Turning My CASIO F-91W Into a Contactless Payment Device

Great project! It's fun to read about all the antenna tuning OP did. Back in high school when one of my metro cards broke in half in my pocket and stopped working, I removed the chip and soldered about a foot of thick wire i had lying around, coiling it up in the size of my fist. Used it like that until that card was emptied, constantly worried that someone would notice and call the cops on this suspicious kid passing the gate with a wire lol

Interesting project but the random italic and bold text gave me a headache trying to read it.

Oh that's cool! I've seen something similar years ago, before phone payments became a thing, but the author dissolved their card (using acetone IIRC) instead of recreating the antenna