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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 1 Guest are viewing this topic. « previous next »
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Author Topic: The need for big deep gold detectors.  (Read 25320 times)
Aziz
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« Reply #140 on: Tuesday December 19 2017 10:01:13 AEDT AM »

  
Hi Aziz,
Who will you have making these coils for us? smile

Hi Digger,

we are making these coils by ourselves in the first instance.
I hope, Coiltek and Nuggetfinder or other coil maker companies will follow us and produce such coils.
(Where the hell are the coil spies? Ring up your boss immediately! It will pay off!!!!$$$$$$$$$$$$$)

Aziz
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« Reply #141 on: Tuesday December 19 2017 10:26:24 AEDT AM »

Let's make some assumptions.

The GPX-5000 has a RX Gain setting level from 1 to 20. The gain could be well linearly divided.
If a RX gain of 7-10 is the working limit on extremely hot ground with large mono coils, then we could have a gain rise of 2 times (+6 dB), when we crank up the RX gain up to 20. So this situation might work.

We also could design the RX coils to 600 µH inductance (that's sqrt(600/300)=1.41 times more loop turn count for the RX coil windings compared to a 300 µH RX coil).
We would be in the safe region (1.41*2 = 2.82 times).
This could really work.

sqrt(800µH/300µH) = 1.63 and the rest by RX gain setting.

Yeah, we have to increase the RX coil inductance somehow.

Aziz
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egixe4
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« Reply #142 on: Tuesday December 19 2017 11:46:50 AEDT AM »

  
Hi Ian,

thank you very much for the infos, you have nicely presented here.

Nobody has obviously used the separate TX/RX coil design in the new coils yet.
happy face

Cheers,
Aziz

What about the GPZ coil?
Is it not a separate TX/RX coil??

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« Reply #143 on: Tuesday December 19 2017 19:15:55 AEDT PM »

  
What about the GPZ coil?
Is it not a separate TX/RX coil??

Hi egixe4,

we want to kill the totally overpriced GPZ. So it doesn't make sense to upgrade the GPZ.


Well, I don't know anything about the GPZ internals, coil plug, the id chip in the coil (is there any?), etc.

One surely could make the principle working on a GPZ. The TX coil has not such a damping resistors due to bipolar constant current pulsing. The separate RX coil would reqire a damping resistor however.

The GPZ has not implemented the concentric co-planar separate TX/RX coil design. They have only the Super-D coil. 14" and 19" I think.

But the old detectors will run even with extra large coils very smooth and quiet. And they will punch deeeeeeeeeeeeeeeeeeeeeeeep into the extremely mineralized ground.

Cheers,
Aziz
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« Reply #144 on: Tuesday December 19 2017 19:47:31 AEDT PM »

Hi all,

I don't think, there is much RX gain margin in the detector settings. We also have to reduce the amplifier noise contribution a bit. It is critical.
So we must increase the RX coil gain by increasing the number of RX coil loop turns (inductance).

QED: RX coil wire must be thick. The total RX coil DC resistance should be 0.4 Ohm. The coil is getting heavy.
It is possible to use thin wire for the RX coil to reduce the coil weight. But the QED box requires impedance matching adjustment for such coils. And won't work for the other coils anymore.

SD/GP/GPX: RX coil wire can be thin. The total DC resistance should be below 5 Ohm.

And the RX coil capacitance should be low on both solutions. The self-resonant-frequency (SRF) should be approx. be at 500 kHz.or above.
Basket weave winding techniqe should meet the desired specification but requiers more winding space. But it is getting critical for small coils due to lack of free winding space. No problem with the big coils, there is enough space.

I have to add high inductance RX coils into the coil simulation comparison. This will take some time.

Aziz
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« Reply #145 on: Tuesday December 19 2017 22:19:38 AEDT PM »

Ok guys,

there is no other way. We must use thin RX coil wire and a basket weave winding technique to lower the RX coil capacitance.
The SD/GP/GPX detectors will cope with the high impedance RX coils.

