Jump to content

Search the Community

Showing results for tags 'detector tech'.

  • Search By Tags

    Type tags separated by commas.
  • Search By Author

Content Type


Forums

  • Metal Detecting & Gold Prospecting Forums
    • Meet & Greet
    • Detector Prospector Forum
    • Metal Detecting For Coins & Relics
    • Metal Detecting For Jewelry
    • Metal Detector Advice & Comparisons
    • Metal Detecting & Prospecting Classifieds
    • AlgoForce Metal Detectors
    • Compass, D-Tex, Tesoro, Etc.
    • First Texas - Bounty Hunter, Fisher & Teknetics
    • Garrett Metal Detectors
    • Minelab Metal Detectors
    • Nokta / Makro Metal Detectors
    • Quest Metal Detectors
    • Tarsacci Metal Detectors
    • White's Metal Detectors
    • XP Metal Detectors
    • Metal Detecting For Meteorites
    • Gold Panning, Sluicing, Dredging, Drywashing, Etc
    • Rocks, Minerals, Gems & Geology

Categories

  • Best of Forums
  • Gold Prospecting
  • Steve's Guides
  • Steve's Mining Journal
  • Steve's Reviews

Categories

  • Metal Detector Reviews

Categories

  • Free Books
  • Bounty Hunter
  • Fisher Labs
  • Garrett Electronics
  • Keene Engineering
  • Minelab Electronics
  • Miscellaneous
  • Nokta/Makro
  • Teknetics
  • Tesoro Electronics
  • White's Electronics
  • XP Metal Detectors
  • Member Submissions - 3D Printer Files
  • Member Submissions - Metal Detector Settings

Find results in...

Find results that contain...


Date Created

  • Start

    End


Last Updated

  • Start

    End


Filter by number of...

Joined

  • Start

    End


Group


Website URL


Facebook


YouTube


Instagram


Twitter


Pinterest


LinkedIn


Skype


Location:


Interests:


Gear In Use:

