Vallon VMH3CS Mine Detector

[6666]

Good work !

[Carolina]

Very nice Kingswood. If the VALLON can handle the soil would definitely scream on that nugget. Good luck to you.

Carolina

[kingswood]

Very nice Kingswood. If the VALLON can handle the soil would definitely scream on that nugget. Good luck to you.

Carolina

Absolutely! Its pretty mild colluvial wash so the Vallon would be fine. I plan to spend some time there to see what else is around, so the Vallon will be used. I like it for pushing the coil right in under branches etc where the 7000 coil is just to big

[kingswood]

Good work !

Thanks Research pays off......eventually

[Carolina]

Kingswood: I have the new Minelab Equinox 800 and although nothing is going to be better than the 7000 for you I think, but this machine hits micro gold like crazy. Multi & 40kHz I think would work great there for you. The reason I mention is it's light as a feather. The VALLON has some weight and the 7000 even more. I think you would like it.

[kingswood]

Kingswood: I have the new Minelab Equinox 800 and although nothing is going to be better than the 7000 for you I think, but this machine hits micro gold like crazy. Multi & 40kHz I think would work great there for you. The reason I mention is it's light as a feather. The VALLON has some weight and the 7000 even more. I think you would like it.

The reports seem good
I do miss using the Vallon. I could swing that all day and no issues....The 7000 needs the harness and even then I get a sore shoulder!!

[ionut_mtb]

I've tried air tests on 1g 18k gold cross and 1.5g 18k earing and not a signal from vallon. I don't know how it can detect sub gram nuggets at good depth.

[Carolina]

My VALLON on 10 sensitivity would hit those targets. I have found ear rings similar to that. It will not hit small chains though.
Mans gold 14k 6 gram band 18". I am currently running a 12" coil a friend wound for me as mostly all I do is beach hunt for jewelry.

[kingswood]

I don't know how it can detect sub gram nuggets at good depth.

I havent found a native nugget withe the Vallon, but can confirm that it indeed does find buried ones
It easily detected my 0.6g nugget buried about 6".
It has also detected tiny bits of lead shot, albeit making just a tiny noise that you would ignore if you hadnt used the Vallon much.

[Ferric Toes]

I've tried air tests on 1g 18k gold cross and 1.5g 18k earing and not a signal from vallon. I don't know how it can detect sub gram nuggets at good depth. [ATTACH]42775[/ATTACH]

18 carat gold is 75% gold and the rest is usually silver or copper. Natural gold nuggets from Australia have a higher percentage of gold which would be roughly equivalent to 22 carat. Silver and copper are better conductors than gold, so you would expect that, at the very least, the conductivity and detectability would not change. However, it does, and quite dramatically the conductivity is reduced. Even a 5% addition of either metal will make the detectability of a gold item, less.

This likely explains why kingswood can easily detect his 0.6gm nugget, but you cannot get a signal from your 1gm cross or 1.5gm ear ring. If your items were bigger, even just double the weight, then you would have a longer eddy current decay and be able to detect those items.

Eric.

[nelson]

Hi Carolina and my appologies for not responding to you on time.

Many thanks for youer full explanation about Vallon.

I will take on mind your comments and i will do a full check of my two units to see if seals and O rings are ok.

Vallon is very sensitive. A friend of mine use it last summer on the beach and he got very surprise how deep Vallon can go.

When i get more details about vallon seals i will share here.

Many thanks and have a nice day.

Regards

Nelson

[ionut_mtb]

18 carat gold is 75% gold and the rest is usually silver or copper. Natural gold nuggets from Australia have a higher percentage of gold which would be roughly equivalent to 22 carat. Silver and copper are better conductors than gold, so you would expect that, at the very least, the conductivity and detectability would not change. However, it does, and quite dramatically the conductivity is reduced. Even a 5% addition of either metal will make the detectability of a gold item, less.

This likely explains why kingswood can easily detect his 0.6gm nugget, but you cannot get a signal from your 1gm cross or 1.5gm ear ring. If your items were bigger, even just double the weight, then you would have a longer eddy current decay and be able to detect those items.

Eric.

i thought that if gold has silver/copper in it will be easily detectable(9, 14,18 k), and pure gold (22, 24k) will be more harder, and with faster coil needed. if that earing/cross would be melted as a nugget will be detectable by vallon? or i will get same result? or 1g 18k gold ring.

Thanks for reply

[ionut_mtb]

Should i make a smaller coil? What benefits can i get over the standard coil. (On gold nugets)

[Ferric Toes]

i thought that if gold has silver/copper in it will be easily detectable(9, 14,18 k), and pure gold (22, 24k) will be more harder, and with faster coil needed. if that earing/cross would be melted as a nugget will be detectable by vallon? or i will get same result? or 1g 18k gold ring.

Thanks for reply

Attached is a plot I did in 1969 using 20mm square gold/silver laboratory standards. These are extremely accurate percentages and the standards were used in calibrating an xray milliprobe. From the left they start at 100% gold and 0% silver and moving to the right through 50/50 to 100% silver and 0% gold. The detection range drops rapidly at the gold end; even 5% silver made a difference. This is due to the faster decay time cause by lower conductivity in the alloy. I have another graph with more data points and for different size coils and also one for gold/copper alloys, but all do the same thing.



On your second point re smaller coil, if the stock coil gives no trace of a signal, then neither will a smaller one.

Eric.

[Qiaozhi]

Attached is a plot I did in 1969 using 20mm square gold/silver laboratory standards. These are extremely accurate percentages and the standards were used in calibrating an xray milliprobe. From the left they start at 100% gold and 0% silver and moving to the right through 50/50 to 100% silver and 0% gold. The detection range drops rapidly at the gold end; even 5% silver made a difference. This is due to the faster decay time cause by lower conductivity in the alloy. I have another graph with more data points and for different size coils and also one for gold/copper alloys, but all do the same thing.

[ATTACH]42812[/ATTACH]

On your second point re smaller coil, if the stock coil gives no trace of a signal, then neither will a smaller one.

Eric.

Hi Eric,

You said that you've attached the plot for gold/silver, but the plot is actually the one for gold/copper. Oops!