Smaller smart card for public transport?

September 11, 2012 5:06 AM

Possible to get/make a small version of my Dutch public transport card?

I've got a Dutch "OV chipkaart" that serves sort of like the British Oyster card - it allows you to check in and out of the public transport system. These cards are credit-card sized. It would be handy if they were smaller so that you could, for instance, attach them to your keychain for easier access. However, they do not officially sell a smaller one (at least that I can find).

Is it possible get or make a smaller version of the card? Where or how would one get such a thing, and would it be legal?

posted by Philosopher Dirtbike to technology (7 answers total)

You might try using the same technique they use on Oyster cards to remove the electronics.
posted by Orb2069 at 5:31 AM on September 11, 2012

If you can work out where the RFID chip and antenna wires go, you can cut down the card, or dissolve the card to get them out and attach them to something else. Here's a video of someone talking about how to do it with an Oyster card. I think this probably does violate the Oyster terms of usage, though.
posted by corvine at 5:32 AM on September 11, 2012

Woops - Better tutorial here.
posted by Orb2069 at 5:34 AM on September 11, 2012

I should add that because the card is checked physically on the trains, the card should not be destroyed in the process, unless it is officially sanctioned by the public transport agency. I can present the larger card when necessary, and use the smaller card most of the time.
posted by Philosopher Dirtbike at 5:38 AM on September 11, 2012

You'd have to clone it then, and I have never seen any sort of RFID cloning tech that wasn't going to work out larger than the original.
posted by phearlez at 6:47 AM on September 11, 2012

If the card is based on a Mifare Classic then it's technically relatively easy to clone, and you might be able to clone it onto a Mifare Classic sticker, which is smaller than a card and flexible, or a Mifare Classic fob. This might not be usable if they're also checking the read-only hardware ID of the chip (which you usually can't clone onto a card - you'd need to use a computer or phone to emulate a card with a copied ID, and as pherlez says this is bulkier)

If you manage to clone a card it might be classed as an illegal hacking attack or fraud - at the very least it probably breaks the rules of use.

Someone in London has an Oystercard wizard's staff. Here's a video showing how to partially dissolve a card and remove a working chip. Obviously this is best done with a cloned card if you need a full size one too.
posted by BinaryApe at 8:43 AM on September 11, 2012

I played around with a Charlie Card for Boston's public transport system. I was inspired by a video where someone had put an oystercard into a trout and waved a fish at the sensor as they went through the barriers.

My approach was to dissolve/soften the card using nail-polish remover. It takes a while so I had it sitting in a jar for about a day. Then I could peel off the outer layer on both sides. I then headed down to the subway to see how small I could make it. What I found was that there is an aerial around the edge of the card which I presume amplifies the signal and when the card is folded into quarters it's not longer sensitive enough to be read. I could fold it in half and it still worked. I thought about cutting out the card and trying to make a small sensor but I never got around to it. I still have my 'skinless' card in my wallet and it has worked fine for two years but it's still credit card sized. I've also never had to show it to anyone official as it might look a bit strange, but I doubt T staff mind.
posted by a womble is an active kind of sloth at 3:26 PM on September 11, 2012