  1. This was mentioned by geof_junk in another thread and had a little Google. Found this https://www.phys.k-state.edu/reu2011/nnorvell/Metal_Detector_Research.html I don’t really understand the technical side of metal detectors. Does this have any application to current day detectors? Will it help cancel out ground noise more? Will the current crossing/not crossing the ‘bridge’ tell you something about what is under one of the receive coils. Although I don’t understand it, I am amazed and a little in awe of those that do 👍
  2. This is a topic relevant to every(?) form of detecting -- ground coverage. I'll list several questions concerns I've had but any replies of course aren't limited to these, nor do they need to address any of them. Just tossing out some ideas to prompt further discussion. 1) What methods and efforts do you apply to ensure full ground coverage in the cases where that is one of your goals? 2) Is your sweep a straight line path or an arc? 3) How long is your sweep? 4) How much do you overlap consecutive sweeps in the direction you walk? 5) How much do you overlap side-to-side swings when following parallel paths (e.g. when walking two side-by-side swaths in the same direction how much does the left end of one path overlap the right end of the next path or vice-versa)? 6) Have you ever measured your coverage? How well do detectors with GPS (e.g. Minelab GPZ-7000 and Minelab CTX-3030) monitor ground coverage to this detail? Have you used other devices to measure ground coverage. E.g. I can imagine a drone with camera could provide useful data. Are there smartphones app that would help quantify coverage?
  3. Just dreaming... What'dya think? Minelab technology going on the next moon mission? X6 must be space-worthy.
  4. If this question has been addressed elsewhere, I apologize in advance and hope someone can give me a link for it. I have noticed that other companies besides Minelab are coming out with PI detectors for less than $3K. How do these detectors compare to the best Minelab detectors for Gold and also relic hunting?
  5. On the Anfibio Multi (and I think Kruzer & others) there is a definite step in sensitivity between 39&40 Gain and again between 69&70 Gain. Is this a change in the Internal Threshold? In a way this would be the inverse of the way the F75 adjusts sensitivity according to Mike Hillis. Regardless, it is a very good set up in difficult sites. Most NM users know about the difference in response speed between 89 & 90 Gain on 3DI. This is different. I had read about these steps in a forum post that quoted Alper of NM. I can't seem to find that post now that I want to re read it.
  6. https://patents.google.com/patent/WO2021016649A1/en?assignee=minelab&scholar&oq=minelab&sort=new This is the most out of this world Minelab detector patent I've ever read. There is so much here, some very sci-fi like, I don't even know where to start. My takeaway is they seem to be positioning themselves for a drone based detector eventually (main details in this patent could be easily transferred to a drone based platform - IMU, GPS, magnetometer, heads up display, FPV, remote control, robotic/vehicle mount, etc) . That is 100% a guess. But in the meantime, there is some interesting, novel items in the pipeline that we might actually see on a machine in closer future? No clue if this is a coin machine or gold machine or if it's something they are actually working on right now or just trying to get control patents on such things for the future which may or may not arrive. One thing is for certain, Minelab is BUSY in the engineering department. A few of the highlights: Heads up display over glasses/head mounted display (aka augmented reality). Settings, target visualization, shading of detected/not detected areas (I asked for this specifically 5 or 6 years ago here, awesome to see it in a patent now). Plus a camera showing the coil (why would you need that if not operating remotely as from a drone?) The detector has a camera, IMU (accelerometer) and magnetometer to determine position with accuracy. The IMU tracks the position of the coil in real time in relation to both the ground and the target, and combined with the camera video feed will provide a "visual" of the target in the ground through the glasses/head display, as in form of a heat map which increases accuracy with each pass of a coil over the target. A GPS tracks the machine position to properly map the IMU/coil visual target data on the ground and let's a user see the mapping as they detect. This data is recorded for future historical use and can be shared. Centimeter accuracy with the visual target heat mapping. Potential operators/users include entities other than humans such as "robots" and "an AI (artificial intelligence) using a metal detector" and this line: "The metal detector may be handheld, mounted on a robotic arm of a vehicle or a robot." Wireless connectivity to computers and phones, transfer of files containing settings configurations from instructors or expert users Remote control of the metal detector through apps on laptops or phones Ability to upload maps, including detecting data, historic human activity, buildings, or other items that seem to indicate custom mapping capability Internet connectivity, potential control through the internet (again, why if not for a drone type device?) "Teamspeak" to other detecting members in the area wirelessly Visual/spatial discrimination Accurate depth measurement Synthesized audio mode, eliminating noise completely and allowing the detector to "recreate" a synthetic audio stream based on data from prior swings Delayed audio processing (enhanced audio) mode or real time audio mode, ability to seperate multiple close targets, reason for this I venture a guess why below ---> This patent actually seems to be describing a completely new method of RX in a detector. Which is actually similar in some ways to the wacky idea I had years ago of reducing EMI/ground noise by emulating a radio telescope array. But in this case they appear to be describing a fairly ingenuous method of doing something similar with only one coil by monitoring RX of the same target at different points in the swing (with the IMU tracking these points) and combining all those RX signals. In this way (and this is my guess, the patent doesn't explain this), you can form a sort of comparator, gradiometer, or interferometer to seperate the wheat from the chaff, so to speak. If that's what they are doing, then I find it to be brilliant. If not, then I just gave them one hell of an idea to patent for the future. That probably sounds like jibberish to non-engineers. But I want people to understand the brilliance in simple terms. Consider this: EMI is random. At any given point in your swing you'll get noise here, but not there. So if you compare two points in the same swing, you