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I just finished the pi felezjoo and would like to know if anyone knows the ideal coil?
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I am using the 300mH and 2ohms polish pi coil works well but I would like to know which is the ideal coil?https://youtu.be/054dXm4kSJ0 -
I think you could do better if you play around with the settings. The most important part on Felezjoo PI is the ABC numbers, what values do you get?
It would be best if you winded a flat spiral coil with the advised inductance, 350-380uH and 1 Ohm resistance.Comment
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I found these values with the Polish pi coil A363 B705 C787Comment
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The closer you are to A:300 B:700 C:800 the better the results you will get. To achieve this you must find the optimum damping resistance for your coil and to do this you must replace (temporarily) R11 with a 5K 2W potentiometer to get optimal ABC values for your specific coil. After you found the exact resistance on the potentiometer you can replace it with a 2W resistor of this value.Comment
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Ok great tip, more first I want to make the ideal coil for felezjoo with 1ohms and 350 to 380uH, I want type referent would have any designer model to copy from coil?Comment
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What size targets are you looking for?Comment
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Something around 25cm to 30cm or as specified by Mr. Hamid that I don't know what it is.Comment
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I followed the specifications of the spider loop coil it really has better gain I have to adjust the damping resistor still the value of A375 was a bit high I have to adjust I bought a 2w potenti I'm waiting to arrive.Comment
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20 cm loop: internal diameter 12.5 cm - 42 rounds - about 24 meters of 0.8 mil wire.Comment
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all the information needed to build the coil can be found at the link below:
https://www.felezjoo.com/viewtopic.p...&t=2305#p94582Comment
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after searching the site, I got this information from Engineer Hamid.
Which I put here for other friends as well.
These are the explanations that Engineer Hamid tried to make on the first page of Chance. With the permission of Engineer Hamid, I put the explanations that I said here.
Everything is ready. How to
wrap a spider loop @}; -
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First of all, we must mention that the spider loop we are looking for is of a simple and one-piece type. If the spider loop used by the designer is in two pieces, which seems to be more useful for coin-finding, so you should use a one-piece spider loop to explore larger targets to optimize the maximum loop size and the final range for large targets. Increase. It is also much easier to build a one-piece model.
Because lowering the capacitance of the special loop for this device is a critical issue; Many precautions must be taken. Finally, the work of making a loop; The lower the starting number of the device with the built-in loop, the better the quality of the loop and the connection cable.
To wrap the spider loop, we need to consider a mold in the form of a circular sheet, preferably made of thin wood with a maximum thickness of 5 mm. To make a spider loop, a number of grooves should be created on the number of people on this mold. The reason for the odd number of grooves is that each round the wire is twisted; If the grooves are the number of people; The next round does not automatically stick to the previous round, and this is what is ideal for reducing the capacitive state! Because the sticking of the wires to each other intensifies the capacitive state. On the other hand, the more grooves there are; The intersection points of the wires increase and the capacitance increases and the construction of the loop mold becomes more difficult. Therefore, the minimum number of grooves required must be considered. Now if we consider, for example, 5 grooves; The loop becomes pentagonal and moves very far from the circle, and due to the large distance between the grooves, the wires are no longer placed at this regular distance, and nothing good comes out of the water at all. According to tests, reviews and research on spider loops; The recommended number of grooves for our loop can be 15. That means we have to create 15 grooves in the shape of our wooden circle. Of course, this number of grooves can be used well if the wire is soft enough. Otherwise, in the case of wired lacquered wires, it may be better to double the number of grooves to maintain the order of the wires.
The width of each groove should be at least 4 times the thickness of the wire used so that the wires can easily pass through the groove. So depending on the thickness of the wire used lacquered or coated; The width of the groove can be between 4 miles to 1 cm.
The length of each groove is equal to the difference between the inside diameter of the loop and the outside of the loop mold divided by 2. For example, if the shape of the circle is 60 cm and we want to take the inner diameter of 50 cm; The length of each groove should be 5 cm.
