This is just a messy first prototype, but I recently tried making an AVRFID tag on a substrate of duct tape. The first attempt involved:
- An upside-down strip of duct tape, as the base for everything else to stick atop
- 100 turns of AWG 40 magnet wire around a ~66mm diameter form, which I then haphazardly squished against the tape
- An ATtiny85 µC in the SOIC-8 package, programmed with the latest AVRFID firmware
- SMT 0.1 µF capacitor across the power pins
- SMT 1 nF capacitor in parallel with the coil, for tuning it to approximately 125 kHz
- Sealed with clear packing tape on the opposite side
It’s ugly, and I really want to try this experiment over again with a smaller IC package, like TSSOP-8. But the card works very well, and the read range is practically indistinguishable from a mass-produced RFID card. I tested this one using an official HID ProxPoint reader.
I’ve been busy, but once I have time to perfect this technique I’m hoping to write some instructions, as it’s a pretty quick and easy way to make a DIY RFID tag that’s actually in a convenient form-factor.