will hear noise one point but not the other point because the "zap" already ended. But you might hear a good target at both points in the swing since it's not random like EMI, it's always there in the ground. So, you can effectively eliminate EMI by comparing what signal is not there at two very close points in the swing, and keep the target since it's always there. Similarly, with ground, the ground changes as the alluvium changes since soil is inhomogeneous. But a target is still the target. So, a similar method can be applied to the ground. In theory, you could use ideas like this to essentially get rid of the Difficult type timings and keep your gains boosted high, and deal with EMI/ground in this way instead which does not require reducing sensitivity. A totally new, novel approach to RX in a metal detector. The audio processing is very slightly delayed because they are using that time to compare measurements at a few different coil positions before letting the audio processor signal that there is a target present. That's my guess. If that isn't what they are doing, then someone else should patent that and thank me for it later when Minelab buys it. Either way, they have something totally new in the RX department here. And the future of detecting looks bright and interesting to me still.
  7. Hello, now here’s an opener that might just get me banned on my first post! Bear with me, my intentions are pure :) Does anyone know if it would be possible to jam an MD signal? The reason I ask is to combat the evident problem we have in the UK with “nighthawks”, illegal detectorists. Over here, any landowner can grant permission for detecting on their land (with caveats, known historic sites are protected by law). What often happens is that such a permission is granted and a detectorist innocently sets about his / her business. Someone less scrupulous spots this person and assumes there may be something important there, so shows up at night with a couple of friends and the landowner awakens to a field / lawn full of holes, then bans metal detecting. Historic sites are also looted. Just an off the wall question, how tricky would it be to build a device to block this on a piece of land? Anyone any ideas?
  8. 99% of my detecting is done on central Florida beaches. Since it’s impossible to establish a well stocked test garden at a public beach, I sorta brought the beach home with me and developed my own private beach garden! I cut slots in two large empty chlorine tablet buckets at various depths as shown from 2 -16 inches. I then filled one with New Smyrna Beach sand and the other with soil...for the few times I land hunt around here. I embedded numerous examples of ferrous and non ferrous targets into paint stirring sticks. I also have several blank sticks I use for gold and silver jewelry as well as artifacts that I don’t want permanently attached to a stick. I then insert the target(s) in the slots, each at its desired depth, and start scanning. This allows me to rapidly change the targets, depth and relative position of each. I can now test for sensitivity at depth as well as separation of ferrous and non-ferrous targets in a variety of scenarios using actual beach sand where I do my detecting. If I want to test in wet salt sand, I just soak the bucket sand with authentic sea water that I also brought home from New Smyrna Beach...and the Atlantic Ocean never even missed it. 😉 Works for me.....
  9. Found this patent that Whites filed and got a patent on in 2014 on a hybrid IB/PI machine. https://patents.google.com/patent/US20110316541A1/en Curious if anyone heard anything about this. Maybe Garrett will take it on?
  10. I know we have had some great advancements in VLF metal detector's over the recent past, but I am hoping that we can keep some of the older design features that seemed to work well. My favorite new technological features being offered in VLF's are Multi-IQ and single frequencies options, fully programmable settings, waterproof, noise cancel, USB chargers, li-ion batteries, Bluetooth headphones, prospecting & coin/relic options, and lightweight. Really a great job by the inventors of these detectors. IMHO I hope we do not lose some of the past designs that worked well, such as the ergonomics of the balanced s rod that would separate in three places for backpacking, the hip mountable brain box, the detectors that would not fall over when put on a little bit of an uneven surface, the 6.5 inch elliptical concentric or double DD coils for great access in rocky areas, the 1/4 inch headphone jack, the spare interchangeable battery pack that takes regular batteries to serve as a back-up for the li-ion battery pack, and higher frequencies options. I would like to see what else had worked well with other detector user, seems like we are always buying aftermarket parts to retain some of these older features where possible.
  11. Not sure where this belongs on the forum, (or if it even belongs here), but this seemed to be the best category to discuss this. Ever since information on the GPX 6000 started to trickle out, I had this nagging feeling something in detecting has changed for those of us who like the thrill of getting to know a new detector. I never would have envisioned the GPX line morphing into a simplified detector. After having the GPX 5000 for a bunch of years now, and using it for relic and beach hunting, I could not imagine relying on a machine that adjust everything for you. I get it that money talks, and when you are a publicly traded company, you go for profit first, and then deny it 😄 And now that there market has switched to an area that probably has very little experience with detectors, the GPX 5000 must have been daunting for them. So they cater to that market. But I was hoping that a new GPX would fix some of the issues that the 5000 had. I was naive. Minelab has never kept the good parts of their previous machines and just added the the things that needed improvements. On the E trac, the best part of it was the depth it had in finding deep silver, in long tones, multi. Also the bouncy numbers helped ID deep Indians. When the CTX came out, it lost some of that fluety tone and they tried to straighten out the numbers to a number 12 line. So a two dimensional screen that worked well was transformed into a 2 dimensional screen that bunched most targets on one line. The The EQ comes out and squashes out the numbers even further. So why I thought the 6000 would not do the same is beyond me. I guess I'm disappointing that the "trend" is to make machines where the manufacturer decides on how your machine is going to be set. I hope someone in my area gets a 6000 and is willing to bring it to the beach to compare settings on deep silver. If it wins, then I will eat my words. I know I will get some slack with people saying it's a gold machine, not a relic or beach machine, but to them I would say.... you should be worried when a company controls your ability to fine tune your machine. Thoughts?
