Building an Arduino speed detector using IR technology to measure the speed of a moving object is much more cost-effective, ...

We can use them to cut things, create laser light shows, and also as a rangefinder.[Ignas] wrote in to tell us about [Berryjam’s] AMAZING write-up on creating an Arduino based laser rangefinder.

[Ronnie] built a laser trip wire complete with an LCD screen and keypad for arming and disarming the system. The brains of the project is an Arduino ... code and wiring diagram available for ...