As the world around us becomes more and more environmentally conscious, alternative energies such as solar power are becoming more and more popular. The following solar charger is very simple and inexpensive to build and could be used to charge cell phones, tablets and other USB devices. 6V solar panel could be easily salvaged from outdoor garden lights. Solar charger uses REG113-5 efficient low dropout regulator that only loses 250mv of forward voltage. Linear style regulators such as a LM7805 or LM317 type voltage regulators lose as much as 2-3V and can not be used in this application. Optionally you may also add four-resistor voltage divider to charge an iPhone or iPad.
1x 6V Solar Panel (2W Max)
1x 1N4004 / 1N5817 (low voltage drop) rectifier diode for blocking reverse voltage
1x REG113-5 LDO Low Dropout Voltage Regulator
2x 10u / 10-35V Electrolytic capacitor to minimize regulator’s output noise
1x USB Type A Female connector
Four resistors will need to be added and connected to USB data pins for charging iPhone or iPad.