@Sorry that handle is already taken, would you care to explain why the local metro machines can't read my card until I take it out of my wallet? The real issue isn't whether it's earthed (with respect to what, anyway?) but whether it has holes. However, given the size of the aerials on those cards (pretty much the size of the card) the frequency of radio waves used is low enough that you can get away with holes on the order of a cm.
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Earthing
@Sorry that handle is already taken, would you care to explain why the local metro machines can't read my card until I take it out of my wallet? The real issue isn't whether it's earthed (with respect to what, anyway?) but whether it has holes. However, given the size of the aerials on those cards (pretty much the size of the card) the frequency of radio waves used is low enough that you can get away with holes on the order of a cm.