Low-Cost Laser-Based Home Security Alarm and Lighting System

As part of the SEJ102 Electrical Systems Engineering Project Module, a group of Electrical and Renewable Energy Engineering students of RIC Deakin Pathway Programme developed a low-cost laser-based home security and lighting system tailored for residential applications. Designed to be an affordable alternative to expensive commercial kits, the prototype utilizes a single-beam laser and Light Dependent Resistor (LDR) configuration, constructed with discrete electronic components and powered by a 9V battery.
The system operates by maintaining a constant laser beam on the LDR. When the beam is uninterrupted, the circuit remains inactive. However, if the beam is disrupted—such as by an intruder—the LDR’s resistance increases, triggering a transistor to saturate, activating both an alarm buzzer and indoor LED lighting. This elegant design not only alerts residents to unauthorized entry but also illuminates the interior for visibility.
The project followed an agile, two-week sprint methodology, from component selection to final testing. All planned milestones were successfully achieved. Impressively, the system underwent 10 indoor trials, achieving 100% detection accuracy with zero false alarms, highlighting its reliability and practical value for low-cost residential security.