Thanks everyone for replying.
Actually I thought of using a laser as birdman said,the intensity of which will outweigh the ambient light,but as I am not an expert in electronics I want to experiment with new circuits and learn something new.
I like crutschow's idea of enclosin the detector in a tube,but I want to do it by using some electronic circuits(the "electronics way".)
@crutschow. I dont understand what kind of filter you mean to say,can you plz explain
As eric said,i need to apply AC type signal,and at the detector I allow only AC signal to pass through.I can generate the pulse type of signal using 555,the problem is how to make a detector.
Can anyone plz help me in that direction.