Monday, July 21, 2014

RFID Shielding

Got a new employee id card today - which is also the RFID card that gets us through the door sensors - and a new ecoPass - the pass that gets us on the local buses for free.  The latter used to be just a sticker that went on the former, but the buses are moving to RFID as well, so now its a card.  Obviously, they conflict with one another; while the ecoPass is in my wallet, the id card won't open doors.

Googled round a bit about RFID interference and shielding, and ended up trying a piece cut out of the back of a Coke can - cut it a couple of mm too big in every direction and fold the edges over to avoid sharp bits.  With this between the two cards, one side of my wallet (the id side) now opens doors again.  I assume the ecoPass should work from the other side of my wallet, though I haven't tested that yet.

As you can see from the back shot, I eyeballed the dimensions and got it too short to cover the complete back of the card; this doesn't appear to matter.

1 comment:

anti ob said...

The door card was working, but I finally tested the bus pass this morning and no dice. I suspect its because of the bits of the aluminum folded over the edges of the card - apparently the wire in the card runs around the edge. So I made a new version just the size of the cards and sandwiched it in the middle with tape, rather than having any overlap. Still works on the doors; I'll have to try the bus in a bit.