The CULD is designed as a simple LED indicator that will light up anywhere ... With a bridge rectifier onboard, it’ll even work on AC circuits, too. [Tom] has built a handful himself, but ...

Fastest finger first indicators (FFFIs) bring precision to quiz games, measuring contestants’ reaction times with accuracy.

Increasingly, cars are equipped with LED indicator and brake lights ... point is used as the light source connected directly to a circuit of modulated current.” Unknown and uncelebrated ...