DIY metal detector Terminator 3 simplified. DIY metal detector (circuit, printed circuit board, principle of operation)
If If you want to make a metal detector with your own hands, then in this article you will find detailed instructions. In particular, technical characteristics, circuits, settings, advantages and disadvantages of MD terminator 3.
DIY metal detector Terminator 3. Assembly instructions
MD terminator 3 is designed to detect objects containing metal in low-conductivity or dielectric array. With the help of MD terminator pro you can find metal in the soil, as well as at the bottom of various types of reservoirs.
Technical characteristics of MD Terminator-3
Main technical characteristics
- Metal detector type: selective
- Discrimination: yes
- Sensitivity adjustment: yes
- Soil balance adjustment: manual
- Operating modes: 2 pcs (“All metals”, “Discrimination”)
- Power: 6 AA batteries;
- Coil: 26cm DD waterproof
Test table Terminator M with DD-26cm sensor. (feel max, discrete on):
- Coin 5 kopecks Ø 25 mm ~ 40 cm.
- Fibula Ø35mm, length ~ 31 cm.
- Roman, denarius ~ 32 cm.
- Gold ring “engagement” Ø 19 ~ 37 cm.
- Silver chain Ø 26 grams. 925 samples ~ 30 cm
- Tin can ~ 67 cm.
- Leather wallet 30 USSR coins - 55 cm.
- Helmet ~ 92 cm.
- Sewer hatch ~ 145 cm.
- Maximum detection range (metal accumulation, tank) ~ 2 meters
Equipment:
- Metal detector block - 1 pc.
- Collapsible workshop rod - 1 pc.
- Batt compartment with power - 1 pc.
- Search coil - 1 pc.
- Coil fastening screw - 1 pc.
The main technical characteristics of this type of device include the following:
1) Detection depth;
2) Discrimination;
3) Ground balance.
Discrimination
This feature allows the metal detector to distinguish metals that it detects in the ground or
At the bottom of various types of reservoirs.
In this mode, the device can be configured for a specific type of metal, cutting off all others. You can also set the detection of all metals.
Detection depth
The most important parameter that determines the effectiveness of using a metal detector.
A device with a 240 mm coil can recognize the following objects at a maximum distance:
· modern coins - 240 millimeters;
· five-kopeck coins from the time of Catherine the Great - 300 millimeters;
· military helmets - 800 millimeters.
Ground balance
Various kinds of objects falling into the magnetic field emitted by the device greatly distort it.
The soil can also introduce distortions. The level of minerals it contains will depend on how many minerals it contains.
Imbalance.
The “soil balance” option is needed to filter out false impulses. The soil can be rebuilt automatically.
Making MDT 3 with your own hands
To create a Terminator 3 metal detector on your own, you need to follow the diagram.
MDT scheme 3
The figure below shows a plan for connecting radio components into one electrical circuit.
Link to full size diagram
Making a circuit board
To make the circuit board of the Terminator 3 metal detector on your own, you need to complete
The following sequence of actions:
- Search on the Internet for a photomontage board of the Terminator M metal detector.
- Printing the image on a printer in full size.
- Gluing paper onto a piece of PCB.
- Cutting the PCB with a hacksaw around the perimeter.
- Marking places for fastening parts with an awl.
- Drilling punctures.
- Cutting out current-carrying areas.
- Removing paper from conductive branches.
- Painting with bare paint.
- Removing remaining paper.
- Etching of metallized surface.
- Final cleaning of the board. 
Assembling the circuit and selecting parts
Before you begin assembling the metal detector, the terminator m should be selected for the circuit board
all components according to the parts list of the control unit for this type of device.
The assembly procedure for the Terminator Trio metal detector begins with jumpers. Then resistors are soldered
and panels for microcircuits. Next, the wires for the radio components are soldered. At the end of the process, make sure that the soldering is completedquality, and the radio components are installed correctly.
Insert the device control unit into the finished circuit.Place plastic handles on the switches, as well as on the resistor axes.Connect the terminals of the block to the sensor.
Components of the MDT 3 sensor
The metal detector sensor is round. Along its perimeter there are contours of enameled wire
ø 0.4 millimeters, being
receiving and, accordingly, transmitting coils. The niche for the wires is made of dielectric material.
