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#1
08-19-2014, 07:32 AM
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Why cant metal detectors have longer ranges like 100 meters or higher?
Hi, everyone, I have a question. metal detectors basically work by inducing a current into a non ferro conductor, the back emf is captured by the receiving coil and thus you have a signal. What I am wondering is why is the metal detector only capable of detecting for a range of only a few feet? The metal detector is similar to any radio Tx/rx.
For example, if you have a strong magnetic pulse train from your detector, and there happens to be a a conductor somewhere around half a mile or just 100 meters etc.. out from you,. it is bound that there will be a current induced in that distant conductor which in turn of course creates a magnetic field which is also spreading out and should reach the detector receiver? Why are these common detectors limited by a few feet? My guess: making an induced current in a distant conductor is easy. But, perhaps receiving the signal of the induced current from the distant conductor is very hard? because the signal is very low? but really in our modern era of electronics, all signals can be detected? please enlighten me thanks best regards levi karl 
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#2
08-19-2014, 11:27 AM
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Metal detectors work with magnetic fields not with electromagnetic fields, the search coil isn't an antenna.
Best regards
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#3
08-19-2014, 11:41 AM
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Hi and thank you for the reply. But I am not sure I understand, because my understanding is that magnetic field is just a current or motion of charged particles. Any magnetic field associated with a copper winding comes from a current of conduction electrons. so why isnt a signal detected further by few feet from metal detectors? Regards Karl
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#4
08-19-2014, 12:18 PM
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The propagation of a magnetic field decreases with the inverse square of the distance while the electromagnetic radiation (not near field) decreases linearly with the inverse of the distance, and then goes much further than a magnetic field, at the same power.
Best Regards
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#5
08-19-2014, 02:09 PM
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I guess you are new to this forum. MFD's (Molecular Frequency Discriminators) have been finding gold for decades. People who try to tell you they don't work, well maybe they just aren't as intelligent as they think. Do some reading on Konstantin Meyl and scalar waves. There are some you-tube videos.
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#6
08-19-2014, 02:14 PM
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I know these two problems however: A-We could debunk this idea because the object itself needs to be at least 1 meter in size in order to reflect the radio energy. (But still a portion of the radio energy gets reflected even if the wavelength is bigger than the object). B-We could also claim that even though small conductors could be distinguished and detected successfully among all the insulating earth media, we would be out of luck trying to figure out what kind of conductor it is. Why? because the reflection ability (and thus what conductor it is) of the conductor would be NEAR IMPOSSIBLE to conclude from the overwhelming noise or ambient radio reflection of the insulating earth media and because a detected strong reflection on your receiver cant differentiate between a big conductor of poor relfectivity and conductivity or a small conductor with superior conductivity and reflectivity. Am I thinking in the right direction? All ideas thoughts welcome. I am just seeing if I can find any possibility through sound established principles. I am aware of wallet hunters.
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#7
08-19-2014, 02:18 PM
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Study Meyl and the longitudinal waves. This is the magnetic component of the wave and is about 1/6 of a wavelength.
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#8
08-19-2014, 02:54 PM
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The skeptics want you to think all LRL's are wallet miners. If you subscribe to that flawed logic then you are being suckered by the skeptics (mostly people who make their living off the metal detector industry). They have motive.
Inflated prices are one thing. A few of the manufacturers actually spend thousands of hours developing the LRL's. And then there are a few who feel like they can steal that info and without any development costs charge ten times more than the thing is worth. If you want info, contact Dell Winders in Haines City, FL. He's the guy who figured out a set of L-rods can be used in place of the electronic receiver. The original MFD's did not use L-rods--they used an electronic receiver.
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#9
08-19-2014, 03:09 PM
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thanks
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#10
08-19-2014, 06:24 PM
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I guess there is kind of a double whammy with MFD's. You have the solar magnetic interference and you have the L-rods. Both these can add significant "play" sort of like loose steering on a vehicle.
Whatever the case, if you can't use the rods you won't get too far. I tell people to learn some form of meditation, but this has fallen on deaf ears. "Don't need that.", "Don't have time.", etc., etc. You'd do well to avoid the rabidly biased naysayers unless you are trying to convince yourself they "can't possibly work". I never understood why anyone would believe someone who can't use the L-rods.
