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Steve Herschbach

Tin, Bolts, Washers, And Other Ferrous Items That Read As Non-Ferrous

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not to mention the old square nails were apparently a much better grade of iron...I have found many that appeared to be just-made...

Thanks for your unending pursuit of knowledge and for sharing the same.

fred

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Thanks Steve, you have just confirmed several of my suspicions. The amount of rust and the location of the rust on nails and flat iron sheets also seems to add to the signal problems.

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I have no idea why this has popped up as a recent thread but I like it - maybe you thought it was pertinent Steve and brought it to the top of the forum?

The first paragraph at the bottom of the Q & A page describes how high frequency detectors are perhaps not the best at discrimination.  Is this perhaps why the discrimination on my Gold Monster has not been as accurate as I was hoping?  I was expecting miracles of course :laugh:

Due to the fact that high frequency is not as good at discrimination is that perhaps just one of the reasons that the multi-frequency Equinox is going to be better at discriminating targets - it has the lower frequency range to assist.  Obviously Multi IQ, processing speed, etc is probably having a greater influence but...? 

And the second paragraph at the top of the page where it is talking about positive and negative signals.  So non-ferrous can ONLY give positive signals whereas ferrous are mostly negative but can be positive.   So that made me think that if something is giving a negative signal at all it can simply be dismissed as rubbish - yippee.        But then I imagined a beautiful big chunk of gold that had a heap of ironstone attached and assume that it might give positive and negative signal responses??  

When responding please take into account that I have never used a VLF with TID numbers or visual displays other than the Monster with its simple Ferrous/Non Ferrous read out  :wink:

Thanks.

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I bump old threads now and then if they seem like they got overlooked. Lots of new forum members did not see the old stuff and don’t look back that far.

The part that is missing here is the ground. A detector sees everything under the coil. The ground is a massive ferrous target. Therefore, ALL targets are a mix of ferrous and non-ferrous signals. Almost any non-ferrous target will read ferrous if the ground iron mineral content is high enough.

The assumption is that if a target gives a ferrous signal it might be bad, so skip it. The way it should be done properly is that if a target gives any non-ferrous response at all, then dig it.

The problem as this article notes is lots of ferrous will read as a very high non-ferrous signal. The trick there is the false signal will typically come in around the silver dollar range on a detector with target id. Gold will read lower. Unless your detector does not have target id (like the Gold Monster, just ferrous/non-ferrous) in which case the false signal just reads non-ferrous.

Which is why having actual target id numbers is helpful when dealing with trash.

 

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Discrimination...... whats that????? I just dig EVERYTHING......regardless, & it pays off. :biggrin: Talking gold detecting only. Cheers.

Good luck out there

JW :smile:  

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I've quickly learnt with my GM 1000 to dig everything, its telling me its junk and I spin the coil around 90 degrees and it's saying its not junk on some passes and junk on other passes so I dig the area and find a little speck of gold and no junk at all.  I just can't trust the discrimination on it, if i did I'd be missing a lot of gold.  My Gold Bug pro's discrimination seemed more reliable, but in saying that, it didn't find these tiny specks at all the GM is finding, they have to touch the coil to make any response at all on the GBP...

The more I use and understand the GM1000 the more I like it.  

 

 

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  • Similar Content

    • By Steve Herschbach
      Which metal detectors have the most reliable target ID numbers?
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      In general iron or ferrous targets produce negative numbers or low numbers. Aluminum, gold, and US nickels produce mid-range numbers. And most other US coins produce high numbers. Other countries coins, like Canadian coins with ferrous content, can read all over the place.
      The scale applied varies according to manufacturer so the number produced by each detector will vary according to the scale used. The 0-100 range for non-ferrous targets is most common but there are others. Minelab employs a dual number system on a 2D scale with thousands of possible numbers, but they are now normalizing the results produced to conform more closely to the linear scale used by other manufacturers.

      Increasing ground mineralization has a huge effect on the ability to get a good target ID. Ground mineralization is nearly always from iron mineralization, and this tends to make weak targets, whether very small targets or very deep targets, misidentify. The target numbers get dragged lower, and many non-ferrous targets will eventually be identified as iron if buried deep enough. Small non-ferrous readings and iron readings actually overlap. That is why any discrimination at all is particularly risky for gold nugget hunters.
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      Higher frequency detectors are inherently more sensitive and are jumpier. So lean lower frequency for more solid results. Multi frequency detectors act like low frequency detectors and tend to have more solid target numbers due to the ability to analyze a target with different frequencies.
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      Minelab X-Terra 705 = 28
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