Constructing a Clap Switch Circuit using 555 IC and Relay

The clap switch circuit is a fascinating and basic electronic project that allows you to control 220V AC appliances using sound.

In this article, we will guide you through the construction details of a clap switch circuit using a 555 IC and Relay

What is a Clap Switch Circuit using 555 IC and Relay:

A clap switch circuit using a 555 IC and a relay is an electronic circuit that allows you to control a device or load by clapping your hands.

This type of circuit is based on the principle of sound detection, and the 555 timer IC is used as a monostable multivibrator to trigger the operation of a relay, which in turn controls the connected load.

Components Required:

The NE555 IC

The heart of this circuit is the NE 555 IC, which serves as an astable multivibrator.

The NE 555 has an oscillation frequency that typically ranges from 670 to 680 Hz.

In this configuration, it acts as a monostable multivibrator, also known as a one shot multivibrator.

This circuit generates a pulse, and the pulse duration is determined by the external R-C (Resistor-Capacitor) network connected to the 555 IC.

Formulas:

Formula for Pulse Width T:

T = 1.1 × R1 × C1

where:

• T is the pulse width in seconds.
• R1 is the resistance in ohms.
• C1 is the capacitance in farads.

Construction details:

Now, let us go through the construction of the Clap Switch Circuit:

• Connect the condenser microphone to the input of the circuit.
• The mic will pick up sound and convert it from sound energy to electrical energy.
• Connect a transistor to the output of the microphone.
• When sound is detected, it raises the potential at the base of the transistor, turning Q1 ON.
• Connect the output of the transistor to the TRIG pin 2 of the NE 555 IC.
• When the transistor turns ON, the potential at TRIG pin 2 becomes low (below Vcc/3), triggering the 555 IC.
• Connect an LED to the output PIN3 of the 555 IC.
• When the TRIG pin 2 goes low, the output at pin 3 becomes high, and a positive clock pulse is applied to the internal flip flops causing the LED to turn ON.

Circuit Diagram

Working Explanation

When you produce a sound near the condenser mic, it converts the sound into electrical energy, which, in turn, raises the potential at the base of transistor Q1, turning it ON.

As the transistor turns ON the potential at TRIG Pin 2 of the 555 IC becomes low triggering the IC.

The output at pin 3 becomes high, and a clock pulse is applied, making the LED turn ON.

The SET state of the flip flop will remain until the next clock pulse.

Advantages and Disadvantages

Advantages:

• Simple and cost effective circuit.
• Can be used to control various appliances.
• No physical switch required.

Disadvantages:

• Sensitive to background noise.
• Limited range for sound detection.

Clap Switch with Relay for Operating 220V Appliances

If you want to operate 220V appliances with clap sound then you can use the following circuits which uses a relay for switching all 220V loads.

Applications

The Clap Switch circuit is not limited to turning LEDs ON and OFF.

It can be applied in various electric appliances such as fans, radios or any other basic circuits that you want to activate using sound.

Conclusion

In conclusion, constructing a Clap Switch Circuit using a 555 IC is a fun and educational project that demonstrates the conversion of sound energy into electrical energy.

With its simple components and working principle, it opens the door to creative applications in home automation and electronics projects.

References:

Clap Switch Controller

CLAP SWITCH A mini project report