But the QED requires a matching network in the coil adapter box for a specific RX coil impedance (lets say 5 Ohm for the RX coil).
Yes, we can make it work for the QED but these coils can't be used on the SD/GP/GPX detectors then.
****!

Aziz
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autitch
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« Reply #146 on: Tuesday December 19 2017 22:32:42 AEDT PM »

Just a thought.  Could someone please measure  the TX & RX inductance & resistance for a Minelab 11" or 18" DD coil.  I  remember  reading some time ago  that the RX inductance was much more than the TX figure but i can't  remember the numbers.  

Azia, I've been following  this  thread  with great  interest from my limited understanding what you are  suggesting is really  a  reconfigured DD coil. As a starting point, to suit  a Minelab GPX the "Revolution" coil Tx RX inductance should more closely match a Minelab DD coil figures.

Furthermore would there be any benefit  in a coil with 16"TX & 10.5"RX or is this concept  better suited to bigger coils?

AuTitch
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« Reply #147 on: Tuesday December 19 2017 23:16:40 AEDT PM »

  
Just a thought.  Could someone please measure  the TX & RX inductance & resistance for a Minelab 11" or 18" DD coil.  I  remember  reading some time ago  that the RX inductance was much more than the TX figure but i can't  remember the numbers.  

Azia, I've been following  this  thread  with great  interest from my limited understanding what you are  suggesting is really  a  reconfigured DD coil. As a starting point, to suit  a Minelab GPX the "Revolution" coil Tx RX inductance should more closely match a Minelab DD coil figures.

Furthermore would there be any benefit  in a coil with 16"TX & 10.5"RX or is this concept  better suited to bigger coils?

AuTitch

Hi AuTitch,

yes, a great idea getting some real figures for some ML DD coils.
I remember 450 µH and 5-15 Ohms for the RX coil.
But I would be very happy, when someone does some measurements like Ian previously did.

Yes, I am suggesting quasi a reconfigured DD coil but it is a concentric co-planar separate (large) TX / (small) RX with the RX coil damping resistors in the small coil adapter box.

"As a starting point, to suit  a Minelab GPX the "Revolution" coil Tx RX inductance should more closely match a Minelab DD coil figures."
Yes, we would get less problems. But the RX coil isn't much critical and we can compensate for some RX gain as the detector wouldn't allow much gain margin I think. The TX coil part should strictly meet the specifications: 300 µH, 0.4 Ohm. But that's not critical at all.

Furthermore would there be any benefit  in a coil with 16"TX & 10.5"RX or is this concept  better suited to bigger coils?
Yes, there is a benefit. This concept is not restricted to a special coil size. It works with any coil size. There are only practical limitations on small coils (winding space, coil capacitance, coil resistance, etc).

The revolutionary benefit is, that the most of the (shallow) ground noise will be bypassed outside the RX coil. And we have less EMI noise too. So we can increase the RX gain and get to the depth advantage region. For the big deep gold on extremely mineralized ground! We also have a better pin-pointing feature. Clear detection signals. And so on.

The new coil could cause a new gold rush on the gold fields.

Cheers,
Aziz
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« Reply #148 on: Wednesday December 20 2017 02:32:12 AEDT AM »

BTW guys,

we are also breaking the limits of the coil size.
You can use coils as large as you can operate with.
No more EMI noise.
Less ground noise.
Going super duper deep.
Operates also on hottest grounds.
Sensitivity to small targets does not decrease compared to the equivalent sized mono coil.
Super pin-pointing feature.

It's really a revolution.
Aziz
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« Reply #149 on: Wednesday December 20 2017 11:33:40 AEDT AM »

Hi all,

the Excel table is growing and growing...

BTW, I have to search the internet for pros & cons using large mono coils and I want to make a visual demonstration, how the new coil will shine over the traditional large mono loop coils. A situation, where the mono loop coil simply fails operation and how to get more detection depth.

