Cat detector/RFID tags and more
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Posts: 46,084
X-raying the "Speed Pass" would yield the contents and determine the size of
the battery. The RFID tags don't use batteries but instead rectify the AC
signal picked up by the loop antenna and use that to charge a small cap and
to power the receiver and the transmitter. I expect that a similar
arrangement could be designed to fit around a cat's neck and supply power to
a low power CMOS version of a NE-555 timer/oscillator which could drive the
loop antenna briefy, just long enough for the trap door receiver to sense the
pulse train generated by the NE-555 oscillator or even by a relaxation
oscillator or blocking oscillator.
I think there are several ways to skin the cat.
the battery. The RFID tags don't use batteries but instead rectify the AC
signal picked up by the loop antenna and use that to charge a small cap and
to power the receiver and the transmitter. I expect that a similar
arrangement could be designed to fit around a cat's neck and supply power to
a low power CMOS version of a NE-555 timer/oscillator which could drive the
loop antenna briefy, just long enough for the trap door receiver to sense the
pulse train generated by the NE-555 oscillator or even by a relaxation
oscillator or blocking oscillator.
I think there are several ways to skin the cat.