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Hardnose
Calm down guy, it
Calm down guy, it
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Hardnose how would you know that you were not picking up nuggets it that type of ground???? your detector wouldn't read them and you would go along on your merry way. Chris opened up ground and discovered the situation!!! while people have realized grounds like these were problems they really didn't know they weren't getting results! learn from what has been discovered, you just can't say someone can't tell you VLF technology can read any ground conditions.
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Anonymous
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This may or may not be of any value but here goes. The pulses from the PI may be magnetizing the ground. Each pulse from the PI will increase the problem. It seems to me that what might be required is a PI with alternating positive and negative or bipolar pulses. This would stop the ground from being permanently magnetized. Some Fisher detectors use bipolar pulses but they do this soley to lower power consumption using a circuit they patented. I am not aware of a prospecting PI detector which uses bipolar pulses but maybe someone knows of one. It would be interesting to see if it helped solve the problem.
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Anonymous
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Hi Steve,
I have been reading some of the posts on the Finders forum but not all. It sounds like Hake has been doing some serious studying of the problem.
If you have read the post by Dave about the bi-polar idea, it is what I was trying to get across in my previous post. Dave did a much better job of getting the idea across.
George Payne did some research in the field of bi-polar pulses somewhere around 1978 and patented a concept of pulsing the ground with negative pulse, then sampling after a positive pulse. The ground would then be pulsed with a positive pulsed again and again sampled (or visa versa). The patent info indicated the ground would retain a magnetic memory and there would be a difference in the ground response between the two pulses. It is an interesting patent. In his design, the information was to be used for ground balancing and the design was aimed at coin hunting.
Obviously ground conditions will change so what works at one location may not work at the next. That is why it will probably require the ability to adjust the duration of pulses of either polarity and possibly the time between them.
This would probably require a microprocessor to make the necessary changes rapidly. I will have to leave this type of design to the Eric's and Dave's of the world. My get up and go, got up and went several years back. Also, it is strange how the days seem to get shorter the older you get (except for work of course). At least they have for me.
Getting back to Hake and his posts, we definitely need more posts like that to provide additional information about the difficulties involved. Once a problem is known, a solution may be found.
Until the problem is resolved bulldozer technology may be the best solution. At least we know it works.
Reg
I have been reading some of the posts on the Finders forum but not all. It sounds like Hake has been doing some serious studying of the problem.
If you have read the post by Dave about the bi-polar idea, it is what I was trying to get across in my previous post. Dave did a much better job of getting the idea across.
George Payne did some research in the field of bi-polar pulses somewhere around 1978 and patented a concept of pulsing the ground with negative pulse, then sampling after a positive pulse. The ground would then be pulsed with a positive pulsed again and again sampled (or visa versa). The patent info indicated the ground would retain a magnetic memory and there would be a difference in the ground response between the two pulses. It is an interesting patent. In his design, the information was to be used for ground balancing and the design was aimed at coin hunting.
Obviously ground conditions will change so what works at one location may not work at the next. That is why it will probably require the ability to adjust the duration of pulses of either polarity and possibly the time between them.
This would probably require a microprocessor to make the necessary changes rapidly. I will have to leave this type of design to the Eric's and Dave's of the world. My get up and go, got up and went several years back. Also, it is strange how the days seem to get shorter the older you get (except for work of course). At least they have for me.
Getting back to Hake and his posts, we definitely need more posts like that to provide additional information about the difficulties involved. Once a problem is known, a solution may be found.
Until the problem is resolved bulldozer technology may be the best solution. At least we know it works.
Reg
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Anonymous
Guest
Hi Dave and Reg,
Most geophysical prospecting PI's (they call it TDEM, or Time Domain Electromagnetics)use alternate polarity pulses. I've not read that they help with ground magnetism but their main purpose is to eliminate the build up of induced polarisation signals which would confuse the conductive response they are looking for.
Eric.
Most geophysical prospecting PI's (they call it TDEM, or Time Domain Electromagnetics)use alternate polarity pulses. I've not read that they help with ground magnetism but their main purpose is to eliminate the build up of induced polarisation signals which would confuse the conductive response they are looking for.
Eric.
