northwest The need for big deep gold detectors.
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australian electronic gold prospecting forum.com  |  Detector Technology and Electronics and new detectors  |  Detector Coils  |  Topic: The need for big deep gold detectors. 0 Members and 4 Guests are viewing this topic. « previous next »
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Author Topic: The need for big deep gold detectors.  (Read 22505 times)
Eski
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« Reply #780 on: Monday June 25 2018 17:46:57 AEST PM »

thanks for that Ian ,
I think the later tx coil is the one with the "round" Windings ?
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Eski
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« Reply #781 on: Monday June 25 2018 17:50:34 AEST PM »

ALso Ian , in that last coil the tx and rx are all encased in the one casing? roughly what sort of separation is there between the 2 coils?

On a side note, i may have missed it , but what machine are you running this on?

Looks good , reckon you'll be testing in no time!

sorry for the twenty questions....
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IBGold
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« Reply #782 on: Tuesday June 26 2018 17:11:23 AEST PM »

Hi Eski the last 3 pictures are the TX mono coil only not to be used in conjunction with the RX coils the others are RX to go with existing TX Mono's as Aziz's ideas.

Regards, Ian. happy face
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Regards, Ian.
Muntari
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« Reply #783 on: Monday November 5 2018 12:37:29 AEDT PM »

Hi All,

Following on from where I left off, many moons ago....
I have managed to get back onto building up my suite of coil platforms that can be taken into the field for real world testing.
Not being 100% convinced with flat wound coils, I back-tracked a bit to look at the bundled versus flat /spiral  arguments and how I could go about getting the best out of both in a large and medium format coil, so from say 300 to 490 mm diameter loop.
The latest posts regarding ground loops and the Bismark coil have prompted me to start posting a little more.
Its also interesting to note my flat wound posted a while ago, resembles the Bismark, so it shows size and ratio thinking are very close and that Aziz was on the right path.
I am convinced from recent field tests that concentric / co-planar coils have their place in nugget hunting and that there is an optimal size and ratio of TX to RX that is required to achieve the best performance.
Concentric designs are not new, they have been around for many years but because of their weight to size ratio, have been relegated down the list on preferred coil types.
Despite this, they have a great SNR  which is very important when looking for deeper objects and hence,the position of the  RX coil, while not critical, is best centred on the TX coil.
In bench tests and field tests alike, I have found that moving the RX closer the TX results in same target depth in air but the SNR degrades.
Likewise the ratio of inductance between TX and RX, you can increase RX gain by adding extra turns but only up to a point for each given size of TX and that ratio is not linear.
Then you throw in the bundle versus flat arguments versus Litz wire and other wire types and the waters become quite muddy.
Everyone has their view on what is best for them, manufactures and serious users and experimenters alike (Ian) have spent many years looking for the holy grail of coils and come up with some outstanding results but like Aziz, I like to question the thinking as it motivates me to find better ways of doing things.
From that thinking I put the theory into practical experiments and get out an test for myself, even if its been done before...I want my data not someone else's, that might not even be available anyway.
So, in the spirit of keep Aziz's original post and theory alive, I will try and post progress over the next year or so on what I've been up to...
I'll post what I can as I get time.
A couple of photos attached on the latest test piece, 3D printed formers that snap together
Print time was 5 hours for the set with clips, TX 390 mm RX 280 mm hieght 10mm width 15 for RX 20 for TX
Total weight of pictured assembly, including wire, is 250grams
A foam spacer is added sprayed with shield material and its ready for field test.

Cheers

Muntari




* Concentric_TX_form1.jpg (135.74 KB, 640x480 - viewed 156 times.)

* Concentric_TX_form1_7X.2.jpg (169.79 KB, 640x480 - viewed 154 times.)

* Concentric TX_RX_1.jpg (93.54 KB, 640x480 - viewed 154 times.)

* Concentric TX390_RX280.jpg (100.55 KB, 640x480 - viewed 154 times.)
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Huego
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« Reply #784 on: Monday November 5 2018 13:43:49 AEDT PM »


Beautiful & tidy and light... great work!!
What detector will you use for testing your coils Muntari?
QED or ML?

regards, Huego
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Views expressed are without prejudice, in the public/consumer interest & their "right to know". Huego reserves his right to: think freely & speculate, make & correct his mistakes, change his mind, expose fools & denigrators if/as required. Fighting greed & injustice with facts as he sees them.
Muntari
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« Reply #785 on: Monday November 5 2018 14:13:21 AEDT PM »

  

Beautiful & tidy and light... great work!!
What detector will you use for testing your coils Muntari?
QED or ML?

regards, Huego

Hi Huego,

Thanks,  yes , needs to be ultra light. detectors used are QED, ML and one other.

Here is shell for last posted,  weight is calculated to be 280 gm so all up will be slightly less than 600 gm...

