"This myth is Busted"

[Nupi]

Nupi you are not reading my posts with attention.
I wrote:
"..The other day i witnessed this nice find: ..."
So i "WITNESSED" and not "I DISCOVERED".
That coin was discovered with X-Terra 70 not with Deus.
We had 3 Deuses and 1 X-Terra in a crew that day.
...
No i don't make traps for my friends. I don't make traps at all.
I just avoid to say every little detail, purposely.
You can think on why.

...
Yes there is always possibility of hard masking. I agree.
Very often situation. Deus is not immune on that too.
...
Coin dried from a moisture.
It takes just several seconds to hold it in hand to get it dry.
Especially on a sunny day under the killing sun.
And than situation with detection is much different.

Take it easy man,
I was only joking you.

[ivconic]

Take it easy man,
It was only joking you.

I prefer Guinness... but Amstel will do the same!

[Nupi]

[Nexus]

http://www.njminerals.org/metaldetec...aloeffect.html

This article is loaded with brainstorming, but no much science.

Some scientific facts.
1. Bronze targets do not form any water soluble salts in the ground or if some of them are the solubility is so low that can not contribute for any reasonable increase of detection field. This is the reason for the coins patina to be so mechanically and chemically stable in the first place.
2. All bronze and copper coins patina compounds are very good electrical insulators without any exeptions. Get some Ohm meter and measure conductivity across coins patina. It is always in the MOhms range.
Now if the patina is not conductive, how can the same salts possibly change the soils conductivity up to the level of detection field increase? It can not happen, period.
3. When a patina is formed over the coin surface the electrical conductivity on the same coin's surface is greatly inhibited. Metal detectors reactions are mostly cause by surface Eddy currents and no so much by Eddy currents going across the bulk mass of the metal objects. If any coin would shed so much of its mass that will contribute to Halo effect in the same amount its surface conductivity will be inhibited due to formation of salts that are insulators regardless of water content. So one will act agains the other.
The micro amount of dissolved metal from the coin can not replace the reduction of the coins surface conductivity, no matter what kind of salt will form, simply because for a greater electrical conductive area the required metal ions will be of much greater amount that the amount lost from the coin surface.

There is the periodic table available where one can find atomic details for all elements and it is quite straight forward to calculate the amount of ions required to alter significantly the electrical conductivity of the surrounding soil. THAT IS IF..... the forming salts were easily soluble, which they are not.

Hoards in pots can never exhibit any hallo effect at all, because there is nothing leaching out of the complete unbroken pot.

Silver forms quickly a black tarnish surface which is also insoluble in water and a very good electrical insulator, so no Halo effect here either.

Gold is just out of the question regarding the Halo effect theory.

The idea of metal ions increasing the soils conductivity is as wrong as it can possible get, because there are no free metal ions left from the coins and all ions released from the coins become a part of insoluble non-conductive salts.

The main reason for the hallo effect theory is the inability of great many treasure hunters ti measure objectively the depth at which their finds were recovered. I have never seen anyone to dig slowly, scraping the soil inch by inch in order to accurately measure what the depth is, therefore no claims in this regard can ever be reliable.

Another fact.
I have placed in parallel holes to the ground surface 3 coins in one hole and one coin in another, 3 years ago. The coins were clean at the time of placement. One Victorian Penny 30 mm and 3 BG coins of 1 lev each placed one behind the other in the same small drilled hole. The depth was 30 cm in highly mineralized magnetic soil.
At first the coins were detectable with reasonable signals even with a 10"DD coils, for about a year and a half period of time.
Only few days ago those coins were not detectable anymore with 13"DD coil, so I had to use 20"DD instead to recover the 3 coins that were together and then by memory I could guess the location of the other single coin. All coins were badly corroded and have turned quite green and were no longer detectable with the same ease as they were after I put them in the soil 3 years earlier.

[Davor]

I have some idea on how the halo may actually work, and the clue was in the way Depth doubler is operated. It basically charges the soil as one would charge batteries. In a process the soil is enriched with ions. I think I know how to simulate this situation.