When assembling Terminator 3 with your own hands, place all the elements on the rod.
Make sure the sensor disk is securely attached.
Install the battery, as well as the control unit for this type of device, so that
it was possible to change operating modes while continuously searching for metals.
You need to embed a handle into the bar so that it is convenient to grasp it with your hand. If desired, you can make an elbow rest from a plastic tube.
Adjustment and preparation for work
When testing the device in field conditions, the sensor should be brought closer to the ground surface and away from
Not. When the signal appears, you can remove it by turning the soil regulator knob.
Unnecessary metals can be cut off by turning the discrimination knob. Sensitivity can be adjusted to depth
recognition of the desired metal.
Setting Discrimination
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, the array of enclosing structures of buildings and structures, in the depths of the soil and at the bottom of reservoirs. A branded device is quite expensive. It is much more profitable to make MD Terminator 3 with your own hands.
Technical characteristics of MD Terminator-3
MD Terminator-3 is a powerful metal detector capable of detecting metal objects at long distances in the ground and under water. The device can also recognize metal in a monolith of various materials (concrete, brickwork, wood, etc.).
Technical characteristics determine the capabilities of the Terminator metal detector in searching for various metals, depending on their volume and depth. The main parameters of the device include the following characteristics:
- detection depth;
- discrimination;
- ground balance.
Detection depth
This parameter is the most important for the device. The high sensitivity of a metal detector determines the effectiveness of its use. The device with a ø 240 mm coil is capable of recognizing the following objects at a maximum distance:
- modern coin with a face value of 5 rubles. – 240 mm;
- Catherine five kopeck coin – 300 mm;
- army helmet – 800 mm.
Discrimination
This option allows you to distinguish between types of metal. In the 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 share of distortions. The degree of imbalance depends on the mineralization of the soil. To cut off false pulses, the metal detector has a built-in Ground Balance option. In MD Terminator 3 (MDT 3), ground balancing occurs automatically.
Making MDT 3 with your own hands
Creating a metal detector with your own hands begins with its diagram. 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 metal detector control unit, you will need to make a circuit board. By following the guide, you can quickly and accurately make an installation site with your own hands.
Instructions for making the board:
- On the Internet, choose a photo of a printed circuit board.
- The printer prints the drawing in full size.
- The paper is glued onto a piece of PCB.
- Along the perimeter of the pattern, the textolite is cut with a hacksaw.
- An awl is used to mark the mounting locations for radio components.
- Punctures are drilled with a mini drill.
- Carefully cut out all current-carrying areas with a scalpel or a suitable cutter.
- The paper is removed from conductive branches and areas of the board.
- Bare areas are covered with paint.
- Remove the remaining pieces of paper. To do this, just 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 cloth soaked in solvent.
Important! When following the instructions, you must be very careful. When cutting tracks, do not allow parts of the metallized coating to separate from the board. Otherwise, the circuit will malfunction or fail altogether.
This completes the manufacturing of the circuit board. Proceed to the installation of the MDT 3 control unit circuit.
Assembling the circuit and selecting parts
Before you begin assembling the metal detector circuit, you need to select all the components of the circuit board. To do this, take a detailed list of parts for the MDT 3 control unit online.
Assembly begins with soldering the jumpers. SMD resistors and panels for microcircuits are soldered in. Then the control wires and other 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 check the quality of the soldering and the correct installation of the radio components. The MC 10 chip is needed to indicate the battery charge level. It costs quite a lot. At the discretion of the home craftsman, you can refuse to install MS 10.
The finished circuit is inserted into the control unit housing. Plastic handles are placed on the axis of the resistors and switch. The terminals of the block are connected to the coil (sensor) of the metal detector.
Components of the MDT 3 sensor
The metal detector sensor is a circle, around the perimeter of which two circuits of wound enameled wire ø 0.4 mm are laid. The circuits are the transmitting TX and receiving RX coils. As a bed for wires, improvised dielectric material is used.
When balancing the device, the coils are rotated in a circle relative to each other. Once the adjustment is complete, the turns of the radial conductors are tightly wrapped with thread. Then the coating is impregnated with varnish.