The design allows for flat and bundle wound

cheers

Muntari




* Concentric housing.jpg (60.44 KB, 640x480 - viewed 149 times.)
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GARY
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« Reply #786 on: Monday November 5 2018 17:12:34 AEDT PM »

  
Hi All,

Following on from where I left off, many moons ago....
I have managed to get back onto building up my suite of coil platforms that can be taken into the field for real world testing.

I am convinced from recent field tests that concentric / co-planar coils have their place in nugget hunting and that there is an optimal size and ratio of TX to RX that is required to achieve the best performance.

So, in the spirit of keep Aziz's original post and theory alive, I will try and post progress over the next year or so on what I've been up to...I'll post what I can as I get time.


A few years back I was privileged to view some in-ground testing which to me displayed how well a CC coil could perform during some in-ground tests at a purpose built test site with the ground at the site being mineralised enough to produce problems using the Normal timing on the GPX. That particular CC round coil was 14" in diameter and appeared to be capable of handling the mineralised ground at the test site better than the larger round Mono coils, an 18" and 22", it was being compared too over the gold nuggets being used for the test results at various depths. Also the CC coil appeared to operate smoother than the Monos when the GPX was set in its Normal timing.

Gary.
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Muntari
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« Reply #787 on: Tuesday November 6 2018 00:07:30 AEDT AM »

Hi Gary,

Yes, that does not surprise me at all. The CC coils do handle mineral soils well in my opinion. The Coiltek ellipitcal mono 600 x 300mm  I have is insanely noisy over mineralized ground compared to the the  CC coil type shown in my earlier posts now while that is to be expected given the mono's size,  the standard ML 280mm round DD is also noisy compared to this concentric which also has a receive coil at 280mm and that was interesting as the ML was my go to coil for tough soils.
The round CC design requires more overlap on the swing but I have an elliptical version in the works too, I just have't completed the cad design for it just yet.

In the workshop, the CC is fine with all the hash produced by my PC and the 3D printer and cnc running close by, in the field it is a stable coil design and I am glad I went on testing with it. Still want to try a few more things which are mainly to do with the weight reduction and ergonomics than anything else.

more later...

Cheers

Muntari
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Doug
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« Reply #788 on: Tuesday November 6 2018 10:48:03 AEDT AM »

  
Hi Gary,

Yes, that does not surprise me at all. The CC coils do handle mineral soils well in my opinion. The Coiltek ellipitcal mono 600 x 300mm  I have is insanely noisy over mineralized ground compared to the the  CC coil type shown in my earlier posts now while that is to be expected given the mono's size,  the standard ML 280mm round DD is also noisy compared to this concentric which also has a receive coil at 280mm and that was interesting as the ML was my go to coil for tough soils.
The round CC design requires more overlap on the swing but I have an elliptical version in the works too, I just have't completed the cad design for it just yet.

In the workshop, the CC is fine with all the hash produced by my PC and the 3D printer and cnc running close by, in the field it is a stable coil design and I am glad I went on testing with it. Still want to try a few more things which are mainly to do with the weight reduction and ergonomics than anything else.

more later...

Cheers

Muntari

What is the optimal way to run these coils?
doug smile
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Muntari
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« Reply #789 on: Tuesday November 6 2018 12:03:00 AEDT PM »



What is the optimal way to run these coils?
doug smile
[/quote]

Hi Doug,
With the ML GP3000, pretty much the same setup as DD but with more sweep overlap and don't use too much tracking.
The threshold is noticeably more stable in mineralised soils
What will be noticed is how quiet they run compared to a mono and DD of comparable size.
I have yet to fully optimise the CC coil for the QED so I cant really give an answer on optimal setting for it just yet,its a bit too early,however, it does work with it.

I will know in a few months the optimal settings for each detector once I have completed all my testing.

The biggest issues being faced is getting time and obtaining Litz wire and so I have been experimenting with other wire types, so things will change accordingly. smile
I have a number of projects on the go all in various stages but all interrelated.

cheers

Muntari

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Doug
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« Reply #790 on: Tuesday November 6 2018 12:33:16 AEDT PM »

  


What is the optimal way to run these coils?
doug smile
[/quote]

Hi Doug,
With the ML GP3000, pretty much the same setup as DD but with more sweep overlap and don't use too much tracking.
The threshold is noticeably more stable in mineralised soils
What will be noticed is how quiet they run compared to a mono and DD of comparable size.
I have yet to fully optimise the CC coil for the QED so I cant really give an answer on optimal setting for it just yet,its a bit too early,however, it does work with it.
On the revamped MPI design, likewise, settings are not like a standard PI so it would not help to post findings on that...

I will know in a few months the optimal settings for each detector once I have completed all my testing.

