Design and Construction of an Automatic Triggered Bell Ringer Circuit

This research work deals with the design and construction of an automatic triggered bell ringer circuit. Several previous attempts have been developed on intruder alert and a motion detection system, complex systems that operate excellently well. The automatic triggered bell ringer circuit integrates knowledge of these previous models and utilizes more readily available components. It also introduces the use of two sensors, thereby increasing its sensitivity. Major components used in the work are the Force and Light sensors, sensors that depict the concepts of pressure and light resistivity/conductivity respectively, and a laser beam directly projected permanently on the light sensor’s surface. A force exerted on the Force sensor triggers a buzzer alarm and likewise, an obstruction in the path of the laser triggers the buzzer alarm. Once there is pressure exerted on the Force sensor, the resistance tends to infinity and voltage dropped across it biases the diode and transistor and the voltage reaching the buzzer triggers it. Likewise, the resistance of the light sensor tends to infinity when in darkness and the voltage dropped across it also biases a diode and transistor and triggers on the buzzer alarm. The work has been tested and seen to have a higher sensitivity, and is much cheaper than its counterparts.