Terminator 3 assembly
All components of the metal detector are placed on a rod no more than 1.2 m long. The length of the lever should not be convenient. Particular attention should be paid to securely fastening the sensor disk.
The control unit with the battery is installed in such a way that a person can simultaneously change the operating modes of the device without interrupting the search process.
A horizontal handle is cut into the bar just above the block for easy grip with your hand. You can cut an elbow support from a plastic pipe and attach it to the bar.
Note! An orthopedic crutch with an armrest is used as a guide rod. A sensor circle is attached below, and a control unit with a battery is installed in the middle part of the rod. Everything that is needed for a comfortable position of the operator’s hand is already on the crutch.
Adjustment and preparation for work
During field testing, the sensor is brought closer and further away from the surface of the earth. When signals appear, turn the soil regulator knob to achieve silence. The discrimination pen cuts out unnecessary types of metals. The sensitivity of the device is adjusted to the required depth of recognition of the target metal.
Setting Discrimination
To set up the discrimination of the metal detector, turn on the non-ferrous metal search mode. To cut off the ferrite point, a balance resistor sets a threshold in the region of 40-50 kOhm.
The discrimination regulator is moved to the zero position. Then the handle is turned clockwise all the way. 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 windings are connected correctly.
Then adjust the visibility of all metals. To do this, use the table below.
Metal Discrimination Table
| № | |
|---|---|
| 1 | How to enable discrimination |
| 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 | Duralumin plugs |
| 10 | Aluminum |
| 11 | Copper is not cut |
Checking the device board
The device 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 repair shop. Within an hour, the technician will test the device board and give recommendations on how to eliminate the identified deficiencies.
Low battery indication
There are often 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 terminals are connected to the power supply of the metal detector. The signal wires are soldered to an LED, which is embedded in the panel of the MDT 3 control unit.
When the battery charge is lost, the LED begins to blink, then when the capacity decreases by 80%, the light begins to light constantly. In this case, the battery is charged.
Additional Information. Factory-made MDT 3 costs from 7 to 15 thousand rubles. In a home workshop, manufacturing a metal detector of this model will cost a maximum of 3 thousand rubles.
Advantages
MD Terminator 3 compares favorably with its analogues in its simplicity of design. A homemade device significantly saves financial costs.
Flaws
It is not possible to use AA size AA batteries. There is no sound control. No visual indication.
The first finds using 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.
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Specifications:
-The principle of operation is induction balanced
-Operating frequency, kHz 8-10kHz
-Dynamic operating mode
-Precise detection mode (Pin-Point) no
-Food, 9-12
-There is a sensitivity level regulator
-There is a threshold tone control
-Ground adjustment is available (manual)
Detection depth by air
-coins 25mm - about 35cm
-gold ring - 30cm
-helmet 100-120cm
-maximum depth 150cm
-Consumption current:
-Without sound approximately 35 mA
Brief instructions
The device is single-tone - this is both a plus and a minus at the same time. It’s a plus because if a clear signal appears in both directions of the wiring above the target, it means there is 90% non-ferrous metal under the sensor. The downside is that there is one tone for all non-ferrous metals. Sometimes the device may mistakenly identify a flat piece of iron (for example, a piece of roofing or a tin can) and pass it off as non-ferrous metal, but with little experience in using the device, such errors are easily distinguishable. The fact is that if there is an error on the hardware, the device will either produce an unstable, ragged signal, or the signal will be stable, but only in one direction of the wiring. The device simply does not produce a signal for ordinary pieces of hardware. A small but very useful trick when searching, if you suddenly doubt whether the metal under the sensor is ferrous or non-ferrous, that is, if the device produces an incomprehensible signal, then you need to switch to the “all metals” mode, if the signal has become clear in both directions of the sensor wiring above the target - This means that there is definitely ferrous metal underneath, but if the signal has not changed, it means that there is definitely non-ferrous metal underneath the sensor. Of course, you need to get used to the device and understand how it works. Although getting used to it happens quite quickly. In two or three outputs you will already be able to almost accurately determine target type.
Powered by a 9V KRONA battery (batteries are not recommended). You can use an 8.4V CAMELION battery.
