Cylinder Coils?

[Tinkerer]

Hi Tinkerer.

Been experimenting with M/Lab coils for years, the ultimate inductance for medium to large deep nuggets is 325uH. If this increases the delay, no matter, you are not chasing tiny gold.

ozgold.

Thank you ozgold for the feedback.

[Tinkerer]

Greetings. In my opinion, visualization of processes is suitable for a better understanding of the current coil. A current coil and sensors. Therefore. I recommend many people to watch this video. This is not my channel and I am not promoting it. However, thanks to the author of the channel for such a vivid presentation. Even without translation, you will understand what it is about. there are several videos there...cycle, I recommend watching everything, especially the macro lines. Yes, this does not answer ALL the questions, but it quite clearly shows this side of the MD structure. It's a pleasure to watch). https://m.youtube.com/watch?v=bnxz8W...GMApACAQ%3D%3D

Thank you for the very interesting link.

[Smirnov-Arta]

Greetings. In my opinion, visualization of processes is suitable for a better understanding of the current coil. A current coil and sensors. Therefore. I recommend many people to watch this video. This is not my channel and I am not promoting it. However, thanks to the author of the channel for such a vivid presentation. Even without translation, you will understand what it is about. there are several videos there...cycle, I recommend watching everything, especially the macro lines. Yes, this does not answer ALL the questions, but it quite clearly shows this side of the MD structure. It's a pleasure to watch). https://m.youtube.com/watch?v=bnxz8W...GMApACAQ%3D%3D

[ozgold]

Hi Oz Gold, i was at Mt Crawford yesterday to test out my new Coiltek 11in Flatwound mono, i was hoping to hit Watts Gully but some bugger got there before me, and I got there at 7.10am (Bugger), so i hit Dead Horse Gully towards the very northern end (next to the house on the hill) and the usual turned up, (Bullets and rust), i'm not going to give it away but by a suggestion of my brother i tried something a couple of months ago, and by testing i can get targets anywhere from 4-6 inches deeper, BUT i still can't fing any Gold in this God Forsaken Gold field, i'm really starting to believe that there never was any Gold on this field (with the exception of the richest part in Watts Gully), have you detected in this field and actually found some Gold?, i know i'm looking in the right spots and i'm coming home with deep targets that no one else is getting, i'm just about at the point of cursing that place and never stepping foot on that bloody soil again ARRGGHHHH!!!!

Nova, I have sent you a personal message: ozgold.

[Nova]

Hi Oz Gold, i was at Mt Crawford yesterday to test out my new Coiltek 11in Flatwound mono, i was hoping to hit Watts Gully but some bugger got there before me, and I got there at 7.10am (Bugger), so i hit Dead Horse Gully towards the very northern end (next to the house on the hill) and the usual turned up, (Bullets and rust), i'm not going to give it away but by a suggestion of my brother i tried something a couple of months ago, and by testing i can get targets anywhere from 4-6 inches deeper, BUT i still can't fing any Gold in this God Forsaken Gold field, i'm really starting to believe that there never was any Gold on this field (with the exception of the richest part in Watts Gully), have you detected in this field and actually found some Gold?, i know i'm looking in the right spots and i'm coming home with deep targets that no one else is getting, i'm just about at the point of cursing that place and never stepping foot on that bloody soil again ARRGGHHHH!!!!

[Carl-NC]

Dear colleagues. I ask you to pay attention again. It makes no sense to talk about an abstract coil, without a circuit and software (if there is one) one or another MD. Physics is the same for everyone. Magnetic flux, voltage, etc. the characteristics of the coil, approximated by the area of the coil, will depend on the power supply of the coil (V)... etc. Therefore, it is necessary to consider some theoretically ideal coil in relation to the circuit and in no other way.

Personally, I wasn't talking about anything in the abstract. I'm talking about making physical coils to determine which topology and what parameters give the best detectability for certain targets. For this, you need to define the basic TX topology (monopolar, bipolar, CCPI, etc) because one coil design might work well with one TX driver but poorly for another.

[bbsailor]

Dear colleagues. I ask you to pay attention again. It makes no sense to talk about an abstract coil, without a circuit and software (if there is one) one or another MD. Physics is the same for everyone. Magnetic flux, voltage, etc. the characteristics of the coil, approximated by the area of the coil, will depend on the power supply of the coil (V)... etc. Therefore, it is necessary to consider some theoretically ideal coil in relation to the circuit and in no other way.

Smirnoff-Arta

I agree with your technical coil observation. There are a few things that could make a difference in detector or coil performance that needs to be kept in the back of the minds of detector and coil builders.

1. Coil wire size. Go to a wire chart and look up the skin effect frequency for your chosen wire diameter.
2. Build a spiral, single layer coil and a bundle wound coil and test them on different TC targets. The spiral, single layer coil will require more turns than a bundle wound coil to get the same inductance.
3. When looking for low TC gold targets, you need to minimize the coil seen capacitance to allow for a higher damping resistor value and earlier sampling and the integration of many sample RX pulses.
4. Shielding the coil will depend what type and size targets you are seeking and the temperature, and environment of where you are seeking your targets.
5. Coil shapes and sizes will depend on whether you are searching for maximum depth or maximum sweep area with a lesser depth.

Optimum coil design is a balancing act!

Joseph J. Rogowski

[Smirnov-Arta]

Dear colleagues. I ask you to pay attention again. It makes no sense to talk about an abstract coil, without a circuit and software (if there is one) one or another MD. Physics is the same for everyone. Magnetic flux, voltage, etc. the characteristics of the coil, approximated by the area of the coil, will depend on the power supply of the coil (V)... etc. Therefore, it is necessary to consider some theoretically ideal coil in relation to the circuit and in no other way.

