jasong

7000 - 15" CC X Coil 6000 - 11" OEM GB2 - 6" elliptical OEM Those 3 coils hardly ever leave any of these detectors now, they suit my prospecting style perfectly. I use the 6000 almost entirely for exploration and thus I prefer the OEM over the smaller Coilteks for ground coverage and depth purposes. It was a hard call between the 15" and 17" CC's, but in the end I realized the times I was glad for a less weight and more mobility were more than the times I was glad for a little more depth, especially as I started working steeper ground.

See if you can get lidar imagery of the area. Prospect pits/spoil piles are easy to see on those, but they have the be high resolution imagery. In the US a lot of the lidar is still the low resolution and the prospects are harder/impossible to see on it, I'm not sure about Australia resolutions.

I wonder if there is any benefit to be had by concentrating flux density via specifically placing ferrous components wound along with a coil (like a steel guitar string for instance). Or ferrite components maybe? Or if that would affect both the ground balance as well as the inductance of the coil such that no (or negative) benefits are gained?

Interesting. The area under each curve should be proportional to the total energy contained in the magnetic field at a given time during the pulse (not equal to, just proportional). So integrating the area below each coil type's curve should give a rough idea of the overall efficiency of each type of coil, by some proportionate factor. IE - It seems to show your wire spacing model which reduces the stray capacitance improves the efficiency of the coil. More of the pulse energy is effectively stored in the magnetic field rather than lost to stray capacitance. It would be interesting to make an algorithmic FE program that brute forces a great number of different designs with the goal of maximizing the area under that curve. Have you experimented with gradient coil windings like they use in MRIs to produce specific linear variations in the field? Not exactly similar, but something like changing winding density along the Z axis? Or other variations... Potentially with the aim of making a really deep coil that doesn't need to be really large at the sacrifice of sensitivity to smaller shallow gold? I guess with these coils there are so few windings that options are kinda limited though. I'm just thinking in terms of shaping those curves to match specific use cases - putting as much of the energy as possible into the places it's needed for different uses, while minimizing energy in the places it's not needed.

$2000 gold inflation adjusted from 2020 is about $2400 today. Gold so far has basically inflation adjusted itself. In USD anyways. $3000 gold and I bet we see the inklings of another gold rush in places around the world where the geopolitics allow for it. Right now I'm not seeing a big rush to gold exploration again here with the Jr miners/exploration companies yet. But there is some activity. They seem to have interest in diversifying to copper/gold deposits though. But I'm hearing some whispers of interest whereas it was kinda dead for a few years. Uranium is the new lithium. Lots of renewed activity.

Keep in mind though - I said the same statement after using the X Coils (and I got flack for it too). I said to me the X Coils obsolete the need for the NF coil. And I still stand by that statement today. But the NF is good coil - great to those unwilling to cut a cable. But to me, that coil was obsolete before it was even released. Similarly, my 4500 hasn't left my closet since I got X Coils and especially since I got my 6000. The 4500 and 5000 are to me very obsolete platforms - I have zero interest ever running them again. And I believe as a platform, the 7000 itself in terms of electronics design and ergonomics is already close to obsolete if it had any serious competitor. It's an old, stodgy, dinosaur platform to me that feels like how the 3500 felt to me when I first started detecting for gold. If not for the X Coils, I doubt I'd use it much anymore quite honestly, but I also don't do a lot of ultra accurate patch cleaning anymore these days either, clearly there is no equal to it yet there.

The reason I am stating my opinion is based on what I am reading in the old and newer modified ZVT patents Bruce Candy outlines that technically speaking, ZVT should be superior to any type of PI due to the relative lack of X contamination during sampling without the pulse decay, as well as the lack of a decay time interfering with target sampling. That isn't what we are seeing today with current models though. At least not exactly. Given that the SDC (IMO anyways) has better or at least equal X ground performance generally than the 7000, and that the 6000 can almost keep up with the GPZ in terms of small bit sensitivity - it stands to reason that the 7000 implementation of ZVT was not optimal early on and has room for measurable improvement. From that, it would stand to reason that almost 10 years of development time should have resulted in a more optimal ZVT implementation by now. Especially in terms of dealing with X component in soils, as well as further refining target sampling improvements. If I've made an error in reasoning there, I'd be curious what it is. Because lacking insider information, that seems like the logical conclusion to make based on the data the public have at hand. I understand the whole withhold technology at a drip pace thing Minelab does, for sure. That's another issue, it's hard to predict what the business department does though, and I suspect it changes with the wind sometimes, so I refrain from speculating there. But if they release an 8000 with better X handling than the SDC, improved target response for both short and long time constants, and more ergonomic to match the 6000 then I stand by my statement - to me that would obsolete the SDC, 6000, and 7000 entirely - as in - I doubt I'd use any of those 3 again if I had such a machine. Improve the EMI filtering and my opinion would likely be strengthened.

