Micheal karas ,can you please explain how the ciruit works

Anil,
Get a book on basic electronics, read it and come back. Michales circuit is so elementary that your question indicates that you desperately need to get a grip on the basics. This is a forum for questions on specific problems not electronics 101 class. By the way, also learn something about being specific, your question, throughout, has been so vague that the only answer possible is, I quote again, "that depends"

Erik