I can’t wrap my brain around how nfc just “holds data” but doesn’t need power to transmit data? Like how do ID cards use nfc?
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It’s an induced field situation. So it works in a similar way a metal detector works (imagine an old creepy fellow waving his metal detector over the beach). In that case, the metal detector has a battery and it sends a magnetic field into the sand. If it hits a hunk of metal, the metal will bounce back a signal, even though it doesn’t have its own battery.
The difference with a nfc chip, like in a credit card, is that the signal it bounces back is very specific because of the shape and pattern on the chip. And a nfc reader is sensitive enough to uncode that signal to get all the information it needs.
It’s an induced field situation. So it works in a similar way a metal detector works (imagine an old creepy fellow waving his metal detector over the beach). In that case, the metal detector has a battery and it sends a magnetic field into the sand. If it hits a hunk of metal, the metal will bounce back a signal, even though it doesn’t have its own battery.
The difference with a nfc chip, like in a credit card, is that the signal it bounces back is very specific because of the shape and pattern on the chip. And a nfc reader is sensitive enough to uncode that signal to get all the information it needs.
NFC **does** need electricity. NFC cards /labels don’t have batteries because they are powered by the reader through induction (the same way wireless phone charging pads do it).
The reader has an moving magnetic field, sends a tiny amount of power to the card, just enough to get it to transmit a weak radio signal with data.
NFC **does** need electricity. NFC cards /labels don’t have batteries because they are powered by the reader through induction (the same way wireless phone charging pads do it).
The reader has an moving magnetic field, sends a tiny amount of power to the card, just enough to get it to transmit a weak radio signal with data.
it gets power just like wireless charger gives power to your phone.
the chip card has a long antenna inside that receives the wireless power, then transmits the signal.
it gets power just like wireless charger gives power to your phone.
the chip card has a long antenna inside that receives the wireless power, then transmits the signal.
It’s similar to the way phones can be charged wirelessly without needing a power cable. The device reading the NFC transmits the power to operate it, that’s why they need to be in close proximity.
It’s similar to the way phones can be charged wirelessly without needing a power cable. The device reading the NFC transmits the power to operate it, that’s why they need to be in close proximity.
There are at least a couple of main ways to do it.
The easiest one to understand is where the tag takes energy from the radio signal emitted by the reader. It then uses that energy to send data back. The tag has an antenna to harvest the energy and enough capacitance/inductance to store it briefly. The reader is both supplying data and supplying RF power to the tag.
The more difficult one to understand is “inductive coupling”. Essentially, the reader and the tag create a circuit, much like a circuit that contains a transformer. Except this transformer has no iron core; it has an air gap that takes the place of the core. Since both the reader and the tag are part of the same circuit, they can pass data back and forth.
There are at least a couple of main ways to do it.
The easiest one to understand is where the tag takes energy from the radio signal emitted by the reader. It then uses that energy to send data back. The tag has an antenna to harvest the energy and enough capacitance/inductance to store it briefly. The reader is both supplying data and supplying RF power to the tag.
The more difficult one to understand is “inductive coupling”. Essentially, the reader and the tag create a circuit, much like a circuit that contains a transformer. Except this transformer has no iron core; it has an air gap that takes the place of the core. Since both the reader and the tag are part of the same circuit, they can pass data back and forth.
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