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Help with Solar USB charger Answered


I'm a bit of an electronics noob, trying to build a solar charger for my brother's phone when he goes camping. I've done some research on the net and built a prototype but for some reason it won't charge my phone through the USB.

My circuit diagram is below. The only thing that needs more detail is the USB charging circuit, which is this one:

Is my wiring setup correct? It may just be that the charging circuit is insufficient and will need to be replaced, but I would appreciate some advice before I go further.




5 years ago

Thanks for the help.

Josehf Murchison

5 years ago

No it is not set up right.

Assuming you are using a LM7805 voltage regulator you need 7 to 35 volts you only have 6 volts.

You need one more solar cell to bring it up to 9 volts and batteries.

And if your drawing is correct you need at least a 1 uF electrolytic capacitor on the input of the regulator to GND and one on the output to GND of the voltage regulator. Something like this circuit.

Remote C 3a.bmp

5 years ago

Keep in mind many smart phones will look for a voltage on the data lines of the USB connection before it will allow the unit to charge. Also you'll need a charge controller between the panels and the rechargeable batteries.