PI Detector for gold

Which DIY PI detector is best for nugget shooting?

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Hi,

If you are planning on hunting gold nuggets, you really do need a detector with ground balance capabilities for the best results.  You will want to try to get the delay down to 10 usec or less if possible also. 

The Goldscan 4 can do this with a few mods and it does have ground balance capabilities. 

Right now, it would be nice to know if anyone purchased pc boards for this detector or has the pcb layout in a format that would allow one to purchase the board with a silkscreen.

BTW, there are a few mods that can be done to make this detector a little better and well as a few simple ideas on coils. One doesn't have to build coils using the basket weave and still make coils that work at 10 usec.  Simply using Teflon coated stranded wire with 600V insulation will allow this to be done. 

Reg

Posted on: January 08, 2011, 09:48:15 AM

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Hi Again,

One thing you can do to any PI that will help some when trying to nugget shoot is to modify any design so you can use a DD coil.  This will allow one to have less ground problems.  The best solution is to have ground balance capabilities but using a DD coil is something that will help on other detectors that don't have ground balance.

Reg

Posted on: January 08, 2011, 09:59:33 AM

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Hi Again,

As you can tell, I am trying to hit the minimum number of posts so here goes another idea for your PI.  You can also add another high pass filter to help reduce the ground signal and this, along with a DD coil further makes it easier to use a basic PI in bad ground.  It certainly will not be a good as a ground balancing detector, but will work better than a basic PI for nugget hunting.

Reg

Posted on: January 08, 2011, 10:01:46 AM

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Hi again,

Well, I need one more post so I will add this bit of info I wrote several years ago.  Here is a link to something I wrote about understanding PI's and now they work. 

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This article is in two parts.

Hopefully, it will help people better understand the PI.  Now, this same article may be on this site but I didn't search for it.  I wrote it for Bill so he could post it on the Nuggetshooter forum but it got picked up and posted in a lot of other locations.

Reg

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I am a new member and don't have a detector right now .  I am looking to buy a PI board or a kit that is best for gold nugget prospecting.  A tall order to be sure  but I have the electronic skills to build a quality detector if you can point me toward the best ones.  I have been considering the 'Chance' but info on it is sketchy and the videos of tests are of large pieces of non gold metals so I'm unconvinced.  I also have been looking at the "Hammerhead I" kit but don't know if it is the best out there for my purpose.  It would be great if the unit would detect a 1/4" gold flake at 3".  Is this even realistic?

Thanks,

Dan

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Hi Xavier,

If building a discriminating PI was an easy task, it would have been done by now. 

Can a discriminating PI be built?   Yep, but it isn't as easy as one might think.  The key reason is ferrous objects cover a wide range of signals.  A good example is what one notices if they use the TDI or the Goldscan 5 designed by Eric Foster.  Actually, the Goldscan 4 displays some of the features also. 

What I am referring to is the fact, thicker iron responds quite differently from other junk ferrous items such as tin cans.  A nail response is very different from a piece of an old rusty bottle cap, or a piece of a can.  This becomes very obvious when you use the White's TDI or the Goldscan and the ground balance is adjusted for normal balance.  Most thin ferrous junk such as a tin can will generate a high tone while a nail will create a low tone. 

At the same time, most small gold, less than maybe a half oz or less will usually create a high tone while only some gold larger than a half oz will cause a low tone.  Fortunately, most gold we find here in the US is smaller so most will generate a high tone. 

When it comes to gold and how it responds on the TDI, a lot depends upon several factors including, size, weight, purity, surface characteristics and how contiguous it is if it is in rock/gold form.  A rock containing several smaller non connected chunks of gold will not respond the same as a nice solid single piece of gold having the same gold weight.

Because of this wide variation in gold itself, it becomes extremely difficult to separate gold from most other items, let alone from the infinite size and shapes ferrous items can come in. 

The best one might hope for is a detector that does a really good job of determining ferrous junk so it can be separated from the non ferrous metals such as gold, silver, lead, etc.  When I mentioned the possibility of a discriminating feature, that is what I was referring to, the ability to distinguish ferrous or at least, most ferrous items from non ferrous items. 

With the above said, one should keep in mind the other problems such as if gold is buried next to or inside a ferrous object.  If this is the case, then the disc feature will not be able to separate the two.  As a general rule, the signal will be determined to be ferrous since it will most likely be the dominate signal. 

As for a discriminating PI, many of you have heard of the Pulse Devil built designed and built by Dave Emory. Most of you who have followed the history of this detector have probably read all the BS about how it doesn't exist or doesn't work.  Well, the design is solid and should work.  In fact, the fundamental concept was built around a detector called the PPD1 built by Eric Foster in the 80's.  This was a discriminating detector capable of determining ferrous from non ferrous items.  Actually, the design worked reasonably well on a clean saltwater beach.  Once a person left a beach and went inland they experienced serious ground signals that masked any form of discrimination.  Thus the design never really gained popularity.  The typical problems experienced by users of the old TR detectors were also experienced by owners of the PPD1.  Ground signals made it impossible to get any depth or have any discrimination features if the mineralization of the soil was bad.

Now, if all the above doesn't confuse a person, then the fact that some people think metals have some form of resonant frequency should.  The truth is, gold, like any other metal, has a different signature that is dependent upon several factors mentioned above.  The signal from gold will vary because of its purity, size, shape, surface characteristics, etc.  Generate any electronic signal into the ground and gold will generate a wide variations of signals.  This is quite obvious if you own one of the earlier target ID detectors since the gold range was most of the meter range. 

Getting back to a PI and discrimination, there are a few designs where multiple samples are taken and the signals analyzed.  Again, the problem with this design is the extremely wide range of signals one might get from both ferrous junk and from gold.

Thus, in my opinion, a different approach would be necessary. 

Reg

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Now I'm mad my post went missing 

Posted on: April 16, 2011, 05:46:38 PM

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OK so here I go again these things happen when there is a message sent at the same time as I send my message I'll just have to learn to live with this.

Firstly I would like to thank you for having confirmed some of the things that I have found out my self and others that I have read on the net also may I say that I really enjoy reading your posts they are informative and motivational. I believe that I do understand what you are saying and I must say that it does make a lot of sense (things that are so easy with a VLF are so hard to do with a PI) what I would like to achieve at the moment is to discriminate (audio) between ferrous and non ferrous metals and yes if there is a gold coin in a can well I'll miss it if I don't dig but I really want to be able to have a different audio signal as where I am detecting is a farm and may I tell you that I have removed loads of steel wire so it would be nice to hear the different audio signal when I hit non ferrous.

All the best Xavier     

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Xavier