"Last winter 2 after reading interesting articles about pinpointers and having studied the schemes available on the Internet, I decided not to repeat these schemes, but to try to develop my own. I immediately looked towards a small but "smart" microcontroller . The attempt was successful. I spent the whole season with it (of course, the Krot-m MD finds the target, but the Gnome-M pinpointer helps to localize it) and I can’t even imagine how I can do without it ... After all, I really want to see what was “ringing” in the ground as soon as possible .)"
Pin assistant on detecting number one!
I present:Pinpointer "GNOM-M" (2010)
Scheme
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Co. Film capacitors C2 and C3 are better. To improve thermal stabilityIt is recommended to install a PTC thermistor in series with R2.
Scheme from TSV with keys
This is what it might look like outside the case a
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Principle of operation The pinpointer is based on measuring the quality factor of an oscillating LC circuit. The approach of metal objects to the circuit leads to a loss of energy (a decrease in the quality factor) and, as a result, a decrease in the signal amplitude on the LC circuit. Measurement, processing, all combing and signal generation to the emitter are carried out by a program hardwired into the microcontroller.Manufacturing: Manufacturing fees (when printing, check the "mirror" box)
not complicated and requires only the skill of mounting smd components, although it is also possible to manufacture on DIP-output components. About Applied Parts. The sensor of the device is a ferrite rod (these are used in transistor receivers) 5-10 cm long and 8-10 mm in diameter. The coils are wound one on top of the other and contain 200 turns of insulated copper wires 0.2-0.3 mm . It is necessary to observe the polarity of the connection, therefore, in the absence of generation (frequency 15-20 kHz), it is necessary to change the ends of any of the windings. It is allowed to change the parameters of the coil - wire, length and diameter of the rod.
Tincture comes down to selecting a voltage of 1.0 V at the 2nd output of the microcontroller with a trimming resistor R2, in the absence of nearby metal objects.
Design There can be any pinpointer - the sensor board and AA batteries or a lithium battery allow you to fit, for example, the device into housing Z-23, orplastic water pipe with an outer diameter of 20mm.
ATtiny13-T - change the period of the tone ( 03.09.2016)
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Everyone can assemble such a device, even those who are completely far from electronics, you just need to solder all the details as in the diagram. The metal detector consists of two microcircuits. They do not require any firmware or programming.
Power supply 12 volts, can be from AA batteries but better than a 12v battery (small)
The coil is wound on a 190mm mandrel and contains 25 turns of PEV 0.5 wire
Characteristics:
- Current consumption 30-40 mA
- Reacts to all metals No discrimination
- Sensitivity 25 mm coin - 20 cm
- Large metal objects - 150 cm
- All details are not expensive and easily accessible.
List of required parts:
1) Soldering iron
2) Textolite
3) Wires
4) Drill bit 1mm
Here is a list of required parts
The circuit uses 2 microcircuits (NE555 and K157UD2). They are quite common. K157UD2 - you can pick it out of the old equipment, which I successfully did
For K157UD2, it is better to put an adapter socket.
We wind the coil on anything of a suitable diameter and wrap it tightly with electrical tape so that the turns are tightly next to each other.
Now we connect everything and try the circuit for performance.
After applying power, you need to wait 15-20 seconds until the circuit warms up. We put the coil away from any metal, it is best to hang it in the air. After we start twisting the 100K variable resistor until clicks appear. As soon as the clicks appear, twist in the opposite direction, as soon as the clicks disappear, that's enough. After that, we also adjust the 10K resistor.
At the expense of the K157UD2 chip. In addition to the one I dug out, I asked a neighbor for 1 more and bought two at the radio market. I inserted the purchased microcircuits, turned on the device, but it refused to work. I racked my brains for a long time, until I just put another microcircuit (the one that I soldered). And everything immediately worked. So that's what a transitional socket is for, in order to pick up a live microcircuit and do not suffer with soldering and soldering.
Purchased chips
Greetings to all lovers of metal detecting. In this article I want to share my experience of assembling a wonderful pinpointer Kid FM2V2, which has high stability and is able to distinguish non-ferrous metal from black. Such a device will become an indispensable assistant for those who like to wander with a metal detector in search of treasures, as well as good entertainment for your children.
Before proceeding with the assembly of the pinpointer, I want to note that this design is made using a microcontroller of the series PIC. If you are having difficulty programming pic controllers, I advise you to start mastering this skill or contact someone who is already in the subject. In any case, the game is worth the candle, as the homemade product shows high stability results and will become a real helper, facilitating the work of the digger. Figure 1 shows the electrical circuit of this miracle device.
Figure No. 1 - electrical circuit of the pinpointer
In general, the scheme can be divided into several blocks, namely:
Below is a list of radio elements used in the circuit.
Since this device was originally conceived as a pinpointer, the following requirements were defined: compact size of the board and search coil, monolithic cylindrical body. The plumbing fits perfectly in the case. PVC, diameter 25mm. From here, the requirements for the printed circuit board were determined. Its width should not exceed the inner diameter of the pipe, and the height of the soldered elements should not prevent the board from freely entering the case. It was possible to achieve compact dimensions by partial application SMD elements. As a result, the etched board looks like this (photo #2).
