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  #21  
Old 09-19-2020, 09:23 PM
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Welcome from Central Illinois!

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  #22  
Old 09-20-2020, 12:06 PM
Sun-Boy Sun-Boy is offline
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Default ...conspiracy...

Nope, no conspiracy theory here, , but posting schematics and theory of operation here isn't gonna happen, for obvious reasons. The analog version vs. the digital, the analog is limited but I think will still work well, I don't think I'll get the depth of the pulse machines, right now I'm testing with a small 3" test coil, so the distance to target is limited - it's roughly the diameter of the coil. Like I mentioned the discrimination is what really interests me, when I get my new 12" coil wound I'll be able to see if this is really feasible or not.
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  #23  
Old 09-20-2020, 04:54 PM
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Originally Posted by Sun-Boy View post
Nope, no conspiracy theory here, , but posting schematics and theory of operation here isn't gonna happen, for obvious reasons. The analog version vs. the digital, the analog is limited but I think will still work well, I don't think I'll get the depth of the pulse machines, right now I'm testing with a small 3" test coil, so the distance to target is limited - it's roughly the diameter of the coil. Like I mentioned the discrimination is what really interests me, when I get my new 12" coil wound I'll be able to see if this is really feasible or not.
Sun-boy, for starters, this is how all the past "incoming-new-mousetrap" narratives start. It's the "big secret" (aka conspiracy type hush-hush) designs that the md'r community is "welcome to lick their chops about". But .... no .... it's proprietary. So there will be no other information forthcoming. Sort of like an Area 51 alien narrative, eh ?

As far as the depth, don't worry: Even if your claimed machine, that can differentiate gold vs aluminum, only works down to 3" deep, then rest-assured : You will be a millionaire. I/we will "gladly pass" pesky gold rings that are deeper than 3" deep

But if this ends up being one of MANY machines that have claimed this in the past , there will be the obvious "out" clause: That, of course, it' not 100%. And naturally, no one's asking for that. Heck, most of us would gladly dig 30 tabs and foil for a single gold ring, eh ? But here's what that "out" has always inevitably allowed for : Is you can NEVER get the claimant to give an estimate of the odds. Eg.: 3 to 1 ? 30 to 1 ? 300 to 1 ? etc... In other words, at what point does it become "random odds" ? And NOT a machine which can tell aluminum apart from gold ?

Sorry to be a kill-joy, but after nearly 45 years in this, I've seen this come and go scores of times.
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  #24  
Old 09-20-2020, 08:53 PM
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The earliest electrical logging tools in the oilfield were conductivity, resistivity and spontaneous potential (SP) tools (1920s). These provided some limited, but very useful information. The oilpatch didn't end its logging tech there. Tom is right that some stuff went lead suit! They added a natural gamma radiation (like a Geiger Counter) log. Then they added some radioactive tools for density and neutron information. Magnetometer info is possible although I don't recall ever seeing one used for downhole logging. Another useful log is the sonic log. You can distinguish between different materials with interval transit time. Interval transit time is used to distinguish between real gold coins and bricks and heavily gold plated, on titanium core, counterfeits. They are nearly the same specific gravity, but differ in their sonic properties. Another interesting approach is ultrasound (like looking at babies in Mom's tummy). This can be imaged in some detail. Maybe Mom's tummy thickness isn't all that much different than our frequent scanning depth. Oilfield also uses ultrasonic logging tools.

All these different physical property approaches require multiple input channels, I would imagine, to more accurately characterize and/or display a target on a MD screen. I suggest that improved imaging and resolution and multi-channel signal integration would be additional frontiers that may be attainable in the relatively near term. The oilfield had to bring every physical property they could implement to bear to improve their scientific understanding of the subsurface. They need to work at several tens of thousands of feet of depth and even laterally into the rock face downhole. Yes, this stuff can get expensive and can be clunky if not miniaturized. Some of it also needs to be well coupled with the scanned medium to get a useful signal return. Maybe some of it can be used to improve MD scanning. Anyone up for microseismic surveys within 18" of the surface? Hmmm, microgeophones!

Sun-Boy, I've been wondering if it is theoretically possible to image a subsurface target using two different, but intersecting focused coil scan fields?

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  #25  
Old 09-20-2020, 09:37 PM
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Default ...subsurface imaging...

When you ask about the subsurface imaging, how large a target and how deep? I ask because you were mentioning deep oil field type of applications.
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  #26  
Old 09-21-2020, 12:33 AM
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Welcome to the hobby and to the Friendly Forum from Wisconsin's tundra. Trapper

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  #27  
Old 09-21-2020, 02:15 AM
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Originally Posted by Sun-Boy View post
When you ask about the subsurface imaging, how large a target and how deep? I ask because you were mentioning deep oil field type of applications.
I'm talking about metal detecting depths as we normally encounter them. I merely used oilfield tools as examples of applying additional technology to work around the limitations of a particular technology for characterizing the physical properties of investigational targets, solid rock for instance. In our case, solid metal cultural objects buried in soil or perhaps nuggets of elemental metal in placer deposits or even shallow veins in mineral exploration/prospecting.

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  #28  
Old 09-21-2020, 02:13 PM
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... from the Land of 10,000 Lakes - Minnesota! Happy hunting!

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