The distance between the grooves on the outside of the loop mold is determined by a simple mathematical relation! For example, for a 60 cm loop that has 15 grooves; We have to multiply the diameter of the loop, the number 60, by the number pi, which is 3.1416, and then divide by the number 15 to get the distance between the grooves from the outside of the loop. In this example, the distance between the grooves is 12.57 cm, which is because the outside of the loop is circular, but the measurement is usually done with a flat ruler; 1 to 2 miles should be considered less, and for example in this example the distance of 12.4 cm is more accurate and more accurate.
However, all these measurements must first be marked with a pencil on the mold and finally check that the number of grooves and their distances are correct and equal so that the loop is very clean and symmetrical. It is necessary to mention that making this loop requires more precision and elegance in making the mold. Otherwise, twisting the wire on this mold only takes a few minutes, and if the mold is good and accurate, it will be very beautiful. So you have to spend a lot more time on making a good template.
Regarding winding the wire on this mold, we act in such a way that we start from a groove and from the inside of the loop mold; We pass the wire through the groove and take it out of the other groove. Exactly while sewing with thread and needle, we pass one groove from below and the next through, and it wraps very quickly and easily. The next round is the same and it is not necessary to change the routine of the wires being upside down at all. Because the number of grooves is odd, the next round that wraps automatically fills in the blanks, but the wires do not stick together. That is, there is always a gap between the wires as thick as the wires themselves. The very important thing about twisting is that the wires have to be pulled and twisted with pressure! That is, they should not be loose and complicated. Otherwise, a good loop will not come out of the water. So when winding, the wire must be pulled by hand so that it is beautifully smooth. The higher the pressure, the better the order between the wires!
However it is possible to wrap at the end of the work; The wires are completely regular and parallel in Nian. So after finishing the work, it is better to straighten the wires by hand because it can answer a little better.
In addition, it should be noted that due to the bilateral nature of this loop, half of the rounds can be seen on one side and half of the rounds on the other side! So if, for example, we are complex in a total of 20 rounds; 10 rounds on one side are visible and countable and 10 rounds on the other side.
Finally, this loop will have two heads, one end coming from inside the loop and the other end outside the loop. These two ends should be inclined towards the center of the loop in order to connect the skeleton handle of the device and the loop cable in that part.
The connection of the loop wires to the cable must be done by a strong and delicate soldering and finally the electrical tape must be used to insulate the connection. Under no circumstances should plugs or any metal connection near the loop be used.
Another point in the spider loop connection is that it is better to connect the wire that comes from the outside of the loop to the shield of the loop connection cable and the wire that comes from the inside of the loop to the core of the cable. Because it looks like this way there will be a little better performance and less noise.
Practically loops larger than 30 cm due to high range as well as more noise; They are not suitable for indoor testing. Therefore, the correct result of the work of larger loops is achieved only in the open environment and nature, which is more in line with the reality of exploration.
Specifications of different models of the proposed spider loop with lacquered wire
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20 cm loop: inner diameter 12.5 cm - 42 rounds - about 24 meters 0.8 mil wire.
30 cm loop: 24 cm inner diameter - 29 rounds - about 27 meters 0.8 mil wire.
Loop 45 cm: inner diameter 39.5 cm - 22 rounds - about 31 meters of wire 1 mile.
Loop 60 cm: inner diameter 55.5 cm - 18 rounds - about 35 meters of wire 1 mile.
Loop 70 cm: inner diameter 65.5 cm - 17 rounds - about 38 meters of wire 1 mile.
Loop 80 cm: inner diameter 75.5 cm - 16 rounds - about 41 meters of wire 1 mile.
Loop 90 cm: inner diameter 85 cm - 15 rounds - about 43 meters 1.2 mm wire.
Loop 100 cm: inner diameter 95.5 cm - 14 rounds - about 45 meters wire 1.2 miles.
