discrimination question

[flash]

I have found that if you set disc. to where a pull tab is gone but can still pick up a penny.With these 2 laying next to each other,moving the pull tab closer to the penny,the signal on the penny starts to break.With the pull tab on top of the penny ,there is no signal at all.

I did this as a test and would never detect with this setting.But I have found that this stays true at the lower scale so long as the 2 items are close to each other as far as disc is concerned.(A small piece of tin foil has no effect on a coin .)But a small piece of iron,which is discriminated out early will make a coin invisible in that situation.

Is this the same with all detectors.

 

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[Slingshot]

Hello Flash; That's the way all the detectors I've ever used reacted to those situations. They seem to read the target closesest to the coil, and usually ignore what is under the topmost target. I've found a lot of coins in hunted out areas by digging the iron targets, and then checking to see if anything was hiding underneath them. It's a lot of work, but there are those pleasant surprises that make it worthwhile.

 

[Darren in NC]

So how would that affect finding a iron pot of gold or silver? Should you be looking for the pot with a pi or mag or looking for the coins with a two-box? Would a two-box "see" the coins or be thrown off by the iron?

 

[Orien]

When searching in an area where there may be a pot of gold/silver i would think that yo would want to search with out any discrimination. A lot of good relics are Iron. The only time i us any discrimination is in parks where i keep it well below pull tab range. I have dug so many pull tabs that i could build a house, but every once in a while those pull tabs are gold so it makes it worth it.
Chris

 

[flash]

younglite

I think you asked ,what would a iron pot filled with gold sound like.Maybe,, "cha -ching ""cha-ching" lol ,just kidding.

For some reason a large piece of iron,down 8-10 inches reads as a coin.At least that is what I get.Someone else ,on one of these forums, said they get the same thing.And was suggested that the coil is getting overloaded and fooled.

I did that test with pull tabs because I have a big park by me that is just full of them.Have found some silver and many wheats but they are far and few between.Its very hard to detect when there are that many pull tabs.In some places ,like around Pavilons,they are every 6"- 10" in all directions for 40 feet .That put me in the outer parts of these high traffic areas.

I'm sure there is silver underneath but I'm not digging em,the amount is too overwhelming.

Good Luck,

 

[Slingshot]

An iron pot filled with gold or silver coins, provided it has an iron lid, will tell your metal detector that there is a large lump of iron in the ground. The electromagnetic lines of flux generated by a detectors coil will travel around the outside of the pot, this is known as skin effect.

 

[bakergeol]

Hey Flash
I believe your pull tab and penny test is flawed if you were using a zinc penny. The conductivity of a zinc penny and a pull tab is pretty close.
Try a test I just did with my X-5. Place a square pull tab on top of a copper penny. Adjust your discrimination until the pull tab is eliminated and then place the square pull tab on top of the copper penny. My X-5 produced a good response. I also placed a 3/4"long rusted nail on top of the copper penny- with the iron nail discriminated out. It again would detect the penny and not the nail. If you can't repeat the latter experiment remember there is a reason why folks pay a $1000 for a X-5.

George

 

[flash]

bakergeol,

That is why I was asking this question.You are the first person that says they have a detector that will pick up a coin in this manner.Give me more info on a x-5 .

And when you say a copper penny,you mean a wheat other than 43-45.

You are correct I was using a zinc penny and a square pull tab.So tell me what your detector does with a zinc penny like I asked.You said my test is flawed because I used a zinc penny,,why though,,because thet are close.So What,the pull tab is discriminated out before the penny.But will make the penny invisible if placed on top.

So you need more of a difference between the 2 metals for your detector to tell the difference.

The fact that you said the zinc penny compared to the copper penny is the difference,shows me that you had the same result with a zinc penny that I have.(and everybody else)So far.

The difference between a 300$ detector and a 1000$ detector ,,,,is 700$ . Tell me more .

I'm not dead set on anything,after all I was asking.I will try this with a copper penny.

The problem is that it seems to work on all scales,so long as the 2 metals are close.("close " being the key word.)

