8khz for small hammered silver

I'm heading out later today to a stubble field that has produced hammered in the past, though the stubble is quite long but spaced well in places and was thinking of trying a 5" coil which to be honest I've never really used. So i was trying a few settings in my garden on some hammered with the small 5'' coil and was quite pleased with the result in 8khz which hit harder than 18khz at 6" on an Edward penny, I'm guessing the coil being small see's the coin as a large item?

ghound Wrote:
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> I'm heading out later today to a stubble field
> that has produced hammered in the past, though the
> stubble is quite long but spaced well in places
> and was thinking of trying a 5" coil which to be
> honest I've never really used. So i was trying a
> few settings in my garden on some hammered with
> the small 5'' coil and was quite pleased with the
> result in 8khz which hit harder than 18khz at 6"
> on an Edward penny, I'm guessing the coil being
> small see's the coin as a large item?

Where abouts are you, Do you live in the UK ?



Edited 1 time(s). Last edit at 08/22/2016 03:55PM by auminesweeper.

Yes Northern Ireland, part of the UK

ghound Wrote:
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> Yes Northern Ireland, part of the UK

Ok Cool, One thing I have found with Stubble is always try and use a round Coil with a cover on it because Stubble will wear the pattern off the plastic Cover inside a couple of weeks, Round coils will pass through the stubble easier than Elliptical coils and puts less strain on the shaft. Any round Coil under 8" would be best, My 6" coil air tests as good as a 6x10 So I would give it a go and see what happens,

Good Luck,

John.

Cheers John

Are you going to tell us what machine this is you're using? If you have 8 and 18 KHz, I would guess the Deus, except there's no 5 inch coil for it?
For what it's worth, 12 KHz area would be my choice.

Pimento Wrote:
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> Are you going to tell us what machine this is
> you're using? If you have 8 and 18 KHz, I would
> guess the Deus, except there's no 5 inch coil for
> it?
> For what it's worth, 12 KHz area would be my
> choice.

He uses the Golden Mask 5 which is dual freq 8khz and 18khz

From what I understand, the lower frequencies hit harder on silver.


Dean

bado1 Wrote:
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> From what I understand, the lower frequencies hit
> harder on silver.
>
>
> Dean

I tend to use 8Khz on the Deus and would agree that i find it hits hammered coins well,must admit at the moment while we have stubble after the harvest i am using the superb 5'' coil on the T2 the most.

Quote: "From what I understand, the lower frequencies hit harder on silver."
Detectors don't know what metal an object is made from (other than perhaps iron / non-iron, though nickel coins read as iron....)
so such statements are very misleading.
A medieval cut quarter penny is 'best-detected' with about 25 KHz, full pennies about 12 KHz, as a rough guide, you can estimate others from these figures.

Well that was a fun two hours, i had the 5" coil bouncing of the stalks like the ball in a pinball machine lol it worked well but was slow going.
Not sure of the 8khz vrs 18khz for differing target sizes as i picked up both big and small on 8khz, nothing deeper than 6"
I did pick up a few bits, nothing of the age i was hoping for but i got a big old half crown which is a coin i very rarely find and a few late 1800's lead bag seals etc so not a total disaster.



Edited 1 time(s). Last edit at 08/22/2016 10:26PM by ghound.

Pimento Wrote:
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> Quote: "From what I understand, the lower
> frequencies hit harder on silver."
> Detectors don't know what metal an object is made
> from (other than perhaps iron / non-iron, though
> nickel coins read as iron....)
> so such statements are very misleading.
> A medieval cut quarter penny is 'best-detected'
> with about 25 KHz, full pennies about 12 KHz, as a
> rough guide, you can estimate others from these
> figures.

Is it more related to coil size versus target size?
When i tested the Edward penny the small coil at 8khz gave a cleaner hit @ 6" than 18khz
Im guessing the silver penny appeared as a large target to the small coil?

It's really hard to pin it down, there's too many variables. True to say there's a 'proportionality' factor that comes into play - if you were after 5 inch targets, you'd be wanting a 30 inch coil, but anecdotal evidence suggests that a typical 8 inch coil is about right for hammered coins. It's complicated by such things as the machines sensitivity. Is it actually more sensitive at 8 kHz than at 18 kHz, not because of the frequency, but because it's optimised more for 8 k, and is running sub-optimal, but still OK, at 18 k ? And as for coil size, does the machine know it's got a small coil on it? If the coil gave 'ID data' to the detector, it could for example increase gain when a small coil is connected.