Well alright then. Pardon my lack of industry connections in which to base my own opinions, I am of course limited to the public information the rest of us are limited to. I detailed the reasoning behind my opinion. But if the conversation is just "I know secret things" then I guess there isn't much to talk about is there? While I may be disappointed if the 8000 doesn't meet my expectations, it's a minor thing. I have more fun looking at technical data available and thinking about what might be. But that's turned into no fun here with the sarcasm, so I'll move on.

Based on what?

Not sure if it's a bean counter thing or an engineering thing. There is nothing to do but speculate since Minelab remains so opaque about literally everything they do. Based on their patents though, I suspect it's the former and not the latter, since the verbiage used in the 2023 patents seems to indicate exactly this - PI's should have no business being as sensitive or as good on X ground as ZVT machines. Yet, they seem to be competitive compared to the 7000, in the SDC's case it's handles X ground better I think while still being quite sensitive. So the logical conclusion to me would be a new ZVT machine improving measurably, at least in terms of ground handling.

Theoretically, the big thing with ZVT was it's immunity to X soil components due to the lack of contamination from having to sample during long decay periods like with a PI. While simultaneously having much greater sensitivity for the same reasons - no pulse decay to muddy the waters, sampling at zero voltage instead, thus it can hear ultra fast transient targets (tiny gold). This should mean that technically the GPZ should vastly outperform the SDC in bad ground. And the 6000 should have no business being close to as sensitive as a good ZVT machine, which means the 7000 was at least semi subpar for a ZVT machine if a PI can match it. I expect improvements. The 8000 seems like it should improve greatly on both sensitivity as well as bad ground handling (well, X anyways, maybe not C/salt). I think many people are expecting far too little from whatever this next machine should be, because all this stuff shoulda been doable by 2017. Now we have a decade of EMI mitigation hardware/algo advancements, better coils, better ergonomics. My expectations are high for this machine. If it ever shows up. I expect a machine that obsoletes the SDC, 6000 and 7000 entirely.

I think the last part is definitely true, maybe the first part too. I did some experiments a while back and found that both large iron targets as well as high EMI levels caused the 6000 to adjust itself in manual, not just in auto. Further, by memory, I believe it stayed dumbed down even after the iron and EMI were removed to some degree, requiring a reset to really trust it was back to normal. I noticed this happening in the field at first but was unsure, but when I posted here a while back about this effect, other people didn't seem to see it, so I tested in my shop and found enough to change my trust in the 6000 personally. I've posted about this a few times in the past here. 6000 is a prospecting machine only to me. I toss it into auto+, and use it for what it is. What happens under the hood is too opaque for me to ever trust it over the 7000 for cleaning applications because there is no way to verify if I am running sub-optimally or not. This is why they need to at least provide some bar graph readouts to show an operator what the detector has adjusted, if controls aren't provided. Not knowing is not acceptable for pro-sumer grade machines IMO. I do like having the auto option though, and I believe it will improve in future releases.

Not coincidence, everything you do online is monitored and fed back to you as ads now. Your browser activity is scraped, your emails are read and monitored. And if you think that's bad, it gets worse. A guy on Youtube a year or two did an experiment to see if his phone was listening to him while it was just sitting there idle. Experiment went something like this: He had no dog, so he chose to start randomly talking about dog toys around his phone (something he shouldn't be suggested ever) for a while. Sure enough, eventually the ads he was getting started showing dog toys. They are watching and listening to your daily life, not just internet activity. Everything you do today is monitored and resold in order to get max clicks from you. Your personal life is a commodity and you are not getting comped for the commoditization of it either. Our personal details are the modern livestock.

Yep that's the one, thanks.

I inherited a few boxes of of older publications from an old oil well log library. Among them is a booklet by the DOI called "Gold in Meteorites and the Earth's Crust". I don't think it's available online though. No scanner here, so here is a photo of the chart from this paper on the general gold content in many types of meteorites, just for general interest. 1ppm = 1 gram/ton more or less. So it seems the iron meteorites are the ones that tend to have the highest gold content.