How do I make a truly versatile solar powered cell phone charger?
I have many questions! I am trying to make a solar powered cell phone charger that has lots of versatility. When no phone is connected, it needs to charge 4, 2500 maH Ni-MH batteries. When a phone is present, it needs to charge from either the batteries or a 12 V, 1.5 W solar panel. I have found several voltage regulator circuits, but I don't understand how to calculate the proper capacitor values to stabalize the current using a PT5101 voltage regulator, or how to get 5V constantly if the voltage ranges from 2.4 V, from the AA's in series, or as high as my 12 V from my solar panel?
I don't want to buy a circuit, or salvage one, but create it from individual components. Any help?.