Hello to all comrades, today we will try to figure out what kind of metal detector is the Terminator? Have you probably heard of such a device? In particular, one of the popular models is the third. A friend of mine, whom we met on the Internet thanks to our hobby, has a “Therma” and this is what he told me about this device.
There are plenty of photos on the Internet, all different modifications:
Regular three:
Terminator M model:
Well, and another photo of two homemade products at once:
The first and most important thing is that this is a homemade metal detector, which means that it is made by ordinary people, or rather by those who are well versed in circuits and electronics. If you are not good at this, then you won’t be able to do it yourself.
They make it according to schemes that are a dime a dozen on the Internet. The most important thing is that there are a lot of nuances here and each “developer” makes the device for himself - changes something, improves it, adapts it. Here is the general diagram - using it you are guaranteed to assemble this MD yourself:
And this is what the board looks like, where everything is already soldered:
“Therma” has several varieties - here we can talk about the “Trio” model, it has been improved, some gadgets have been added to make the search more convenient and comfortable. The Trio already has 2-tone identification and, compared to older models, it is more convenient for them to search.
The Terminator 4 model is already considered obsolete, but those who started with it speak warmly of this model and continue to use it. It was “invented” already in 2007, while the “troika” is already 2009.
Three and four are most often single-tone devices (however, now two-tone models have also begun to be assembled), but the “Trio” is already 2-tone. So if you decide to buy a “thermal”, then it’s better to take a two-tone model. Still, when there is no display that helps in digging, and you have to navigate only by sound, then the more tones, the better. And here, single-tone homemade products, of course, lose out to factory devices, which have several tones by default.
There are also PRO models and a recent new product - 2012. We won’t talk about them here for now, because in price they are already comparable to professional-level devices.
Which is better, Terminator or Garrett Ace 250?
As you can see, this MD is practically in the same price category; the third “term” on thematic forums can be bought for 4-5 thousand rubles. Whereas 250 ICQ costs at least 2 times more.
However, at such a low price in terms of depth, “Thermal” makes Asya, it sees colored targets deeper. Of course, if everything is configured correctly and the operator fumbles.
On the other hand, ICQ’s convenience and information content are an order of magnitude higher, and if you are a complete newbie to coping, then I would advise you to take a factory device. And ICQ is still time-tested - a worthy entry-level device.
Does this MD have a pinpointer?
A pressing question, because now they have become more alert to installing DD coils on them, and without a pin they have to dig huge holes, and even the search technology, when you cross a target, does not help. The answer is that there is no pinpointer, and therefore we recommend purchasing an inexpensive manual pinpointer from this list.
How well does he see small targets?
The design of this MD is such that it sees “small things” just fine and easily copes with all entry-level devices - graters and ICQ. Again, let us remind you that it will be difficult to master this device from the very beginning.
What is this metal detector for - for coins or for war?
Here the answer suggests itself - most often this model is discussed on forums dedicated to war cops (in particular, Reibert), and therefore they use it for this purpose. They dig for shell casings, helmets, rifle bolts and other things of interest to war seekers. However, antique diggers who use these devices place it above the ICQ 250 and the 34 Minelab grater, primarily in terms of detection depth.
Which MDs are “Terminator” most often compared to?
Most often they are compared with devices of the same level - in particular with the Cardinal Profi MD from the Sturmlab office. However, as diggers note, “Thermal” is more balanced, there are fewer glitches (Cardinal often starts if you wave the reel on dewy grass). Well, I also note that the food lasts longer.
In general, after talking with the comrade, I got the impression that the device is actually very worthy, well, it’s not for nothing that it has so many fans and admirers. Plus they are actively improving it, adding more and more new features.
And now I’ve already seen quite “sophisticated” metal detectors with a convenient panel and a pleasant design on sale. And in terms of characteristics, they say that they compete even with Minelab’s mid-range and top-end detectors - 705 grater and Exp. So this MD is worth paying attention to. Well, if you are comfortable with a soldering iron and are tinkering with all sorts of circuits and transistors, then maybe you should try assembling it yourself? Fortunately, the Internet is full of schemes, and there are many thematic forums.
And finally, a video of a cop with Therm-4 - the quality is so-so, but what discoveries and most importantly - a new, lyrical song about diggers. I advise you to watch it even purely because of it. Well, you can clearly see that with this MD it is quite possible to dig for ancient coins.
One gets the feeling that there are simply no other signals, only coin ones) And there are no false ones either, which indicates good settling from the ground and the general setup of the device.
