ECE Projects!!

FIG. CLAP SWITCH USING 555 A condenser microphone is placed before Q1 and the collector of Q2 has to be connected to the terminal of capacitor C2. Whenever there is loud sound produced near the condenser mic, pin 2 of 555 gets triggered and it switches on the LED D1. We can adjust the sensitivity of the circuit using a variable resistor in place of fixed resistor R5.

Clap switch circuit The operation is simple. Clap and the lamp turns on. Clap again and it turns off. The electret microphone picks up the sound of your claps, coughs, and the sound of that book knocked off the table. It produces a small electrical signal which is amplified by the succeeding transistor stage. Two transistors cross connected as a bistable multivibrator change state at each signal. One of these transistors drives a heavier transistor which controls a lamp.   It works even if you omit that 4.7 Megohm resistor. The transistor types are not critical and any n-p-n silicon transistors should work.