I dissolved the card in acetone to extract the NFC chip and its antenna,
Wouldn’t the acetone also dissolve the insulation around the antenna wire? So when it touches itself, it shorts itself out, and – electrically speaking – you only have one turn of thicker wire?
Wire that thin is usually insulated with an enamel coating. I’d guess it’s either unaffected by acetone, or just tougher to breakdown. Allow the card to dissolve, but remove and dry asap, don’t let it linger longer than necessary.
My guess is it wouldn’t work. On a magnetic antenna, the number of turns don’t affect range, but they do affect the frequency to which the antenna is tuned. It needs to be tuned roughly to the frequency the protocol operates on, otherwise it won’t work.
In addition to that, these antennas also need to pick up power, which is also relative to the number of turns.
Seems like something to experiment with at some point. I do have access to test contactless card readers but not sure how they would feel about me destroying the test cards.
Well if it dissolved any insulation, it will not work, as the coil isnt even coiling. It is not a one big coil buy just two ends shorted(or as in the picture, a very small coil. Since this works i can only conclude coating does not dissolve in acetone
Wouldn’t the acetone also dissolve the insulation around the antenna wire? So when it touches itself, it shorts itself out, and – electrically speaking – you only have one turn of thicker wire?
Wire that thin is usually insulated with an enamel coating. I’d guess it’s either unaffected by acetone, or just tougher to breakdown. Allow the card to dissolve, but remove and dry asap, don’t let it linger longer than necessary.
Veritasium demoed this a few weeks ago while discussing tap-to-pay security and a vulnerability with apple pay+visa.
Only one way to find out, good thing that these don’t cost any money and you can just ask for a new one.
Maybe take some cash out first to cover any payments you may need to make it it breaks in some way.
If OP is using it and is happy with it, maybe one turn of wire is enough for it to still work, maybe with reduced range?
My guess is it wouldn’t work. On a magnetic antenna, the number of turns don’t affect range, but they do affect the frequency to which the antenna is tuned. It needs to be tuned roughly to the frequency the protocol operates on, otherwise it won’t work. In addition to that, these antennas also need to pick up power, which is also relative to the number of turns.
Seems like something to experiment with at some point. I do have access to test contactless card readers but not sure how they would feel about me destroying the test cards.
Well if it dissolved any insulation, it will not work, as the coil isnt even coiling. It is not a one big coil buy just two ends shorted(or as in the picture, a very small coil. Since this works i can only conclude coating does not dissolve in acetone
It depends on the insulation used, which can vary a lot for thin enameled wire.