But here’s a test video about the “Trio” model - it’s more fun and understandable:
A metal detector is a very specific and unusual tool that not every person may need. Despite its uniqueness, a metal detector is the dream of many people. Most people try to purchase such equipment, but you can make 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.
This metal detector model 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 is worth noting right away that assembling a metal detector with your own hands according to detailed instructions will be very difficult for those who have never been interested in such things before and have not used such equipment. It will be really difficult to carry out such work, but you should not be afraid of this: it is enough to carefully prepare for the process and collect all the necessary parts and elements.
A metal detector can search for coins and other objects at different depths:
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 its analogues, which can only determine the depth of an object, this model determines the metal from which the object is made.
To assemble and configure the metal detector you will need the following equipment:
When purchasing the entire metal detector kit listed above, you will have to shell out a tidy sum. In order to save money, many users prefer to limit themselves to a virtual measuring system based on a personal computer. You can find suitable software designed for such purposes on the Internet.
By design, the Terminator 3 metal detector is a standard coin detector, which has undergone some changes that allowed it to detect gold and ignore other non-ferrous metals. When using a circuit with a special “all metals” mode, the device can search for any scrap metal. The standard scheme allows a metal detector to search for coins, nothing more.
The non-standard use of logic as an op-amp is the basis of the metal detector circuit. The disadvantage of this is unnecessary noise and unknown CG of all microcircuits. Of course, it is possible to use domestic logic to create a device, but this risks having too wide a spread of parameters. You can reduce damage and avoid additional problems by replacing the sound chip with a domestic analogue.
The price of the Terminator metal detector is in the average range. When compared with similar devices of the same category, Terminator 3 outperforms them in such parameters as object identification accuracy and search depth. Cheaper analogues are significantly inferior to Terminator 3 in all respects.
On the diagram of the metal detector, certain components are marked, which are taken into account, since during further assembly you will have to focus on them. This may also be necessary when setting up your metal detector.
The release of current fluctuations by the generator is carried out after connecting the transmitting coil to it. Such oscillations 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 generated field, the search coil is balanced with the 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 it is real. It is connected in such a way that the direction of current movement in it is opposite to the receiving coil. Balancing RX and TX is achieved by unwinding from the compensation coil.
An oscilloscope controls the balancing, due to which the minimum amplitude is set in all positions of the handle. 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 increase again. TX and RX must first be adjusted by 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.
There is no need to adjust the CX frequency. When a metal object appears under the sensor, the balance is upset, which provokes the flow of current into the RX, which is then supplied to the pre-amplifier and synchronization detector, which records the phases of the incoming signal and outputs them to the amplification channels. In the latter, all received parameters are amplified and fed to the MC8 comparator, which compares the received signal levels and activates the sound generator.
The operating principle of almost all metal detectors is similar to each other, with the exception of some nuances. In most cases, they affect the detuning of the device from the ground. In the case of the Terminator M metal detector, the detuning is phase.
After soldering all the parts of the circuit, the printed circuit boards of the metal detector are checked. This is done to check the quality of soldering of the circuit and its performance.
The check is performed as follows:
When the battery is low, the metal detector beeps at regular intervals. This is accompanied by continuous lighting of the LED and a sharp decrease in the sensitivity of the sensors.
The metal detector frequency settings 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.
"Terminator Trio" is a two-tone metal detector equipped with a DD-coil measuring 250 x 300 mm. Equipped with four settings modes - "Sensitivity", "Volume", "Discrimination" and "Ground Balance" - and a switch between ordinary and non-ferrous metals.
The advantage of the Terminator Trio metal detector is the confident identification of objects made of non-ferrous metal. The device finds non-ferrous metal in 85% of all detections, the remaining 15% are for iron and rusty objects.
Another plus is the absence of false positives. Many analogues react to the edges of dug holes, grass stems or small wiring, which is not the case with Terminator Trio.
The only disadvantage of the metal detector is its poor detection of rusty iron. In almost all situations, when the device gives a dirty signal, that is, a mixture of black with an admixture of color or, conversely, color with an admixture of black, there is a rusty metal object.
Of course, this drawback can simply be ignored, but there is a possibility of losing some of the finds due to an incorrect signal. The only way to differentiate between a clean color signal and a dirty signal is when you gain experience working with a metal detector.
Reviews left by users for the “Terminator” indicate that the maximum search depth of the metal detector exceeds that of another model, the “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 searching 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 spade 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 begin 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 at the same time, the “Terminator” is more suitable for those seekers who want to try their hand at instrumental search.