The biggest issues being faced is getting time and obtaining Litz wire and so I have been experimenting with other wire types, so things will change accordingly. smile
I have a number of projects on the go all in various stages but all interrelated.

cheers

Muntari


[/quote]

thanks! happy face
I guess the most sensitive coil would be bundle wound TX and flat wound RX?
Keep us informed  on the MPI project particularly for new member who might be unaware of what it is.
Here is the link to the MPI project
  
link-http://australianelectronicgoldprospectingforum.com/diy-detectors-read-all-about-the-aziz-mpi-and-moodztinkerer-pi-detector/blast-from-the-past-mpi/
doug smile
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Muntari
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« Reply #791 on: Tuesday November 6 2018 12:53:35 AEDT PM »

"I guess the most sensitive coil would be bundle wound TX and flat wound RX?"

It could very well be as there is not much difference on the bench and in most hot soils I have tested (between fully flat and bundle).
TX coil still needs to be fast but with good design and construction, bundle wound should suffice.
Getting the ratios correct is the balancing act needed.

The revamped MPI is just going to be my test bed, it will never be sold commercially, it's too complicated and costly to produce and I don't need the BS that comes with it  happy face
In a nutshell, it is a hyped up DSP engine with data logging capabilities, invaluable for field research
Its just good to have a new perspective on my old designs...and I'm having too much fun with coils atm.

cheers

muntari
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« Reply #792 on: Tuesday November 6 2018 14:29:05 AEDT PM »

  
The revamped MPI is just going to be my test bed, it will never be sold commercially, it's too complicated and costly to produce and I don't need the BS that comes with it  happy face
cheers
muntari

Costly detectors are no problem for some people who are happy to fork out $10K!
doug  smile
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« Reply #793 on: Tuesday November 6 2018 14:35:52 AEDT PM »

  
Getting the ratios correct is the balancing act needed.
cheers
muntari
What do you mean by this? The inductive ratios  between the TX/RX or simply the wire turns ratio? One idea you might think about is one that the late Jim Stewart was perusing with his CC coil and this was to be able to raise or lower the center coil.Jim never fully explained this idea so I am not sure what was behind it.
doug smile
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Muntari
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« Reply #794 on: Tuesday November 6 2018 14:54:03 AEDT PM »

Hi Doug,

The inductive ratio / RX gain and SNR balancing act.
On the CC coil yes vertical adjustment, I did this with the MPI where each RX coil was raised or lowered in respect of it's position within the linear array.
Could be interesting to re-visit but it will essential only change the RX signal gain, in an array it was important, in a hand held it would allow optimum SNR but at a cost of depth.

Cheers

Muntari
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Muntari
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« Reply #795 on: Tuesday November 6 2018 16:31:59 AEDT PM »

  
  
The revamped MPI is just going to be my test bed, it will never be sold commercially, it's too complicated and costly to produce and I don't need the BS that comes with it  happy face
cheers
muntari

Costly detectors are no problem for some people who are happy to fork out $10K!
doug  smile

Sorry missed this post, yeah, I guess so but for me, I am happy to enjoy what I do without all the problems  happy face
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« Reply #796 on: Tuesday November 6 2018 22:55:34 AEDT PM »

Quote
The revamped MPI is just going to be my test bed

Is that the one you chucked out all the pcb's ?
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Muntari
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« Reply #797 on: Wednesday November 7 2018 09:57:35 AEDT AM »

Yeah, that's the one, chucked out everything to do with it, hardware, software, engineering notes, the whole lot.

That was along with another 25 years worth of projects and surplus electronics stuff that was just cluttering up my workshop.

The MPI circuits have been redesigned using latest technology, its half the size and uses off the shelf DSP modules and custom front end boards.
I just had to research new components, redesign boards and write a whole lot of new code, the method was still in my head so not so bad.

cheers

Muntari
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« Reply #798 on: Wednesday November 7 2018 13:08:15 AEDT PM »

  
In a nutshell, it is a hyped up DSP engine with data logging capabilities, invaluable for field research

cheers
muntari

The data data logging capabilities  are in my opinion incredibly important both  for coil testing and data acquisition over various ground types.  The latter may lead to  better or individualized ground cancelling algorithms.
doug smile
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« Reply #799 on: Wednesday November 7 2018 14:09:49 AEDT PM »

Yes, as a tool, data loggers are a must for field research and further to that, a tool with some DSP grunt is invaluable for filtering and segmenting data on the fly.
You can exclude, include, mix data depending on the experiment.

On CC coils, you mentioned Jim's idea of adjusting the RX vertically and I said I had done this with the MPI too.
Well, to add to this a little more, I have previously mentioned my use of gradiometer type coils which is akin to Aziz's 'top hat' in many ways.
Now this is where you can use the adjustment, the top RX coil is moving in relation to the co-planar RX /TX combination and the reason it is done, is to achieve better SNR without the loss of depth that would happen if you moved the co-planar RX up or down relative the TX.
If you move it up, you loose equivalent depth.
Thanks to Corbyn's and Colani's early work and MRI research, the light bulb turned on in my head a long time ago, not about the electronics, about the coils.

more later

Cheers

Muntari

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australian electronic gold prospecting forum.com  |  Detector Technology and Electronics and new detectors  |  Detector Coils  |  Topic: The need for big deep gold detectors. « previous next »
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