  12. I'm looking for a Compass metal detector catalog that includes the Compass Gold Scanner, and Compass Gold Scanner Pro models. The full line catalog, and this would be about 1990-1992 or thereabouts. I'm adding a few key older metal detector catalogs to the Downloads Area to provide basic info on older models. I do not need a ton of catalogs, just key years where major model changes occur, as things moved slower back then. If the catalog was in pdf format that even better, but Googling only turns up a couple older catalogs, nothing I can find covering the Gold Scanner era. I am more than happy to pay for a print version if need be, so I can scan into pdf and put up for people to download. Thanks in advance for any help. Me and my Compass Gold Scanner, back around 1990:
  13. XRF's hold sort a mysterious place on the shelf of semi-unobtainable prospecting equipment. 99% of prospectors don't need one. Maybe this post will help clear up some of mystery around these devices, and show where they can actually be worth the outlay of capital. And why for almost all recreational/hobby prospectors, they are not worth the money. What does an XRF do? In very simple terms you point it at an object and it will tell you what elements are in that object. More on this, and why it isn't this simple, momentarily... After sometime over 5 years of searching, I was finally able to find a used XRF I could afford to finance recently. These are not tools for recreation. They are expensive and require understanding how they work, what tasks you need to accomplish, and understanding the limits of XRF. The trick with these units is to find one with the proper calibrations already installed as they can be many thousands of dollars to send to the manufacturer to get configured correctly for mining/prospecting uses and to add/subtract elements or to calibrate for certain matrixes (silicates/iron/etc). X ray tubes and X ray detectors are about $6k each to replace, and recalibrations are about $1500 a pop, so even maintenance is crazy expensive. It's a tool you need be certain you need or can put to good use before buying one. And buying used, it's probably best to find one with as few hours use as possible to delay the inevitable tube replacement, as well as with a recent calibration certificate. My unit is an XMET 7500 made by Oxford (now Hitachi). The more common units people generally see are the Olympus and Niton guns. This unit has basically every mining calibration Oxford offered on it in addition to soil and other specialized mining related modes, which is very valuable and very useful for prospecting. It also detects down to magnesium without any fancy helium purge techniques. The guns sold on ebay with only alloy calibrations are pretty useless for prospecting without spending a lot of $$$ on additional calibrations. Some other things to consider are the machines themselves vary greatly between model numbers and some models may be unsuitable for specific uses in prospecting. A few things to educate yourself on are: Beam energy and detector type (determines if certain elements can be detected at all, and how accurately) Electrode composition (Gold electrodes have lower sensitivity to gold in ores, for instance) Calibration to light elements, or ability to detect certain elements I don't think an XRF is particularly useful for people who are only looking for gold. Due to the electrode limitations, the PPM minimum to detect gold in ores can often be above what would be an economic (and thus desirable) concentration in gold ores. But, looking for tracer elements (stuff like Pb, Cu, As, Zn, etc) can be quite useful. It can also help outline buried ore bodies which can then be explored mechanically via drilling or other methods. For prospectors branching out beyond just gold however, an XRF can be even more useful. And that's when one needs to understand the elemental limitations and what your application specific uses are. Any affordable XRF today will not detect lighter elements than magnesium. Some will detect to magnesium, but then do not contain calibrations to allow it (extra $$) and some require helium purging to measure light elements. Elements like hydrogen, carbon, oxygen, and sodium are very common "rock building" elements. But XRF readings will lack these measurements. So, when a looking at a rock your readings will often give fractional (less than 100%) results. This is why - the missing mass is tied up in atoms lighter than magnesium. Fortuantely, a lot of common rock types have unique fingerprints still in elements such as Mg, Al, Si, P, S, Cl, K, Ca, and Fe. But some don't. This is why it's important to understand what you are looking for first in the field, and then find a tool that is going to match your needs. Further, a lot of minerals in certain locations but not other locations will also have further fingerprints in other elements such as Cr, Co, Mo, Nb, certain compositions of rare earths, etc. To make it more complex (this part took me a while to wrap my head around), each calibration within the machine may or may not be configured for some of these elements - even if they are within the range of detection of the machine! Like, an alloy calibration will have little use for silicon or calcium. Conversely, a mining calibration without magnesium or calcium may be next to useless depending what you are looking for. Of course, it costs extra money to add elements and even if you have for instance a precious metals calibration that includes platinum, the mining mode may not itself include platinum and that's more $. That is why the matrix matters, each mode can be calibrated to a specific matrix. Like mining modes are generally going to assume that the sample is mostly silicon, whereas precious metals mode might assume the only things that exist in the universe are metals. So if you analyze solid metal with mining mode it may misidentify elements thinking they have to be metals when they aren't, same as if you analyzed a piece of gold ore in precious metals mode where it will try to assign certain non-metallic spectra in the ore to something like gold or platinum, giving you false positives. This is why calibrations available and elements assigned to that calibration is so very important when it comes to XRF and accurate results. Why else is XRF bad for gold-specific uses? (I emphasized this because this is primarily a gold prospecting site, even though I prospect for many other things myself). First one needs to understand how XRF works - simply put it kicks a few electrons out of a few different orbitals around an atom at discrete energy intervals (these are spectral "lines"). When another electron falls into the empty orbital