We face a lot of problems everyday to charge our mobile phone batteries. Here is a simple and effective way to charge your mobile phone batteries with a 9v Battery. You can check the status of the battery pressing a switch which can show when to change the batteries.
The circuit diagram for the ±5V supply from a 9V battery is built around a 9V battery, voltage regulator IC 78L05, CMOS voltage converter ICL7660 and a few other components. Voltage regulator IC 78L05 converts 9V battery input into regulated 5V. This 5V output from IC 78L05 is given to pin 8 of ICL7660. ICL7660 and capacitors 10u and 10u form the voltage inverter section that converts +5V to -5V. Converted -5V supply is available at pin 5 of ICL7660. Converted ±5V supply is thus available at connector DC-DC Boost Convertor. You can Charge mobile with the DC-DC Boost Convertor.
Battery status indicator is built around two transistors BC 547. It is simple to understand. If the battery voltage is 6.9 volt or lower, RED Led gets on. If the battery voltage is greater than 6.9volt, Green LED gets the power. Switch is given for low battery consumption.
This way you can charge your mobile batteries with this circuit.