Design of an automatic light bulb using the LDR (Light dependent resistor) darkness/ light sensor.
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In todays' word, lights are very much required in almost all commercial buildings. Due to busy lifestyle of human beings, switching operations on lights are not carried out on time and a huge amount of electricity is been wasted. In the present system, it is observed that lights are not turned OFF even when there is ample amount of light after sun rise and are turned ON before sunset. Even in timer based light control systems, the ON and OFF time differ noticeably during sunny and rainy days. To over come these problems, an automatic light controller is to be designed. The project aims to eliminate the manual operations and to design an energy efficient automatic light controller using light dependent resistor(LDR) and relay. The LDR is the sensing element in the automatic lighting system. This automatic lighting controlling system requires less maintenance and it is highly reliable. the 10K variable resistor adjusts the sensitivity of the LDR that is, either highly sensitive to darkness or low depending on the environmental conditions and weather(changes in the illumination of sunlight). The changes in the voltage across the LDR circuit and the ON and OFF time settings are analyzed by the LM358 IC and enables the automatic switching operation when the switching conditions are satisfied, moreover, the changes in the voltage switch either the relay ON or OFF when the voltage is low and high respectively across the LDR. The system is highly reliable and economical and requires very less maintenance.