to replace the vacancy, another X Ray is emitted at this discreet energy. Unfortunately, some elements have some very close to identical spectral lines. Look here at some lighter elements and see the overlaps on this visible spectra chart that we use to ID elements in stars? Some might be familiar with these from astronomy or high school. Well, the same happens in the X Ray realm. This is coincidentally why ionized gases look a certain color to us and how "neon" signs can be different colors (different elements inside the tubes). The same thing happens in the X ray spectrum, just not visible to our eyes. Except when the X ray spectra is reaaaaaaally crowded around the gold lines. Making it hard for specific ID's when other elements with similar lines are also present in ore, and unfortunately some of the elements are also commonly found with and around gold mineralization. Combine this with the anodes on many affordable XRF's being gold which itself interferes with really precise Au measurements, and you can see why an XRF isn't the best tool for specifically gold prospecting. Here is an actual XRF spectrum. You can see how very common accessory gold ore elements populate and crowd the gold spectral lines at various orbitals. And also how you might be missing critical lines if your X ray tube only goes to say 15kEV instead of 40kEV (EV stands for electron-volts), you might miss some Ag, Ru, Cd, or Zr fingerprints in this specific case. Now notice how iron stands all alone? That's why some elements (iron) are easier for an XRF to ID than others like gold. So for some such tracer elements in soils and ore, and identifying certain minerals which really can only be accurately identified via spectroscopy or thin sections as for some gems, an XRF can save months of time and thousands of dollars for in field qualitative assays to do first stage determinations, ie, wether a resource is simply present or not, ignoring actual concentrations. This is why it's so important for anyone considering one of these units to know exactly what they are looking for first, to know the limitations of XRF, and to know if a unit will meet their application specific needs. Almost every company I spoke with had a story about a prospector, or even a few cases some junior mining companies, who purchased an expensive unit only to find it wouldn't work at all for what they needed to do. So hopefully this clears up a little mystery about XRF's and maybe saves someone from making an expensive $15k mistake. I am by no means an XRF expert and everything I know is just self taught. So if I've included an inaccuracy then please correct me. This is not intended to be definitive, but just to share what I've learned over the years in a few pages of simpler to understand jargon for those prospectors interested in these devices. More later with some actual measurements...
  14. Good morning all! I saw a post yesterday where someone mentioned the possibility of linking the equinox to an audio analyzer to get a visual readout on target tones and I found the idea fascinating. I've never seen this done and was curious what the old hands here thought about the idea. I'm sure the engineers at minelab (or any other shop) configured the sound of their machines with the human brain in mind, so our wetware may already be the best analyzer there is. But I can't help but wondering if a visualization of the audio would provide interesting heretofore undetected differences in targets that appear to be mostly indistinguishable to a rookie ear, namely uniform can slaw and pulltabs. Anyone here have any idea?
  15. After a rather long hiatus (knee replacement) I finally was getting out to do a little detecting this weekend and found that my pinpointer had decided to go on a walkabout. Over the past few months I’ve directed several forum members to opportunities to purchase a TRX and now I needed to find one for me. Not an easy task. There is a used one on Ebay right now with bid already over $200 with five days yet to go….. OK, to the point of this post. Searching around I did stumble across a site selling TRX’s for $55 ea for a lot of 10 pieces, with about $150 for shipping (~$70 ea). Normally I would just move on assuming that this is more Alibaba/Aliexpress knockoffs but I decided to do a little more looking around. They list a fairly wide range of detectors and brands, including a number of MineLab models. My understanding has been that MineLab is very aggressive in shutting down dealers carrying counterfeits. Doing some online searching I didn’t find specific mention of counterfeit TRX’s, though plenty of discussion of Whites detectors, particularly the GMT. The Goldbug 2 and GPX 4500 were also quite popular. Here’s my questions. Do you think there is a possibility this may be a legitimate dealer? Last fall just after White’s announced their closing there were some dealers who were discounting their inventory before Garrett said they would be covering warranty issues. Does MineLab truly aggressively go after dealers selling counterfeits? How much mark-up is there on detectors, and could this be a dealer who is not following the pricing “covenant” or functioning as a middleman to smaller dealers? I will admit that prior to retirement I might have thought about taking a fly at these just for the hell of it, I’ve certainly taken bigger gambles (and losses) on gold stocks. At worst I may have been able to unload them as fakes that work as well as other pinpointers that sell in the $50 range – or just another bad stock investment. There’s always that risk when we buy anything used on EBay, Craigslist, Treasure Classifieds, TreasureNet , etc.,(i.e. the TDI SL I recently bought that wouldn’t ground balance and hopefully can be repaired), and I question the number of “new” gpx4500’s I’ve been seeing pop up in ads lately (really, how many people are going to buy one and then sell it unused at a significant discount?). Well, I’ll keep looking and hopefully a reputable dealer will find some hidden in their stockroom.
