This is a sound sensitive circuit, When sound is produced it is changed into electric energy through condenser mic and LED turns on.LED turns on sound signal and turns off automatically after few seconds, the LED on-time can be varied by changing the value of 100mF capacitor.When Capacitor value is changed from 100mF to 10mF the LED on-time is decreased.
When you will by the condenser mic, it will come without wires and you have to solder two wires for either polarity. Below the mic you will see two terminals, the dotted part is -ve and one without any mark is +ve
This was the thing which bothered me for a while
Your Clap should be loud, you can also blow air from your mouth on the electric condenser to turn on LED lolo :p
Its fun !! Enjoy