Portable cell charger circuit

If you got a cell phone which you loves, but it don't have enough battery time then this circuit is for you, unfortunately in some 3rd world countries where there is large load shedding this circuit is a must. For making this circuit you dont have to be a circuit genie, its really simple :)

Here is the list of thing you need :

Solder iron (of course :p )
breadboard or vero borad
female nokia or micro usb pin
two way double toggle switch
2x 3.7V betteries (Li-ion)
100uF electrolytic capacitor
330uF electroltyic capacitor
LM2575 regulator IC
1N5819 zener diode
330uH inductor

Now lets get to the point, Here is the circuit diagram,

It uses two li-ion battery, the input is from the cell phone charger pin, the switch is used to toggle between series and parallel connection of batteries, for charging the batteries must be connected in parallel mode, for the operation of the regulator they must be connected in series so that their voltage add up to provide the adequate input for the regulator, the regulator is a switching type regulator which is very power efficient and dont need a heat sink unless you are using it for charging mutilple cell at the same time.