SparkFun Electronics Commentsurn:uuid:214d0e4e-f1b1-d287-ce26-ac5b4c9f82492024-03-29T07:10:14-06:00SparkFun ElectronicsShapeShifter on So you want to talk about RFIDShapeShifterurn:uuid:cf45c837-7e5d-83ec-d30e-9037e80251a02020-07-22T05:10:26-06:00<p>That library likely didn't use RFID, unless they were also using it to check in/out books electronically without scanning a barcode or using a paper slip. More likely, they were using an electromagnetic security system, similar to what you see in retail stores for high value items. The tag and the detector is simpler and less expensive.<p>Instead of a programmable microchip with a unique identifier, an EAS (electronic article surveillance) system tag uses two simple magnetic strips. The detector puts out a low frequency magnetic signal that causes the strips to vibrate against themselves, putting out a signal that the detector can pick up. The tags can be magnetized/demagnetized to prevent or allow this vibration, allowing an item to pass through silently or to trigger the alarm.</p><p>In a retail setting, they normally only deactivate (magnetize) the tag by passing it over a device at the checkout. But in a library, they can easily turn a book's tag on (demagnetize) or off (magnetize) when it is checked in and out.</p></p>
bboyho on So you want to talk about RFIDbboyhourn:uuid:dfecaf6f-3ab2-73a7-31f9-4a760c06ee042020-07-21T11:15:55-06:00<p>Yes. XD<blockquote>
<p>Getting started with RFID is as easy as taking candy from a... candy vending machine.</p>
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Customer #134773 on So you want to talk about RFIDCustomer #134773urn:uuid:333e6b5f-f69c-bd4f-e5c1-2bdd7c4f2eec2020-07-21T11:00:23-06:00<p>Cute video, Rob!<p>FWIW, I recall having a credit-card sized RFID tag back in the mid-70s when I was working in a factory that would gain access to certain "restricted" parts of the factory. They seemed like "PFM" (Pure Magic) at the time.</p><p>My next encounter with RFID was that the college library a few years later had tags in all the books, and scanners at all the exits. If you had a book that hadn't been checked out, it would sound alarms. When you checked out a book, they'd pass it over some sort of device that set some flag saying it was OK to pass through the scanner gate. My understanding was that when a book was "returned", it got passed over another device so it would then set off the alarm again. Since your personal books (e.g., text books) didn't have tags, they wouldn't set off the alarms. I never did find out much about that system, as my stint of taking "library science" (in lieu of PE, which I had a doctor's excuse for) in high school was well before this was common in libraries. (I had to type up many cards for the card catalog...)</p></p>