There is no need to write about turning it on and off, everything is already clear with this. So
Adjustment:
1) Ground balance (GB) - the detuning from the ground is very sharp, you can easily cut off copper along with the ground. Therefore, when detuning from the ground, the handle must be turned carefully (little by little). This is done like this: For example, you went out into the field, turned on the device, lifted the sensor from the ground and lowered it to the ground - if a signal was heard on the ground, then turn the B\G knob slightly counterclockwise and repeat raising and lowering the sensor. This is done until the ground signal disappears. As already written, you cannot twist the BG, otherwise the copper will be cut off. For a better reference, it is advisable to make a mark on the body of the device in which position of the handle and the ground is cut off and the copper is clearly visible.
2) Discriminator for cutting off unwanted targets - when turned counterclockwise, it cuts out metals in turn from cigarette foil to brass. Only the copper remains uncut.
3) Sensitivity knobs. There are two of them, one is a coarse setting, the other is a smooth adjustment. The smooth adjustment knob is set to the middle of the revolution, and the coarse feeling adjustment knob is turned until small (very short) false beeps appear and is moved back slightly. After this, using the smooth adjustment knob, the sensitivity is adjusted so that there are no false alarms and the sensitivity is at the same level. The device itself is very sensitive, so you should not abuse the sensitivity adjustment. Again, to avoid false positives.
4) Switch for “color only” and “all metals” modes – switches these modes. In the “all metals” mode, the device reacts to all metals, and the detection depth increases slightly.
5) Beach mode switch “gold only” – switches the device to this mode and works only when the other switch is in the “color only” mode. In the “gold only” mode, the device gives a signal only to gold, to aluminum caps with rings (such as TUBORG), to silver, to aluminum pull tabs from beer cans and to modern white goods (except for five-ruble coins). It can also give a signal to strong a rusty beer cap, but this is rare.
6) Sensor cable - it must be wrapped around the device rod and secured tightly in two or three places either with self-tightening plastic clamps (usually sold in car dealerships) or simply with electrical tape in order to prevent the cable from moving during the search. The fact is that the device does not provide a buffer to exclude false alarms from cable movement (many purchased devices, by the way, also do not install this buffer since it reduces the target detection depth). Well, that seems to be all. Happy Findings!
Fig 1. Device diagram.
P.S. The archive contains all the information necessary for assembly. This device was assembled by me personally, it works great!!!
Terminator 3 is a coin detector that operates on the induction balance (IB) principle. The Terminator 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 configuration.
The main advantage of 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 Terminator 3 metal detector
| Principle of operation | IB (Induction Balance) |
| 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 |
Detection depth of objects in the ground with a 240 mm coil:
- Coin 5 Russian rubles - 22–24 cm.
- Coin 5 kopecks of Catherine - up to 30 cm.
- Helmet - up to 80 cm.
Metal detector Terminator 3 - VDI scale
Thanks to this, the Terminator is able to effectively distinguish gold products from other metals.
Metal detector Terminator 3 - diagram and necessary components
Schematic of the Terminator-3 metal detector
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 circuit to people who have experience in making metal detectors!
DIY metal detector Terminator-3 - detailed manufacturing instructions
First, let's take on the printed circuit board. We solder jumpers into it, then SMD resistors, then panels for microcircuits and other parts.
Terminator 3 metal detector board
The 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. It is better to use a multi-turn resistor as a tuning resistor.
Assembled Terminator 3 metal detector board
After soldering the metal detector, the board must be washed with alcohol, dried and visually checked for defects and stickiness.
Then, without the coil, you can check its performance. For this:
- Turn on the power to the metal detector.
- Turn the sensitivity control until a constant sound appears in the speaker.
- We touch the sensor connector with our fingers, the sound should be interrupted for a second.
- When turned on, the LED should blink and go out.
To do this, we need 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. You can also wind it in parallel with 2 reels.
Step-by-step detailed instructions for creating a coil for the Terminator-3 metal detector:
- On a sheet of plywood we draw a circle with a diameter of 200 mm for the TX (transmitting) coil and 100 mm for the RX (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, we wrap it with thread.
- 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, and on top of it we wrap aluminum foil for the screen with a gap of 1 cm.
- We again wrap electrical tape over the top 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. After that we solder it. We connect the middle terminal of the transmitting coil to the negative 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.