A large coil is useless, when you can't operate it or have to decrease the RX gain setting for proper operation.

Oh man!, I'm tired... Cheers.. Aziz
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deemon
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« Reply #150 on: Wednesday December 20 2017 12:29:56 AEDT PM »

  
Hi all,

I don't think, there is much RX gain margin in the detector settings. We also have to reduce the amplifier noise contribution a bit. It is critical.
So we must increase the RX coil gain by increasing the number of RX coil loop turns (inductance).

QED: RX coil wire must be thick. The total RX coil DC resistance should be 0.4 Ohm. The coil is getting heavy.
It is possible to use thin wire for the RX coil to reduce the coil weight. But the QED box requires impedance matching adjustment for such coils. And won't work for the other coils anymore.

SD/GP/GPX: RX coil wire can be thin. The total DC resistance should be below 5 Ohm.

And the RX coil capacitance should be low on both solutions. The self-resonant-frequency (SRF) should be approx. be at 500 kHz.or above.
Basket weave winding techniqe should meet the desired specification but requiers more winding space. But it is getting critical for small coils due to lack of free winding space. No problem with the big coils, there is enough space.

I have to add high inductance RX coils into the coil simulation comparison. This will take some time.

Aziz

Hi Aziz !

Your coil idea looks interesting , but the RX ringing problem might be hard to solve ... Don't you think about shorted RX coil and a current signal pickup instead of voltage ? As you remember , I used this solution in my first recuperative PI and later in the square-wave approach and never had a problem ... so you can try it in your device as well .
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« Reply #151 on: Wednesday December 20 2017 14:15:02 AEDT PM »

  
  
What about the GPZ coil?
Is it not a separate TX/RX coil??

Hi egixe4,

we want to kill the totally overpriced GPZ. So it doesn't make sense to upgrade the GPZ.


Well, I don't know anything about the GPZ internals, coil plug, the id chip in the coil (is there any?), etc.

One surely could make the principle working on a GPZ. The TX coil has not such a damping resistors due to bipolar constant current pulsing. The separate RX coil would reqire a damping resistor however.

The GPZ has not implemented the concentric co-planar separate TX/RX coil design. They have only the Super-D coil. 14" and 19" I think.

But the old detectors will run even with extra large coils very smooth and quiet. And they will punch deeeeeeeeeeeeeeeeeeeeeeeep into the extremely mineralized ground.

Cheers,
Aziz

Hi Aziz,

I'm not suggesting making or upgrading coils for the GPZ
Simply replying to your statement made earlier
“Nobody has obviously used the separate TX/RX coil design in the new coils yet”

The Standard 14” GPZ coil is indeed a Separate TX/RX design Coil
Here is a picture of it for you.



* Super D coil .JPG (27.88 KB, 393x311 - viewed 122 times.)
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GARY
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« Reply #152 on: Wednesday December 20 2017 15:12:55 AEDT PM »

I wonder how much the depth potential of the DOD type round coil is governed by the length and width dimensions of its TX winding?

In the CC type round coil then its TX winding is much larger in dimension since it is around the circumference of the coil.

I had thought the dimension of the TX winding aids more towards outright depth?
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IBGold
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« Reply #153 on: Wednesday December 20 2017 16:34:00 AEDT PM »

Hi Aziz ,

You are correct with your inductance and resistances for the DD coils and they also do have a damping resistor on the RX I tested the concentric with the RX damping resistor on the QED and I do not believe they are compatible ( poor performance ) will try it on a Minelab and report back.

Regards, Ian. happy face now it works.
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Aziz
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« Reply #154 on: Wednesday December 20 2017 20:29:58 AEDT PM »

  

Hi Aziz,

I'm not suggesting making or upgrading coils for the GPZ
Simply replying to your statement made earlier
“Nobody has obviously used the separate TX/RX coil design in the new coils yet”

The Standard 14” GPZ coil is indeed a Separate TX/RX design Coil
Here is a picture of it for you.


