The materials you will need:
-A 6V solar cell, you can use a 12v solar cell also.(I use two 6v solar cells to get more current)
- Voltage regulator 7805
-1 female usb connector, or female to female usb adapter
-1 1n4007 diode
-two electrolitic capacitors 10nF 16V
-1 ceramic capacitor 22pF (optional)
-Solder iron and solder
For the spanish version please enter to my site: www.bioespin.com
Step 1: Pinout, Understanding Connections
The pinout of the 7805 is in a image here. The first pin counting prom left to right is the voltage In. In here you can connect every voltage source from 6V (7V in some) to 12V to assure you have 5V in the Vout pin. The second pin is the ground, and the third pin is the one that is always 5 Volts.
You just have to connect the solar cell to the Vin and the ground to the ground.
The pinout for the usb is also really simple. If you look it whit the copper looking up and counting from right to left, the first pin is 5 Volts, and the 4th pin is ground. I will upload a image to you to see it clearer.