A PCB business card with a batteryless LED, powered by the phone that taps it
Kevin Tang engineered a unique PCB business card that illuminates a Charizard's tail when tapped by a phone, creatively demonstrating NFC energy harvesting. This project navigates the complexities of custom hardware design and overcomes software roadblocks with a bespoke iOS app. It's a prime example of technical ingenuity, blending functional art with deep dives into wireless power transfer, making it a captivating read for the HN audience.
The Lowdown
Kevin Tang shares the intricate process of creating his distinct PCB business card, moving beyond conventional paper to craft a functional piece of art. This innovative card not only facilitates sharing his website via NFC but also features a batteryless LED that illuminates upon phone interaction, subtly demonstrating an often-underestimated aspect of NFC technology: the phone actively powering the tag.
- Novel Design: The credit-card sized PCB boasts a sleek glossy black finish with gold artwork, an integrated NFC antenna, and a Charizard graphic whose tail glows red thanks to a strategically placed LED.
- Energy Harvesting: A core innovation is the batteryless LED, which draws its power entirely from the energy harvested from the tapping phone's NFC radio field, challenging the common perception of NFC tags as purely passive devices.
- Code-Driven Hardware: The entire board design, including intricate traces and the antenna coil, was parametrically generated using KiCad's Python API, emphasizing reproducibility and precision in hardware development.
- Hidden Details: The card's reverse side is artfully designed like a component datasheet, complete with antenna resonance mathematics and decoy chip contacts, a clever nod for observant engineers.
- Manufacturing Accessibility: Tang utilized services like JLCPCB for affordable fabrication and assembly of ten cards, highlighting the increasing accessibility and ease of modern hardware production for hobbyists.
- Overcoming Software Hurdles: Initial attempts to write data to the card with standard NFC apps failed due to the specific NTAG I²C Plus chip's blank state and lack of NDEF formatting, revealing a common pitfall in hardware-software integration.
- Custom Software Solution: He developed a concise iOS Core NFC app to send raw commands directly to the chip, successfully formatting and writing the URL, underscoring that the 'last inch' of software is often the most critical step in hardware projects.
Tang's project ultimately celebrates the power of curiosity and ingenuity, transforming a simple business card into a tangible demonstration of wireless power transfer. It effectively illustrates how a deeper understanding of underlying technical principles can unlock new possibilities, inspiring the creation of everyday objects that 'come alive' only when actively engaged.