Hi egixe4,

indeed, the GPZ coil has a separate TX/RX coil.
But they are in a more or less induction balanced arrangement and are not concentric co-planar design.

My bad in naming the new coil.

concentric coil: can be everything
concentric co-planar coil: can be everything
concentric co-planar TX/RX coil: better
concentric co-planar separate TX/RX coil: much better

Anyone with a better name?

Cheers,
Aziz
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« Reply #155 on: Wednesday December 20 2017 20:33:39 AEDT PM »

  
Hi Aziz !

Your coil idea looks interesting , but the RX ringing problem might be hard to solve ... Don't you think about shorted RX coil and a current signal pickup instead of voltage ? As you remember , I used this solution in my first recuperative PI and later in the square-wave approach and never had a problem ... so you can try it in your device as well .

Hi deemon,

we don't want to change or modify the existing detectors.
We only want to change the coil design.

Taming the ringing between TX and RX coil is not a big deal.
When properly damped, there won't be any ringing.

Cheers,
Aziz
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« Reply #156 on: Wednesday December 20 2017 20:51:52 AEDT PM »

  
Hi Aziz ,

You are correct with your inductance and resistances for the DD coils and they also do have a damping resistor on the RX I tested the concentric with the RX damping resistor on the QED and I do not believe they are compatible ( poor performance ) will try it on a Minelab and report back.

Regards, Ian. happy face now it works.

Hi Ian,

regarding the ML DD coil: is the RX damping resistor placed in the coil or coil plug housing or is it placed in the ML detector box?

It would be nice, if you could measure some DD coils for us. We would see the variance of the coil parameters. Would you be so kind and do some DD coil measurements for us?

Regarding the new coil: Please wait until I have presented the coil simulation results. I'm almost finished.
Cheers,
Aziz
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« Reply #157 on: Wednesday December 20 2017 21:06:21 AEDT PM »

  
I wonder how much the depth potential of the DOD type round coil is governed by the length and width dimensions of its TX winding?

In the CC type round coil then its TX winding is much larger in dimension since it is around the circumference of the coil.

I had thought the dimension of the TX winding aids more towards outright depth?

Hi Gary,

a good approximation for an 
equivalent mono loop round coil diameter = sqrt(length*width),
where length and width are the dimensions of the TX coil.

DOD coil design is not optimal for big deep gold on highly mineralized ground. You are dealing with high ground response too.

Cheers,
Aziz
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« Reply #158 on: Wednesday December 20 2017 22:07:52 AEDT PM »

Hi guys,

I have to draw some magnetic field sketches yet, what is happening in the highly mineralized ground with the magnetic fields penetrating the hot ground. You will see then the real benefit of the coil design. Simple air tests won't show the benefit of the coil design. Only tests on the real hot ground will reveal the real benefits. Unfortunately, my coil software does not support the simulation of magnetic fields in hot ground so I have to draw some sketches for you and they will take some time of course.

Following facts on hot ground:
- Magnetic fields get refracted when penetrating a hot ground. The more, the higher the ground mineralization.
- The steeper the magnetic fields, the less refraction is there. 90 degree magnetic fields won't be refracted at all.
- Most ground noise is caused nearby the edge of the TX coil (nearby the TX coil windings). The magnetic fields are very strong there. The Magnetic fields are very much refracted and they finally go almost horizontal in the ground layer and hence causing shallow affected ground noise.
- This large shallow affected ground noise is mostly bypassed around the RX coil and won't be detected in the RX coil. The RX coil is focussing to the steep (deep) penetrating magnetic fields.

I hope, I can show you this in a sketch.

Cheers,
Aziz
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« Reply #159 on: Thursday December 21 2017 01:02:36 AEDT AM »

I think, I'll write a PDF document to explain the principle.
All info will be compact and I can embed graphics, tables and so on.
But you have to wait longer for the results.
Aziz
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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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