CHISOM NKECHINYERE IGBOKWE

Motion detection is now crucial for modern security frameworks and energy conservation efforts, offering superior protection and mitigating energy waste from appliances left running. This project addresses the need for a reliable, economical, and highly effective sensor system by focusing on the design, construction, and testing of a Passive Infrared (PIR) Motion Sensor prototype. The primary goal is to create a robust device capable of identifying movement across a complete three hundred and sixty degree field of view, enhancing its utility over standard directional sensors and providing a valuable contribution to localized security solutions. The technical implementation began with a robust Power Supply Unit built from scratch. This unit uses a step down transformer, a full wave bridge rectifier, and a large smoothing capacitor to transform high voltage AC into smooth DC. An LM7805 voltage regulator guarantees the stable five volt supply essential for the sensitive electronic components. The Sensing Circuit uses a PIR sensor and a Fresnel lens to detect infrared energy. The weak analog signal generated by moving heat sources is processed by an operational amplifier and a comparator to create a clear digital trigger. This trigger then activates a transistor to energize an electromagnetic relay and a buzzer, which serve as the system's immediate response mechanism. Testing confirmed that the prototype successfully met all objectives. This included the reliable detection of motion within the predetermined area, the empirical definition and adjustment of the effective detection range, and the successful fine tuning of system sensitivity. Furthermore, the strategic design achieved the critical goal of wide coverage. This project validates the construction of a low cost, energy efficient device, affirming the practical application of knowledge in electronics design, power management, and embedded systems, and establishing a successful framework for automated lighting and intruder alarm systems