It's not that difficult to assemble. This will require certain financial and time costs, but at the same time, the user who assembles the metal detector on his own receives certain benefits as a bonus.
"Terminator 3" is a fairly powerful device in comparison with similar branded metal detector models. Considering the fact that you can assemble it yourself with the possibility of saving money, it is more accessible, profitable and attractive to users.
Correctly assembling and setting up a metal detector without the necessary experience is quite difficult. Beginner radio amateurs on 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 ability to independently assemble the device and an affordable price. You can find the necessary diagrams on the Internet on specialized forums of specialists professionally involved in searching for metal objects. The creators of the device are always ready to provide advice to those who plan to assemble a metal detector on their own.
For those who do not want to spend money on a branded device, I suggest assembling a Terminator 3 metal detector.
The search characteristics of this device can compete on the same level with purchased brands costing under $200. Terminator circuit solutions are almost the same as in branded devices of the TESORO line, but easier to configure and manufacture.
The device showed its best performance, discrimination at a high level, low current consumption of the device, cheapness and availability of parts, as well as the ability to work on heavy soils. The device board has been tested and works great.
Specifications:
Operating principle: induction balanced
Operating frequency, kHz 7-14 kHz
Operating mode dynamic
Power, V 9-12
There is a sensitivity level regulator
There is a threshold tone control
Ground balancing is manual.
Detection depth by air with DD-250mm sensor
Coins 25mm - about 30-35 cm
Gold ring - 30cm
Helmet 100-120cm
Maximum depth 150cm
Consumption current:
No sound approximately 35 ma
Metal detector diagram:
Board in .lay format:
We transfer the tracks onto the textolite using LUT (Laser Ironing Technology).
We poison the board, for example, in ferric chloride.
We tin the paths and drill holes for the parts.
We start the assembly by soldering in 16 jumpers, then carefully solder in the SMD resistors, then the sockets for the microcircuits and everything else.
It is better to take a multi-turn variable resistor threshold regulator (the setting is more comfortable), but you can get by with a regular one, in this case you need to turn it more carefully.
The board is ready to be inserted into the case. The MC10 chip and its harness do not need to be installed; this is a low battery indicator.
A small recommendation regarding the manufacture of the device board. It is advisable to have a tester that can measure the capacitance of capacitors. The device has two identical amplification channels, so the amplification through them should be as identical as possible; for this, it is advisable to select those parts that are repeated at each amplification stage so that they have the most identical parameters as measured by the tester (that is, what readings in specific cascade on one channel - the same readings on the same cascade and in another channel), and it is also advisable to select circuit capacitors C1 and C2 with the same readings on the tester, this will greatly facilitate your setup of the device.
Making a coil
The DD sensor is manufactured according to the same principle as for all balances..
TX is the transmitting coil and RX is the receiving coil. Number of turns - 30 turns with wire folded in half, wire diameter: 0.4 enameled winding. Both 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 a tester and connect the beginning of one arm to the end of the other, the middle output of the coil is obtained. The middle TX pin is connected to the minus of the board (without this the generator will not start), the middle RX pin is needed only for frequency tuning, after tuning the frequency (resonance) it is isolated and the receiving coil turns into a regular one (without output).
The receiving unit for tuning is connected instead of the transmitting one and is tuned 100Hz-150Hz below the transmitting one. The balance is achieved by shifting the coils (as on wedding rings) relative to each other. The balance should be within 20-30mV, but not higher than 100mV. After winding, the coils are tightly wrapped with thread and impregnated with varnish. After drying, wrap tightly with electrical tape around the entire circumference. The top is shielded with foil; between the end and the beginning of the foil there should be a gap of 1 cm not covered by it, in order to avoid a short-circuited turn. Each of the coils is adjusted in frequency separately; there should be no metal objects nearby.
I didn’t bother too much with the body :))
On the signet, instead of C1.1 and C1.2 (TX circuit capacitors), only one capacitor (C1) is placed, the frequency at which the entire device will operate will depend on its capacity, so it is not necessary to be tied to exactly the capacitor value indicated on scheme. For example, we set C1 on TX with a capacity of 100 nf, and set C2 on RX to 100 nf + 3.3 nf, and at the same time I get an operating frequency of the device of 10.5 KHz. You can also set other values (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 the discrimination will be worse for some targets, and vice versa, the higher the frequency, the shallower the depth, but the better the discrimination for some targets (such as gold, for example).
