HAW HAW HAW HAW!

[Triple Zero]

I wondered about those, but no I don't think they are RFIDs. They've been there for a really really long time.

AFAIK those are based on some kind of coil. You can see it in certain types of them, they look like a sticker that's made of an 8-sided spiral of metal print, is a coil. Something something magnetic field something electric current something, and the alarm goes bleepy when you pass it. I'm not entirely sure how they disable those coils, though. Maybe they actually short them using a stronger magnetic field that burns part of the circuit.

Fun thing to try is, if you have a big loop of cable, say UTP network cable, and you roll it up in a coil, a fairly normal way of storing large ends of cable, it should trigger the alarm as well.

[BadBeast]

I've noticed those coils in modern Passports, and the inside pages of Library books. Both of which link up to central databases. Presumably they all have a identifier, like an individual barcode that activates / de-activates them. But I'll try that coil thing next time I'm going to the Library.

[Remington]

Shops in UK are now using small adhesive strips, about an inch long, and a quarter inch wide, that are deactivated at the tills with a magnet. If they are not deactivated, an alarm sounds as you go out the door. Is this RFID?  

Not RFID. RFIDs are distinguished from those magnetic tags in that RFIDs can store information.

/themoaryouknow

[Template]

I wondered about those, but no I don't think they are RFIDs. They've been there for a really really long time.

AFAIK those are based on some kind of coil. You can see it in certain types of them, they look like a sticker that's made of an 8-sided spiral of metal print, is a coil. Something something magnetic field something electric current something, and the alarm goes bleepy when you pass it. I'm not entirely sure how they disable those coils, though. Maybe they actually short them using a stronger magnetic field that burns part of the circuit.

Fun thing to try is, if you have a big loop of cable, say UTP network cable, and you roll it up in a coil, a fairly normal way of storing large ends of cable, it should trigger the alarm as well.

If I'm thinking about the same thing you are, it might be a big, crude RFID tag.
More likely, I imagine, is that the sticker circuit is a resonant circuit.  It would soak up oscillations near some set frequency -- which is why only the stickers set off the detector.

Of course, my memory of EM devices is fuzzy.

[Triple Zero]

Okay, but any idea how the disabling of those things works?