Photo number 2 - the appearance of the printed circuit board
The board is designed in such a way that SMD elements are installed from the side of the tracks, and output elements - from the opposite side. Photo No. 3 shows a board with soldered SMD elements. All of them are sized 1206 .
Photo #3 - pinpointer board with soldered SMD elements
For a microcontroller, it is better to use a socket DIP8, to always be able to extract it and reflash if something goes wrong. Also, I repeat that the capacitor C1 on the 33 nF it is better to use a film one, this will provide additional stability of the generator frequency when the ambient temperature changes. There are no special requirements for the rest of the elements. Photo No. 4 shows a view of the board from the side opposite to the tracks.
Photo No. 4 - board from the mounting side of the output elements
So, we figured out the board, but this is not enough. There are a few more stages ahead before getting the finished pinpointer. One of these stages is the manufacture of the sensor (coil). This is a rather painstaking task that requires some preparation and preliminary calculations.
To begin with, we will determine the diameter of the wire that is available and the diameter of the coil itself. In my case, there was an enameled copper wire with a diameter 0.4mm. As for the diameter of the coil, the following rules must be taken into account: the larger the diameter, the more sensitive the device, i.e. it is able to detect a metal object at a longer distance, and vice versa, sensitivity decreases with a decrease in diameter. Since my plans were to use the case 25mm, it was decided to wind the coil on the frame, with a diameter 20mm to be able to hide it inside the case. The water pipe was perfect for the mandrel 20mm and a pair of lids from eggplants with water, the distance between which is about 10mm. (photo No. 5).
Photo No. 5 - Mandrel for winding the coil (d = 20mm)
When the technical part is ready, the question arises, how many turns to wind? The program will help answer this question. Coil32. Download the program, run it and perform a series of actions below.
First, unpack the archive with the program and run the file Coli32.exe. After that, the main window appears, shown in screenshot No. 6
Screenshot #6 - Coil32 program after launch
In the initial state, the program does not have plugins for the calculations we need. Therefore, they need to be downloaded. The program itself allows you to do this. To do this, go to the menu " plugins" and in the drop-down list select " Check for updates", as shown in the screenshot above. After that, the corresponding window will open, shown in screenshot #7.
Screenshot #7 - Plugin Manager
Install all the plugins offered by the program using the buttons " Download"and close the manager. The program will ask you to restart, we agree and after restarting again go to the menu" plugins". Now there is a whole list of additional calculators from which we need only one with the name " multi-loop"(screenshot #8)
Screenshot No. 8 - choosing the necessary plug-in for calculating the pinpointer coil
In the window that appears, fill in the cells with the necessary parameters, namely:
After that, we press the calculate button and we get the result shown in screenshot No. 9:
Screenshot No. 9 - the result of calculating the coil parameters for the pinpointer
As you can see from the screenshot, you need to wind 249
turns of wire 0.4mm on the 20 millimeter frame to get the cherished 1500uH that the scheme requires from us. We will not argue - we will wind ...
In order to somehow facilitate the winding process, I assembled a masterpiece of engineering from a children's table, a small vice, and other rubbish at hand. The result is shown in photo #10.
Photo No. 10 - preparation for winding the coil
Immediately I notice that the coil is wound in bulk. It makes no sense to try to lay the turns, but it is still better to distribute the wire evenly over the entire winding area. For the convenience of counting turns, it is better to put some kind of mark on the restrictive end - it is easier to track each completed turn. During winding, it is better to turn off the mobile phone and close in a separate room so that no one can knock down. After the work is done, it is necessary to carefully remove the coil from the frame and pull it with threads around the entire perimeter, as shown in photo No. 11.
Photo #11 - Freshly baked pinpointer coil
To add strength to the coil and prepare it for shielding, we wrap it with ordinary stationery tape, as shown in photo No. 12
Photo No. 12 - preparation for shielding
Since the pinpointer works on the principle of measuring the frequency of an oscillatory circuit, this implies high requirements for frequency stability and protection against interference. If the frequency stability is provided to us by the generator circuit, then the shielding of the coil will provide protection against interference.
For shielding, you can use ordinary food foil, which almost everyone has in the kitchen, or something similar. We wrap the coil with foil, leaving a small empty sector in the area of its conclusions. This is required in order not to get a short-circuited loop through which no signal will pass at all. A stripped copper wire is additionally wound on top of the foil, which will later be soldered to the common minus on the board. Below is photo No. 13, which clearly shows the screening process.
Photo No. 13 - shielded coil
In order for the whole thing to hold on and not fall apart, you need to strengthen the coil with another layer of adhesive tape or electrical tape. And only after that you can relax and consider the coil completely ready. The result of my efforts is shown in photo #14.
