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uses solar panel and rechargeable batteries to charge iphone 4s
will have toggle switch between recharge and discharge batteries for continuous use of batteries to charge phone. Iphone requires 5V as well as a 2.2V identification pin. Current is maxed at 1.0 A and 5 W for a standard charger. Must use voltage regulator to protect circuit. A rectifier diode must be used in series with the positive terminal of the solar panel to avoid and back emf, which could either damage the solar panel or drain the batteries when not in use. This ensures that the panel is only adding charge to the batteries over time. A SPDT switch will be used to toggle between charging and recharging modes. A status led will indicate whether you are charging or charging. Four rechargeable AA batteries will be used to supply adequate voltage and current to the circuit. Each battery is rated at 1.2 V and 2000mAh.
Note: Account for voltage drop of about 0.7 V in rectifier diode.