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  1. #16

    Aug 2005
    12

    Re: Resistivity machines...for real?

    Boattow -

    The older model is available on Carl's site. The more current project and data logger still require you to order back issues from EPE.

    I may have a copy of the article, drop me a PM.

  2. #17

    Apr 2007
    8
    All Types Of Treasure Hunting

    Re: Resistivity machines...for real?


    Hi,

    May I offer a few comments related to the wide range of posts on this topic?

    All of the comments, shared experiences and suggestions can be summed into a "body of knowledge" on this very important issue - I thank you all in advance!

    Treasure hunters include a wide range of personalities with even wider experience and education on the subject. I have to give everyone here a lot of credit for their personal interest, enthusiasm and dedication to learning, experimenting, testing, evaluating, and offering opinions. This is the most important aspect of treasure hunting - simply put having the right tool (or tools) to find treasure.

    The tools and the users combined with the objective have to be compatible with each other. On one end of the spectrum is the 10 year old with a 10 dollar detector in the park looking for nickels and dimes. On the other end is a Publicly traded mega-dollar exploration company using a Transient EM system with a coil 1 mile long on a side looking for a multi-megabuck volcanogenic gold-platinum massive sulfide.

    What are the trade-offs?

    We probably all agree, the 10 year old can't afford nor has he the technical background to plan and execute a large scale TEM survey. The trade-off is in cost of technology, required training, application or objective, and desired outcome. A very comfortable point of view is in the middle.

    Setting a realistic objective:

    I want to find a one ounce gold nugget at 2 feet! Since most hand-held detectors can detect to a depth of at best 12 inches - the 2 feet objective opens a new realm not covered by the largest number of prior search activity. It places most wage earners in a position to meet the knowledge and cost factor requirements.

    Realistic knowledge requirements:

    Serious metal detecting requires a person having the ability to understand the capabilities and limitations imposed by certain laws. - The laws of physics! I know I can't buy a bee-bee gun for 10 bucks that will shoot a bee bee pellet 3 miles. I'm qualified!

    Cost factors:

    What should a metal detector cost? Can one person with little or no knowledge or experience research existing patents, create a design, document, prototype, test, develop, manufacture, support a working, middle of the line metal detector for $300.00 a copy?

    Unfortunately, Probably not.

    Looking at the $10.00 (Chinese made) detector - it's probably a $50.00 detector. I don't think you can buy one for much less. It will be an early technology BFO - low cost design that uses $10.00 worth of materials and has a production of 100,000 units. Ignoring the profit motive, the units are cheezy and too limited in applications.

    The alternative - mass production $100 - $200 detectors are too limited in capability - the manufaturers still rely on selling 100,000 to half a million or more units world-wide.

    Looking at the $300 large single coil - or small two box detector. The parts cost is about $100. for Radio Shack parts and PVC pipe. One full day of labor at $200. and sell it for $300.?

    The $500 - $1000 detectors use precision low noise amplifiers - a requirement for resolving targets at depth. The amplifiers are $30. (cost) you will have $200 in parts, $100. in powder coat aluminum, $100. sales commission, and that leaves a little to pay the designer, assemblers, phone support, low rent facilities and tax man.

    The "bonafide" $1000 - $10,000 units require more knowledge and are technically advanced in terms of proper setup, operation, calibration, skill in measurement, and interpretation of data. These are sold in small volume, and use high cost components to perform as advertised. High power reliable solid-state switches can cost $200 each - transmitter uses four. The Power ratings fall in the realm of 1000 watts or more and give reliable, repeatable results to a couple hundred feet.

    Looking at upper end units that are produced one-at-a-time by a "group" of degreed engineers and management/marketing/technical people. Each member of the group gets a a 50k - 150K a year salary. It all adds up to a million dollar payroll combined with a half million for the facility. The market may consume 20 to 50 units a year. those 50 units absorb the fixed costs of $20K each. With a guaranteed continued market and a 20 percent profit margin - it's easy to visualize a $30K cost. These systems are repeatable, calibrated to an industry acceptable standard and offer results that veture capital and banking institutions will accept when used by the average publicly traded mining company. The application is moderate sized - less than 1 km high grade metaliferous targets.

    Just for the sake of mentioning it - The top dogs of the treasure hunters are the megabuck mining companies with airborne TEM systems that they lease for 10K - 100K per day. The post-processing can take days or weeks and adds a 100K to the tab!

    But, does it discriminate? No!

    Thanks for taking the grand tour. I invite follow-up questions and suggestions.