Photo No. 14 - fully finished coil
Most of the work has been done. We solder everything into a single whole and check the operation of the pinpointer on the table. Battery is best for power KRONA"with a special holder for it. The pinpointer worked for me the first time and I did not find any difficulties. Even with the coil flattened under the future case, it works stably (photo No. 15)
Photo No. 15 - the pinpointer is ready to be placed in the housing
The circuit is a fairly simple analog pinpointer for people who are searching for coins, but cannot afford to buy a professional pinpointer. I personally collected this sample and confirm its full performance. I built a printed circuit board specially for him, which can be found at the end of the article. According to the characteristics of the pinpointer, it’s not bad enough, for target designation of the find, that’s it ....
Scheme of pinpointer MINIMAX-PP-2
And finally, a few photos of the assembled board.
Introduction
For a long time I suffered with clarifying the find in the ground, since my metal detector has a large coil, and finding a small object spent a lot of time detecting it. Finds such as buttons, small crosses and coins-scales are small in size, sometimes in order to catch it was necessary to sift more than a dozen handfuls of earth. And if you went to detect at night, the situation is even more complicated. Who is engaged in the cop of antiquity will perfectly understand me. To reduce the detection time of an already found object, diggers use additional devices - point metal detectors (pinpointers). The name comes from the bourgeois word - point-point. When the Great USSR suffered its collapse, our domestic manufacturer was no longer up to the development of point metal detectors, although by that time there were already industrial metal detectors of domestic production.
What is a pinpointer. The same metal detector but with a narrowly focused coil wound on a rod.
Commercially available pinpointers cost a lot.
Pinpointer Garrett Pro Pointer
- 6200p
Also on the Aliexpress website there is a Chinese podebka under Garrett for 2000r. Judging by the reviews, people are not happy.
The circuit is very simple, only 3 transistors, the most important thing is that it does not require any settings and starts working immediately after assembly. The power supply is 2 AA 1.5 V cells, in my case, a 3.7 V li-ion battery. Signet.
The diagram shows a number of transistors for the master oscillator, I personally used kt3107 and kt3102, they are in almost all radio stores, it will not be difficult to find them. Film capacitors are recommended, I did not experiment and set it as recommended by the author. C1 and C3 2 consecutive 1n 100 or more volts. If you take it with a lower voltage, a breakdown is possible, since the voltage on them can rise close to 100 volts. Any diodes can be installed, planned red glass ones can be pulled from old boards. Polevik, I personally put bs108, showing better results than 2n7000 (they love it on the forum). You can experiment and choose an even better one, it is important that the gate opening voltage is 0.8-1.5 V)
Coil
The coil is dangling on a ferrite rod, 5-6 cm long, 8-10 mm in diameter, 500-600 turns with 0.4 mm wire, it is desirable to concentrate more turns at the end of the rod, it will be higher from the nose. I took a ferite from an antenna with a conductivity of 800, perhaps a ferite with a higher conductivity will show better results. According to the plan, the frequency on the coil should be within 15 kHz, measured with a cartoon, I got 14.5 kHz. The frequency increases with a decrease in the number of turns on the coil, as well as with a decrease in the value of c1 and c3. It is not recommended to increase the frequency by reducing the number of turns, the feel will be worse from this. At the end of the winding, I filled the coil with epoxy, under vacuum in a housing from a 10 cc syringe, which will allow me to work in adverse weather conditions.
Indication
As an indication, the author proposed to use an active buzzer, an element that you have seen more than once on old motherboards, or electronic alarm clocks. An active buzzer differs from a passive one in that it already contains an audio frequency generator and when the power is connected, observing the polarity, it starts to squeak. The passive just clicks like a regular speaker. If you come across a passive buzzer, you can assemble the circuit below, and you will have an active one =)
Also, as an indicator, you can use an LED, a vibration motor from a 1.5v mobile phone, or an unknown huergu.
setting
After collection, it should start working immediately, the setting is carried out by a variable (you can adjust the sniffer) or a trimming resistor, setting the threshold for the field worker (the maximum sniffer without going into interference. C4 should be at least 50v. (See diagram) With a well-assembled and tuned device, the spit should be about 5 cm on a coin of 5 kopecks of the USSR.If the feel is lower, check your coil, 500-600 turns should be wound with high quality.C1 C3 - film, with a voltage of at least 100 V. Also, a large accumulation of rosin or flux in the frequency - driving part The frequency on the coil is about 15 kHz.
Features of the scheme.
When turned on, it goes into interference, after being brought up and sharply removed from a metal object, it stabilizes. (The reason in my case is the location of the elements, in particular, of an unknown khuerga, is too close to the coil.)
After warming up for 10 seconds, you can set the feeler higher, if you set it earlier, it will go into interference. (In my case, the reason is probably the same)
Unstable operation - chuyka drops (problems for forum participants where this device is discussed)
The frequency and soldering are normal, but the sensitivity is low - there may be problems with the field worker. Opening parameters 0.8-1.5v.
The coil squeaks very weakly and thinly.
In the cold, the chuyka drops a little, but when using a variable resistor, it is easily adjusted.
In the field conditions, the device showed itself perfectly. Stable scale detection - 3cm, coin 5-6cm, cross 6cm. When detecting at night, it is simply indispensable, it saves a lot of time retrieving the find. At the end, as expected, video test)
