Instructables

How to make a RFID bracelet for a travel card (Oyster card)?

Im trying to make a bracelet which incorporates my London Oyster Card (RFID travel card) so i can just swipe my wrist and not faff about with wallets or pockets etc but I am having a few issues.

The basic design is going to be simple and effective. I will have a length of regular guage wire around the wrist, secured by a single wire connector/ terminal block (see photo). It will prob be a earth wire, as it is a fancy colour. The RFID will be placed inside the plastic connector and hot glued end end to secure it and keep out the elements. The RFID's aeriel wire will be inside the earth wire heatshrink, it will be a loop of wire and can be as thick as it needs to be.

I keep having problems though, I cant get the chip out of the card in one piece. I have been using nail varnish remover but with mixed results.  

When/if I do get the RFID chip out of the card, i will need to solder a new aerial and I am unsure about the process. Does the length/gauge of wire matter for the function of the RFID? im thinking about its frequency. Will it need to be ceramic covered wire to avoid shorts?

Has anyone put a contactless travel card into other things? Or has any experience dealing with this sort of area? I would very much appreciate any help or advice.

Picture of How to make a RFID bracelet for a travel card (Oyster card)?
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Jsmxbox2 years ago
People have done this by leaving the card in nail polish remover (acetone) for a few hours the plastic card goes soft allowing you to peal it apart giving you the RFID chip with arial attached they then roll the arial into a smaller loop and it seems to work fine

*** Video here http://www.youtube.com/watch?v=1BT6MU3gH80
Clodester (author)  Jsmxbox2 years ago
Been then there done that oysters 1,2 and 3 melted that way. The man did and update to that saying ppl were reporting problems. The acetone was as nearly as slow or selective as to what melted. This is because the design and is now different, in that the RFID is embedded differently, meaning removing the chip still usable is bloody hard!

have a what! >>>http://www.youtube.com/watch?v=Y0NM1pl8Vgo
orksecurity3 years ago
I'd suggest instead coming up with a wrist-wallet of some sort to hold the card. I know folks who carry our version in the back of their gloves during the winter. I keep mine positioned in the wallet so I don't have to take the card out; I just hold the whole wallet up to the reader. I've seen other solutions. With a bit of creativity, you can probably find one that works for you. It won't be as elegant as you might like, but the card isn't _that_ bulky...
Clodester (author)  orksecurity3 years ago
I do have the card in my wallet, but it is still awkward to sort out when your rushing. As to the forgery side. I have no interest (or skill) in hacking or rfid manipulation. I just want to turn the aerial into a different shape than the flat card shape it is currently.

Its not about bulk, its about convenience. I am aware others have done it in the past, but cannot find enough info on it. I also know in other countries the travel card RFID chip is incorporated into a range of items to aid in convenience. In Hong Kong you can get the octopus card (their version of oyster card) in watches. Its hardly the instructables spirit to be defeatist and just not bother because its not bulky. The gloves is a nice idea though thank you.
Not accusing you of forgery, just mentioning why this may (or may not) be more difficult than it seems even if you do get the coil figured out.

Yeah, alternative form factors would be convenient; I can potentially see a market. Unfortunately, as far as transit passes go, the current manufacturers would be only ones you could really sell the idea to... but there are other systems which would benefit from the convenience boost.

Some of the recent electronic auto keys (the Prius in particular) are set up with a longer-distance communications system so the car can lock and unlock itself without your ever having to take the transponder out of your pocket. That wouldn't work for the transit-pass application, of course; you want very limited range there so you don't wind up with the wrong card being billed.
frollard3 years ago
the length/ number of coils is arguably the MOST IMPORTANT factor. it has to resonate at the exact frequency the original did, or it won't induce the current into the chip. measure the distance, and make it exactly the same, preferably the same number of wraps in the coil.

Remember, the coil scans sideways, 'flat', not edge on - so you will have limited results having the coil wrapped around your wrist.
Note too that most of the manufacturers explicitly do NOT want you trying to do this, since it's one of the steps toward figuring out how to forge value onto the card. Their design may include something specifically to make this kind of disassembly difficult.