Clap Switch Circuit Using 555

The clap switch circuit is not a new idea for the electronics hobbyist. Previously we had posted a simple clap-operated switch. Now, here is a clap switch circuit using 555, used to control any appliance by clapping five times. We used here decade counter for the right clap code i.e. only the right clap activates the appliance (five claps within the preset time interval of 10 seconds).

Description of Clap Switch Circuit Using 555

The clap switch circuit using 555 is built around timer IC 555, decade counter IC CD 4017, a few transistors, MIC, and a few passive components.

The MIC₁ (condenser microphone) is used here as a sensor, senses the clap sound, and further convert it into an electrical signal. The output electrical signal from MIC₁ is so weak that it needs amplification; this work is done by transistor T₁. The amplified output from the collector of transistor T₁ is given to pin 2 of IC₁ (NE555), configured in monostable mode.

The trigger from the amplifier produces a clock pulse at the output of pin 3 of IC₁. Glowing LED₁ indicates the clock pulse at output pin 3. The output from pin 3 of IC₁ is given to clock pin 14 of decade counter IC₂ (CD4017). Firstly, when the power is given to the clap switch circuit, the output from pin 3 is high and glow LED₂, glowing LED₂ indicates that the switch is ready for use. At this time all other outputs of the clap switch circuits are low. The output from pin 1 is used for activating the appliance via relay RL₂.

At each clock (generated from each clap), the output of IC₂ gets incremented. The output from pin 2 of IC₂ is used to activate IC₃ configured in monostable mode. The output from pin 3 of IC₃ is used to drive relays through a driver circuit build around transistor T₃.

IC₃ acts as a monostable multivibrator (timer) with a period of approximately 10 seconds, which provides a delay time to turn on an appliance even after completing the five claps before the preset time of 10 seconds. The reset pin 15 is connected to contacts of relay RL₁ for the preset time of 10 seconds.

Check out other clap switch and sound operated circuits posted in bestengineeringprojects.com

1. Clap Switch Cum Touch Switch
2. Clap Switch Circuit
3. Sound Operated On-Off Switch
4. Sound Operated Intruder Alarm with Flash
5. Op-Amp 741 Based Sound Operated Light

When all the five claps are applied within 10 seconds, the outputs at pin 1 of IC₂ go high and relay RL₂ is energized to turn on the appliance just after the de-energization of relay RL₁. Table 1 shows the On/Off condition of the appliance for every clap. In the wrong clap code, the high output of IC₂ reset it via its pin 15 and the appliance doesn’t turn on.

TABLE 1

PARTS LIST OF CLAP SWITCH CIRCUIT USING 555