amplification channels. If you are assembling the device for yourself, pay attention to the selection of parts for the symmetry of the channels. I will not pay attention to the filter and the discharge signaling device - these are not the main blocks.

You will find a clearer image of the MD T3 circuit and printed circuit board drawings for conventional radio components and SMD on the forum. Having assembled the Terminator 3 metal detector, after conducting an initial check of the power supply and sound generator, we install the microcircuits and turn them on, while measuring the current without sound and coils. It can range from 10 to 30 mA, and with sound up to 50 mA. The current should not exceed these indicators if all the ratings of the parts are met.

You can check the metal detector at this stage by setting the p7 (Disk) knobs to 0k, p8 (BG) to 100K and the p39 (Senses) resistor to set the sound at the threshold of a breakdown. Touch PX or c5 with your finger and the sound should fade or disappear for a short time.

Now we wind the coils. I prefer the DD sensor - it's easier to set up and no coils are needed - simple and convenient! First I made this template:

Not a tricky thing, but it allows you to massively repeat the coils and achieve the identity of the half rings. To make such a template, you need a base and material for the frame itself. After, we cut out the template, make a cut of about 1 cm for the convenience of removing the coil and a cut in the base - also about 1 or 2 centimeters. As a wire receiver (let's call it that), I use electric brackets, with which wire No. 6 is pierced along the plinth, I glue them around the perimeter with hot-melt adhesive - there is enough strength! We wind the coils with a 0.4mm wire into two wires of 30-35 turns. After tightening with ties. And remove, tightening with threads, remove the ties. After we tighten it with thin tape, we make a screen from aluminum tape without a gap, but with an overlap. And in order to avoid a short-circuited coil, we wrap it with adhesive tape in the place of overlap so that the foil does not touch each other. We solder the wire to the aluminum tape, it is not necessary to wrap it with a puddle! You can also use a layer of adhesive tape to seal the sensor. Then we wrap it with fiberglass and into a mold for pouring. We make the form in foam. To adjust the discrimination of the T3 metal detector, you first need to prepare targets - copper (but not copper-plated textolite), ferrite, also a piece of cigarette foil, an aluminum cork and, if possible, coins. Now setup. It all starts with setting the sensor to a frequency. We connect the first coil to the generator with capacity c1 and watch the frequency (remember, if necessary, you can lower or increase it with additional capacity). After that, we take the second coil and connect it to a generator with a capacitance c2 and adjust the frequency one hundred hertz below the frequency of the first one and we will have it RH. After we connect the coils to the MD in their places and reducing them to 0, measuring the amplitude at c5. Resistors BG = 100k, DISCREAM = 0, the switch is in color only mode and we begin to adjust the VDI scale. We take a piece of ferrite and pass it over the sensor - if there is no signal, then add a capacitance to the TX, if there is a capacitance to the RX until the ferrite is cut out 30-40 kOhm BG. Make sure that the sensors are connected correctly by passing a ferrite and copper over the sensor, one signal to copper, a double tone to ferrite. Then everything written above will work.

When setting up a metal detector, each of us has encountered, or will do it, the need to tune the metal detector, or rather the coils for it, to the desired frequency. Whoever has a frequency meter, an inductance meter and an oscilloscope, in principle, can cope without the attachment recommended further. If there are no special devices, we make a simple device that turns a PC into a meter. All you need to assemble it is a connector, 4 x 10 kΩ resistors. Jack into your computer's sound card. So, we are looking for a connector, it is desirable that it coincides with what will later be placed on the body of your MD (coils can be directly connected to our device). I took a two-pair audio-video jack from the TV (these are found on VCRs, game consoles (dandy) and audio recorders). I carefully unsoldered it, took a small piece of getinaks, drilled holes in it for jacks, soldered. Next, we proceed to the markup - I separated the contact pads from the total mass (what is inside the tulip) and soldered a 10 kΩ resistor.

