This circuit can switch two or more devices on and off in response to a series of rapid handclaps. The claps are picked up by an electret microphone and amplified by a 741 op amp (IC1). IC1 is ...

Here is the circuit of a highly sensitive clap switch that can be operated from a distance of up to 10 metres from the microphone. Signals picked up by the microphone are amplified by transistors T1, ...