Basic Question about Discrimination

[Rudiger]

Hi. I haven't had much to do with coin detectors, but I had a brief play with an X-Terra 30 and I noticed how limited its range was on an Australian 5c coin (say 2") compared to about 8" on a 20c and a $2 which isn't much bigger than the 5c. I know the machine chooses to not respond to some targets because it barely beeped on some foil yet it would get the foil at roughly 8" in what I suppose was an all metal mode (I can't remember how it was labelled). So the question is, was it choosing to respond weakly to the 5c? Perhaps that's what coin machines do, but not being experienced wouldn't know. I'd assumed it'd respond strongly, but let you "discriminate" based on the readout. But if it did choose not to respond well to the 5c, why would it do that, because I'm assuming that 5c pieces are made of a similar "good" material to the other coins? And I never touched the Patterns button, in case that could explain it.
Thanks.

 

[Jackpine Savage]

I know that here in the US nickels near iron are some of the toughest targets to find there is. They read very erratic and drop way down the scale when co-located with iron. They can be very iffy signals at best.

Tom

 

[Digger]

The metallic composition of the Australian 5-cent coin is the same as the 10-cent, 20-cent and 50-cent coins. 75% copper and 25% nickel. The only difference is their size. The two dollar coin that you mentioned, (as well as the one-dollar coin) has a different composition, using a 6% aluminum alloy, along with the copper and nickel. So, if you can detect the 20-cent coin at 8-inches, I can't think of any reason you shouldn't be able to detect the 5-cent coin at a depth proportional to the size. And there isn't that much difference in the size! Hmmmmmmm! Can't explain that one. HH Randy

Australian coins [2]
5 cents 75% copper, 25% nickel 2.83 g 19.41 mm
10 cents 75% copper, 25% nickel 5.65 g 23.60 mm
20 cents 75% copper, 25% nickel 11.30 g 28.52 mm
50 cents 75% copper, 25% nickel 15.55 g 31.51 mm
1 dollar 92% copper, 6% aluminium, 2% nickel 9.00 g 25.00 mm
2 dollars 92% copper, 6% aluminium, 2% nickel 6.60 g 20.50 mm

 

[Mick in Dubbo]

Hi Rudiger.
Welcome to the findmall site.
You're spot on in regards to the limited range on the 5 cent
piece.Did some experiments on my X-terra 30 with it and some other similar sized coins, a sixpence which has identical dimensions but with 50% silver content. The range in an air test was identical to the 5 cent piece.A 1 cent piece (97% copper) had to be closer still to the coil to be picked up.Again due to the fact that it is smaller again.
I have found that when I go detecting, $2 dollar coins generally give off a weaker signal than a $1 coin.Quite often they can be quite an iffy signal.$1 coins always give a strong signal.Again, this is all size related.Kinda makes me wonder how many I've missedThat said.The $2 coin's size is not all bad news.Due to their size; it can make it hard to hear when they fall out of your pocket.What is also interesting,is the fact that I find more $2 coins than any other!
I don't know if this sensitivity issue is confined to the X-terra's or if it is generic to all coin machines.Perhaps someone with experience with other machines can comment further on that.
A couple of other points to consider 1)a 5 cent reads 8 on the VID, which puts it in an area of discrimination where all the junk is. So if you want to hunt them, you are going to dig up a lot of junk.
2)When coins stay in the ground for a while, they start to corrode. What this does, is create a halo effect around the coin,which makes it a lot easier for the detector to pick it up.
You should give coin hunting a try.The (gold coin) patches are a lot easier to find, The detectors are a lot cheaper, hunted out patches replenish, the cost to get to your favorite spot is a lot less, the time commitment is a lot less and the financial rewards would probably be higher; Oh and did I mention they fact, that you can still hit "the BIG ONE!" ( had a fellow detectorist in Dubbo find a coin worth $7000 3 months ago!)
Just some food for thought.
All the best.
Mick Evans.

 

[Rudiger]

Thanks guys.
I've since had another quick look at the manual (I don't own it) and learned that the machine starts in the Pattern mode. I'm surprised no one mentioned that after my comment about my not having touched the Pattern button. The Pattern (I think it's called Pattern 1, but there is only one on the X-Terra 30) is designed to knock out ferrous and aluminium, though I don't think that explains it's poor range on the 5c because you've just said the 5c has the same composition as the 20c.

 

[Mick in Dubbo]

Rudiger.
I think it is size related, as mentioned above.It doesn't seem to matter what the coin is made of, the coil for the X-terra doesn't seem to be very sensitive to small coins.:sad:

 

[Mick in Dubbo]

Got help on this one.Simple and obvious when shown.
The poor response is occurring because when you turn on the detector, it goes into factory preset settings.While this is OK for detecting larger coins, it is no good for smaller ones.Solution.Turn the sensitivity up to maximum.Problem solved.
Sometimes you don't see the forest for the trees.
All the best Rudiger.
Mick Evans.

 

[James/Washington]

When the power button is pressed to turn the Xterra-70 on, it does indeed come on in the 'Coin & Treasure Mode Factory Presets' in 'Discrimination Pattern 1'. This is true UNTIL any change is made to the presets. You MUST remember that any changes made to this 'Factory Preset' will be held in memory when the detector is switched off and the next time the detector is turned on, the detector will come on with the changes made and will continue to do so until other edits are made. So, the detector 'remembers', in memory, what edits are made and 'saves' them when the detector is turned off. I have mine set where I want it and each time I turn it on I just need to set 'GB' and detect. About the only other setting I may change is the 'sensitivity' and occasionally the 'noise cnacel'. From time to time, I do cycle through the 'Menu' button just to make sure the settings are correct. If needed the factory settings can be reset by following the instructions on page 44 in the manual. I love the fact that this detector remembers these settings because the area I hunt is fairly constant and I mainly hunt schools and parks and have found the settings I like to use are constant, except for 'GB', almost everywhere I hunt. So for me there is no constant fiddling with the adjustments which means more time spent hunting.

 

[tink]

Been reading along with the post here. I know you are talking about Australian coins here. Seems to me the copper in those coins would halo pretty fast and be easier to find, reguardless of size. As far as U.S. coins and size goes, the X30 I just got hammers dimes. I know it does a great job on nickels also. I am concerned a little about the pennies thou, I know know needs them. But I only found two of them out of all those dimes and nickels. Pretty unusual for the place I was hunting as I passed most of the up with the 3300.