At the other end of the board, I cut out 4 separate patches, soldered the remaining resistor leads to them. Here we have a small fee. In the bins I found two unnecessary wires (left from some kind of amplifier), at one end there is a jack - at the other 2 tulips (stereo jack). I cut off the ends of the tulips, soldered the screens to the mass, the central cores on their heels on the board. We sign where which channel is on the board near the connectors (we check the mass with a tester - this is the edge, the first channel is the tip, the second channel is the middle). We connect the finished device to the computer, one jack is on line in, the other is line out. The main task then becomes the use of software. I use the SPECLAB, Oscilloscope, audioTester V1.4e program (the programs are on the site in the section). We connect the coil to the board in the way it should be connected to the MD, to the connector leading from line out and put the program with the generator. For work I use two programs:

1. audioTester V1.4g (generator of any shape, dual-beam oscilloscope, spectrum analyzer).

2. SpectraLab V4.32.13 (frequency meter, spectrum analyzer, phase meter).

These programs work up to 44 kHz, but they are more than enough to work with a metal detector. Now let's move on to the setup. This setting is suitable for any MD, including the Terminator we are assembling, but here it will be described in relation to the Volkstrum-Sm scheme. First, we measure the frequency (SpectraLab): at U4B / 12.13 - it should be 8192 Hz (if it is slightly different, we write down the value for ourselves). 1. We install the resistor R23 vertically and "bite off" the conductor connecting it to U4 / 1. Now we fix the coils so that there is no metal approximately one meter away. We turn on the audioTester program (generator) and connect it to R23, and the multimeter to the JP4 connector. By changing the frequency of the generator (in the program), we find the resonance for max. voltage on the multimeter. By selecting the exact value of the capacitance installed on the coil (adding small capacitances), we achieve resonance at 8192 Hz (or at the recorded value). We insert the receiving coil into the JP4 connector and repeat the setting on it. 2. We restore the R23 gap and connect the coils to their regular places. We connect audioTester (oscilloscope mode) to U1A/1 and move the TX coil to get the minimum readings. We fix the TX coil and repeat step 1. After several passes, we fix the position of the TX coil. Fill it with epoxy and connect the middle output to the TX cable. We measure the values ​​of the selected capacitances on each coil and replace them, if possible, with single capacitances with a small TKE. Capacitances are obtained in the region of 0.06 microfarads. We glue the plastic corners for attaching the rod and cut off the extra pieces on the base.

Assembling the Terminator metal detector requires a minimum of time, and the device impresses the user with its high sensitivity. The device demonstrates performance sufficient to detect various artifacts at a considerable depth. The device is supplemented with a metal discrimination complex, which makes the search more convenient. The device is able to linearly remove the VDI scale, demonstrating a low operating current, which extends the life of a single charge.

Assembling a terminator model metal detector is not difficult. To complete the work with your own hands, you will need the skills and tools that everyone has. A properly assembled detector is able to detect the presence of artifacts in heavy ground. Performance characteristics make the device the best in its class. The terminator is used to detect coins, and the principle of operation of the device is the induction balance technology. The assembly is based on Tesoro products, but has important differences, both on a constructive and operational level. A feature of the device is the detection of metal at the limit values ​​of sensitivity. Therefore, the device is popular among craftsmen who prefer their own assembly.

Specifications of the metal detector

The Terminator 3 device has a number of indicators that determine its capabilities.

Detection depth with 24 cm coil:

• Coins of the Russian Federation - up to 24 cm;
• Coins of the Russian Empire - up to 30 cm;
• Helmets - up to 80 cm.

Other characteristics of the detector:

• Operating frequency indicator - 7-20 kHz;
• Available modes of operation - "Discrimination" and "All metals";
• Ground balance - in manual mode;
• Power - 9-12 volts.

Do-it-yourself detector "Terminator 3"

Structural features make Terminator-3 difficult to assemble. Making for beginners is an extremely difficult task. Therefore, only experienced people with experience in electrical engineering should use the proposed Terminator metal detector circuit.

Create a device helps:

• Oscilloscope;
• LC meter;
• Multimeter;
• Standard set of tools.

If the equipment is not at hand, then computer emulators are a substitute, which are not difficult to find on the Internet.

Circuit board manufacturing

Assembly is done using a mounting plate. It is not easy to find a ready-made board on the market, so you will have to create it yourself. The circuit dimensions are about 104×66 mm. The diagram image should be printed with appropriate dimensions. It remains to trim the edges, leaving a margin of a centimeter on each side. At hand, there should also be a foil textolite of identical sizes with a margin of a centimeter. Cleaning of textolite is carried out with emery until a shine appears. The work requires care so as not to accidentally remove the copper layer.

