Thanks a lot shirazmacuff for the nice explanation.
I am looking into this currently and try to tweak it a little. Just a confusion. In your circuit diagram where are you connection the positve end of your battery ? In all the circuits I have read on the internet, while using npn transistor we connect the positive of the battery to the base. But you have connected -ve. Will it actualy work ? I will try when I go home.....
Also is it possible for you to post the exact values of resistors and the transistor which you are using. I am only askign so that I can verify it against my calculations. Or let me know which transistor to use and I will try calculating the values of resistors and get it verified with you.