  16. I was out yesterday and remembered that the Gold Modes (I use Gold 1, if that matters) can be used to investigate iffy targets. Then I had a thought when I noticed a lot of ferrous hits per swing (likely nails) while searching in Park 1 (no notching/discrimination), gain of 24, Recovery Speed = 4, Iron Bias F2=0 -- I switched over to Gold 1 and the target rate per swing increased dramatically, something like a factor of two! (Note: there aren't hot rocks in this location and I checked that ground balance was correct. I'm pretty sure these are bits of iron such as nails or pieces of wire.) I also checked in Park 1, 4 kHz since there have been reports here that this sometimes eliminates iron grunts. That wasn't the case. This got me thinking about what the Gold modes are, or at least how they are different from the other modes. In limited testing (@40 kHz) I've found that they can detect coins deeper (or maybe 'farther from the coil' is a better description) than the other modes. Once again having to deal with the confusing (non-standard) nomenclature, it seems that the Equinox Gold modes act & perform similarly to the "all metal" modes of other manufacturers' detectors such as the Fisher F75. (For example, the only tone option is Voltage Controlled Oscillator = VCO.) Dave Johnson has used multiple terms to describe that kind of mode, including 'single filter' (see F75 user manual). In other words, it's as close to a raw signal as you can get if using motion to maintain stability. So that leads to the question: is this all the Equinox is doing in Gold Mode -- using the minimal amount of signal processing to keep the response stable? I can think of one filtering option available in the Gold modes which isn't present on traditional all-metal modes of other detectors -- discrimination/notching. But even for that, the F75 all metal mode has digital target ID readout so something is going on there, although in that case possibly in parallel.
  17. I’m a newbie and saving up to buy my 1st metal detector. Meanwhile I’m rockhounding a lot. I’m curious if folks have successfully applied portable ground penetrating radar (or other portable detecting devices) to predict likely location of crystal pockets in the hard rock, like in dolomite (for locating pockets of Herkimer Diamonds) or in granitic pegmatite (for locating pockets of gem tourmaline crystals) ? Any pointers would be appreciated.
  18. Has anyone done a comparison of the mineralization readouts of various brand detectors on the same ground? I know Fisher F75 is considered a standard. I would like to be able to compare my NM Anfibio readings to other detectorist's ground conditions. F75, Deus etc. Also what GB settings others consider mild----hot ground.
  19. So I thought I would throw a spanner into the discussion. Here goes. We have heard of the double D coils what about a triple D coil. Well that outside my knowledge but let look at a quad D coil the oldest ground balancing coil. Have a look at these links.....LINK....https://www.phys.k-state.edu/reu2011/nnorvell/Metal_Detector_Research.html and more detail.....LINK....http://41.67.20.41/bitstream/handle/123456789/18621/Metal%20Detector.pdf?sequence=1&isAllowed=y Are we on topic. _________________ Regards Geof. geof_junk Contributor Plus Number of posts : 794Location : Gippsland AustraliaRegistration date : 2008-11-11
  20. In addition to nugget hunting I am also a history buff and I would like to learn more about metal detector technology, its history and sequence of development. I understand that the BFO (Beat Frequency Oscillator) technology was used in the very early metal detectors. Right now I would like to learn what is the difference between TR (transmitter receiver), induction balance, and VLF technologies and when was each one introduced to the market. Is there anywhere where I can find a list of manufacturers, the models (technology) they offered and date range they were offered? I have searched the forum without success. Is there a link to a thread or article that I have missed? Thanks in advance for your help.
  21. Norvic asked why I was so proud of a VLF when I own and have posted much success with the other higher end detectors. It was my post on rating the higher end Minelabs....so here goes. There are many factors to my craze and style of detecting, but my finds are the facts and not many people can compare, unless they too use the tools (detector) and hunt the style I do. I consider myself a gold hawg or gold pig. I chase it all in terrains flat or tall. Terrain - I live in the Northwestern state of Idaho and much of my detecting in the surround state of ID., is Oregon, Nevada and occasional Montana. For the most part, OR, MT and ID are pretty much the same with steep terrain mountainous rough country. A day of electronic prosecting and hiking in such states, is much harder on the body for a guy my age, heck it’s harder for anyone. Going to Arizona, Rye Patch and other Northern Nevada high desert areas is a treat for my body in more ways than one. Maybe that is why so many people detect there? It’s easy to drive and get to without walking…boy are most of us lazy? YES, including me at times, but not in my home state (backyard where I play). The ID, OR, MT mountains have steep ravines/canyons and the water is at the lowest point. Here is the many miles of hand placer workings, dredge tailing and hardrock mining ore dump piles. The gold I am chasing is the stuff the old timers missed. Pic below - This huge ore dump pile produced a few thousand dollars in Specimens. This is the not so steep side and we had to tie off with ropes on the other side. Half the targets would roll down the hill and need to be found during a break when we were at the bottom. The PI's can't see this time of gold. Trash - Trash is my treasure in a way.. as I know the site has not been hunted as hard. Trash is what most detectorists hate, and I too get that way on occasion, but I know if I'm patient, I'll eventually be rewarded. A big factor I run into is 100 to 150 yr old man made trash from the early prospectors. They left much of it on the hill, in the placer digs and tailing piles. Many of the small mining camps were right on or near their diggings and they just tossed the old food cans, tobacco/coffee tins and worn out leather boots with hundreds of nails and broken, picks/ax heads shovels aside. Pic below- In old tailing piles a lighter, faster, better ID detector is best. He who digs the most non ferrous targets in a day, get to smile all the way home. Pic below- is the 1 pound specimen after cleanup. Tools – Know your detector, its limitations, strong and weak points. Bigger deeper detector is great in flat terrain and areas with limited trash. Raw depth and power is amazing to have, when the target you dig a foot or so deep is not a sardine can. How about a shovel head at 2 feet or more? Think about it and what you do when digging 5 or 6 of those an hour with your big deep penetrating detector. What does your body have left in the tank? My lighter VLF is easier to swing in rough terrain, has better Iron and Target ID, is not as deep or powerful in trashy sites. It saves me time from digging unknown iron targets, it saves me energy from digging deep holes, it saves me energy from having to pack around a bigger bulky detector. The proper detector for the site is a must and in many cases my lighter, faster, better target Identification, sub $1000 investment is the right tool. Pic below - This golden oreo was recovered in old hand placer workings with my VLF. Having what I consider the best identification VLF gold detector on the market saves me time. Pic below - It was recovered