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We impose the drawing of the circuit on the textolite. We provide reliable fastening with glue or electrical tape. A center punch is suitable for marking functional holes, after which you can peel off the diagram. Next, holes are drilled exactly according to the marks. The hacksaw will allow you to cut the textolite to the specified dimensions. Being careful, tracks are applied to the surface using a permanent marker or varnish. Before continuing work, we wait for complete drying.

Further, the terminator 4 model metal detector requires board baiting. Here you need hydrogen peroxide (3 percent composition), as well as citric acid and table salt. Peroxide (100 ml) and 30 g of acid mixed with 5 g of salt are poured into the container. Stir the solution until completely dissolved. A detailed instruction for creating a metal detector with your own hands involves the subsequent placement of textolite in a container with a solution. Next, wait until the copper coating dissolves. The process is accelerated by heating and stirring.

After the etching is completed, it is required to remove the marker or varnish with acetone. The solution is removed from the surface using water or alcohol. The resulting paths are puddle with solder, but you should avoid getting it into the holes.

We assemble the scheme and select spare parts

Based on the diagram below, we perform the assembly process of the entire circuit board.

The list of parts from which we assemble the terminator 3 metal detector is shown in the following figure.

Scraping of microcircuits

Jumpers are soldered from the side of the radio components. Work is carried out using varnished or insulated wire with a minimum cross section. Jumpers are shown in the picture as thin stripes. Soldering of smd parts (elements of increased thermal resistance) is carried out from the side where the board tracks are applied. They are marked in yellow on the diagram. Next, the connectors and the remaining parts are soldered.

The cable outlet for attaching to the housing is required for the following parts:

• On-off regulators;
• Sound and light indicators;
• Batteries;
• Mode switch.

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Winding metal detector coils

The next step requires a 0.4 mm enameled winding wire. It must be folded twice to get two ends and two beginnings. Winding should be in parallel mode from 2 coils. On the plywood we draw a circle of 200 mm for the transmitting coil (TX) and a 100 mm circle for the receiving coil (RX). We drive nails in cambric around the circumference in increments of 10 mm. Tubes are required in order not to damage the insulation during winding.

The transmitting coil requires 30 turns wound with twin wire. Next, we impregnate the coil with varnish and wait for complete drying. After that, tying with threads should be done. The coil can be removed from the plywood mandrel and the core soldered to form a one-piece 60-turn winding. As a result, we get two extreme and one middle bends. The final step is to wrap the coil with electrical tape, on top of which a layer of aluminum foil is applied. The use of foil allows you to create a protective screen. On top of it we wind electrical tape, which will protect the shielding layer.

Let's move on to work on the receiving coil RX. The process is also performed, but taking into account the mandrel of 100 mm, 48 turns are required. Winding is carried out with a double wire. We connect the middle output of the TX coil to the minus on the circuit board. A similar output of the RX coil is required for tuning, after which it needs to be isolated. The compensating coil is wound with a single wire and is 20 turns. The diameter of the coil is chosen so as to put the product inside the TX coil.

Setting up a metal detector Terminator

The first task is to equalize the frequency. To do this, we connect the TX winding wire to the contact of the connecting wire, and then to the minus of the board. We connect the oscilloscope to the board according to the "minus to minus" principle. We connect the probe with the plus sign to the output of the coil. The obtained values ​​are recorded. We perform a similar procedure for the RX coil. Ideally, the receive coil is 100 Hz below the transmit coil frequency. The adjustment is made using 500 pF capacitors connected in parallel to C1.

We connect the RX-coil and the CX with a margin, which will allow for tuning in the future. After connecting the oscilloscope, set the time to 10 ms and the volt to 1 V. The adjustment is carried out in order to obtain the smallest amplitude. You should be prepared to often solder the output of the CX coil to reduce the number of turns. After reaching the specified parameter, we move on to the next value and repeat the procedure until the minimum frequency is obtained at the smallest volt / division.