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#11
08-19-2014, 09:15 PM
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If you haven't already read it, I would suggest you get a copy of "Inside the METAL DETECTOR" -> http://www.geotech1.com/forums/conte...metal-detector And ... I wouldn't waste any time with L-rods or MFDs.
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#12
08-19-2014, 10:10 PM
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The question perhaps doesnt have to do with metal detectors . so let me try to make an example I have a neodymium magnet that can induce very clearly a field at any conductor hanging from a thread across the room.-the conductor moves that is- My room is about 25ft. So seemingly the first step is established into simulating a distance object. The next step is receiving the information which could be the tricky part. I may have a mental block but it looks like there can be only two solving approaches for the next step: A-The new of course much weaker magnetic field induced in the distant conductor may be too weak for me to still detect it at the 25ft distance ? perhaps a super sensitive magnetometer could help but I understand that the field would be very low. B-(the better solution?) Detecting by receiving the electromagnetic wave with an antenna. I.e, after we have excited our little conductor from a distance with our strong magnetic pulse train of a specific frequency from the tx, current is induced in the distant conductor at the same frequency and now we receive the weak electromagnetic wave of the same frequency emanating from the conductor. I am really not sure if my point is clear but I would love why this cant work ? thanks
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#13
08-19-2014, 10:17 PM
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Quote:
http://www.mountainman.com.au/kural/kural029.htm
__________________
Global capital is ruining your life? You have right to self-defence!
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#14
08-20-2014, 01:35 PM
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Did you look at the Meyl videos? He has a website with some other info on it. You see the longitudinal waves and how the flux lines "bundle" to the receiver because it is in resonance. There is little loss of energy. Of course this is totally different from the transverse wave that electrical engineers wrongly apply their principles. I have to assume they do not have a clue on this although I have suggested many times that they know and are hiding it. The thousands of hours the skeptics ave spent trying to convince people that the MFD's can't possibly work you gotta believe they have motive here.
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#15
08-20-2014, 01:54 PM
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When I say that some form of meditation is essential to any L-rod work, most people run away. I'll say it again, you have to quiet the mind to be able to sense the subtle energies that create the "body response". I learned with a device that had a skin galvanometer hooked up to it. I learned to sense the body response. No doubt many of the failed L-rod wannabe's are not able to achieve this just because they think they are superior, think they know more. I call it the Natural Selection process.
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#16
08-20-2014, 02:14 PM
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__________________
Global capital is ruining your life? You have right to self-defence!
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#17
08-20-2014, 02:33 PM
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I've worked with many different types of locators over the years. I like the frequency generators but they don't always work. When Dell Winders and Vernon Rose were working on the MFD's with the electronic receiver, they learned so much about the signal lines and how the interference affects things. It's a lot more difficult to see what is going on with only a set of L-rods to work with.
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#18
08-20-2014, 10:15 PM
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#19
08-20-2014, 10:16 PM
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#20
08-21-2014, 02:19 PM
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I compare it to learning to play golf. Many people do not have the patience. And I always get a chuckle when someone who can't use a set of L-rods tries to tell others they can't possibly work. That's the Natural Selection process in action.
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#21
08-22-2014, 02:33 PM
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Again, I say watch the Meyl videos and read some of his website. maybe you will learn something. Study the near field. If you are using 300MHz, well the near field is not too far, maybe inches. The frequencies used in the MFD are in some cases less than 100Hz, but even at 5KHz it's a few miles. Not saying an MFD can pick up a target at that distance, but maybe if the target is a large vein.
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#22
08-24-2014, 03:35 PM
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Some guy from MIT was talking about the Witricity which is very similar to what Meyl is doing. He said using the resonance is almost a million times more efficient compared to induction (like a transformer).
Yeah, the biased don't want to discuss this one.
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#23
08-25-2014, 03:00 AM
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http://www.longrangelocators.com/for...&postcount=214 "I can find a signal line without rods. I hold my arms out from my sides and relax my wrists so my hands point down somewhat. I call it the scarecrow stance. Then I walk around the transmitter (arms parallel to signal line) until I feel the psychic electricity. I can't pinpoint the target with this method, just the signal line. I use the Revelation Locator Rod. There is no other rod that has as low stiction. It has an extremely low start-up torque threshold that borders on the infinite. Of course it's not, but it's imperceptible". Best Wishes,  J_P
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#24
08-25-2014, 07:28 AM
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After a healthy amount of reading of your posts, others´ and this and other sites, am I correct to sadly see that there is not a single working machine/concept/idea so far ? Anyway I am thinking about using metal detectors but with bigger coils to increase the range to some meters at least and yes I know the sensitivity is going down but I will be working in really remote areas, no houses or power lines so hopefully any big non ferro metallic conductor is the point of interest. My question is this: can I just install a home made big coil to one of the metal detectors? or is there special electronics or a limit to how big a coil can be?
