solar power to charge batt or capacitor

Blake

hey,
Can anyone point me to a circuit diagram or tutorial or the like for charging a battery via a solar panel. I have an art·project in mind to use a basic stamp to charge a AA battery via solar panel which would then be used to play an mp3 player. I am also wondering if i could use a capacitor instead of the 1.5 volt battery. I only want to play a five minute selection on the mp3 player per charge.

So far I have been able to power up a Bs2 with a 10Volt, 150mA solar panel. I would love if someone could explain to me how to incorporate capacitors into this or a battery charging senario.

Thanks,
Blake

Mike Green

A great resource is the Wikipedia. Do a Google search on "Wiki supercapacitor". These are very large value, low voltage (5-6V) electrolytic capacitors that are excellent for this sort of thing. You'll need a diode between the solar panel and the supercapacitor to prevent the supercapacitor from discharging through the solar panel in the absence of sufficient light. You'll also need a resistor and Zener diode in series across the supercapacitor to prevent the solar panel from damaging the supercapacitor when the light level is high enough to produce a voltage in excess of the supercapacitor's maximum voltage. The resistor will load down the solar panel and the Zener will conduct when the voltage exceeds the rated Zener voltage.