How do those magnetic strips on c.d.s (& electronic equipment) work?
April 29th, 2010 | by admin |I know that they put those little magnetic strips on c.ds and such at record stores and when you buy the c.d. they de-magnetize them (or something). But if you try to take it out of the store between those posts at the doorway, the alarm sounds.
What I want to know is how that works? Why does the alarm go off???
Does anybody know the ‘mechanics’ of it?
(I’m not trying to steal things, just understand how it works technologically.)
Generally, it’s not magnetic, it’s a Radio Frequency ID tag, or RFID for short.
They amount to tiny radios that react when they are hit by a specific radio frequency. The stores have radio emitters set to the right frequency at the door, they usually look like gate posts you have to pass thru to get out. When the RFID tag gets hit by the signal, they respond with a signal of their own, and the security system is looking for that return signal. If it receives one, it triggers the alarm.
It used to be that the RFID had to be removed physically, to keep the alarm from going off on properly purchased goods. But todays more sophisticated RFIDs have a deactivation signal. That is what they are doing at the counter when they "demagnetize" the tag. The counter device is sending the "turn off" signal that is supposed to disable the RFID.
2 Responses to “How do those magnetic strips on c.d.s (& electronic equipment) work?”
By juicy_wishun on Apr 29, 2010 | Reply
Generally, it’s not magnetic, it’s a Radio Frequency ID tag, or RFID for short.
They amount to tiny radios that react when they are hit by a specific radio frequency. The stores have radio emitters set to the right frequency at the door, they usually look like gate posts you have to pass thru to get out. When the RFID tag gets hit by the signal, they respond with a signal of their own, and the security system is looking for that return signal. If it receives one, it triggers the alarm.
It used to be that the RFID had to be removed physically, to keep the alarm from going off on properly purchased goods. But todays more sophisticated RFIDs have a deactivation signal. That is what they are doing at the counter when they "demagnetize" the tag. The counter device is sending the "turn off" signal that is supposed to disable the RFID.
References :
By mustangamer on Apr 29, 2010 | Reply
That magnetic strip holds a type of ID number. When you pay for the item, the security system is told that that ID# has been paid for so it won’t set off the alarm. If you don’t pay for it, the system ’sees’ that the ID# that it sees has not been paid for, and sounds the alarm.
References :