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
High voltage coin cell I blew up the original PCB on a bistable cholesteric display, so I built a coin-cell Joule thief to crank out 27V and bring it back to life. A simple two-inductor setup with a 27V Zener does the trick—about 10 mA while the button’s held. Then I got fancy with a regulated version (just one extra transistor) that tops the cap to 27V and basically idles—average draw lands around 1.53 mA. It’s neat, tiny, and perfect for this low-current reset job. Full build and measurements are in the video. 26 September 2025
More fun and games with high voltage Hey everyone! I know it's been a while since the last video, but things have been crazy busy with shipping off the ESP32 Rainbows. Lately, I've been diving into the world of high voltage again. My last endeavor with a high voltage board led to some gnarly waveforms and flickering LEDs, so I tested with beefy resistors but wasn't thrilled with the results. Fortunately, I've found some nixie tube driver boards that work wonders with LEDs, providing smooth output with little ripple. Still, playing with the old boards has its thrill—hello, 787 volts and some wild sparks! Stay tuned for... 14 June 2025