Dealing with those pesky bottle caps

Rudy

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The MXT discrimination and sensitivity is such that many bottle caps (the crimped steel ones) will ID as a good quarter or dime signal, depending on how rusty they are, when your coil sweeps are centered over them.

The XLT and DFX, with their Signagraph capability, have an easier time of it. The Signagraph will show the target with multiple separated bars and give the bottle cap away.

When I am hunting with my MXT in an area where these bottle caps are plentiful, the easiest way to identify them, rather than digging them, is to take another pass over them in discriminate mode, but this time do it with the edge of the coil, instead of the coil centered on the target. "Rimming" the target this way will let the detector show them up as ferrous targets. This technique will work with just about any VLF detector.

Try it!
 
One thing that I've noticed with my explorer, is that the threshold will blank out sooner over a bottle cap than it will a coin; the same holds true for buried cans or other junk items, especially if they are large.
 
My Excalibur used to love bottlecaps Rudy.. since switching to the Detector Pro I don't find them anymore because with the DP is gives a distinctive signal.. I dig a few but nothing else sounds like that and I pass them over now :)
 
My Excalibur used to love bottlecaps Rudy.. since switching to the Detector Pro I don't find them anymore because with the DP is gives a distinctive signal.. I dig a few but nothing else sounds like that and I pass them over now :)

Yes Craig, on the DetectorPro the crimped bottle caps have a distinctive sound. Hard to describe it, but easy to recognize it.
 
Amazing : my humble bounty hunter Lonestar won't even whisper on a bottlecap in the disc mode !

The Minelab Quattro shows a strong +18 signal when it is new, rusted ones are signalled by an unstable jumping signal.

When I used manual GB detectors, I remember all bottlecaps being clearly IDed or rejected as iron if the GB was slightly negative.

HH

Nick
 
those crimped bottle caps...

hi,

yes, those points on the crimps likely act as 'amplifiers' for the back emf induced by the detectors on the bottle caps.

similarly when a tidal wave rushes up onto a beach when it comes ashore it is 'amplified'.:?:

i am not sure i understand why that qualifies as aplification but i know that it does and is one of the reasons that tidal waves are so devistating. the energy from the wave is 'amplified' as it rushes up onto land.

it seems like that is analogus to what is happening to the charge when induced on one of those crimped caps when you sweep your coil over it...

the charge sweeps up onto the cap and its crimped points. the longer it has been in the soil the better ground it has which is the source of extra electrons and why objects that have been put down awhile are stronger targets.

perhaps this is why detectors can discriminate them with such certainty. their conductance is somewhat variable as charge builds on them. they become electronic gearboxes. their charge buildup is somewhat faster/stronger then can be accounted for by the transmiter coil output.

i will try rimming targest like rudy said to see if i can tell a difference... after i read what he said a couple of more times...:?:

and memorize what he said about the sounds detectors make.


-zander
 
My experience:

On the Whites XLT, all bottlecaps sound like quarters.

On the Whites ProXL6000, the majority of bottlecaps "break up"
 
When I first started out with an Explorer SE I hunted with factory presets. After a while I wanted to learn the sounds in AM with out constantly looking at the display.
I was digging quite a few crown caps as they do sound good but always hit in the lowest right hand part of the screen.
As far as I know nothing els of interest is in that lowest right hand part of the display.
So I hunt with crown caps and nails X'ed out.
Now screw caps are a different story they hit right up there with coins so I will just keep digging them:(
 
Re: Rudy

Hey Rudy as a new MXT user what do you mean in discriminate mode, are you talking from '0' on disc to running it up or ? thanks for the info. CNR
 
Hey Rudy as a new MXT user what do you mean in discriminate mode, are you talking from '0' on disc to running it up or ? thanks for the info. CNR

Good question.

I meant Discriminate mode, as opposed to being on the all-metal non-motion pin point mode.

The MXT has a true progressive discriminate mode and when you set the discriminate setting to zero you are in all-metal motion-required.
 
This is a old post, but man I just tried this on my At Pro with iron audio on & could tell the difference 100% between a bottle cap & a coin.. Thank you Rudy for this great post.. :grin:
 
Since Rudy referenced this thread in another thread, thought I'd bring it into the light! :D
 
With my 2500 I can pull quarters out of the middle of a bunch of bottle caps. They don't affect it. It seems to love quarters. The other day on thirteen quarter readings, twelve were quarters. The other . . . a dollar coin.
 
Over time, I learned with a bottlecap, the vdi's will bounce by many numbers when you get to the edges of a sweep over it...with a quarter, the vdi's will vary by only a number or 2...9 times out of 10 this is accurate.
 
With my F75 I learned to raise the coil as I swing over the target. The vdi for a coin remains steady but a bottle cap varies by a large amount. Also my new AKA Signum has a S algorithm that lets you know it's a bottle cap.
 
When you spot holes left by other detectors, check them. Besides not properly filling their holes, they often can't find the target. I have found a lot of coins in such holes or right next to them.
 
At pro I can tell bottle caps based on low high low tone they give.... coins don't sound same as bottle cap on at pro. :)
 
Amazing : my humble bounty hunter Lonestar won't even whisper on a bottlecap in the disc mode !

The Minelab Quattro shows a strong +18 signal when it is new, rusted ones are signalled by an unstable jumping signal.

When I used manual GB detectors, I remember all bottlecaps being clearly IDed or rejected as iron if the GB was slightly negative.

HH

Nick

I found the same thing with my Bounty Hunter. That's the only downside that I see to the Ace. It loves bottle caps. Loves them.

BCD
 
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