Design and Development of Low Cost Security Alarm Using Optoelectronic Device

Nowadays security has become a major concern in our modern world due to the high rate of robbery, thief etc. in many important places such as home, museum, office, and other business places. Due to the importance of security in our lives as humans, this research work aims at designing a security system that could be used in home, museum, office, and other business places as well. The designed security system is simple, effective and cheap. An oscillator circuit is designed to produce a desired frequency and a photo transistor is used as a sensor. This sensor spreads the frequency around a certain area. When unauthorized entry occurs in this area the frequency detects it. Then the sensor passes a signal to a speaker through certain amplifiers and then the speaker produces sound. This security system is operated by an external power supply. An additional power supply (a battery) is used as an alternative power supply. When there is no external power supply, the security system is operated by this additional power supply.