Power supply :
LM2575 Switching Regulator 1.2-12V for Solar

Here is circuit power supply switching regulator, use IC LM2575 (good and easy IC switching regulator) for cotrol Voltage output 1.2V - 12V From Input Voltage 12V-20V. Detail see in circuit.

This circuit is suitable for a variety of uses. If you have a solar powered 12 Volt lead-acid battery power source, the circuit can be used to efficiently power lower voltage devices. It can be used to provide power to devices that normally use a set of small batteries for power. Common voltages such as 1.5V, 3V, 4.5V, 6V, 7.5V, and 9V can be produced by this circuit. The circuit has been used to power small fans, portable radios, a miniature TV, and more.