Cheap Laser Tripwire Home Security Alarm System
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 p...By: TechMartian
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