It's got me head scratching!

ghound Wrote:
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> [i89.photobucket.com]
> ood/Mobile%20Uploads/20160822_223303_zps7mbyjsu2.j
> pg
>
>
> Well that was a fun two hours, i had the 5" coil
> bouncing of the stalks like the ball in a pinball
> machine lol it worked well but was slow going.
> Not sure of the 8khz vrs 18khz for differing
> target sizes as i picked up both big and small on
> 8khz, nothing deeper than 6"
> I did pick up a few bits, nothing of the age i was
> hoping for but i got a big old half crown which is
> a coin i very rarely find and a few late 1800's
> lead bag seals etc so not a total disaster.

Don't over think it because I have hit bits of lead a 1/4 the size of a match head with a 5khz machine so just get out there and have fun, I hit those coins you have there in the 5 to 12"+ range using a 14 kHz machine so you 8 kHz is working real good, but I would try a 9-10" Concentric or DD and see if you are missing any deep ones, But I would try it over the patch you have just done and if nothing is there then just keep going,

John.

If you do decide to overthink it, which I for one have a hard time not doing, type COINS "RESONANT FREQUENCY" without the caps into the search field on Google. You'll find everything from patents for electronically identifying the quantity of coins in a stack by determining the stacks resonant frequency to explanations of how you can use multiple coils with different characteristics to identify the size, composition and, if you know the country of origin, the face value of a coin.

I've read a few of the results and for the most part what they say makes sense IF your operating in a controlled environment. As always when you throw in soil composition, moisture levels, EMI, dissimilar adjacent objects etc. things get dicey and you have to rely on your detector's ability to counteract these things. If however your detector can counteract these things then it is possible to determine which frequency is better suited for each type of target. The V3i has the somewhat limited ability to do this by transmitting 3 frequencies and using the one that gives the strongest response to determine target ID.

Now all we need is for someone invent a coil with an automated variable magnetic footprint and we'd be in business.

Hey there
- why not go for an old winner,- Eva and I used the CZ 6 with the small "hockey puck" the 5" coil, with great success.
Simultanously transmitting 5 and 15 khz sniffed out small 1 - and 2 skilling silver coins both from pasture and woodland.
The two pulltab segments reported most of the thin silvers both on ground and in ground between man made iron
in a fairly stable way. The only important thing you had to remember was to swing real s l o w - and I mean real slow......

trond



Edited 1 time(s). Last edit at 08/24/2016 10:45AM by trond.

trond Wrote:
-------------------------------------------------------
> Hey there
> - why not go for an old winner,- Eva and I used
> the CZ 6 with the small "hockey puck" the 5" coil,
> with great success.
> Simultanously transmitting 5 and 15 khz sniffed
> out small 1 - and 2 skilling silver coins both
> from pasture and woodland.
> The two pulltab segments reported most of the thin
> silvers both on ground and in ground between man
> made iron
> in a fairly stable way. The only important thing
> you had to remember was to swing real s l o w
> - and I mean real slow......
>
> trond

I can basically replicate that by using my DFX running the dual 3khz and 15khz and 5.3 6'' Concentric coil,although if i was to make a choice it would be in single 15khz mode though,but i do also agree with you swing very slowly.

Junk and Disorderly Wrote:
-------------------------------------------------------
> trond Wrote:
> --------------------------------------------------
> -----
> > Hey there
> > - why not go for an old winner,- Eva and I used
> > the CZ 6 with the small "hockey puck" the 5"
> coil,
> > with great success.
> > Simultanously transmitting 5 and 15 khz
> sniffed
> > out small 1 - and 2 skilling silver coins both
> > from pasture and woodland.
> > The two pulltab segments reported most of the
> thin
> > silvers both on ground and in ground between
> man
> > made iron
> > in a fairly stable way. The only important
> thing
> > you had to remember was to swing real s l o
> w
> > - and I mean real slow......
> >
> > trond
>
> I can basically replicate that by using my DFX
> running the dual 3khz and 15khz and 5.3 6''
> Concentric coil,although if i was to make a choice
> it would be in single 15khz mode though,but i do
> also agree with you swing very slowly.

I agree swing too slow with a small coil and you will miss the target completely, if a person has multiple Coils ( Not Mentioning any Names ) but it is always best to test each coil and work out it's best response speed.

John.