DIY on Dhiru's Notebookhttps://rfcorner.in/tags/diy/Recent content in DIY on Dhiru's NotebookHugoenSat, 24 Oct 2026 00:00:00 +0000Mains Power Detection, Minus the Mainshttps://rfcorner.in/posts/mains-power-detection-minus-the-mains/Sat, 24 Oct 2026 00:00:00 +0000https://rfcorner.in/posts/mains-power-detection-minus-the-mains/An ESP8266, two resistors, and a small 18650 UPS turn an isolated 5 V adapter into a mains-availability monitor.