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Anonymous
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Hi reg and all. The patent you are talking about is US Patent number 4,110,679. It was issued on August 29th 1978 to George C Payne of Tempe Arizona. You can get a copy of it from the US Patent and Trademark Office at www.uspto.gov You will need a TIF viewer to get the drawings. This is indeed a very clever patent. Whites, the assignee to the patent never used it!!! The patent teaches how to cancel the ground and simultaneously discriminate against iron with a PI using a Dual D search coil with zero motion. The iron discrimination takes advantage of the irons hysteresis. The drawback to the method is that it would seem to work best at a low pulse repetition frequency of about 270Hz. George Payne was the inventor of the VLF ground cancelling detector. He is one of the best konwn names in detector design. Dave. * * *
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Anonymous
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HI Dave
I believe that the reason Minelab developed the GP Extreme was in fact to counter the magnetizing effects of the detectors pulses and work at a lower power output than the SD's I am not certain if this is absolutely correct but it is what I was told. We need Bruce Candy on this forum to explain how things work. Unfortunately for Minelab the GP is not working quite as well
as was hoped.
Howard my prospecting mate is currently digging up a few nuggets in cenrtral Victoria with his GP and has dug some rather deep holes, unfortunately not for gold but the GP is getting good penetration.
Cheers
Steve D
I believe that the reason Minelab developed the GP Extreme was in fact to counter the magnetizing effects of the detectors pulses and work at a lower power output than the SD's I am not certain if this is absolutely correct but it is what I was told. We need Bruce Candy on this forum to explain how things work. Unfortunately for Minelab the GP is not working quite as well
as was hoped.
Howard my prospecting mate is currently digging up a few nuggets in cenrtral Victoria with his GP and has dug some rather deep holes, unfortunately not for gold but the GP is getting good penetration.
Cheers
Steve D
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Anonymous
Guest
Hello donq2,
As the name of the game is to pick up nuggets, I, as probably Chris is , be quite frustrated and peeved off, to discover that my metal detector had been incapable of detecting those precious little objects, that were the reason that I was there for in the first place.
It dose not have to be gold that would upset anybody. I imagine that it would apply to any type of material recovery by the use of a metal detector that I had for that purpose and in this case gold prospecting.
The need to pick up and read the desired target in a given situation is obviously crucial and to have your worst fears revealed and "confirmed" like Chris, and by the way, many others have, lets you see what inadequacies some metal detectors have. From what I remember, the concept of layer removal by mechanical means for the recovery of gold is actually an old and proven concept that was used all over the West Aussie gold fields including up at Eneaba back in 1979.
Again I am not saying that VLF CAN read any ground conditions. I am asking whether someone has tried a multi frequency vlf detector and confirmed that it is as incapable of detecting the nuggets that the other detector has not.
How would we know? We could always make a test bed in "situ" at the site to simulate the location of a nugget.
This would be done at the moment of mechanical recovery, cat d9 or whatever, after the patch of ground was identified as "hot" and impenetrable by any detector or the detector was found to be incapable.
At that point, one could then "knock" themselves out and throw all the theoretical ideas at it to find a solution.
I really wish some one might have been able to actually confirm to me if the Explorer XS has been tried by them in a similar curcumstance that Chris has found himself in. It would save me a 350 mile plus one way trip by car to find out for my self. That is about how far I am would be from Chris and his "situation" and I do not think that he is about to grant me the oportunity to find this out, personally, with the MY Explorer XS.
Anyhow have a good one.
DAVE Di
As the name of the game is to pick up nuggets, I, as probably Chris is , be quite frustrated and peeved off, to discover that my metal detector had been incapable of detecting those precious little objects, that were the reason that I was there for in the first place.
It dose not have to be gold that would upset anybody. I imagine that it would apply to any type of material recovery by the use of a metal detector that I had for that purpose and in this case gold prospecting.
The need to pick up and read the desired target in a given situation is obviously crucial and to have your worst fears revealed and "confirmed" like Chris, and by the way, many others have, lets you see what inadequacies some metal detectors have. From what I remember, the concept of layer removal by mechanical means for the recovery of gold is actually an old and proven concept that was used all over the West Aussie gold fields including up at Eneaba back in 1979.
Again I am not saying that VLF CAN read any ground conditions. I am asking whether someone has tried a multi frequency vlf detector and confirmed that it is as incapable of detecting the nuggets that the other detector has not.
How would we know? We could always make a test bed in "situ" at the site to simulate the location of a nugget.