To assemble the board correctly, start by checking the correct power supply to all components. Take the circuit and the tester, turn on the power on the board, and, checking the circuit, go through the tester at all points on the nodes where power should be supplied. Where there should be 4 volts, then there should be 4 volts (well, plus/minus a few millivolts), and so on at all points. The second point: - The same applies to checking the assembly, turn the sense knob to the maximum and turn on the power of the board - the speaker should produce a continuous sound, when you twist the sense knob towards a decrease, the sound should disappear. If so, then the board is assembled correctly.
Next, we set all the knobs to zero (that is: the B\G knob - the ferrite is not cut out, and the discriminator knob - not a single color is cut out, the switch is in the "color only" mode), set C5 to start with 4n7, passed the ferrite over the coil ( if there is a double beep, then everything is fine, if there is a single beep, it means the ends have been switched to the TX in places), connect the oscillation probe to output C5 and move the coils to achieve a minimum amplitude.
So the device works, on which TX or RX coil should you solder additional capacitors when setting the reaction to metals? If ferrite is visible throughout the entire R8 range, then on RX; if ferrite is not visible throughout the entire R8 range, then on TX. Chocolate foil is at one end of the scale, copper is at the other end. This is what you should be guided by.
Here is the entire VDI scale as a guide, with the discriminator knob positioned at minimum, the device should see all non-ferrous metals, when screwing the discriminator, all metals should be cut out in order up to copper, copper should not be cut out, if the device works like this, it means it is configured correctly.
In this article I would like to post a diagram of a metal detector called Terminator-3. It has justified itself both by frequent assembly by radio amateurs and by good search characteristics, as discussed further in the sequel. The design of this metal detector, developed by Yatogan (Yatogan, MD4U forum) and Radiogubitel (MD4U forum), has circuitry similar to devices from the famous Tesoro company, but is much easier to set up. The impetus for the dissemination of this development was the printed circuit boards (with modifications and improvements) of another homemade product - A2111105 (MD4U forum, Soldering Iron forum).
Metal detector characteristics:
detection depth - 5 rubles Russia - 22-24cm;
Catherine's nickel - 27-30cm;
helmet - about 80cm;
beer can under - 1 meter.
The detection depth is given for medium-mineralized soil (chernozem) with a sensor with a diameter of 240 mm along the wire. I want to say a little about discrimination: if in other devices of this class there is a certain discrimination threshold when detecting a target (i.e. the device sees an object at the maximum detection depth, but cannot recognize the type of metal from which the object is made), then in the Terminator this is a drawback practically absent - the device recognizes most objects at the maximum detection depth.
I’ll make a reservation right away - assembling and setting up this IB device will be almost impossible for users who are just starting their journey in mastering radio electronics, and even experienced electronics engineers can make mistakes. What, scared? But not everything is so sad - you just need to prepare properly and not rush. And the forum will help you with this.
Firstly, to assemble and set up the device, we will need instruments such as a multimeter, an oscilloscope, an LC meter (to select elements with identical characteristics for both channels of the metal detector), and we may also need a generator and a frequency meter. Of course, such a set of instruments costs a lot of money, and not every do-it-yourselfer is able to purchase it, but you can try to create a virtual measuring system based on a personal computer. Fortunately, there are a lot of useful programs on the Internet for these purposes.
Device diagram: in the “document” at the bottom of the material
Terminator3 is a single-tone metal detector based on the IB principle. Simple as three kopecks and reliable as a bulldozer. This is a pure coin machine with a simple modification that allows you to search for gold on the beach while ignoring most colored debris. Although the T3 is a coin machine, it can also be used for searching through the war and for collecting scrap metal. But for this it is necessary to introduce the “all metals” mode into the circuit (which is provided on the circuit and on the board); initially the circuit was without this mode.
The circuit is made with non-standard use of logic as an op-amp. The downside is that the KU of the mikruhs themselves is unknown (therefore, to average the parameters of the mikruhs, the cascades are parallelized), and the noise level is higher. It is possible to use domestic logic in this circuit, but it is not necessary, since the spread of parameters will be even greater. The only thing is that you can replace the sound generator with a domestic chip without damage. I would also like to add that in terms of depth and accuracy of target identification (color/non-color), the Terminator 3 metal detector is on par with branded brands in the mid-price category, and is head and shoulders above inexpensive branded MDs. This is not only my personal observation, but the general opinion of quite a large number of people who have used it. Of course, for this to happen, you need to assemble and configure it as expected, and not as you have to.