It should be mentioned that the number of grooves in these loops is left to the manufacturer and there is no noticeable difference. However, the grooves should be the number of odd numbers and the distance between the grooves can be easily calculated from the formula mentioned above. In the case of lacquered wire due to its wire state; Reducing the number of grooves reduces the loop order, so it may be better to increase the number of grooves. In any case, these issues are specified precisely only when making the loop. The use of coated wire sprayers with a total thickness of 1.5 to 2 miles, which has a core sprayer with a thickness of 1 to 1.2 miles can have a much better result than lacquered wire, and due to the softer spraying wires, the number of grooves can be easily reduced. At the same time, the order of the wires must be observed. If coated wire is used due to different thickness; A little change in the loop specifications is necessary to get help from the flat loop calculation program.
The width of the grooves should be about 8 mm on the outside of the loop, which becomes slightly narrower when it goes inwards. The length of each groove to be created is equal to the difference between the inner and outer diameters of the loop divided by 2. For example, the length of the groove mentioned in the 60 cm loop should be 2.25 cm, which is the result of 60-55.5 / 2. In fact, mentioning the inner diameter number for this type of loop is only to calculate the length of each groove! Otherwise we are not dealing directly with measuring the inside diameter.
In addition, these loops are designed so that about 0.5 cm of empty margin remains on the outside of the loop so that it is not difficult to wrap the final rounds and the maximum useful space of the loop mold is used well. So, for example, for a 60 cm loop, it is enough to consider a circular plate with an exact diameter of 60 cm to make everything right.
In the case of loops where the number of cycles calculated is an odd number; It should be noted that because half the cycles are seen on each side; One side of the loop actually looks one more round. For example, in a 30 cm loop with 29 wire turns; At the end of the work, 15 turns of loop on one side and 14 turns of wire on the other side should be counted.
The calculation of these loops is such that the capacity will be about 400 microns and therefore there is no need to measure with an inductor. However, for better assurance, the capacity should be measured and at 30 microns less or more than 400, if there is, there is no problem. Otherwise, you have to do more or less one round to get the capacity right. The resistance of all these loops is between 0.6 to 1 ohm, which is quite suitable for this circuit.
The magnetic field of the loop is directly related to the square of the current flowing through the loop as well as the capacity of the loop itself! For example, when you double the current through the loop; The energy of the magnetic field of the loop is quadrupled. If you double the capacity, the field energy will still double. But you have to be very careful when you increase the capacity; In practice, the amount of current passing through the loop is reduced! So this product does not change much overall, and in the case of a pulse system, it also depends to some extent on the pulse width.
But reducing the resistance of the loop as a direct factor always leads to an increase in the current passing through the loop and consequently the magnetic energy of the loop.
These are simple and specific problems in theory. But in the sensitive system of a pulse metal detector, not everything is to the energy of the magnetic loop! Otherwise, with voltage methods or using a very thick wire for the loop, the power of the waves can be increased. But most of the time you see that going too far is not the right answer. Depending on the type of circuit; Reducing the loop resistance to a lesser extent leads to instability and malfunction.
The only thing that perhaps few people pay attention to; Need to increase the energy of magnetic field lines for large loops in terms of the number of turns of the wire is less and therefore less field lines! So for larger loops, you should always try to adjust the circuit in such a way that it responds to the loop with less resistance. This is one of the reasons why some friends think that a circuit with a large loop does not work as expected! While the large and small circuit of the loop can not understand at all! There are other points in making any loop that are either important for the circuit or for the magnetic field energy required for the metal sense.Comment
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any recommendation on shielding material for this machine? except graphite spray and scotch 24
has anyone done shielding to FPI coil before?
another question
the point on the pcb for shield connection is negative of the battery not the analog ground
is it ok?Comment
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at the end of page 94 the shielding is mentioned https://www.geotech1.com/forums/show...il-now)/page94Comment
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