Search the Community
Showing results for tags 'coils'.
-
With the official announcement on May 15 of the (hopefully) mid-summer release of the Garrett Apex there was considerable discussion of the (only) stock coil planned for release and its affects on depth. Within that discussion Chase gave me incentive to do some testing. This post is a result of that, but since I think my testing is applicable to more than just the Garrett Apex I'm creating this post in the general DetectorProspector forum. The gist of the topic there was how much compromise the 6" (wide) X 11" (tall/high - my choice of word) Apex stock would have on depth. As I mentioned I have quite a few coils for each of my detectors, but subsequently I realized there was one detector (Fisher Gold Bug Pro) and coil combinations (5" DD round and 5" X 10" DD elliptical) which would best address this issue. (I also have some other options -- White's TDI SPP and Minelab X-Terra 705 -- but those are a bit less ideal as will be discussed later. Since I have two other coils for the GB Pro I decided to include those for completeness although they add more variables/concerns and thus don't fit quite as neatly as the other two. I initally started with my variable depth test stand which allows me to vary the depth of small targets in 1/2 inch increments from ~ 1" down to 12" depth in the ground. However, in the midst of that part of the study I realized that I have some (likely iron) trash targets in the field-of-view which compromise the tones/measurements. Fortunately I also have two cleanly placed buried coins -- a copper alloy Lincoln Memorial USA penny buried at 5" depth and a Jefferson nickel alloy 5 cent piece at 6 inch depth. Neither of these currently suffers from nearby trash targets. I subsequently altered my study to use those targets for the coil performance tests. Unfortunately these also aren't ideal since under the conditions of testing they are too shallow to determine in-ground depth limits. What I did as a hybrid compromise is to carefully (i.e. measurably, with shims) raise the coil above the ground until the signal disappeared. For a second (more/less confirmation) test, and one that should be easily repeatable by anyone with the same/similar detector and coils, was to then perform a standard air test. Let's start with the conditions of the tests: 1) Ground conditions -- moist ground (we've had a typical wet Spring season), Fe3O4 mineralization measure of 2.5 bars on both the Fisher Gold Bug and Fisher F75 (2.5 meaning that about half the time I see 2 bars and half the time 3 bars). 2) Gold Bug Pro running in "all metal" ("motion all metal" in USA terminology which I like to call minimally filtered), max gain, threshold at 11 (which is about where Kevin Hoagland calls "mosquito buzzing in your ear"), no headphones (so detector's speaker). 3) My precision for "depth" is 1/2 inch. That coincidentally was the height of the shims I used in the hybrid test and also my ability to control the hand-held coin distance in the air test. 4) My determination of (maximum) depth limit was simple. I increased the depth until I thought I could barely detect an audio signal. I then decreased the target-->detector distance by 1/2 inch and required that I subsequently heard a clear signal. If not I reduced the depth/distance and repeated. Here are the raw data results. I'll explain the meaning of the columns shortly. You can see the four coils I tested. The first three are all Fisher manufactured and the last is the NEL Tornado. Rather than to use the nominal product quoted dimensions ('dim' short for 'dimension' in the column headings) I actually measured the coils and interpolated to account for the fact that a coil doesn't typically have a single extent but rather is a bundle, and further that the bundle obviously fits inside the housing. For the closed coils this is obviously more vague but in those cases I just used half an inch less than the housing dimension. An addition oddity is that DD coils aren't really simple ellipses but some overlap of two independent elliptical coils. 'geom mu' is the geometric mean of the two just determined transverse dimensions -- more specifically the square root of their product. Hopefully you'll see later why I calculated that quantity. It's not really relevant for the main conclusions I draw. The last two columns are the actual distances between the target and coil for the limiting distance (see item 4 above). In the case of the air test that is obvious. In the 'part ground' test that is the sum of the depth of the coin in the ground and the height of the coil above the ground for both coins. At this point I think it's worth discussing some caveats/assumptions/limitations of this test. Then if you've stayed with me I'll go a bit farther and hypothesize on how to use these data to draw conclusions for other coils. 