Load current, dropped voltage and size considerations in LDR based light control system

Energy consumptions are dominated by lighting and air conditioning. Automatic controlling is the solution as human awareness is unreliable. Lighting and air conditioning can be automatically controlled by employing light sensor as well as human existence sensor. Light bulb and street lighting have been widely equipped by light sensor such as the light dependence resistor (LDR). LDR sensor circuit can be made transformer less and transformer based. Transformer less LDR circuit can be integrated into light bulb while transformer based LDR circuit is designed as a standalone device. This paper examines power consumption, load current and circuit size of both LDR circuits. Experiments show that transformer less LDR circuit consumes higher power with limited load current. However, its size is smaller. On the other hand, transformer based LDR circuit consumes less power and provides larger load current. But the challenge is the transformer size to overpower the transformer less circuit.