It is a pretty common first project to use an Arduino (or similar) to blink an LED. Which ... light that only works in the dark. A simple circuit, but it just goes to show that we tend to forget ...

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

To actually power and control the entire circuit, [Martyn] used an Arduino loaded up with a program ... and warning indicators working with the LED bar array / tachometer, everything will look ...