[Nexus]

I have some idea on how the halo may actually work, and the clue was in the way Depth doubler is operated. It basically charges the soil as one would charge batteries. In a process the soil is enriched with ions. I think I know how to simulate this situation.

The metal detectors do not transmit ions, nor they can possibly influence the soil chemical balance that will result in release of any free ions and from here follows that the soil can not be simply enriched with ions by a Depth doubler. A Depth doubler will be an electronic solution to increasing the bulk sensitivity of any metal detector 64 times, that is if the doubler doubles anything for real in the first place.

Learn how to accurately measure the depth of all your finds and then you will see the real facts regarding Halo effect.

I suppose just as fishermen like to believe in catching the Moby-****, treasure hunters would very much like to believe that their detector can go twice as deep in the ground as they can in air. IF ONLY.

[Davor]

As you wish.
I have no reason to doubt the reports on Depth doubler. I may only try to simulate the mechanism it initiates. Some of my finds were far deeper than I'd ever expect those targets to give any reaction in air, and that's what makes no sense if the halo effect is not real.
So, with a hypothesis halo is for reelz, and there is/was a device that somehow provoked it, I may only seek reasons why it works. I may or may not find if it fits my model. Either way I/we may learn something.

[Skippy]

I think the 'Inverse 6th Power' effect is very relevant to the 'halo effect' discussion.
Even if you proposed that "halo effects cause a +20% increase in target signal" , that still represents just 3% depth increase. To make any obviously measureable 'depth gain', quite significant signal strength gains are needed.

I'm not so sure how much adverse effect major corrosion has on detectability of the coin itself. I feel that the porous 'sponge-like' metal is significantly higher in resistivity, and that makes the coin 'higher-frequency' , which in turn can make it stand out less from the ferrous/mineralised soil signal. But I'm not so sure the coin actually appears 'smaller' or 'weaker', ie. harder to detect.
A comparison with a freshly-manufactured clone of the coin/item would be interesting. Example: a typical hammered Medieval Penny we find in the U.K has a well-known composition, Sterling Silver 92.5%, and thickness, diameter, weight are all easily measured. I think there would be some good science to be done there.

And regarding this statement from Georgi:
"I have never seen anyone dig slowly, scraping the soil inch by inch in order to accurately measure what the depth is"

I actually dig this way on undisturbed ground like pasture, woodland. I use a pinpointer to guide my digging, and work my way carefully to the target, mainly in order to avoid damaging it. As a result, I get to see quite accurately how deep many of my targets are. While many are at quite a respectable depth, I've not had any that stood out as 'amazing', 'unusual' etc, like some of those claims I see people make on forums. And the targets would all be found 'deeper' in an air test.

[Nexus]

As you wish.
I have no reason to doubt the reports on Depth doubler. I may only try to simulate the mechanism it initiates. Some of my finds were far deeper than I'd ever expect those targets to give any reaction in air, and that's what makes no sense if the halo effect is not real.
So, with a hypothesis halo is for reelz, and there is/was a device that somehow provoked it, I may only seek reasons why it works. I may or may not find if it fits my model. Either way I/we may learn something.

Ok, I'v red some information on the Depth doubler. The way it works is simple and can be replicated for any other detector.
4 metal rods are placed in a square position on the ground and eventually surround some area of a few square meters or so. Electrical charge that can be almost any wave form is put trough the rods into the ground. So when this electrical charge hits metal targets it induces Eddy currents in them making them to appear much closer to the metal detector, thus getting deeper results.

However this device is not a component of a metal detector,but it is an external power station in a manner of speaking.
So any method that can be applied to excite metal targets in the ground will have the same effect.

The Depth doubler does not work on Halo effect basis, but on the basis of inducing stronger Eddy currents in the metal targets compared to the Eddy currents induced by your metal detector, but without the consequence of ground interference increase.
You see there is so much power output one can use on any metal detector before the ground interference goes out of hand completely.
So do not waste your time with Halo effect theory, just supply that Depth doubler with more power.

