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

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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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  • 6 months later...

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:


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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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  • 1 month later...

Further to what has been written in the above answers...

Some searchplaces are so instested with iron that they're pretty unworkabke...Again, I have to bring out european pure nickel coins ( as are canadian coins too) .

You face an iron infested place?  Well, just do as usually, using your best settings for the places.

Then use a NO MOTION mode on the same place, and just ground balance it to salt...

What now will happen is all PURE ferrous targets will be IGNORED, all ferrous alloys will give signals. Pretty useful for relic hunting and Canadian coins hunting.

Purists will state that de detector will not be tuned to the actual site conditions...believers will walk away with finds...

This trick is very useful once you understand it...I had plenty of succes in relics and coins using  this trick with the GBPro in all metal mode, GB to "0"  From then on, you will know what you were missing... 

If the detector beeps, dig !! no matter if the ID is a ferrous one  !! 

Happy hunting...!!

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