[Ronnie] built a laser trip wire complete with an LCD screen and keypad ... the Arduino sees that voltage drop and then turns on the alarm buzzer. The value that triggers the alarm is set mid ...

But fear not, for [dekuNukem] has found the solution with Daytripper. This wireless laser tripwire communicates back to your computer using NRF24 (2.4 Ghz on the ISM band) and can be used to ...