    Chuck

  3. #18
    Rock

    Re: Resistivity machines...for real?

    Here are some links that I have found. I am currently building a metal detector that is supposed to detect a coin at a depth of 15" or so. Total cost will be ~ $30. It is an induction balanced unit and not a beat frequency oscillator. This unit is able to be assembled by a novice.

    http://geotech.thunting.com/pages/me...chless300c.pdf

    Here are plans for building a earth resistivity system. I haven't started this one yet but from looking over the information you may want to find a friend with a little electronics experience. Maybe not though. I have found that nothing is rocket science not even rocket science.

    http://geotech.thunting.com/pages/ge.../erm1a_300.pdf
    http://geotech.thunting.com/pages/ge.../erm1b_300.pdf

    This site is absolute wonderful for plans.

  4. #19

    Nov 2007
    1

    Re: Resistivity machines...for real?

    Does anyone have any info about Heritage Geophysics resistivity meters?

  5. #20

    Nov 2007
    13
    2 times

    Re: Resistivity machines...for real?

    The Mother-Lode-Locator resisivity meter Dell Winders was talking about belonged to me. We found two caves or tunnels at the site he mention in his post. It is a two probe system, and like Carl says is not as stable as 4 probe meters. It is good at finding caves or tunnels, but poor in locating small metal caches. I have since sold it. I now use a Vibraground, and The Nilsson 400 resisivity meters. They are both 4 probe systems, and are far better instruments than the MLL. at a fraction of the cost. Sometimes you can find them on ebay.
    Resisivity is hard work, also you can not just go out and buy a resisivity meter and expect to start finding treasure without some knowledge of resisivity. There are a lot of different arrays you can setup using resisivity, and each one is used depending on what you are looking for. Yes they work. But before buying one do some studying on resisivity.
    I ran a test over my test garden with the Mother-Lode-Locator, Vibraground, and Nilsson 400 setting side by side. Between each data reading in the test, to make it as accurate as possible I switched the probe leads from one unit to the next, and wrote down the data reading from each instrument before moving the probe to the next position. I then entered this data manualy into computer software.
    The test garden used in this test has a 10 gallon milk can buried 6 feet, a small metal tool box buried 1 foot deep, 3 empty holes I dug with a tractor post hole digger 12" in diameter, and there is some farm junk in the grid.
    You will see in the grid the difference between a 2 probe system and a 4 probe system. Notice how the 4 probe systems bring out the milk can better than the MLL.
    http://lrlman.com/Pages/GCG/Comparison.pdf
    http://lrlman.com/yabb/Images/MCData.pdf
    kybob


  6. #21

    Oct 2007
    Bimini, Bahamas & Atlanta, GA
    Fisher 8-x, Garrett Sea Hunter
    37

    Re: Resistivity machines...for real?

    Interested to know more about TEM systems? Where should I look?

  7. #22
    Home of the Arc-Geo Logger imaging systems... As seen on the History Channel

    Dec 2005
    Louisiana
    Arc-Geo Logger-TM-808-Garrett XL500-Deepstar
    198
    3 times

    Re: Resistivity machines...for real?

    Who makes the TEM systems?

    Tim

  8. #23
    us
    Dr.

    Nov 2006
    Vicksburg, MS
    Geonics EM61-MK2, Geophex GEM-3, GapEOD UltraTEM III, Minelabs F3, Foerster MINEX 2FD 4.500
    78
    10 times
    All Types Of Treasure Hunting

    Re: Resistivity machines...for real?

    One of the previous questions was about TEM systems. One of the more common system is the PROTEM from Geonics (www.geonics.com). It comes in three versions, the 47, 57 and 67 depending on how much power you need and depth of investigation. I think the price range is from about $80K to $150K.

    For the question about inexpensive resistivity systems, read the link below. There was an amatuer archaeology group in the UK with the same desire. One of there members was an electronics engineer. He determined that he could make a four electrode system that was comparable to the Geoscan Research system that could sell for $1000. The problem came when you need to pass UL or CE certification to sell the units.

    http://www.cix.co.uk/~archaeology/ci...ity/resist.htm

    The post by geowizard was an excellent explanation of how instrument manufacture works. Resistivity systems work very well for near surface geophysics work, but only work in specific situations. Here are some of the companies that make resistivity systems.

    IRIS Instruments
    AGI
    ABEM
    Campus
    Scintrex
    Geoscan Research
    Ryan E. North
    Research Geophysicist

  9. #24
    ec
    Apr 2011
    14
    3 times
    I Use resitivity meters in my work Resistivity meters are allot of work if you use them correctly I take as many as 900 readings in a day. But the Info you get back is very reliable . If your looking for treasure it helps if its large. I have looked at the resistivity meters in the medal detecting websites and I'm a bit skeptical mainly because of how simple the proceedure is to use them . If they really worked I would think noone would use the units I work with but they are the mainstay of the industry . So having said all that a simple low priced unit is the LANDMAPPER but unless your pretty sharp its going to take you awhile to learn how to take the readings and then you have to learn the software and I still do not have that understood but my son does . But its a real scientific device that will tell you whats in the ground down to 10 meters easy but if you think your just going to pop it out of the box and do it your nuts .. plus you better be pretty sure your in the area of a Target because just blind searching would be hopeless it take a very long time to do just one profile in a day. A profile is 10 meters deep 70 meters long
    Last edited by Landfar; Feb 27, 2014 at 11:40 AM.

  10. #25

    Apr 2007
    8
    All Types Of Treasure Hunting
    Resistance and Resistivity are two different things;

    We can measure resistance with an "ohm meter". Two probes, connect the probes and read the meter. There are only two probes.

    The circuitry in the meter includes a battery. The battery provides a voltage that creates current flow through what ever it is you want to measure the resistance of. The meter is calibrated and the battery must be at the required voltage to get a correct reading. Always "zero" the ohm meter by connecting the leads together and adjusting the "zero" adjust or if it's a digital ohm meter, you press the "zero" button. Calibration can be checked with precision resistors.

    Resistivity is a measurement of a volume of earth (or other material). Resistivity requires FOUR probes. Two probes generate a current that flows through the ground. Two other probes measure voltage at specified distances (spacing). A system to measure Resistivity can be made by the "average" person!

    Here's how:

    You need a voltage source and two steel stakes to connect the voltage source to the ground. The amount of voltage can be 24 volts to 36 volts for starters. Place the two stakes 10 meters apart. These are the "current" electrodes (probes). Use a switch to turn the voltage on and off. The measurement electrodes should be "non-polarizing". Metal measuring probes can produce a galvanic voltage that interferes with your readings. Do a search for non-polarizing electrodes. You will need a Digital Voltmeter to measure the current. The DVM connects in series with the battery and the probes. Be sure it is set to measure "current".

    Place the two measurement electrodes at equal spacing between the two current electrodes (4 meters apart). Connect a DC volt meter between the two measurement electrodes. You can get a Digital voltmeter from Radio Shack. Doesn't need to be high priced!

    When the switch is turned on, you will measure a voltage between the two measure electrodes. After each measurement, the battery polarity should be reversed. The reason is because the voltage leaves the ground slightly charged.

    Next, I will tell you the rest of the story to calculate Resistivity and offer advice on distance to place probes, etc.

    - Geowizard

  11. #26
    LRL fraud debunked

    Dec 2010
    ciudadano del universo, residente de El Paso TX
    BS detector
    1,185
    408 times
    Underground detection

  12. #27

    Jan 2008
    251
    272 times

    I just looked on ebay and there are two Associated Research Vibrogrounds for sale. They are 4 terminal units. There is the model 293 for $99 that comes with 4 earth probes and the model 263 (what I've got) for $150. There is free earth resistivity software on the internet.

    Randy


  13. #28
    us
    The cave guy

    Mar 2015
    Beans Cove Pa.
    122
    173 times
    All Types Of Treasure Hunting
    Would the Associated Research Vibroground model 263 be decent enough for void or cave detection? I am not an avid treasure hunter and only have one treasure project on the plate. I am an avid caver and this unit may work for us, but I would like some input on its capabilities such as depth. Any opinions would be greatly appreciated.

    Don Carns Jr.

  14. #29
    Charter Member
    us
    Jul 2006
    Florida
    Minelab_Equinox_ 800 Minelab_CTX-3030 Minelab_Excal_1000 Minelab_Sovereign_GT Minelab_Safari Minelab_ETrac Whites_Beach_Hunter_ID Fisher_1235_X
    38,079
    30284 times
    All Types Of Treasure Hunting
    Smart max, welcome to Treasurenet, I am sorry but you can not post links to websites selling detector supplies if they are not supporting vendor.
    PLEASE READ OUR RULES. CLICK HERE TO READ ------> TreasureNet.com Rules

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  15. #30

    Nov 2004
    72
    3 times
    Hi Aaarth iv'e been in another country and didn't visit this forum too often. for a person of you're abilityes one would expect that a bilionair would have better things to do....

 

 
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