April 4, 2026
Tap to argue: who pays the power bill?
Show HN: I made open source, zero power PCB hackathon badges
Battery-free hackathon badge sparks 'zero power' debate and budget brawls
TLDR: An open-source hackathon badge uses an e‑ink screen and NFC taps to work without a battery. Commenters cheered the design but clashed over the “zero‑power” claim and real costs, weighing bulk pricing and hand‑soldering against assembly services—because cool swag is only fun when your wallet survives.
Show HN lit up after a hackathon in Singapore dropped an open‑source, battery‑free badge with an e‑ink display and tap‑to‑update NFC. Devs swooned over the copper art, but the comments turned into a wallet vs. wizardry brawl. One organizer sighed they “haven’t been able to get quite that fancy due to cost,” while others latched onto bulk quotes around $5 for the board and another $5 for the screen—cue “just hand‑solder it” vs. “pay for assembly and your sanity.”
The spiciest thread: what does “zero‑power” actually mean? Skeptics asked if the trick is just using your phone’s energy via NFC; veterans chimed in with e‑paper lore: these screens hold an image without juice, then sip a tiny burst when you tap. One commenter flexed with 'ePaper picture frames' that wake over NFC to swap photos, sending imaginations racing for business cards and museum tags. Cue jokes: 'Zero power? My phone battery says hi.'
Meanwhile, layout nerds demanded: did you use a plugin to draw that NFC antenna? Praise poured in for the clean routing and first‑try success, while others ogled the symmetrical CAD art. Verdict from the crowd: slick idea, bold claim, and a build that's begging for clones.
Key Points
- •RP2040-based hackathon badges use passive NFC and an e‑ink driver to enable core features without a battery.
- •The PCB is a two-layer design with ground fills on both layers and CAD-modeled, symmetrical artwork.
- •Programming involves installing a Pi Pico MicroPython bootloader via USB‑C and uploading firmware with Thonny.
- •Customization is supported through a config.json and by replacing bitmap images, with Magick suggested for image conversion.
- •Manufacturing via JLC PCBA costs about <$5 per board in bulk plus ~$5 for the e‑ink; MOQ is ~ $100 for 5 with PCBA, and hand soldering may be cheaper.