This is a simple Ni-Cad battery charger circuit with Led indicator. it's not a automatic charger but when the battery is fully charged the led glows and you have to turn off it manually. use a 3mm red led and for power supply use a 9v transformer. I have build this circuit and it's working great without any problem.
parts you need :
Led 3mm ( Red) you can use any color you like but red is better because it grabs Attraction