I Built a 27V Circuit to Fix This $3 Gadget I revived a cheap scribble pad by swapping its fried board for a tiny PCB that boosts a coin cell to 27 V—enough to cleanly reset the bistable LCD. It’s a Joule Thief with Zener regulation and twin 220 µH inductors (mounted in opposite orientations), pulling ~17 mA during charge and ~7 mA while regulating. It’s coin-cell friendly, works great, and just needs a bit of case surgery for a perfect fit. 07 November 2025
A nicer repair After my previous messy attempt, I aimed for a more refined repair by carefully matching and tinning the bodge wire. Despite a minor mishap during the cleaning, the final result is much cleaner thanks to solder resist. I feel like I'm improving! Watch the video to see the process! 07 August 2025