Detailed description of setting up the Terminator3 metal detector. Firstly, you need to look at the diagram where the nodes are indicated, so we will be guided by the nodes, in the future this will be useful for configuration. So, a self-oscillator produces current fluctuations when you connect a transmitting coil (hereinafter referred to as TX) to it. These vibrations come out of the MC1 chip in the form of a meander (like rectangular patterns on ancient Greek temples and amphorae). Now the receiving coil (hereinafter RX), it also has a current induced by TX (which creates a field) and it must be balanced with TX by this current (field) (that is, subtract the RX field from the TX field), and for this we need a compensation coil (hereinafter referred to as CX). In the DD sensor, CX is virtual, in the “RING” sensor it is real in the form of a coil. Here we connect it so that the current in it runs in the opposite direction in relation to RX (I will explain how to determine this later, when at least one of them is soldered by someone board) and by gradually unwinding the turns from it, we balance the TX and RX in current (this is called zeroing, balance, in other words).
We control the balance using an oscilloscope, achieving the minimum amplitude in all positions of the v/division knob in turn. When we reach the point when the amplitude begins to grow again, the tuning loop comes into play (it is made from one of the ends of the CX). But before that, we must adjust TX and RX in frequency, while making RX 100 Hz lower than TX (this will be the starting point point for further adjustment of the “window” of the metal scale). The coils, one at a time, are connected to the device generator and oscilloscope and tuned to the desired frequency.
CX does not need to be adjusted by frequency. What we get is that when there is a metal object under the sensor, the balance is upset (in one direction or another, depending on the metal), and a current begins to flow into RX, which from it enters the pre-amplifier, where it is amplified and fed to the synchro detector (see diagram) , and the synchro detector (SD) detects the phases of the incoming signal and outputs all this to the amplification channels, in the channels this matter is amplified and goes to the MC8 comporator, the comporator’s task is to compare the signal levels in the channels and if they match, the comparator gives permission to operate the sound generator. In general, this is how all balance beams work with minor differences; the differences relate mainly to the methods of ground detuning. In the Terminator, phase detuning (cutting, in other words).
Checking the metal detector board after soldering: Turn on the power on the freshly made and thoroughly washed board from flux, do not connect the sensor, unscrew the sense knob until a constant beep appears from the speaker, touch the sensor connector with your finger - the sound should stop for a second. If this is the case, then everything is in order and the board is soldered correctly and without jambs. When the power is turned on, the diode should blink and go out; when the power is turned off, the diode lights up and goes out slowly. Looking ahead: Indication of a low battery looks like this: the device begins to emit frequent signals with the same period of time, the diode is constantly on, and the sensitivity drops sharply.
Frequency tuning. All settings are made with the cable with which the device will continue to work. You cannot change its length after setting it. If you have experience in making sensors for a balancer, then it will be easier for you.
Terminator 3 is a coin detector that operates on the induction balance (IB) principle.. The Terminator circuit was developed based on metal detectors from Tesoro. But it has a number of differences, both in the operation of the metal detector itself, and the process of its manufacture and configuration is simplified. Also, a great advantage of the Terminator is the ability to recognize metal at the limit of sensitivity (even with minimal target acquisition, it detects it quite accurately).
Operating principle – IB (Induction Balance)
Detection depth of objects in the ground with a 240 mm coil:
5 rubles Russia – 22-24 cm.
5 kopecks of Catherine - up to 30 cm.
Helmet – up to 80 cm.
Operating frequency – 7-20 kHz (Depends on the coil and capacitors C1 and C2).
Search modes – “Discrimination” and “All metals” can be switched.
Ground balance is manual.
The power supply for the metal detector is 9 – 12 volts.
The picture below shows the division of the VDI scale of the Terminator-3 metal detector. 
Thanks to this, the Terminator is able to effectively distinguish gold products from other metals.
Terminator-3 has a high level of complexity for self-production . Therefore, it will be extremely difficult for a beginner to do this. We recommend that this circuit be assembled by people who have sufficient experience in electronics and the manufacture of metal detectors! But if you feel strong enough, then the process of making Terminator 3 will be described below and all the information necessary for this will be collected.
To manufacture and configure the Terminator-3 metal detector, in addition to the standard set of equipment, you will need: Multimeter with capacitance measurement, Oscilloscope andLC meter. But this equipment can be replaced with computer emulators, circuits and programs for which are freely available on the Internet.
