Using a few diodes and a LED, you can make a nice indicator as shown in associated schematic diagram that can be used for a lot of applications (with a bit of luck). It’s quite suitable for use in ...

Signals when an on-circuit battery is exhausted, 5V to 12V operating voltage A Battery-status Indicator circuit can be useful, mainly to monitor portable Test-gear instruments and similar devices. LED ...

The world needs more blinky lights, and [Bertus Kruger] has created a neat way to make lights blink wirelessly. He has a footprint in the middle of the board for soldering the castellated ESP8266 ...