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Comment by macshome | Hacker News Reader

As an American, the part of the story that is very interesting to me is that Canadian coins have enough ferrous content to be picked up by a magnet. Wouldn’t the ability for coins to become magnetized cause all sorts of issues for the internal workings of vending machines and other coin slot using mechanisms?

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IIRC many vending machines operate or operated on the magnetic properties of coins even. At least in my country before the Euro some did.

There are only several properties that can be easily distinguised from coins without complex digital processing: weight (and its distribution), sizes, conduction and ferromagnetism.

Looks like all current Canadian coins can be picked up -- $1, $2 .25, .05, .10. (couldn't test pennies as Canada hasn't had them for a while).

I suspect US quarters would have the same makeup

US quarters cannot be picked up by magnets.

Interesting that they exist interchangeably in all vending machines, etc in Canada.

Canadian vending machines are happy to accept US quarters at par. Why pay for a more sensitive mechanism to prevent someone from giving you a more valuable coin. Although, probably not more valuable enough that it's worth filtering out from change boxes to deposit with a US based bank instead.

Otoh, there are coin mechanisms that can check for and reject quarter sized objects that are attracted to magnets; they might not be installed everywhere that takes US quarters, but if an operator starts getting a nuisance amount of CA quarters, they will be. See this doc [1] for a description of a pretty discerning mechanism (although it accepts both US and CA quarters, a slightly different design could reject CA quarters)

[1] http://segalandassociates.com/Documents/Coin-Mechanisms_Slug...

American coin mechanisms in vending machines and arcade games have magnets to filter out Canadian quarters.

I thought all coin mechanisms use magnets to differentiate coins, no?

A coin drops at a known speed and the right coin will get pulled by the right amount by a magnet or get rejected.

Not in the US - I think they use diameter and weight.

Sounds like slug heaven. But I guess if they don’t take $1 coins, it’s not as worth it finding a washer that will go where a quarter goes.

It sounds like you're thinking of separating coins using eddy current braking [1]. This works even for non-magnetic coins because the effect is a function of the metal's electrical conductivity.

If you have a silver coin or a small piece of copper pipe and a large, strong neodymium magnet, then you can easily observe this effect at home by putting the metal sample on a table and quickly waving the magnet past it as close as you can without touching it. The metal will slide across the table following the magnet, despite the metal itself not being magnetic, because the moving magnet induces eddy currents which temporarily create a magnetic field like an electromagnet. Other metals besides silver and copper exhibit weaker responses due to higher electrical resistivity.

[1] https://en.wikipedia.org/wiki/Eddy_current_brake

Thanks for explaining. Wondered how non-ferro coins were handled.

TD Bank in Canada had coin counting machines for customers for a while. I dumped a few hundred $ in and was very happy when it kicked back some silver coins to me.

How nice of them!

Pretty interesting table here: https://en.wikipedia.org/wiki/Penny_(Canadian_coin)#Composit...

I had thought pennies were made of zinc towards the end but that was only for a couple years. Then they were made of steel which should be magnetic.

As an American, the part of the story where a single coin is valuable enough to bother with is very interesting to me. Our failure over years to introduce a working dollar coin (much less a toonie) is frustrating.

This was 40 years ago and he was stealing hundreds of coins a day.

Also, I'm sure you realize, but the US has had dollar coins since at least 1971. The public never really had much interest in using them and with cash use declining, I wouldnt expect that to change.

I didn't read the "failure to introduce" as meaning no coin was created, but more as "failure to launch" in that it was just never picked up by the population. My largest concern with the dollar coins where they were too similar to quarters in size and were often used in error as a quarter. it is the primary reason I've heard to explain the lack of acceptance.

The coins don’t work unless you stop production of, and start reclaiming the bill variant.

Nobody wants to carry change, so of course they favour the bill rather than the coin.

Canadians didn’t have much interest in carrying the toonie either, but had no choice in the matter.

The problem is actually pennies. There aren't enough coin slots in cash register draws so there is no where to put dollar coins. If we got rid of pennies we would have a place to put them.

You're right, I do realize!

If they were fishing quarters, they'd have a $44k in "side income". The coin's value ultimate doesn't matter if you're willing to steal 500 of them every single day.

The US and Canada discontinued silver coins at about the same time (mid-1960s). The US went for a copper-nickel alloy sandwich and Canada went for pure nickel (which I believe is now nickel-plated steel).

We have tons of vending machines, and coin slots and I've never had or heard of such a problem? Completely anecdotal but still.

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