Hi Are you still talking about our project and your thread got moved?
http://www.electronics-lab.com/projects/power/035/index.html
You don't need a switch if your battery cells are all the same size. Just wire as many battery cell holders in series as the number of cells that you use. The circuit has current regulation so it automatically adjusts its voltage to match the number of battery cells that are being charged, up to its voltage limit.
You don't need to change the voltage regulator to get more current. Just reduce the resistance of the pot. With the pot set to zero ohms, the 10 ohm resistor sets a current of 5V/10= 500mA of charging current. With the pot at max resistance then the total resistance of 110 ohms set a charging current of 5V/110= 45.5mA.
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