This would be done at the moment of mechanical recovery, cat d9 or whatever, after the patch of ground was identified as "hot" and impenetrable by any detector or the detector was found to be incapable.
At that point, one could then "knock" themselves out and throw all the theoretical ideas at it to find a solution.
I really wish some one might have been able to actually confirm to me if the Explorer XS has been tried by them in a similar curcumstance that Chris has found himself in. It would save me a 350 mile plus one way trip by car to find out for my self. That is about how far I am would be from Chris and his "situation" and I do not think that he is about to grant me the oportunity to find this out, personally, with the MY Explorer XS.
Anyhow have a good one.
DAVE Di
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Anonymous
Guest
Hi Eric and all. This subject certainly raises some interesting opinions !. One thing I'd like to add is that the ground is not what I would call noisy and the monoloop coils SEEM to handle it OK. I'm wondering if this could be due to the Tx field being immediately dissipated by the magnetic red clay to the extent that there is no remaining field for the Rx to pick up ??. Noisy ironstone ground obviously retains sufficient EM flux for the Rx to hear, but this red clay doesnt do so. Cheers, Chris Hake.
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Anonymous
Guest
Hi Chris,
As you have seen, this subject is of considerable interest and there has been a lot of good feedback. From the pictures you sent it looks as though you have a nice flat, and fairly uniform surface, once you have
As you have seen, this subject is of considerable interest and there has been a lot of good feedback. From the pictures you sent it looks as though you have a nice flat, and fairly uniform surface, once you have
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Anonymous
Guest
Hi Chris,
Your condition sounds much like an area around Rich Hill Arizona. There the bulldozer technology was about the only thing that worked also. The ground was very red and the clay was very dense. When moist, it was almost impossible to dig a hole using a small hand pick. You would just slam the pick point into the ground and then spend some time trying to get it out.
SD's weren't available or just coming on the market when the area I was hunting was being bulldozed, so VLF's were the machines being used. We experienced the same thing with them. There just didn't seem to be much ground penetration.
Later, the SD's were used and they seem to experience the same problems.
Once the ground was disturbed, we would find nuggets in the pushed material and in the scraped area.
I am curious if the red clay were you are operating is also extremely dense. Is the clay moist at sub-surface levels? Also, once the ground is disturbed, did you try burying a target and then checking for maximum depth? We did and it seemed like there was some depth loss but not what we felt we were experiencing in the undisturbed ground.
Finally, did you try a VLF at the site? If you try a auto ground balance unit, try setting the balance to fixed and then turning the machine on. I would expect that when you lower the coil to the ground, there will be a very loud audio response.
Reg
Your condition sounds much like an area around Rich Hill Arizona. There the bulldozer technology was about the only thing that worked also. The ground was very red and the clay was very dense. When moist, it was almost impossible to dig a hole using a small hand pick. You would just slam the pick point into the ground and then spend some time trying to get it out.
SD's weren't available or just coming on the market when the area I was hunting was being bulldozed, so VLF's were the machines being used. We experienced the same thing with them. There just didn't seem to be much ground penetration.
Later, the SD's were used and they seem to experience the same problems.
Once the ground was disturbed, we would find nuggets in the pushed material and in the scraped area.
I am curious if the red clay were you are operating is also extremely dense. Is the clay moist at sub-surface levels? Also, once the ground is disturbed, did you try burying a target and then checking for maximum depth? We did and it seemed like there was some depth loss but not what we felt we were experiencing in the undisturbed ground.
Finally, did you try a VLF at the site? If you try a auto ground balance unit, try setting the balance to fixed and then turning the machine on. I would expect that when you lower the coil to the ground, there will be a very loud audio response.
Reg
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Anonymous
Guest
Howdy Reg. Yes, your situation at Rich Hill sounds identical to mine. The clay is something like red rubber and if your pick is blunt, it just bounces back off it !. Also spot on with your feeling that once the dozer has scraped off about 6-8", the SD seems to get decent depth again. This suggests that, as Steve D said, there is a thin magnetic field at the top of the red clay layer and by scraping it you break up the field, allowing the SD to penetrate fairly normally. The business of magnetics and EM fields sure is a tricky one eh !. Cheers, Chris Hake.
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Anonymous
Guest
G'day Dave. You are very welcome to try your Explorer on my patch and I'll split you 50/50 with any gold it gets. Lets do it, email me at hakey@emerge.net.au. Cheers, Hakey.