Hand Clap Electronic Control

We have all seen the commercial on TV .......... CLAP - ON - CLAP - OFF - THE - CLAPPER ............ well here is a circuit that will perform that same function.

Circuit operation is as follows. A single hand clap will be picked up by the electric mic which is coupled through C1 into the op amp IC1. The output of IC1 triggers the 555 IC timer IC2 which is configured as a monostable multivibrater. The trigger pulse is stretched by IC2 and outputs a pulse to IC3 a D type flip flop. Because of the three state counter arrangement of IC3, two sharp claps are required before IC3 will output a high to Q1 which will turn on K1 relay and any device connected to K1's switch contacts. ....

Link : Hand Clap Electronic Control