The Terminator 3 is a metal coin detector that operates on the induction balance (IB) principle. The Terminators scheme was developed on the basis of MI Tesoro. However, there are significant differences from these metal detectors, both in the operation itself and in the process of its manufacture and adjustment.

The main advantage of the MI Terminator 3 is the ability to recognize metal at the limit of sensitivity (even with minimal target acquisition, it detects it quite accurately).

Technical characteristics of the metal detector Terminator 3

Principle of operation	IB (Balance Induction)
Search modes	"Discrimination" and "All Metals" are toggled.
Operating frequency	7-20 kHz (Depends on the coil and capacitors C1 and C2).
Nutrition	9–12 V.
Ground balance	manual

Depth of detection of objects in the ground with a coil of 240 mm:

• Coin 5 Russian rubles - 22–24 cm.
• Coin 5 kopecks of Catherine - up to 30 cm.
• Helmet - up to 80 cm.

Below is a visual representation of the VDI scale division of the Terminator-3 metal detector.

Metal detector Terminator 3 - VDI scale

Thanks to this, the Terminator is able to effectively distinguish gold items from other metals.

Metal detector Terminator 3 - scheme and necessary components

Scheme of the metal detector Terminator-3

Terminator 3 is quite difficult to make on your own. It will be extremely difficult for a beginner to do this. We recommend assembling this scheme to people who have experience in the manufacture of metal detectors!

Do-it-yourself Terminator-3 metal detector - detailed manufacturing instructions

Let's start with the printed circuit board. We solder jumpers into it, then SMD resistors, then panels for microcircuits and other details.

Metal detector board Terminator 3

Capacitors in the board must be metal-film with high thermal stability. In addition, it is recommended using a tester to select the most identical parts in terms of parameters on two parallel amplification stages and the values ​​​​of capacitors C1 and C2 so that everything is as identical as possible. This will make the setup much easier for you. As a tuning resistor, it is better to use a multi-turn.

Assembled metal detector board Terminator 3

After soldering the metal detector, the board must be washed with alcohol, dried and visually checked for defects and stickiness.

Then, without a coil, you can already check its performance. For this:

1. Turn on the power of the metal detector.
2. We unscrew the sensitivity knob until a constant sound appears in the speaker.
3. We touch the sensor connector with our fingers, the sound should be interrupted for a second.
4. When turned on, the LED should blink and turn off.

If so, then the board is soldered correctly. Now you can start making the coil.

To do this, we need a winding enamel wire with a cross section of 0.4 mm. We fold it in half in advance so that we have 2 ends and 2 beginnings. It can also be wound in parallel with 2 coils.

Step-by-step detailed instructions for creating a coil for the Terminator-3 metal detector:

1. On a sheet of plywood we draw a circle with a diameter of 200 mm for the TX coil (transmitting) and 100 mm for the RX coil (receiving).
2. Then, in increments of 1 cm, we drive in cloves around the entire circumference (preferably in cambric, so as not to damage the wire insulation when winding).
3. On a mandrel of 200 mm we wind 30 turns, folded in half with a wire. Then we impregnate the coil with varnish, and after drying, wrap it with a thread.
4. We remove it from the mandrel and solder the middle, obtaining a solid winding of 60 turns. We got 2 extreme and one middle branch.
5. Then we wrap the coil tightly with electrical tape, and on top of it we wind aluminum foil for the screen with a gap of 1 cm.
6. Again we wind the electrical tape on top to protect the foil. We first bring the ends of the windings out.
7. Then we wind the receiving coil on a 100mm mandrel - 48 turns also with a double wire. After that, we sleep. We connect the middle output of the transmitting coil to the minus on the board to start the generator, and the middle output of the receiving coil is needed only for tuning, then it is isolated and not used.
8. We wind the compensating coil with a single wire - 20 turns. We select its diameter so that it fits snugly inside the shielded transmitting coil.

We take the cable for the coil 4-core in a common screen.

Now we connect the TX (transmitting coil) to the board (the middle terminal and the coil screen to the minus of the board). We connect the oscilloscope, the negative probe to the minus board, and the positive probe to one of the ends of our coil.

Note! When adjusting the coil, there must be no metal objects around it!

So we connect everything and look at the oscilloscope, what frequency is obtained. Then we write down the value and put the coil aside.

