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 ...

These light up paper circuit cards were much easier to make than I expected and only need a few inexpensive materials.

You’ve probably heard of light-emitting diodes, a type of energy-efficient light. While they’re good for practical reasons—say, illuminating a room or a passageway—they can also add a little bling to ...