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#25
08-25-2014, 10:43 AM
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You are correct to see not a single working machine/concept/idea. You do not see them because the only working LRLs that are viewable are experimental LRLs which cannot be relied on to give positive repeatable results like metal detectors do. As an example, there are the Morgan PDK clone mods of the Alonso Pistol detector. We also have a number of other allegedly working LRLs shown in these forums such as the swinging rod thingies that Mike (Mont) assures you will work. But most of these only work when skeptical people are not watching them work. With that said, there is still something to the concept of long range detection of metals that have been buried a long time. Gold, silver, copper and other metals do corrode after being buried long enough. The corrosion is not much for gold, but enough to cause interactions that can be measured as tiny variations in electronic activity that would normally occur in the vicinity if the metals were not buried. The mechanics of this process is complicated, and would take several pages to explain the basics. But the bottom line is even noble metals can become detectable from a distance if they are buried in the ground for long enough and the soil conditions are favorable. Is there not a single working LRL? LRL manufacturers know something is happening with long-time buried metals to make them detectable, but they don't know the full mechanics and physics involved, so they manufacture equipment that might work in some circumstances, but usually fails to work with any kind of reliability. Thus, we see a lot of LRL owners who are disappointed with the performance of their expensive investments. Then we have some manufacturers like OKM and others who manufacture completely fraudulent equipment that does not do what they say it does, as proven by Morgan, when he visited the factory and found their best locator could not find a treasure he buried in shallow dirt outside their factory. One of their employees even advised him he would be wiser to spend his money on a used Mercedes Benz instead of their locator. Unfortunately, there are a lot of LRL manufacturers who produce this kind of crappy fake LRL. But there are real long range locators that do really find long time buried metals such as gold, silver, copper, bronze, aluminum and others reliably from a long distance. These are not available for the general public to buy, and you will not find anything published about this technology in any treasure hunting forum. But there is one exception that I have found. Andreas is a member of this forum who appears to have designed several LRLs which have a track record of finding treasure from a distance. How reliable? I don't know. But I heard reports from Mexico, Greece, USA and the UK that they are very reliable. His machines work on two different principles. The less expensive and shorter range version uses VLF electromagnetic principles to detect, and the more expensive longer range version uses infrared detection methods. In addition, he recently posted circuits for free use to build a working long range locator made from modifications and improvements to the old Alonso pistol detector. The problem is his solution for long range detection using the Alonso method requires micro-adjustments which are nearly impossible for people who don't have the equipment to calibrate them the way he does. Still, you can buy the detectors he designed to locate up to 30 meters distance from the Crypton company: http://crypton.com.gr/ Also be sure to read his posts about his solution to long range locating using the Alonso method, and building a locator that finds only gold... http://www.longrangelocators.com/for...ad.php?t=18956 About putting larger coils on a metal detector: Larger coils can probe deeper than small coils generally. However, when you put a larger coil on a metal detector, you also lose the sensitivity that smaller coils have for finding small metal objects, such as necklaces made from tiny chain links, and small nuggets, etc. Large coils are generally used for finding large metal objects that are deeper, such as meteorites or buried cannons, old trash dumps, large ore bodies etc. I've seen home-built coils with up to 5-ft diameter on PI machines. But that is general. There are probably some specialty large coils that do other things besides find large deep objects. There are limits to what kind of coil you can put on a metal detector. The electronic properties of the large coil must be compatible with the detector you are using. This is why it is most often done with PI machines, which are easier to match. VLF detectors can also be fitted with large coils, but these are more difficult to build and balance. You may want to look in the Geotech forums for some help about the kind of treasure hunting you want to do. They have a number of threads where people show how they connected large coils to PI detectors to hunt for deeper treasures. You will also find some of the brightest metal detecting engineers in the world posting in the Geotech forums - http://www.geotech1.com/forums/forum.php Best Wishes, J_P
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