Micah's bloggy widget ([info]scanwidget) wrote,
@ 2008-08-22 00:36:00
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Simplest RFID reader?


That's a Propeller microcontroller board with a few resistors and capacitors on it. Just add a coil of wire, and you have an RFID reader. Here's a picture of it scanning my corporate ID badge, and displaying the badge's 512 bits of content on a portable TV screen:



If you're into that sort of thing, I wrote a forum post with technical details and pretty oscilloscope screenshots.

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yay
(Anonymous)
2008-08-22 08:22 pm UTC (link)
Sweet =D how far away can it succeed at reading the cards? NIST uses those LF cards to control access too. I've heard some stories about success reading them from a meter or so through big stone walls, given a large well-matched coil and a good amount of power :)

-Dan

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Re: yay
[info]scanwidget
2008-08-22 10:18 pm UTC (link)
Hiya Dan!

I think my max read distance is about an inch or two. It will read with the card still in my wallet and I don't have to press it completely up against the wood block.. but it's certainly not a long distance RFID reader. This design wasn't really striving for maximum performance, given that there are no active components at all ;)

I might have to try giving it a real amplifier for generating the carrier, tuning my coil a bit better, and adding a fast comparator for doing signal detection. With those improvements, I wouldn't be surprised if I could get 6 inches or so. Maybe if I'm lucky, a whole foot?

--Micah

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