[ozgold]

I have often heard that the SD2200d was the deepest detector for large nuggets. So I suggest we use the specifications of the SD2200 for comparison.
The SD2200 is a traditional Pi platform and is therefore limited to around 300uH coil inductance. about 300uH is the "brick wall" limit of the traditional PI.
If you increase the inductance, you increase the delay to the first sample.
This brick wall limit means that you have to use fewer and fewer turns of wire as you increase the diameter of the coils.
The depth of detection is directly related to the diameter of the coil.
Since on the traditional PI you can not increase the number of turns, you increase the current Amps. This makes a stronger field, but entails many other problems.

The AMX platform has demolished several of the "brick wall" limits. It is closer related to the GPZ 7000, but not the same. I would say it is the most modern or advanced PI platform in the making.

Hi Tinkerer.

Been experimenting with M/Lab coils for years, the ultimate inductance for medium to large deep nuggets is 325uH. If this increases the delay, no matter, you are not chasing tiny gold.

ozgold.

[Carl-NC]

The spiral coil calculators will probably get you close enough. For 1mm wire, I find that N=23 is just slightly low and N=24 is slightly high. I would go high and then remove an inner winding if needed.

From the table in post #6 you can see that magnet wire is plenty good for SRF and even has a low R(100kHz). However, with 1mm wire this might have higher self-eddy losses so you may need to consider litz.

The best way to wind a spiral is to print a plastic holder. You can spray adhesive on a disc, but I found that it's not tacky enough and dries out before I get done winding. So instead, I sprayed adhesive on a disc and then laid duct tape adhesive-side-up on the disc. The duct tape is very tacky. For a starting inner diameter I used a plywood disc purchased from here. In fact, I bought a bunch of their discs and made bobbins for winding coils 3" up to 12".

[Smirnov-Arta]

....

There's nothing wrong with that if it doesn't work out the first time). This is normal! Make 1 test run for 20 turns. Measure the data...and you will understand what needs to be changed. More or less turns. With regard to 300uH...this is a conventional conventional meaning...if there are small deviations plus/ minus...It won't matter. With regard to the resistance of the coil itself. It's not that simple. Yes, of course, it is desirable that it tends to zero (ideal). BUT! As a result, we need to create a field... That is, you need to take into account the power supply of the circuit...6/9/12V. I mean, you can make more coil resistance, but then you need more power. The field will end up being almost the same. The choice is yours).

[Tinkerer]

And what is the difficulty? If the diameter of the coil TX is 300mm, then the length of the coil is 940 mm. In order to get 300 uH, only 19 turns are needed. I leave the choice of the wire diameter to you. The technology of winding any flat coil will not be difficult for you to find on the Internet. It is possible technologically with templates pre-made on 3D printers. But, if for 1 sample, it is possible, with the help of ordinary thick paper / cardboard and glue, to make 19 turns. The first turn (internal) is more difficult to make, the rest will lie next to it easier. Believe me, it's nothing complicated. It will take no more than 1 hour)...maybe faster when you practice). Try it, there's nothing complicated!

Smirnov, thank you for your feedback. I appreciate your help.

I have no problem building the actual coil, but first I want to get the numbers right.
To compare the bipolar TX with the monopolar TX of a traditional PI, We need to have comparable parameters.
The Minelab mono coils are well known. This is why I want to use a known Minelab coil for comparison.
The Minelab coils are quite specific in their parameters, This is where the numbers: 300uH, 0.4Ohm 300mm diameter, come from.

[Smirnov-Arta]

...

And what is the difficulty? If the diameter of the coil TX is 300mm, then the length of the coil is 940 mm. In order to get 300 uH, only 19 turns are needed. I leave the choice of the wire diameter to you. The technology of winding any flat coil will not be difficult for you to find on the Internet. It is possible technologically with templates pre-made on 3D printers. But, if for 1 sample, it is possible, with the help of ordinary thick paper / cardboard and glue, to make 19 turns. The first turn (internal) is more difficult to make, the rest will lie next to it easier. Believe me, it's nothing complicated. It will take no more than 1 hour)...maybe faster when you practice). Try it, there's nothing complicated!

[Tinkerer]

Good morning,
A cylindrical coil doesn't make sense...It has already happened.
Once...Theoretically, it was considered that a cylindrical coil is capable of reducing the level of field tension/impact on the first/upper layers of the soil (0-10 cm)...the theory has not been confirmed by practice. Therefore, I do not recommend repeating this, although if you want, then try it. The "ideal operation" of the coil, ... the creation of a uniform electromagnetic field, etc., is created by a flat coil, with a pitch (distance between turns) of winding equal to the diameter of the wire. This is implemented in some MD's...
(sorry for the Google translation)

Thank you for your feedback, Smirnov,

How do you build the flat TX coil with 300uH inductance, 0.4 Ohm and 300mm outer diameter?

[Smirnov-Arta]

Good morning,
A cylindrical coil doesn't make sense...It has already happened.
Once...Theoretically, it was considered that a cylindrical coil is capable of reducing the level of field tension/impact on the first/upper layers of the soil (0-10 cm)...the theory has not been confirmed by practice. Therefore, I do not recommend repeating this, although if you want, then try it. The "ideal operation" of the coil, ... the creation of a uniform electromagnetic field, etc., is created by a flat coil, with a pitch (distance between turns) of winding equal to the diameter of the wire. This is implemented in some MD's...
(sorry for the Google translation)