at 16" with Minelab EQ-15" coil. Yes I'll be going back over this area with the new CoilTek NOX 15" round as it is even deeper. Gold Knowledge- This is confusing to so many people as they think gold is gold. Yes I too used to think the same way. Luckily I hunt a variety of gold producing locations and sites I like to detect and learn from. My many years of comparing/testing detectors at such sites has given my staff and I an understanding of gold, its characters, density and how the elusive Au responds to the varying detector models from the different manufactures. Many of the nugget photos being shared on social media in years past were dense solid gold pieces and they are beauties. That’s what the detector could easily respond to. In more recent years, the sizes of the nuggets became smaller and we started reading about and seeing some nice specimens. The newer GPX detectors with their advanced tuning and soil timings (Fine Gold) would outperform their older brothers (SD/GP’s) on smaller and courser gold, so when get to make more of those finds and share them. Most recent years has us using SDC-2300 and GPZ-7000’s. Again, the gold gets smaller and the amount of crystalline gold, wire gold, salt/pepper specimens are being unearthed with these detectors supersedes that of their older brothers the GPX series. Pic below - This softball sized specimen was found with a VLF and has multi ounces of gold. VLF picks it up deeper than many bigger detectors. Pic below - This beautiful 3" long quartz and gold specimen came from a trashy ore dump pile with a VLF. Pic blow- These quartz cocoon wire gold specimens bring a premium and come out of hard rock ore dump piles. Pic Below - The PI's don't see these rare pieces, the 7000 barley does on a select few. Pic below - I have a feeling the extra sensitivity of the new GPX-6000 will do even better. Proof – The facts are in the vault at the bank. I own beautiful specimens pieces recovered with detectors and have tested many on a variety of detectors. I have gold finds that are multi ounce pieces and they contain 2 or 3 ounces of gold in them, but for some reason an SD or GP don’t see them, even less than an inch. I also have such pieces my GPX 5000 does not see, but my GPZ-7000 does. What is most amazing, is I have pieces of gold with multi ounces of metal and even the ZED has issues or can barely respond an inch or two away. If this is the case, then why do I have these find gold pieces of art? I’ve taken the time to test and learn my detector tools and have found a certain trusty VLF sees them all, can ID them all, is lighter in weight and so I get to hunt longer, saves me energy since I don’t dig as deep for unwanted targets. Pic below - This specimen came from dredge tailing and the speckled pieces like this get missed by most PI's. Pic below- Over $800 in gold in this 3 ounce specimen and my VLF does better than my GPX-5000 and my SDC-2300. The SDC goes deeper than the GPX. You better know your gold and your detectors capabilities or lack of. Pic below - This 3 ounce specimen was found in trashy hand workings. I actually had a GPZ-7000 here for a couple hours and gave up because of the amount of item trash. A GPX-5000 with DD coil run with DISC mode would be better than my GPZ, but then again my NOX does even better. Better target identification of my NOX, is most important at the site this 3+ oz'er came from. GPX-6000 – A new tool and one that has Gerry very very excited. Now we are about to get a revolution of Geo Sensing Technology with PI power and capabilities for a wider variety of gold textures, densities, characters and sizes. Minelab (and their track record) is even telling us some of such capabilities and so I and a few of the guys who do not like to miss gold, are getting ourselves prepared, getting our old sites, lined up and making sure we are going to take advantage of the stragglers. Remember when the SDC-2300 and GPZ-7000 came out and all the slow response from the majority. You folks missed the opportunity of a lot of gold. My guys and I were killing it in NV and AZ on those so called worked out sites. Was it a gamble to spend that kind of money? If that’s what you love/enjoy and if you have a good track record with Minelab, it’s bet I’ll take most every time. I don’t lose detector bets very often. Pic below- This stunning collectible specimen was found by my brother with his SDC-2300. It came from a place he had previous hunted and found gold with his GPX-5000. The 5000 does not even whisper on it. Minelab claims the GPX-6000 is more sensitive than the SDC-2300 & GPZ-7000. I can't wait to use the GPX-6000 at the site and many others. Hopefully this story and the pics I shared will help educate some of you on how the different detector technologies produce more gold. I realize it's hard to put down your old reliable detector as it has probably and hopefully served you well. If your sites are getting thin of targets and or gold, just maybe a new detector can put the smile back on your face? I'll go back to this simple statement I have said below in other posts and it is the absolute truth. You can't find what your detector don't see. PS - I’ll be honest though, for me it’s the lighter weight, better ergonomics, not being tethered in a harness and User Friendly that has me sold. The extra gold my new GPX-6000 is going to find, is a bonus. PPS – I’m just as eager to test the GPX-6000 with some of my gold and see how much better/worse it does than my GPX, SDC and GPZ. (I'm educating myself). PPPS – I still feel there will be a place for my VLF, as it’s lighter, and have better target ID. See you in the gold field, where the most knowledge is learned. Or speed it up with our 3 days Field Training at www.gerrysdetectors.com Happy Hunting. Gerry
  22. Greetings fellow detectorists, I'm hoping someone with a deeper understanding of the technological methods of the Equinox series might be able to shed some light on why certain Interrogation methods work they do. I think we are all aware of the little trick whereby a potential target in the mid conductor range in multi frequency can be examined in 10hz; a sudden jump from the teens to the twenties indicates a likely bottle cap. My questions are two fold; first, what is responsible for this phenomenon? Why does a change in frequency potentially change the vdi of a target, and what determines when a change occurs? Second, is there a potential logic here that one can use to devise further Interrogation methods using similar principles? Looking forward to your insights!
