Nowadays sound operated switches becomes very common in our modern life. Here is a simple and inexpensive design of clap operated switch, which is very easy to assemble by hobbyists at any level. With this circuit, the device switches on by first clap and it switches off by the next clap. The circuit is designed using four transistors and a very few number of components. About the Circuit: The sound signals generated by making a clap are received by condenser microphone, shown in the circuit diagram. Microphone converts these sound signals into equivalent electrical signals. These signals are amplified by transistors Q1, Q2 and Q3. The amplified signal is given to driver transistor Q4. During the first clap, Q4 turns on and relay connected to the collector of Q1 gets energised. On next clap, Q4 turns off and relay goes off. Again when the next clap comes, the procedure repeats as above.C1,C2 & C3 are coupling capacitors. D6 LED indicate the realy is on condition.

Nowadays sound operated switches becomes very common in our modern life. Here is a simple and inexpensive design of clap operated switch, which is very easy to assemble by hobbyists at any level. With this circuit, the device switches on by first clap and it switches off by the next clap. The circuit is designed using four transistors and a very few number of components. About the Circuit: The sound signals generated by making a clap are received by condenser microphone, shown in the circuit diagram. Microphone converts these sound signals into equivalent electrical signals. These signals are amplified by transistors Q1, Q2 and Q3. The amplified signal is given to driver transistor Q4. During the first clap, Q4 turns on and relay connected to the collector of Q1 gets energised. On next clap, Q4 turns off and relay goes off. Again when the next clap comes, the procedure repeats as above.C1,C2 & C3 are coupling capacitors. D6 LED indicate the realy is on condition.