Question about coin

[dbanner]

I tested a modern bronze coin from my country and found that a US quarter discriminates out before the bronze coin, which I find perplexing.

So I looked up the composition of this particular coin and it is made from bronze, which as I understand is an alloy of copper and usually tin.

But as of 2017, it was changed to a steel core with a copper overlay. The funny thing is the US quarter still discriminated out long before the steel and copper coin.

So I checked the discrimination chart / Phase of metals, and sure enough, copper should be discriminated out long before a US quarter, and surely long before silver.

On my bounty hunter discovery 2, I turn the discrimination to the maximum, US quarters are gone, but this copper and steel core coin and also the bronze coin still appear alongside a silver coin.

Same thing happens with my TGSL.

Is this normal? I'm not sure about a steel core coin, but surely a bronze coin should be discriminated out at the maximum discrim setting, unless of course, it too has a steel core????

This is the coin.https://en.numista.com/catalogue/pieces926.html

[dbanner]

This coin is bad news for VDI and silver targets!!!!

[Skippy]

We have copper-plated steel-core coins here in the U.K. They are low value 1 and 2 pence coins:
https://en.wikipedia.org/wiki/Penny_...ecimal_coin%29
They replace a bronze version, that was a very high copper content ..97%. The bronze coins read very high up the disc scale, as they are high copper content. The steel-cored ones are seen differently by different machines. Some see the copper coating well, and they read a little bit higher up the scale than the bronze ones. But other machines see the core effect, and they give jumpy numbers.

[kt315]

thats false time DB. time of the Degradation of all. i sell now TDK cassettes. MADE IN JAPAN! i sold 4 pcs i did have.
https://www.ebay.com/itm/333475049124

[Nandor]

Dbanner were are you from?

[Ferric Toes]

We have copper-plated steel-core coins here in the U.K. They are low value 1 and 2 pence coins:
https://en.wikipedia.org/wiki/Penny_...ecimal_coin%29
They replace a bronze version, that was a very high copper content ..97%. The bronze coins read very high up the disc scale, as they are high copper content. The steel-cored ones are seen differently by different machines. Some see the copper coating well, and they read a little bit higher up the scale than the bronze ones. But other machines see the core effect, and they give jumpy numbers.

I observed that with a PI, the decay curve varies greatly with changes in orientation of a coin with a steel core. With the coin in the normal orientation parallel to the plane of the coil the decay is fast and mainly eddy current generated. This is because steel is considerably less conductive that copper. With the coin at right angles to the coil the eddy current response is at a minimum but the steel core gives a viscous magnetic reponse that has a much longer decay. This would also have an effect on the phase response which will jump from one to the other as you scan over it.

Eric.

[dbanner]

Dbanner were are you from?

[Nandor]

This forum is Great!