I'm not very knowledgeable about RFID tags, which is what I think
these are. But my understanding is that RFID devices have no internal
power; they get their power from the nearby scanner, and otherwise
can't transmit anything.
But I think I've not actually seen one either. The theft-deterrent
tags I've seen (and taken apart) on purchased items in the past, had
no apparent active circuitry such as an IC in them and seemed to be
just a tuned circuit of some sort. (I'm sure this shows my ignorance
about them. Someone will probably point out that they also had
something like a diode, which I didn't see.)
> BTW: Is an aluminumized static bag sufficient to shield credit
> cards and driver's licenses from undesired scanning or is something
> more robust required?
Good question. For ordinary credit cards without a smart IC, they use
a magnetic strip, and a static bag provides little if any shielding to
magnetic fields unless it's mu-metal or some other magnetic material,
which I'm sure they aren't. On the other hand, you've got to be
really close to the magnetic strip to read it.
I really don't know if they shield RFID type signals. I thought the
conductive substance is a very poor conductor, and rather thin, so it
might not do much to the RF.
My driver's license has optical scan codes on it (1D and 2D barcodes)
and I think that's it.
Andy
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