With a little work, you could probably adapt this idea to any number of circuits out of the 555 playbook, like a PWM generator, for example. There’s almost nothing a 555 can’t do.

Droplet and StackAR, developed by MIT’s Media Lab, allow users to set timers or program an Arduino using light-based communication. By pressing the tool against a screen, flashes of light can ...

Runner and Arduino enthusiast Nikodem Bartnik has created a DIY 100m sprint timer which is placed at the finish line and signals the start of timing via an audible bleep from its integrated ...