This solar birdhouse light is an economical circuit of a mini solar lighting system circuit is presented here. At the heart of the circuit is a mini 6V/2W solar panel. Here, this solar panel is used to charge a 4V/800mAh rechargeable battery through a charge current limiter circuit built around an adjustable 3-pin regulator LM317T (IC1).
Resistor R1 sets the output current. The lighting circuit comprising 20 white LEDs are directly powered the battery. Swich S1 is a simple on/off switch. Assemble the circuit on a small PCB and enclose in a suitable cabinet. Fix the solar panel on the top of the cabinet and power switch and LEDs on the front side.
Specification of a typical 6V/2W solar panel:
Assuming a 6 hour sunlit day, a 2 watt panel (near 150mA current set by the regulator IC1+R1) will pump about 900mAh into the battery. Solar charging current can be reduced by increasing the value of R1 ,say from 8.2 Ohm to 10 Ohm.