Crystal Radio is still relevant in the 21st

Yes, I know that there's not much worth listening to on AM radio.  But it's still fun to build a crystal set,  mentioned here:

https://wb9kzy.blogspot.com/2022/01/alfred-p-morgan.html

I recently saw this Superboy's Workshop Razor Blade Radio which I'd like to try:

 

Watching this Vertitasium video reminded me of crystal sets:

source: https://www.youtube.com/watch?v=YSJY3DvnybE

It showed multiple places where the concept of a bare bones crystal radio (basically a diode and a tuned antenna) was used by the CIA for bugging the Soviets.  It is also used in RFID tags to provide power.  And it is used in credit cards and debit cards to power the chip.

One thing they didn't do too well in the video was differentiate between credit cards and debit cards.  About the only place I use a credit card on the island is at Mann's store.  But somewhere I do have some thin sheet metal - might be hard on the wallet though.  I think I will also stop carrying my debit card.

Nikola Tesla is probably shaking his head up in engineering heaven, micropower ?  He thought he was on the track of transmitting megapower :)

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm