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Offline kendavid
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« Reply #20 on: September 27, 2009, 07:42:47 am »
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Quote:Posted by goldigger
What do quarks say? Aflack?

goldigger


That's exactly what they say.. and then they Pierre'  Grin

Ken

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« Reply #21 on: October 01, 2009, 01:53:36 am »
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Quote:Posted by kendavid
That's exactly what they say.. and then they Pierre'  Grin

Ken


I think this forum is sharpening you a bit.  Grin

Its almost as funny as the theory on what makes the *noise* in a magnetometer..... you have not read THAT one, I bet: Domains??? Rubbing??? How weird! Check it out and you will see.  Shocked

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« Reply #22 on: October 01, 2009, 09:33:32 am »
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Quote:Posted by goldigger
I think this forum is sharpening you a bit.  Grin

Its almost as funny as the theory on what makes the *noise* in a magnetometer..... you have not read THAT one, I bet: Domains??? Rubbing??? How weird! Check it out and you will see.  Shocked

goldigger


Well maybe I haven't been sharpened enough because I searched the boards of the forum for domains and rubbing... I even searched the web and came up with an interesting geo-prospecting site but nothing turned up in this forum. Shocked
It sounded "funny" so I really want to read it!  Embarrassed

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Offline goldigger
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« Reply #23 on: October 03, 2009, 01:57:49 am »
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Quote:Posted by kendavid
Well maybe I haven't been sharpened enough because I searched the boards of the forum for domains and rubbing... I even searched the web and came up with an interesting geo-prospecting site but nothing turned up in this forum. Shocked
It sounded "funny" so I really want to read it!  Embarrassed


You will not find it on the forum, it was mentioned in several pdf,s that I down loaded in a Google search for fluxgate magnetometers... I will see if I can find the exact pdf and upload it. Poisanally, I think it was heifer dust!  Shocked

The lower the operating frequency, the higher the noise level, so I can not find any reason for NOT using a much higher frequency, say the colour burst frequency for NTSC TV, which is 3.579545 mHz and the crystals are cheap, plentiful, and so are the DIP oscillators. I happen to have some T62-6 toroid cores (powdered iron) that I might make a fluxgate sensor with.... I just HAVE to try it.  Cheesy

If I use a 14.31818 mHz xtal, and a FF div by 2, I can set up a phase comparator, with the other FF half, to control temperature variations, or compensate for same. Using 14.31818 should not interfere with the fluxgate action as the 2nd (and unusual) harmonic is what comes out of the second coil of the fluxgate sensor. This would be 7.15909 mHz.

Since I want the amplitude output, I can, also, feed this to a phase comparator, and get the frequency shift component caused by temperature drift. Right?  Cool

Then I will need a logger or strip chart.

I just happen to have a bunch of 3.5795 mHz xtals (hams use them for filters.)

goldigger

Here, have a look:

g

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« Last Edit: October 03, 2009, 02:12:24 am by goldigger »
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Offline kendavid
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« Reply #24 on: October 03, 2009, 03:45:21 am »
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Quote:Posted by goldigger
You will not find it on the forum, it was mentioned in several pdf,s that I down loaded in a Google search for fluxgate magnetometers... I will see if I can find the exact pdf and upload it. Poisanally, I think it was heifer dust!  Shocked

The lower the operating frequency, the higher the noise level, so I can not find any reason for NOT using a much higher frequency, say the colour burst frequency for NTSC TV, which is 3.579545 mHz and the crystals are cheap, plentiful, and so are the DIP oscillators. I happen to have some T62-6 toroid cores (powdered iron) that I might make a fluxgate sensor with.... I just HAVE to try it.  Cheesy

If I use a 14.31818 mHz xtal, and a FF div by 2, I can set up a phase comparator, with the other FF half, to control temperature variations, or compensate for same. Using 14.31818 should not interfere with the fluxgate action as the 2nd (and unusual) harmonic is what comes out of the second coil of the fluxgate sensor. This would be 7.15909 mHz.

Since I want the amplitude output, I can, also, feed this to a phase comparator, and get the frequency shift component caused by temperature drift. Right?  Cool

Then I will need a logger or strip chart.

I just happen to have a bunch of 3.5795 mHz xtals (hams use them for filters.)

goldigger

Here, have a look:

g


The only advantage of lower frequencies that I am sure of is penetration capability. The higher the frequency, the higher the power requirement for the same penetration. That's why VLF emitters were so popular with folks that use ground-resistivity detectors (which I think is heifer dust ... too many variables).

Do you think this "Zeus" technology is using fluxgate sensors and phase comparitors to detect temperature variation such as one would find with cavities, metals, water etc. versus normal soil? If so, what sort of power would be required at the higher frequencies to achieve the desired results (assuming a desired depth of up to 150 feet in normal soil).

Ken  Wink



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« Reply #25 on: October 03, 2009, 06:14:22 am »
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Quote:Posted by kendavid
The only advantage of lower frequencies that I am sure of is penetration capability. The higher the frequency, the higher the power requirement for the same penetration. That's why VLF emitters were so popular with folks that use ground-resistivity detectors (which I think is heifer dust ... too many variables).

Do you think this "Zeus" technology is using fluxgate sensors and phase comparitors to detect temperature variation such as one would find with cavities, metals, water etc. versus normal soil? If so, what sort of power would be required at the higher frequencies to achieve the desired results (assuming a desired depth of up to 150 feet in normal soil).

Ken  Wink




I do not know Zeus technology, but for land use, it does not have to penetrate anything, actually, just take a measure of the local magnetic field.... I can not see penetration... if the field (distortion?) of any orebody or buried metal, reaches the fluxgate.... it will be detected. The thing is it has to be sensitive enough to read the variation. Towed marine versions have to be away from the towing ship so definitely
need a lower frequency, maybe.

The driving signal, is in a toroid, and that does not create a field. The only leakage is straight through the donut hole, just like a black hole, where xrays leak out at the poles. The core saturation creates a 2nd harmonic, and the level of the second harmonic is the indicator.

When you have a crystal oscillator, its output is rich in odd harmonics, 3rd, 5th, 7th, 9th and so on and the even harmonics do not exist, or are very low level. That means 2nd harmonics are a bit unusual.

OK, I figure on using a T62-6 core or a T50-6 core, the winding on the core can be resonant while it is driven with a 5 or 6 turn loop. The outside winding can be resonant at the second harmonic, this would cut the harmonic noise, at least, but not the Domain Rubbing.  Grin

On the low frequency version, enough inductance to achieve resonance just can not be achieved.

I calculated a 40 turn T50-6 will be 6.88 uHY and will need 287.3 pf to resonate to a 3.5795 mHz driving signal. The input would be through a 23 turn loop wound over the resonant coil. The 2nd harmonic coil will have to be some where between 60 and 80 turns, I figure. To be resonance tuned with a variable capacitor. Or am I out to lunch, here.?  Shocked

Sensitivity is the critical thing.  :Smiley

goldigger

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« Reply #26 on: December 02, 2009, 12:35:57 pm »
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Hi GD, your site wouldn't open up, not there anymore... Chuck

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Offline GoldDigger1950Topic starter
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« Reply #27 on: December 02, 2009, 12:52:43 pm »
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Quote:Posted by chase3285
Hi GD, your site wouldn't open up, not there anymore... Chuck


Ah, well. Such is life. Try here:

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http://www.marketwire.com/press-release/Ivanhoe-Mines-Ltd-TSX-IVN-1077782.html


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