Cheap Laser Tripwire Home Security Alarm System
Shared by TechMartian on instructables:
This is a simple and cheap home security system that costs only $ 15, to ward off nosy siblings and burglars alike. It comprises of a laser used as a ‘tripwire’ and a photosensor to detect whether this laser beam is blocked or not. If it is blocked an intruder, an ‘alarm’ will sound off using the piezo buzzer. The alarm I chose is the beautiful sounds of Pachelbel’s Canon in D major.
I was inspired to make this from spy movies with high-end home laser security systems where the protagonists sprays aerosol and navigate around a complex laser setup.
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