Credit Card Chip used to make Crystal Radio

Billy Cheung decided to build a crystal radio using a rather unconventional detector – the smart chip in a common credit card

This is possible because the smart chip on many credit cards contains a diode. It’s then a simple matter of hooking up the right pads on the credit card to the rest of a crystal radio circuit, and you’re all set. Of course, Billy goes the whole hog, building the entire radio on a single credit card

Media story and video - https://hackaday.com/2020/06/01/credit-card-chip-used-to-make-crystal-radio/

Billy Cheung's blog - http://billydiy.blogspot.com/2016/04/my-crystal-radio-shows.html?view=sidebar