1) Although I chose a detector/coils combination that was as consistent as I could be (same manufacturer and same 'width' coil), it has been discussed on this forum previously (sorry, no link) that the quality control of coil manufacture is a difficult task. It's certainly possible, although not necessarily likely, that my 5" x 10" elliptical coil is a high end tail performer among its peers and/or my 5" round is a low end performer. 2) With any measurement, there are in particular systematic errors and biases. I can't "double blind" my method. That is, I do know which coil I'm testing at a given time and if I have a prejudice for or against a certain coil that could show up in the results. Also, statistical uncertainties (more succinctly, how repeatable are my data) can contribute to errors. It is worth pointing out that swinging the heavy NEL 15" coil effectivly makes taking in-ground measurements with it difficult. As a result I was unable to confidently get a max depth reading for the penny using that coil, which is why that cell is blank. No problem with air tests because there, as is standard (?) I mounted the detector in a stationary horizontal position and just 'swung' the targets to determine the (max) limit distances. Again, it's really the 5" round DD and 5" x 10" elliptical DD that are most relevant. The others are include for information purposes but also to add to the plots I show later. As you can see, in these tests there is a clear and significant advantage for the 5" x 10" elliptical over the 5" round in both the hybrid test and in the air test. OK, I now go a bit deeper. Is there a mathematical relationship which can predict coil depth performance if I know the coil dimensions? Compared to above this is another leap into the unknown with additional uncertainties. However, here are a couple plots which seem to indicate relationships between the potential maximum detectable depth and the geometric mean of the coils width and height dimensions. (Sorry for the confusion but the Blue dots in both plots are for the 1 cent piece and the red dots are for the 5 cent piece.) It's better to look first at the 2nd plot -- air test. There appears to be nearly linear relationship between max depth and the geometric mean of the coil's dimensions, although it appears to trail off with the large (NEL) coil. Superimpose upon that the effects of ground noise and you see a further deterioration both in absolute depth and also in the trend which is shown in the first plot. Simply put, it is well known that mineralized ground, even moderately mineralized as in my back yard, negatively affects attainable depth. The larger the coil, the more ground it "sees", and thus the more ground interferes with performance. I'll finish by pointing out that this isn't the first study I've made. Back 3 years ago when DetectorProspector member Karelian made detailed measurements of a large collection of mono coils on a White's TDI in both ground and air, I noticed the depth vs. geometric mean relationship. However, without a theoretical (physics/engineering) reason to expect this relationship, at this point it's merely a convenient correlation. Karelian's data are further muddied by the fact that the coils studied have many manufacturers: Coiltek, White's, Miner John, Nugget Finder, Minelab,... I could show those results but I think I'll await the reactions to the above. I can also do more tests (e.g. with the X-Terra although there is not clean comparison of round vs. eliptical coils with the same width, at least in my collection) or repeat these. I await your posted reactions (including yawns ?).
-
I did a coil test some time ago using a Tdi Pro OZ, quite a variety of coils involved. Just a bit of information not wanting it to go to waste. The test area was located in the middle of the Golden Triangle in Victoria, Australia. Looking at the images the test site is located on a area that produced large nuggets. Heavily mineralized to give the depth tests some authenticity. Targets were varied as were the coils tested. The Tdi Pro was ground balanced, gain was at 5, conductivity was in ALL, pulse delay was 10. Frequency was set in the middle and the audio was boosted by a Nokia MD-11 external speaker. Only clear repeatable signals were recorded. All targets were buried in the ground sideway from a miners hole, so as not disturb the soil on the surface or above the target. Only the 1 grain ingot and one 0.5 gram gold coin were buried from the surface disturbing the ground. Not sure how useful this is for Tdi SL users, deduct 10% maybe.. Just gives a sense of what is realistic is this one location at that one time with the Pro with the variety of coils available back then. All the best, Karelian
-
Has anyone had issues with the coil covers falling off? I have. Garrett acts like this is new to them. They sent me another cover for better fitment, but it fit the same. Then they sent a coil and cover, but there was no difference in fitment. NEXT ISSUE: I did an air test win a small gold piece. The Axion detected it at 2.5-3”. I air tested the same piece of gold with my GMX Sport, it detected it at 4-4.5”. This was also the case with the ATX. is the air test the issue?
-
I figured it was time to change the battery for my X--35 9" coil, I watched all the videos on how to do it , I figured it would be a cinch, but after i got the little plastic plate off the bottom of the coil a hard piece of foam was glued in so hard over the little battery connector I could hardly get it out , then i looked to find the connector to unplug the old battery and could not even see it , It was totally covered in epoxy glue I pulled on the wire and it broke off, apparently the temp worker filled it with glue and completely covered the battery plug in making it impossible to remove, why me ? why does it work for everyone else but when i go to do it its covered in glue, ? I was pissed now it will cost me 300.00$ to get the HF coil . I will never buy another X-35 because I have no assurance the battery plug will not be glued over again . at least the HF coil its possible to change the battery
-
Based on some posted consternation based on the anticipated price point for the Minelab Manticore accessory coils, I thought I would put out some price points for popular Simultaneious Multi-Frequency (SMF) metal detector accessory coils, and coil prices for other popular single frequency, selectable single frequency, SMF and PI detectors, for reference. These are approximate retail prices for new coils (in US $) scraped off the internet and don’t reflect dealer discounts, package deals, or sale specials. Legend LG 28 - 11" Stock - ~$135 LG15 6" Round - ~$120 LG24 9.5x6" - ~$135 LG30 12X9" - ~$150 LG35 14" - ~$170 Nox 6" Round - ~$180 10x5" Elliptical (Coiltek) - ~$235 11" Stock - ~$229 14X9" (Coiltek) - ~$260 15x12" - ~$240 15" Round (Coiltek) - ~$290 Manticore Stock 11" - ~$?? M8 - ~$341 (Pre-release estimate based on currency conversion) M15 - ~$417 (Pre-release estimate based on currency conversion) Deus 2 9" Round - ~$399 11" Round - ~$399 13X11" - ~$399 Other Coils: Fisher "Triangulated Biaxial 12" Coil" for F75 - ~$199 Detech Ultimate 7" (Teknetics and Fisher F75) - ~$130 Detech Ultimate 13" (Teknetics Greek and F75) - ~$180 Detech Arrow (Simplex, Fisher, Teknetics Greek and G2+) - ~$150 - $165 Nel Snake - ~$120 - $130 Minelab XTerra Pro - ~$?? Minelab Vanquish (Multi IQ) - ~$100-$140 (size dependent) Minelab CTX3030 11"/17"(FBS 2) - ~$350/$400 Garrett AT Series Coils - ~$130 - $160 (size size dependent) Garrett Ace Apex Coils - ~$135 - $190 (size dependent) Nokta Simplex+ - ~$110 - $170 (size dependent) Nokta Impact - ~$110 - $230 (size dependent) Nokta Anfibio/Kruzer - ~$110 - $220 (size dependent) Pulse Induction: Garrett Axiom Coils - ~$280 - $320 (size dependent) Minelab Commander 10x5" DD (GPX) - ~$225 Minelab Commander 11" Mono/DD (GPX) - ~$270/250 Minelab Commander 15X12" DD (GPX) - ~$375 Minelab Commander 18" Mono - ~$441 Coiltek GoldenHawk 10x5" Mono (GPX) - ~$420 Coiltek 14" Anti-Interference DD (GPX) - ~$410 Detech 12.5" DD (GPX) - ~$300 Detech 15" Spiral Wound DD (GPX) - ~$425 Detech 15" Ultra Sensing Mono (GPX) - ~$425 Commentary - Legend accessory coils are a great value overall consistent with the detector itself, even compared with single frequency detector accessory coils. The unofficial Manticore accessory coil prices (if they hold) are somewhat consistent with Deus 2, perhaps its most direct competitor, although the Deus 2 coils pricing is complicated by the fact that they are wireless, smart, and, therefore, are self-powered which is not the case with the Manticore coils other than perhaps limited pre-filtering and ID chips. The Coiltek NOX coils demand a slight premium vs. the Minelab OEM Nox coils. The higher end Deus 2 and Manticore accessory coils are priced similar to GPX pulse induction coils.
