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. Two more claps will clock IC3 again
and will turn off Q1 and any device connected to the K1’s contacts. I
had my unit connected to my xmas tree lights so that I wouldn’t have to
crawl behind the tree to turn the lights on and off. Sensitivity for the
circuit is R3 and should be adjusted so that the circuit ignores normal