For ease of manufacturing and setting up a metal detector, you will also need Terminator-3 diagram broken down into nodes:
Several versions PCB routing for the Terminator 3 metal detector can be downloaded in this archive -
Parts List for the manufacture of the Terminator-3 metal detector in *.doc format (For a board with SMD resistors) -
We make a printed circuit board. Then we solder jumpers into the board, then SMD resistors, then panels for microcircuits and then the rest of the parts.
The capacitors on the board must be metal film with high thermal stability. It is also recommended to use 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 greatly facilitate your setup. It is also better to use a multi-turn trimmer resistor.
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 the functionality of your board. Turn on the power of the metal detector, turn down the sensitivity control until a constant sound appears in the speaker, and touch the sensor connector with your fingers, the sound should be interrupted for a second. When turned on, the LED should blink and go out. If everything is so, then the board is soldered correctly. And you can start making the coil.
Manufacturing a 200mm ring coil for the Terminator-3 metal detector
To make it, we need winding enamel wire with a diameter of 0.4 mm. We fold it in half in advance (So that we have 2 ends and 2 beginnings), or we wind it in parallel from 2 coils. Next, on a sheet of plywood we draw a circle with a diameter of 200 mm for the TX coil - the transmitting coil, and 100 mm for the RX coil - the receiving coil.
Then, in increments of 1 cm, we drive in nails around the entire circumference (preferably in cambrics, so as not to damage the wire insulation during winding).
We wind 30 turns of double-folded wire onto a 200 mm mandrel. Then we saturate the coil with varnish, and after drying, wrap it with thread. Then we remove it from the mandrel and solder the middle, obtaining a solid winding of 60 turns. We got 2 extreme and one middle tap.
Then we wrap the coil tightly with electrical tape, wrap aluminum foil for the screen over the electrical tape, with a gap of 1 cm, and again wrap electrical tape over the foil to protect the foil. We first bring the ends of the windings out.
Then we wind the receiving coil onto a 100mm mandrel - 48 turns, also with a double wire. And then he gets drunk. The middle terminal of the transmitting coil is connected to the minus on the board to start the generator, and the middle terminal of the receiving coil is needed only for tuning, then it is isolated and not used. The compensating coil is wound with a single wire - 20 turns. Its diameter is selected so that it fits tightly inside the shielded transmitting coil.
We take a 4-wire cable for the coil in a common screen.
Now we connect the TX (transmitting coil) to the board, connect the middle terminal and the coil screen to the minus of the board, connect the oscilloscope, the negative probe to the minus of the board, and the positive one to one of the ends of our coil. When setting up the coil, there should be no metal objects around it!!! And so we connect everything and look at the oscilloscope to see what frequency we get. Then 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 lower than the TX frequency by 100 Hz. 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 the middle RX pin is isolated, and we proceed to mixing the coil. We connect the coils according to the diagram below.
We place the coils in a pre-prepared mold for filling with epoxy resin. We take an oscilloscope, a negative probe to the minus of the board, a positive probe to the output C5, set the division time on the oscilloscope to 10 ms and the division of 1 volt 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 up one turn from the CX (compensation coil) from the soldering side to RX, bite off this turn and solder it again. And we observe a decrease in amplitude. We carry out this procedure until the amplitude becomes zero. Then we reduce the volt/division and continue to wind the turns until we reach 0 at the very minimum resolution of your 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 our fill; this will be our compensating loop, which will help us bring the coil together.
We fill the sensor with epoxy resin but only half the depth of the mold. Then, after it hardens, we connect an oscilloscope, bend our loop into the inside of the mold and begin to twist and twist it, trying to find the minimum amplitude value. After this position has been found, we fix the loop with glue, check the balance again, and fill our form to the end.
After you have made the coil, you need to adjust the Terminator 3 metal discrimination scale
The correct setup should look like the table below
This is what a finished homemade coil for the Terminator-3 metal detector looks like
You can also make a DD coil for Terminator 3. Detailed description of manufacturing a DD coil for the TERMINATOR 3 metal detector -
Conclusion:Terminator 3, although quite complex to manufacture and configure, will require some effort on your part. But a carefully and correctly assembled metal detector will delight you with the quality of its work and pleasant finds. Terminator three will work on par with branded metal detectors of the mid-price category, and in addition to your labor, it will require low material costs.
The following people should be thanked for the development of the Terminator-3 metal detector: a2111105, Yatogan, Radiogubitel, Elektrodych from the md4u.ru forum
When writing this material, data from the sites was used:
