Low Profile Light: Grindhouse Open Source Release
  • SixEchoSixEcho July 13
    Low Profile Light is a tiny NFC powered LED implant. It is notable for being little more than 1cm^2 in area, and storing energy in supercapacitors instead of batteries.

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    I have seen a huge number of topics recently about NFC and the prospect of tiny LED implants, so i thought i'd share this, maybe someone can get something useful out of it.
    It was developed as a successor to Northstar 1, but in the end we decided to focus on more feature-heavy implants, and this design was abandoned.

    It is a full featured chassis, theoretically capable of communication, power, and wireless arduino code push, all through NFC. It can carry enough power to light the LED for one minute at 100% duty cycle. (or 10 minutes at 10%...).

    This design has not yet been proven to work. It's only got two chips though so if you're keen it should be pretty easy to finish off. Or you can just copy the parts you like. We built two prototypes but never got around to doing anything with them.

    I'm releasing it without any kind of license. You can modify the design, or even build and sell them if you want.

    tech info:
    NFC chipset: AMS AS3955 (this thing is the star of the whole show).
    Controller: Atmel ATTiny13
    Tiny SMD supercaps: Seiko CPH3225A

    download link:
    https://drive.google.com/drive/folders/0B3p99D0AGrsEYlZ1Z09JN0tQYkk?usp=sharing

    included are Kicad files, bill of materials + part sources + expenses, and a picture of the layout.

  • Wow thanks
  • That as3995 chip is looking pretty convenient there. Did you make that chip talk to anything via spi?

    Btw as for future designs, you may want to replace the attiny13 with an attiny841. Same size but way more flexible for different tasks (that's other tasks than blinking an LED). Amount of RAM is most noticeable.

    Not sure if a 40buck cap bank is the right tool for the job here. Varta's V18HRT might fit the bill for high current loads a bit better.

    But my real question would be how to assemble this. The cap bank  and the chips, no big deal. But the antenna? Magnetic shield and the nfc antenna stacked on top with 2 wires running down (there's an unconnected trace on the pcb so I'd assume it that way). Assuming 0.8mm pcb that'd be 1.6mm from the caps and chips, and 1.6mm from 2 pcb's stacked plus 0.2mm from the magnetic shield. 3.4mm total?