A PCB business card with a batteryless LED, powered by the phone that taps it
kevin.mdWe just did this https://news.ycombinator.com/item?id=49478426 this is starting to become the risc v of fpga resumes. It's certainly work and making anything that exists and works even somewhat is commendable but it's getting played out
The most interesting open source example of this I can think of is Ben Krasnow's (and friends') temperature reporting magnetic stir bar:
https://www.youtube.com/watch?v=nh1SIfipQs4
The temp sensor and transceiver PCB are cast into urethane and the coil gets installed into the hotplate. In theory lets you do all kinds of interesting stuff like monitoring when you can't get a wired probe into the vessel, or to drive a control loop that actually monitors the liquid and not the plate temperature.
AI:DR
> Once you’ve felt that, you start seeing NFC taps differently. You’re not reading the tag. You’re powering it.
I stopped at this line too. My AI detector is too bad right now
is it possible to do this with a wearable? say jewelry? i've been fascinated with the whole digital to physical world dislocation and this inspires me to dust off an old idea of around the world "collecting" passport stamps but the only way to actually collect them is by a physical tap. similarly, i can see jewelry that lights up upon being tapped by a phone or together. fun
"is it possible to do this with a wearable?"
Yes, but there are limits on the minimum size. The smallest off the shelf tag I have seen is about 10mm diameter disk sticker.
6eah you can make the chip tiny but not the coil, it needs to capture enough energy from the field.
There are 3x3mm NFC chips but their read range is 2mm..
Next stage EInk card having a personalized Information and / or pitch..
If you ever build that deck, Joe, call me?
2nd one this week on this site. must be a trend or something?
Dude did you even read your post ? None of the sentences make fucking sense
one of the coolest things I've ever seen
at least https://news.ycombinator.com/item?id=49478426 shared a github.
A few months ago some dude offered a very fancy business card: it looked really gorgeous and all tech. Don't remember all the details but it was shiny and had tiny components etc.
So I took it and was going to put me in my wallet and the dude interrupted me and say: "No, no, you can't have it, I've got only one, you need to scan the QR code".
I found that incredibly cheap ; )
P.S: and also I don't scan random QR codes.
That's pretty cool!
website is down
Author here. One thing that didn't make it into the post: there are no hand-drawn traces on this board. I find mouse-driven PCB layout maddening, so the whole card is a Python script driving KiCad's API—antenna coil, lettering, everything. Retuning the antenna meant changing one number and re-running the script, which as a hardware novice was the difference between finishing this and giving up.
The chip is NXP's NTAG I2C Plus. I picked it for the energy-harvest pin (that's what lights the LED) and only realized later that it ships without NDEF formatting—which is why every consumer NFC app refused to touch it. Sending it raw write commands through Core NFC turned out to be much less scary than I expected: the part that matters is about 60 lines of Swift.
I still can't get over JLCPCB assembling ten of these for about $75.
That made the post? Everything in your comment is in the post, AI summaries aren't very popular.
> I designed the whole board as code, which I’d recommend to anyone who, like me, finds dragging traces around with a mouse maddening. KiCad—the free PCB tool—has a Python API, so the entire card is generated by a script.
My guess is that the whole project including the selection of chips was made by an AI.
My guess as well. I don't like it when humans silently pass off LLM writing as their own.
I also don't like it when humans silently pass off LLM work as their own.
Prompting is not the same as doing the work. There are ways to genuinely collaborate with LLMs, but if someone silently takes full credit for work generated by LLMs, my assumption is they probably vibe coded it.
Plus, I spend my free time expending effort to consume human generated content. I’m okay with slop someone pays me to deal with, but don’t expect people to read your hobby related post when you couldn’t be bothered to write it.
> I still can't get over JLCPCB assembling ten of these for about $75.
I remember years and years ago I made some business cards out of 304 stainless with a laser etched design and bottle opener on the side (before that whole idea became mass marketed). It cost me over a hundred bucks for ten, wild that you can get whole pcb assembly done for less now days.
I can understand because I find MCAD drafting to be a chore and like that I can describe a script to generate geometry now for most things.
Even still, it's difficult for me to fully get it. There is so much art in ECAD layout. There are many dimensions to weigh and high levels of thought and care can result in a higher quality, lower cost product. Many nuances are not properly captured by simplistic automations or chatbots and won't be for some time. Things that accelerate schematic capture, layout capture, library management, and simulation are all useful tools. They're most effective when used with care and thoughtfulness.