Resistivity machines...for real?

[shiva]

Hi! I have been wondering if ground resistivity locators such as the MotherLoad Locator, Accumeter's locator, or the GPRs actually work as described. Does anyone have any actual experience with them or have the opinion of someone who does?

As a follow up to this question, I had read on an archive of the Geotech forums that these devices are disgustingly overpriced and that a DIY kit from a EPE magazine article will build you the exact same thing.

I am sorry if I missed a similar thread when looking, if this has already been covered in another thread, I would appreciate a link to the former thread.

Thanks!

 

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[aarthrj3811]

Hey Shava....Did you ever open up a can of worms. To the best of my knowledge the Mother Load and Accumeter are Long Range Locators. Earth Resistivity is a whole different subject. I have not used? ---- products so I can't say how good they work. I own 2 LRL's and they work for me but are not perfect. If they operate with the use of Dowsing Rods rods there is a few things you should check before you consider buying one. There is a little test at? http://www.#@!$%#@!.net/success.htm that will be helpful. Learning to Dowse without the use of a field generator was a break through for me.? I disagree with Carl on LRL's but agree that you can save a lot of $ by building you own Field Generator.....Art

 

[Carl-NC]

"Disgustingly overpriced" sums it up pretty well.

The Mother Load Locator, Accumeter, and Kellyco GPL are all Earth resistivity meters (ERMs), not LRLs of the dowsing variety. ERMs "really work", and are very useful devices for some tasks, especially archaeological ground mapping. These particular 3 you mention, are what I call "Poor Man's ERMs" because they are terribly outdated* 2-probe designs that no serious archaeologist or treasure hunter would bother with, and for which a $50 bill and a trip to Radio Shack and Home Depot will pretty much get you everything you need to build one. Or, you can pay $1000's for someone else to build it.

The EPE project is a far better true 4-probe design, and even has a much-needed data logger and mapping software, which the PoorMan-ERMs lack. And you can still build one for a heap less money, maybe as little as $100.

- Carl

*The "Survey Meter" project on Geotech is EXACTLY the same design. 1971 I believe.

 

[shiva]

Thanks for the feedback thus far. Carl, I think you are the person in the forum thread I was referring to!

I actually have gone ahead and grabbed the 2003 back issues that cover the more up to date datalogging program and design. I read through the older item and was not 100% clear on a couple of things, if you wouldn't mind lending your expertise to a couple more questions on this subject...

1) From the older article I grabbed while I wait on the back issues to arrive, if making them yourself is stainless steel the preferred material or is there a more preferred material to use?

2) I am still not completely sure I understand how this arrangement works in terms of the current going through the rods and which rod is picking up interference from another? Is there any way this can be "dumbed down" so that I understand exactly how the rods are measuring the resistance that is coming from the rods themselves?

Thanks for your patience with me by the way.

 

[Dinkydick]

FWIW Just get the articles written by John Becker. I have built many of the projects
he puts in the magazine and found them all to work.

The resistivity meter takes a lot of time learning how to interput the readings. Building
it is very simple if you just know how to solder. I plan on using my meter when I have
a lot of time to stake out a search area and follow it through. At present I have only
located the water table level in my yard. That was easy to see.

I have also built his magnetometer and it also works.

Take a look at the book "Seeing Beneath the Soil" by Anthony Clark. In it are explanations
on how all this equipment works and shows the results obtained for analysis. Then you
can be the judge of what equipment you need for the task at hand.

I have the equipment to program PIC chips for these projects. HH

Dinkydick

 

[gldhntr]

resistivity meters are helpful, but not in all searches....they are useless in sandy soil, will give you fits in too wet clay , never even try in areas of quartz rock as unless you are wanting to crush ore for the minerals inside that the machine is picking up on you will be wasting your time, and digging big deep holes as the machines readings will show gold or silver very strong.....they will not read through bricks {underground vaults, or cellars },,, or glass, plastic, and a few other natural materials.....also if the ground is too wet or too dry, your readings will be affected also.......i am not bashing the use of the machines, just giving fair warning , that they are very good in the right place and element, but are useless in others.......i have used these many times, and will again, ...they are great for locating tunnels or unlined vaults,, and anything else as long as the conditions are right for its use.......i also suggest looking around alot before running out and purchasing a machine costing several thousand dollars thinking that it will magically lead you to your treasure because of the price....just another lesson learned the hard way by..............gldhntr.................also as of late there are data loggers and computer programs that are used in conjunction with the resistivity meters that make identification and reading results 100000 % better and easier i hear, and hope to be able to try these out in the near future.............g

 

[Carl-NC]

1) From the older article I grabbed while I wait on the back issues to arrive,? if making them yourself is stainless steel the preferred material or is there a more preferred material to use?

SS probes will not corrode which is nice, but with a 4-probe design the probe is not as much an issue as with a 2-probe design.

2) I am still not completely sure I understand how this arrangement works in terms of the current going through the rods and which rod is picking up interference from another? Is there any way this can be "dumbed down" so that I understand exactly how the rods are measuring the resistance that is coming from the rods themselves?

Not sure what you mean by "interference". Two probes are used to inject a forced current into the soil. Since it's a forced current, probe resistance & galvanic action have little effect. Another two probes are used to measure the resulting voltage drops in the soil. Since they feed a high-impedance measuring circuit, probe resistance has little effect and galvanic action is almost non-existent.

You say that ERM's work. Try telling that to Mark and Jeff of Pa. They say it is in the same catagory as LRL's? They say that ERM's and LRL's are in the same catagory. How so? They say neither works. You say ERM's work but LRL's don't. I say that both of them work and I hope to prove it.

Mark, Jeff... ERMs work. They are not LRLs. LRLs work too, but not the way everyone wished they did.

I have seen at least a hundred times you saying that ERM's can be made for less than $100. Most now sale from $3,000. to $10,000. If they are so cheap to make why don't you go into business. Labor cost can't be that high. You yourself just now said that they work. I have always heard that if you could build a better mouse trap that it would make you rich. Here's your chance. I would like to purchase one of those cheap working machines that you can build.

Well, I just might do that. What do you think would be a fair price for a 4-probe ERM with data logging and software analysis?

- Carl

P.S. -- gldhntr is correct... as with any equipment, ERMs have their limitations.

 

[nugget]

Dell Winders
what kind of MLL / ERM are you using....what is the specific model...
the is interpretation is very very clear....did you made an excavation already?
what is the result?

 

[gldhntr]

i believe dell is referring to the mll-100 = mother load locator, ground resistivity unit........have alot of experience with this unit......................gldhntr

 

[nugget]

i believe dell is referring to the mll-100? = mother load locator, ground resistivity unit........have alot of experience with this unit......................gldhntr

can u give me some link for this mll-100, coz i cant find one....thanks...what is your opinior regarding this resistivity...does it work well....how about this "poormans resistivity", the twin probe TR resistance meter...is it ok? there is a similarity on home made resistance meter that is very cheap...from EPE...they call it PIC base earth resistivity logger that costs only 72 USD, less the probes(you have to build one), with free software..any comment on this?

thanks

 

[nugget]

hey dell....do you have a data logger for mll-100...what model...if none...how did you come up with the picture...did u enter the datum manually... how did you do it......any info please......

 

[nugget]

I don't own an MLL .We used one that was purchased by a friend that lives in another state, I entered? the data manually, and probably incorrectly, a year after the data was cvollected.

Requested MLL Link:? http://treasurenow.com/html/MLL.html

dell
can u give me a view how did u do it manually...i cant visualize your procedure...thanks

 

[nugget]

Carl,

You say that ERM's work. Try telling that to Mark and Jeff of Pa.? They say it is in the same catagory as LRL's? They say that ERM's and LRL's are in the same catagory. How so? They say neither works. You say ERM's work but LRL's don't. I say that both of them work and I hope to prove it.

I have seen at least a hundred times you saying that ERM's can be made for less than $100. Most now sale from $3,000. to $10,000. If they are so cheap to make why don't you go into business. Labor cost can't be that high. You yourself just now said that they work. I have always heard that if you could build a better mouse trap that it would make you rich. Here's your chance. I would like to purchase one of those cheap working machines that you can build.

Yes Carl...build us some ERM, especially the twin probe from EPE with data logger...make it for sale for us..maybe less than 300.00USD complete with accessories....the twin probe ERM with data logger is almost the same price as the two probe from accumeter,fitzgerald etc....make our investment
worthy....THis is an appeal to all electronic engineer and technician...build us a very very cheap ERM...not the "cheap" ERM that cost 2000.00USD...i can
try to build some, but its time consuming to a beginner like me and it might not work the first time...and the components are not available to all countries...or the substitute components i dont know....SOS...

Does anybody in this forum build/assembles EPE earth resistivity meter with data logger and make it for sale? i want to buy one hopefully not to exceed 300.00 dollar complete set...and the other one ERM two probe like this. http://www.thunting.com/geotech/pages/geo/projects/survey/survey150.pdf...with complete set, operational for less than 300.00USD also...i beleive its a decent prince then...

 

[Hoss KGC]

Does anyone know if the EPE articles are posted anywhere on the net? I have one of the parts but not both. I'd like to build it and see how well it works.
Thanks,
Boattow

 

[oldman]

I'd say resistivity machines are real but do not work as advertised. Like so muich of This treasure hunting equipment, sounds great as advertised but falls short in the field. BP

 

[shiva]

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.

 

[geowizard]

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

 

[Rock]

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/metdet/projects/matchless/matchless300c.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/geo/projects/erm1/erm1a_300.pdf
http://geotech.thunting.com/pages/geo/projects/erm1/erm1b_300.pdf

This site is absolute wonderful for plans.

 

[jkiwi]

Does anyone have any info about Heritage Geophysics resistivity meters?

 

[kybob]

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