[Nexus]

I'm not so sure how much adverse effect major corrosion has on detectability of the coin itself. I feel that the porous 'sponge-like' metal is significantly higher in resistivity, and that makes the coin 'higher-frequency' , which in turn can make it stand out less from the ferrous/mineralised soil signal. But I'm not so sure the coin actually appears 'smaller' or 'weaker', ie. harder to detect.

This is exactly how it goes with old coins in the ground. Your post actually reminded me about many Roman silver coins that have become sponge like, after centuries of decay of the copper in them, as there are no pure silver Roman coins at all. So when the copper burns out from the soil acidity those coins become real pain in the neck to find and discriminate properly.

[Skippy]

The 'sponge' factor is very noticeable for Saxon Sceatta. They are actually rather thick and 'chunky', but small in diameter (typ. 10mm). However the silver is debased, 50 - 80% likely, and 1300 years buried gives plenty of time for most/all of the copper/tin/lead to vanish. As a result, the ones I've dug have corner freqs (-3dB freq) from 25KHz - 50 KHz. I bet a fresh clone would be 3 - 6 KHz, based on modern coins, eg. U.K 50% and 92% threepence / sixpence.

[ivconic]

I think the 'Inverse 6th Power' effect is very relevant to the 'halo effect' discussion.
Even if you proposed that "halo effects cause a +20% increase in target signal" , that still represents just 3% depth increase. To make any obviously measureable 'depth gain', quite significant signal strength gains are needed.
I'm not so sure how much adverse effect major corrosion has on detectability of the coin itself. I feel that the porous 'sponge-like' metal is significantly higher in resistivity, and that makes the coin 'higher-frequency' , which in turn can make it stand out less from the ferrous/mineralised soil signal. But I'm not so sure the coin actually appears 'smaller' or 'weaker', ie. harder to detect.
A comparison with a freshly-manufactured clone of the coin/item would be interesting. Example: a typical hammered Medieval Penny we find in the U.K has a well-known composition, Sterling Silver 92.5%, and thickness, diameter, weight are all easily measured. I think there would be some good science to be done there.

Quite correct.
Few posts earlier i mentioned the "republican" and "colonial" mints very purposely. To emphasize the huge differences between alloys and quality and diversity in such targets.
And that's also has a lot to do with what you can expect on the field.
It's quite different situation with modern coins which are made with pretty high scale of uniformity. With those you know what to expect.
Here is the photo that shows the diversity. Two coins, same nomination, same age, same site, same mint. Distance between them was 15 meters.
The one on the right side preserved better, the one on the left side is burned totally by the organic waste. Quite different two targets in the Deus's "eyes".
Another photo; most of the finds are from the very same site.
Almost all of those were "deeper" in soil than later in air. What was the difference? Significant and very noticeable. From 1cm up to 5-10cm.
It is hard to make mistake on this, it happens all the time at some sites.
However; it will never happen on testing bed.

[Davor]

...So when this electrical charge hits metal targets it induces Eddy currents in them making them to appear much closer to the metal detector, thus getting deeper results...

Er... no. It is not how the device was supposed to be operated, and that's why I think the ion mechanism should be examined. The Depth doubler was supposed to "charge" the soil for half an hour or so, and I believe it has to be accepted quite literally. If ions due to oxidation are present around a target, those should at least provoke some salt-like detection in a volume far exceeding the dimensions of a very target. I'll try to model that and see where it leads.
If there is nothing to it, no big deal. Nothing changes.

[6666]

First time I have heard of Depth Doubler, it runs off 12v motor bike battery, less than 1 amp

http://compass-metal-detector-forum.548136.n2.nabble.com/Depth-Doubler-Manual-td4407630.html

[ivconic]

First time I have heard of Depth Doubler, it runs off 12v motor bike battery, less than 1 amp

http://compass-metal-detector-forum.548136.n2.nabble.com/Depth-Doubler-Manual-td4407630.html

I collected those screenshots too. Very hard to find more details.