The hope is always that a good business card will leave a good impression. For those in the electronics field, they also serve as an opportunity to showcase creative design skills. [Wilson Harper] demonstrates that ably with a rather nifty energy-harvesting build.
The card is based around a thin PCB in the typical business card size. It’s populated by 21 Charlieplexed LEDs, a small microcontroller, and some supporting components. Now, this is normally where you might expect the device to be powered by a small coin cell, maybe deftly integrated into the PCB thickness itself to make the card less cumbersome. But no—[Wilson] went a different route. The thing is that in 2026, most of us are carrying phones with NFC readers built in. Thus, the card was built to harvest this source of energy with a PCB trace antenna, designed with the aid of STM’s antenna inductance tools and an LLM script lobbed into KiCad. All one needs to do is to pop the card on the back of a phone and the LEDs animate joyfully.
Design files are on Github for the curious. You might also like to check out some of the fancy business cards we’ve featured in the past. Of course, if you’re working on just such a project yourself, you’re more than welcome to send it in to the tipsline!
How can this be made in a more hacky way? NFC harvester made from discretes? Use a random MCU to fake an NFC tag?
Im working on a quite similar project right now. But i use a seperate coil with a full bridge rectifier to harvest the energy and charge caps. Cant get more descrete like than that.
Using a seperate nfc tag to make the phone keep the field up you get quite a lot of energy.
Might try getting the card to talk to the phone, displaying your resume or your company product range or whatever
https://dangerousthings.com/products/rdc Using this for years now …
Using-an-off-the-shelf-component-for-its-indended-purpose-a-day.
From the linked article:
Someone learned something in a cool way. I’m glad Zoe wrote this one up, even if you aren’t.
Leave a sneering comment a day
Equally as sneering let’s keep comment sections kind and useful eh (for reference should the comment be taken down the comment I’m replaying to said ‘leave a sneering-comment-a-day’)
+1 – friendly reminder to some people here that we’re not all experts, and actually relish those fundamental, neat little starter projects, Age 8-88
Couldn’t you do this using all the WiFi signals around us, or is that too low power?
I have no time or expertise to do any of these awesome projects. Does anyone make the hackaday gadgets and sell them?
Nice work