-
I’m interested to see if there are noticeable differences in performance for the available coils that are out. I see manufacturer specific coils and then some made by Coiltek and others (I don’t recall their names). My question is, do any of you suggest a particular coil manufacturer over another? I don’t mean 6” vs 9” vs 11” and so forth, just curious if a particular coil manufacturer appears to make better product. I have a a 5x10 coiltek for my 900 and I don’t really feel it works any better than the standard coils.
-
Has anyone on this forum gone about the process of designing their own custom coils to go with some of the more popular detector models on the market? I only have a Gold Bug 2 at the moment and it does alright for what I purchased it for but I was wondering if I might be able to get some more coverage and detection ability out of it when I take it down to the beach I live near to see if the rich people have lost anything. It does just fine out in the desert with the stock 6" coil and I have never felt the need to buy one of the larger coils as I just do not think those would really fit how I most use the detector out in the desert. Anyway I obviously am considering trying to build a couple different sizes and geometry coils to use with my GB2 but also would love to hear about what other people have done with other detectors. Would love to get a little more guidance than my sorta basic electronics knowledge, intuition, and searching the web.
-
While running my hands along a coil cable, I noticed a pin-sized thorn had pierced the cable, broken off, and embedded itself inside. Tweezers were of no use as the splinter was too deep and brittle. It got me a wondering if any one has any experience regarding the potential impact of such an injury to the coil cable and it’s insulation. Any thoughts?
-
Maybe I haven't been paying attention, but with the recent push towards digital multifrequency flagship detectors, why have concentric coils been shunned? I don't think it's an engineering/physics issue although I can't rule that out. The White's Vision/V3/V3i/VX3 had concentric coil options and it was digital multifrequency. Did any of the Minelab BBS, FBS, FBS2 models have compatible concentric coils, either in-house or 3rd party aftermarket?
-
That 17” Minelab mono is pretty sweet. Just used mine for the first time today and it honked on little tiny pieces of lead 2”-4” deep. I was in pebble to cobble sized rocky terrain interspersed with small boulders and only a few plants (desert mountains). I was going pretty fast, trying to beat the sunset at my last spot for the day and was surprised how small the lead was I kept picking up. It’s a great coil for doing quick surveys over large areas and really doesn’t weigh a lot. I have a Coiltek 14 inch mono , but it just seems kind of heavy and bulky compared to the 17. I haven’t done sensitivity comparisons with them yet. Both are relatively new for me. The stock 17 is a great coil if you need to cover a lot of ground, else the smaller Coils like the CT 10x5 would obviously be best for vacuuming between the rocks and underneath bushes.
-
I'd like to focus on searching for 1-3 oz (2-4 square inches) or larger size targets that are deeper, perhaps more than one foot down. The ground I'm searching is moderately mineralized and easily handled by the 11x7" mono. I currently have the 13x11" DD and the 11x7" mono. Would the 16x14" mono be a significant improvement in depth for larger targets? I understand the differences between the DD and mono coils, but I don't fully understand their differences in detection depth, especially on larger targets. Thanks for any help or comments. Az_Ed
-
I have 2 coils for my Equinox 800, the normal 11 inch and the 15 x 11 coil…. I have the aftermarket coil supports and would ask if there is a 2 part epoxy glue that could be applied to fasten these coil supports to the coil WITHOUT causing any interference with the coil’s performance ?…. Or maybe use CRAZY GLUE ? … thanks for helping…Al
-
Back when I started using the AT PRO back in 2009 Garrett recommended doing a factory reset when you changed to a different coil on the ATP my question on the Garrett 24K is this also the recommendation when changing to a different coil, or is performing a factory reset UN necessary on the 24K when changing to one of the different coils still learning the 24K and liking it a lot
-
With the release of the Xterra pro showing that all these coils are only limited to a chip and not the coil itself, it should be possible to hack the chip or override the chip with another. When I was younger this was easily done in gaming systems to make copied DVDs work to play copied games. Anyone know if this might be getting “worked” on for the coils? Small market though, maybe not worth the time of an ambitious electrical engineer unless they were an avid detectorist. @phrunt I’m winking at you ?? You seem to have the “know how” or the “contacts”, plus all the coils?
-
Yesterday I went to my beach and left the 6" Equinox coil on for an extended hunt. I had used it a couple of days before on a high iron beach so that I could hear targets clearly. Yesterday's hunt turned out to be an experimentation of sorts. What could I really find on a 'tough' beach with the little coil. I've found gold jewelry on the beach with it before. When I first got the coil I wasn't able to go nugget hunting so I went to a beach. Right out of the box as they say I found 4 little gold rings many years ago. I pretty much put the little coil away over the years in favor of the 15" coil and occasionally the 11" coil. Coverage is the operating logic to that. I feel 'naked' without the big coil. Yesterday I was willing to experiment. After selecting the frequency and then ground balancing I was able to go to 25 on the sensitivity/gain. This let me hear my threshold and without chatter so it was a matter of swing speed. There weren't a whole lot of targets so each time I'd find one I would try to find a patch. I managed to find a couple of them as you can see and some interesting targets in the 1.5 hour hunt. The rack on the left is one of the largest objects I've found on this beach. It was down about 8" and it weighs about 5 lbs. Some of the quarters were down about the same depth. The knife blades were iffys I think because they are mostly stainless steel. The silver Thailand earrings were in the wave wash and are very light at 3.2 g and were found together as displayed. After a bit of learning the capabilities of the little coil again I then wondered what is best. Do you take a small coil and use it at maximum sensitivity or do you take a larger coil and turn down the gain? This would go for other types of detecting as well. This is certainly a reason to have multiple coils.
- 10 replies
-
- 14
-
- jewelry detecting
- coils
-
(and 1 more)
Tagged with:
-
-
For those of you thinking about buying yourself a bigger coil for your Equinox, here's how big they are compared to a size 10 foot (see table below).. I find that measurements on paper (like 15x12'' or 15'' round) are hard to picture in my head without something to compare them to.. Hope this helps.. ?
-
I have a question regarding Whites DF coils on the TDI Pro or 'sl' and other variations,i am aware the difference between say a DD and Mono coils etc,but how would the experts describe the DF coils as in the stock and 7.5'' DF coils are these classes as 2 Mono coils within one another or have i got this completely wrong. As far as i can tell both the inner and outer coils within the coil case operate complete independent from one another,anyone have knowledge on how one would describe these DF coils,of course i could be totally wrong and would like some help from the electronic whizzkids ? Many thanks
-
The chart shows current GPX-6000 coil sizes, weights, and areas. I hope this chart can help you find out which coil to bye in the future. Phrunt- the 6 X 8.5 specifics have been added to the chart.
-
While reviewing some more of my archived files I found the coil winding specifications for one of White's Electronics BFO metal detector coils. Data was provided by the White's Factory. This coil was called the "Triplet Coil". It was manufactured in the late 1960's and early 1970's. My information is from May 1969. During this period there were several BFO coil sizes offered: a 3-inch coil for nuggets, a 6-inch coil for coins and a 12-inch coil for large objects. The Triplet was designed to combine both the standard 6-inch coil and the 3-inch nugget coil with an additional 2-inch coil for added sensitivity for small objects. Single coils were wound using a wood based enclosure. The Triplet Coil was encased in a molded plastic housing. For those of you who have a vintage White's BFO metal detector and would like a combination coil or those of you who wish to build a replica of a vintage White's BFO metal detector I have attached a PDF of the winding details for your viewing pleasure. BFO Triplet Coil winding instructions.pdf
-
trying to decide , 11inch coil x35 or the 11x13 x35 anyone have experience with both