- We wind the compensating coil with a single wire - 20 turns. We select its diameter so that it fits tightly inside the shielded transmitting coil.
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 of the board, and the positive probe to one of the ends of our coil.
Note! When setting up the coil, there should be no metal objects around it!
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 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 RX pin and proceed to connecting the coil. We connect them according to the diagram below.
Connecting coils to the Terminator 3 metal detector
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 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 up one turn from the CX (compensation coil) from the soldering side to RX, bite off this turn and solder it again. 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 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 our fill - this will be our compensating loop, which will help us completely connect the coil.
Making a coil for Terminator 3 with your own hands
We fill the sensor with epoxy resin, but only half the depth of the mold. After hardening, we connect the oscilloscope, bend our loop inside the mold and begin to twist it, trying to find the minimum amplitude value. After the position has been found, fix the loop with glue, check the balance again and fill our form to the end.
- See also diagrams and instructions on how to make
Note! Copper should not be cut!
First, after balancing, we check that the connection is correct. The metal discrimination knob is at zero, the ground balance knob is in the middle position, the sense knob is adjusted, and the mode switch is in the color only position.
Take a piece of ferrite 1x1cm and some copper part. We turn on the device and first wave the ferrite over the sensor, then the copper. There should be a double beep for ferrite, and a single beep for copper. If it’s the other way around, then we swap the ends on the TX.
It is best to take several targets from different non-ferrous metals, because the device cannot always react to copper - it is not yet configured.
In fact, the general meaning of checking the correct connection comes down to the fact 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 turned on correctly.
Next, set the BG knob to 40 Kohm, the discriminant knob to 0 Kohm and set up the scale of non-ferrous metals. This is done by adding or reducing the capacity of loop capacitors. Depending on where we add or reduce the capacitance (on TX or RX), the phase “window” into which our scale should fall will shift in one direction or another. If we reduce the capacitance on TX, the “window” moves towards low-conductivity metals (towards foil), if on RX, the “window” moves towards highly 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 the contour connectors (on the TX or on the RX). We ensure that all non-ferrous metals given in the table are visible, and a piece of ferrite is cut out at the BG handle position of approximately 40 Kom.
Capacitors C5 and C12 also move this “window” a little, but with them we adjust more subtly. We set C5 - 10nf and don’t touch it anymore, C12 is first set to the maximum amplitude on leg 12 of the preamplifier (MC2), and then with the position of C12 after the main setting we achieve a more accurate and final setting 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 perform, so approach this matter responsibly.
The Terminator 3 metal detector is quite complicated to manufacture and configure; its creation will require some effort. However, a carefully and correctly assembled device will delight you with the quality of its work and pleasant findings. Terminator 3 works on par with branded metal detectors of the mid-price category, and its creation by hand is relatively inexpensive.
Video on how to make Terminator 3 with your own hands:
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.
Metal detector "Terminator 3"
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.
Detection depth
A metal detector can search for coins and other objects at different depths:
- Five rubles - 22-24 cm.
- Catherine's nickel - 27-30 cm.
- Helmet - 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 its analogues, which can only determine the depth of an object, this model determines the metal from which the object is made.
Metal detector assembly
To assemble and configure the metal detector you will need the following equipment:
- Oscilloscope.
- Multimeter.
- Generator.
- LC meter
- Frequency meter.
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.
Metal detector circuit
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.
Metal detector cost
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.
Setting up a metal detector
On the diagram of the metal detector, certain components are marked that 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.
Checking the device board
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:
- The printed circuit board of the metal detector is thoroughly washed to remove traces of flux remaining after soldering. It is advisable to remove all residues, since they can cause breakdowns and malfunctions in the future.
- 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, simply touch the sensor connector with your finger. Interruption of the emitted sound signal when touched indicates that the metal detector board has been soldered correctly.
- The LED always blinks and goes out after turning on the power. When the power is turned off, the diode lights up and gradually fades out.
Low battery indication
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.
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 settings modes - "Sensitivity", "Volume", "Discrimination" and "Ground Balance" - and a switch between ordinary and non-ferrous metals.
Advantages
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.
Flaws
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.
Search depth
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.
Results
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.