We do the same with the RX receiving coil, measure its frequency, ideally it should be 100 Hz lower than the TX frequency. If this is not the case, then it is necessary to adjust the frequency by selecting a loop capacitor. As a result, you should get, for example, 9.1 kHz TX and 9.0 kHz RX.

Now we isolate the middle terminal of RX and proceed to the reduction of the coil. We connect them according to the diagram below.

Connecting coils to a metal detector Terminator 3

We lay the coils in a pre-prepared form for pouring epoxy. We take an oscilloscope, a negative probe to the minus of the board, a positive probe to the C5 output, set the division time to 10 ms on the oscilloscope and division 1V per cell.

We look at our picture on the oscilloscope: there is no balance yet, so the vertical amplitude will be large. Then we wind one turn from the CX (compensation coil) from the soldering side to the RX, bite off this turn and solder it again. We observe a decrease in amplitude.

We do this procedure until the amplitude becomes zero. Then we decrease the volts / division and continue to wind the turns until we get to 0 at the lowest resolution of the oscilloscope. It is clear that it will not be ideal, but you need to find the number of turns, after winding which it will begin to grow again. This position is our intermediate balance.

Now we fix the coil, make a 10-15 cm loop from the CX output and bring it outside of our fill - this will be our compensating loop, which will help us to completely bring the coil together.

Making a coil for Terminator 3 with your own hands

We spill the sensor with epoxy, but only half the depth of the mold. After solidification, we connect the oscilloscope, bend our loop inside the form and start twisting it, trying to find the minimum amplitude value. After the position is found, we fix the loop with glue, re-check the balance and fill our form to the end.

• See also diagrams and instructions on how to make

This is how the finished homemade coil for the Terminator-3 metal detector looks like 4 20 kopecks USSR 5 3 kopecks of the USSR 6 Lead 7 Sleeves 8 Silver 9 5 kopecks of the USSR 10 Aluminum plugs 11 Aluminum

Note! Copper should not be cut!

First, after balancing, we check the correct connection. The metal discrimination knob is set to zero, the ground balance knob is in the middle position, the sense knob is adjusted, the mode switch is in the “color only” position.

We take a piece of ferrite 1x1cm and some copper detail. We turn on the device and wave first the ferrite over the sensor, then the copper. There should be a double beep on the ferrite, and a single beep on the copper. If vice versa, then we change the ends to TX in places.

It is best to take several targets from different non-ferrous metals, because the device can not always give a reaction to copper - it has not yet been set up.

In fact, the general meaning of checking the correct connection is that a single signal should sound on a colored target, and a double signal on a piece of ferrite. If so, then the coils are connected correctly.

Next, set the BG knob to 40 Kom, the discrim knob to 0 Kom and adjust the scale of non-ferrous metals. This is done by adding or reducing the capacitance of loop capacitors. Depending on where we add or reduce capacitance (on TX or on RX), the phase “window” into which our scale should fall and will shift in one direction or another. If we reduce the capacitance on TX, the “window” moves towards low-conductive metals (towards the foil), if on RX, the “window” moves towards high-conductive metals, such as copper.

In general, we look at the table and, based on what your device “sees” after balancing, we figure out where we should add contour conduits (on TX or on RX). We strive to ensure that all non-ferrous metals listed in the table are visible, and a piece of ferrite is cut out at the same time in the position of the BG handle of about 40 Kom.

Capacitors C5 and C12 also move this “window” a little, but we correct it more subtly with them. We set C5 - 10nf and do not touch it anymore, we first set C12 according to the maximum amplitude on leg 12 of the preamplifier (MC2), and then by position C12 after the main setting we achieve a more accurate and final adjustment of the metal scale. That's basically the whole setup.

Its target detection range and correct discrimination will depend on the quality of the setup work you have done, so approach this matter responsibly.

The Terminator 3 metal detector is quite complicated to manufacture and set up, its creation will require some effort. However, a neatly and correctly assembled device will delight you with the quality of its work and pleasant finds. The Terminator 3 performs on a par with mid-range branded metal detectors, and it is relatively inexpensive to create it yourself.

Video on how to make Terminator 3 with your own hands: