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