Good Luck,,,,

 

[bakergeol]

Flash
To answer your question the penney was a regular copper wheat penney. The X-5 will not detect a zinc penney lying below a square tab on pull tab discrimination only copper pennies, dimes and quarters.
I am a bit confused- the above sentence is what you want right? The very last thing you want is to be able to detect a zinc penney below a pull tab- right? I don't pick up zinc pennies off of the street and I certainly don't want to dig them.
To help prevent us from digging zinc pennies the X-5 has a zinc target check. Depress the toggle and medium and low conductivity targets from zinc pennies to iron will not respond. Only copper silver and some gold coins(also large iron) would respond. So you dig these. A lot of good stuff could be missed but you are cherry picking.
Yes you are right zinc and pull tabs are both in the middle conductivity range.
By the way- I expect a lot of other top of the line detectors can do what the X-5 does with regard to discrimination. Like most top of the line detectors it has its' strong and weak points.
George

 

[Lowbatts]

I have found that a small pin staple will completely mask an 1892 Qrtr if that staple is an inch or two above the qrtr. However when targets are in contact with one another the detector will often go bouncing on it's signal or average the two into a single, sometimes inaccurate id category. For instance if you happen into multiple coins as often happens in sand or playgrounds you may get a foil indication if there is a zinc and a qrtr or a nickel, a copper and a qrtr.

If there is any horizontal separation in the targets, the machine should be able to tell you there is more than one target in pinpoint mode. When that happens it's always dig dig dig.

 

[flash]

I stand corrected.Sorry,I see I was wrong from the start.I did not realize the signifigance of using a zinc penny for this test.I also thought I had done this test with other coins with the same result.But I did not.

I just did this test again without the zinc.On a copper penny ,the pull tab does change the reading a little,but is still in the coin range.And has no effect on a dime or Quarter.This is with the pull tab directly on top of the coin .(touching)And with disc. turned down to where it will pick up the pull tab.It still rings in as a coin.

I found that as you seperate the pull tab(pt) from the coin,I used books to do this and a quarter.And the pt is directing over the quarter.As the distance gets further it starts to move down the scale ,up to 2 " seperation ,then it reads as a pull tab.I'm sure this is much less with a dime or copper penny.I'm sure in ground conditions will change this also.

Thanks for straightening me out on this.I'm much happier with these results than my first halfhearted bogus test.Had I done this correctly the first time,I would not have posted.

Good Luck,,Thanks

 

[Orien]

Hey you guys leave all those pennies, i will be right behind you scrubbing the ground for them. I pick up every penny i see on the ground, got a jar of them worth a hundred bucks or so. Money is money no mater how big it is. I pick the little teenie tiny specks of gold out of the pan the same way. It all adds up.

Chris

 

[bakergeol]

Hey Chris
Regarding not detecting zinc pennies. For a lot of us it is not really a monetary issue. A lot of us have only a limited time we can spend in our hobby and we do not wish to waste our limited time digging zinc pennies. It is amusing that we don't mind digging wheat pennies even if the value in most cases is essentially the same(thrill of digging an older coin I guess). Heck most of the IH pennies we dig have little value because of their condition.

One beach hunter that I know of regards all modern coins as trash as he is only looking for gold. Another hunter sets his detector to ignore modern coinage as he is looking for deep, older coins.

We do what we have fun doing. If you are having fun digging zinc cents great. If one does not enjoy digging zinc- you should not be doing it. (By the way folks IH pennies are close to zinc so dig deep zinc).

If I was in this hobby for the money I would have quit 30 years ago. Whereas old coins are common, valuable old coins are rare.

To be honest most folks don't find enough in their outings to pay for their gas. Finding an extra 100 zinc pennies per outing is certainly not going to change that fact.(I paid 199 zinc pennies per gallon last time I filled up).

George

 

[flash]

I dig all coins,zinc included.The way I see it.If i'm gonna dig trash items ,hoping they are gold.I will dig zinc,hoping there is deeper silver.

Although I did quit digging them one time .When I found a place in a church yard where the adults must through money in the grass for the kids to find.I've been there twice now,10$+ each time.I dig some pennies each time but then go for the 5 's,10's and quarters.The last time I was there.Before I left I scanned the area,40 ft by 40 ft,sounded like a flock of geese.It's still loaded.

I just might go there tomorrow. :idea: I need some batteries. :P

Good Luck,