1130
Necessity is the mother of invention (thelemmy.club)
submitted 3 months ago by to c/linuxmemes@lemmy.world
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Toot

Mastodon post with no text and an image showing a Monobank card strapped to the back of a Pinephone with some rubber bands. The text within the image reads "Contactless payments on PinePhone (working Google Pay/Apple Pay alternative)".
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[–] 460 points 3 months ago* (40 children)

I'll do one better:

Reshaped payment card's NFC antenna

My payment card was just a bit too wide to fit in my cellphone's cover. The phone's own NFC antenna is at the top - and I use it all the time - so the card had to be at the bottom of the cover to avoid triggering the phone all the time, in portrait orientation so-to-speak.

So I dissolved the card in acetone to extract the NFC chip and its antenna, then carefully reshaped one end of the antenna so it's a bit less wide (and since I couldn't modify the length of the wire or the number of turns in any way to avoid de-tuning the antenna too much, I sort of accordioned one side of the rectangle to accommodate the extra length of wire).

Then I set the new shape of the antenna permanently by carefully applying a piece of packing tape over it, flipped it over, taped over the other side to seal everything, then carefully cut around the new, ultra-thin, stubbier contactless payment "card".

Now it fits really smartly in my cellphone cover!

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  • [–] 25 points 3 months ago (7 children)

    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?

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  • [–] 19 points 3 months ago (3 children)

    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.

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  • [–] 7 points 3 months ago (2 children)

    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?

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  • [–] 17 points 3 months ago

    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.

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  • [–] 12 points 3 months ago*

    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 of antenna shorted(or as in the picture, a very small coil. Since this works i can only conclude coating does not dissolve in acetone

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  • [–] 15 points 3 months ago* (last edited 3 months ago) (3 children)

    Have you ever run into difficulty with needing to authenticate with chip+PIN? Like while traveling?

    That would be my big concern with this; it would make it very difficult to pass a PIN check, to say the least!

    Super cool idea. I might just try it myself and see if I run into issues.

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  • [–] 24 points 3 months ago (2 children)

    What I modified was in fact a contactless payment token. It had the form factor of a payment card, but it only does NFC.

    I have another card for chip+pin.But I almost never use it where I live, because all limits were lifted on contactless payments a few years ago. If I try to pay something really expensive contactless, it will ask me for the pin - which is specific to the payment token.

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  • [–] 1 point 3 months ago (1 child)

    Do you mind if I ask what bank issued those? Why? Does the chip+pin also tap or are they features on totally separate cards?

    I've never heard of a separate tap to pay token (outside of perhaps transit passes or like, arcade cards), and never a card based tap transaction that asks for a pin.

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  • [–] 5 points 3 months ago*

    Payment tokens are very common. Usually they're sold as keychains, wristbands or rings, and they're provisioned to work with the myriad of payment processors out there - which aren't banks.

    in my case, it's a token from iCard. The way it works is, it's connected to a regular bank account number with an IBAN number (supplied by iCard when you activate the token), and you transfer money to it that you can then spend with the contactless token. The nice thing is, if you lose it, you can't lose anymore money than you put on it.

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  • [+] 14 points 3 months ago (2 children)
    [deleted]
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  • [–] 5 points 3 months ago (5 children)

    Kudos for the effort. With that said, this would definitely raise some eyebrows if you have to return the card when getting a new one.

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  • [–] 3 points 3 months ago (2 children)

    The bank just mails the new card to me. I still have old debit cards.

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  • [–] 2 points 3 months ago (1 child)

    Knowing the reliability of our postal services, I would very much prefer to receive it in person. Of course there are security measures (activating it only when you get it and so on), but still.

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  • [–] 1 point 3 months ago

    Our bank will just print a new one on the spot for you if you go to their office. As long as you're ok with your name and card number not being embossed. They have to order away the embossed ones – but you can still pick them up in person.

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  • [–] 1 point 3 months ago (3 children)

    Well, what if you need an actual card for identification in the bank or something similar? Do you just show them the dissolved one?

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  • [–] 10 points 3 months ago (1 child)

    Don't know about OP but gov ID works for that purpose. I'm more worried about when they go to a store that doesn't accept tap.

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  • [–] 4 points 3 months ago

    I was thinking about this, and there are two easy workarounds, I think:

    1. If possible, get a second active card in the same name. Ideally, a full-identical cloned card. Not sure if this would be allowed, but if not...
    2. Add another authorized user to your account and never give them the card, then just dissolve that card for tap payments.

    But, in either case, I do think you might run into a different issue: automated fraud detection sometimes requires me to chip+PIN, even for transcribed below the tap limit. This has happened to me when traveling. I don't think there would be any way around that, and if you then fail to authenticate with chip+PIN, it's reasonable to think that the bank would lock your card for contactless payments until you successfully authenticate the card again with chip+PIN. (To be clear: this is only speculation; not sure if that would be an issue in practice.)

    So, I suspect that whether this would work or not might depend on your institution (or maybe jurisdiction?)

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