  23. Hey guys, Can someone explain to me in simple terms what is it and what we accomplish by using a slight ground balance offset (either positive or negative) on our machines? I remember for example that when using an Xp Deus in the past, whenever I needed some little extra depth boost I was manually set the GB a little lower than the actual ground phase of my area but in the expense of greater ground noise and instability...the opposite when I needed a more quiet run....However I never deep dived into this concept and never understood how and why this really worked. Would be great to understand this now, and in order to help me (and because each machine has a different GB scale), let's assume a Ground Balance scale of a Makro Multi Kruzer (which I'm expecting soon). So...In a Makro M. Kruzer, let's say that machine grabs (via pumping) a Ground Phase of 70 in our area... 1) What if I manually set my GB slightly HIGHER than 70 (eg at 75) regarding ground noise, depth abilities and targets detection? Will the effects be the same for both low & high conductors or tiny & large targets? 2) Same as above, what if I manually set my GB slightly LOWER than 70 (eg at 65) regarding ground noise, depth abilities and targets detection? Will the effects be the same for both low & high conductors or tiny & large targets? 3) Will this GB offset apply also in the salt water the same way? (I recently whatched a guy reviewing and using a Multi kruzer in the salt water, and he manually increased his GB value on purpose while he was trying to detect a small gold chain underwater...never understood why he did such a thing and how this works) 4) Lastly, please define which side is "positive GB offset" and which side is "negative GB offset" in Makro machines..... May sound obvious but, in some machines higher GB Phase means hotter ground but in some other machines higher GB Phase means milder ground (the opposite). So to tell me that "a Positive offset means moving the GB value to the hotter side of scale & the effects wil be that..." may mean nothing if I don't know which side is hot and which side is mild...hope that makes sense. I don't have a clue which side is hot & which is mild in Makro GB Scales so would be nice to enlighten me and correlate your answers with this! Hope my questions makes sense... Regards, Argyris
  24. (Long article. If you think you'll get bored of the background info and stop in the middle, skip to the Testing section to see what a metal detector has to say.) Introduction Detectorists occasionally come across ceramic tableware/dinnerware at sites. For example, I found some in a ~1880's Colorado ghost town. A friend of mine found a piece (which I was able to identify and date to the 1890's) near a high altitude Colorado miner's cabin associated with a small silver mine. Western USA explorers/settlers/miners may seem backwards and uncivilized (and that is true in some cases) but often they longed for the finer things of the lives they left behind. Ceramic dinnerware was both utilitarian and aesthetic. Coin&relic detectorists around the world use pottery and other ceramic pieces, often found on the surface, to indicate good places to detect. In a previous life 😁 (actually 1998-2015) I was a avid (make that obsessed) collector of dinnerware by a particular USA manufacturer, accumulating a collection of 2000 pieces by scouring antique malls/shops but also occasionally other sources like rummage sales and Ebay. Not surprisingly I did a lot of research on the subject during my collecting years. Here are some results relevant to metal detecting. Plausibility In this first photo are two 6" diameter plates, both with filigree decoration and an edge line. The lower decoration is gold and the upper one is platinum (often mistakenly but understandably called 'silver'). The upper piece was manufacture in 1937 and the lower (gold) one in 1952. Each sold (usually as part of a set) for considerably less than $1 -- let's use $0.20 as a reasonable amount. Can we possibly reconcile these two 'facts' -- precious metals on inexpensive items? It is known that gold can be worked into very thin sheets. According to Wikipedia, typical gold gilding is 100 nm thick. ('nm' is the abbreviation for nanometer. There are a billion nm in a meter.) Scientists in the laboratory have done ~200 times better -- less than 0.5 nm which is actually about 2 gold atoms in thickness! Coatings on precision mirrors (e.g. astronomical instruments) are also about 100 nm in thickness -- same as fine gilding -- and that is thick enough to reflect in the high 90% decade at infrared wavelengths. About 15 years ago I took a tour of the Homer Laughlin China factory in Newell, West Virginia -- located in the very tip of that spike in West Virginia's NW part, along the Ohio River across from East Liverpool, Ohio and about 45 miles WNW of Pittsburgh, Pennsylvania. They actually took us to the factory floor and one of the things they showed us was a technician/artist painting the gold edge line on a piece. The claim was that it was pure gold (24 kt) but my research indicates it was more likely 22 kt. I calculated the approximate amount of gold on the edge line of the lower plate in the picture above and at today's price ($58.54/g) it comes out to about $0.06 worth. However, when that piece was made, gold was $35/oz (a factor of ~1/60 compared to today) so that material cost would have been more like $0.001 (at tenth of one cent) for a 6" plate. That certainly seems plausible, even if the thickness was several times that 100 nm assumption. Testing I used the Minelab Equinox 800 with 11" coil, Park 1 mode, gain of 24 in 10 kHz, 15, kHz, and 20 kHz modes (MultiFrequency too noisy with EMI) to see if the following soup bowl would give a signal. This is a rather extreme example in terms of the amount of platinum for an inexpensive piece of dinnerware to contain. The platinum band is 1/2 inch wide (1.27 cm) and the total calculated mass is about 0.011 g (assuming 100 nm thickness of pure platinum, so adjust accordingly). At today's price of $36.49 g those assumptions translate to $0.40 worth of platinum in this dish (I don't know the platinum spot price when it was manufactured in 1932). The digital Equinox's TID waffled between 1 and 2 and the signal strength was maximized when the coil was centered over the dish, with the coil about 1 inch above the platinum band, resulting in 3 arrows out of 5 ("depth meter" reading). Sweeping over the entire dish also gave a weak hit when the edge of the coil crossed the edge of the band. I also tested a similar sized dish which had just an edge line and filligree decoration similar to those shown in the first photo. There was no noticeable response by the detector on that one.
  25. I noticed early on that in discussions about the conductivity of gold, that gold is considered a low conductor. This is confusing to me. My understanding was that gold is a high conductor, whereas only 2 other metals are higher conductors. Silver being the highest conductor, and copper being the next highest, allowed by gold. Iron is way down on the list. Can anyone please explain this?
×
×
  • Create New...