A very simple portable solar charger electronic project can be designed like in this schematic circuit , using some common electronic parts .
As you can see in circuit diagram , this portable solar charger circuit , is based on a LM358N operational amplifier and one transistor . This regulator provide a constant 2.4 volts DC and can be used for powering small devices that needs to be powered from two AA battery cells .Because the regulator has a low drop down voltage of 0.3 volt you should take care about this when you choose solar cells . Maximum load current for this solar charger electronic circuit project is around 125mA typically , enough for small portable devices like radios .
This circuit will provide a fixed output voltage and don’t require any other adjustment .