What is a Clap Switch : Circuit Diagram & Its Working

An electronic device that can control light appliances by users clap action is a clap switch. It was invented by R Carlile, Stevens, and E Dale Reamer on 20th February 1996. The main advantage of this technology is that it is mainly helpful for a mobility-impaired person. The condenser mic is one of the main components in the circuit that tracks the input clap sound based on the pitch of clap and transduces this sound energy into some electric pulses. These electric pulses are the desired input to the clap switch circuit. This article gives an overview of the clap switch.

What is Clap Switch?

Definition: A clap switch is an electronic circuit, which controls electrical appliances like a bulb, tube lights, etc with user clapping action. It is mainly useful for a person who cannot move his legs.  The clap switch circuit can be designed in two ways using  555 IC and without using a 555IC.

Required Components

The main components of the circuit are

• 555 IC – IC 1
• CD 4017 IC – IC2
• Relay -r1: A relay is a switching device, which is used to switch the circuit on when required and turn off whenever required.
• Resistors – 100 Ω (R1), 560 Ω (R2), 4.6 KΩ (R3), 18 KΩ *3 (R4), 33 KΩ (R5): A resistor is an electronic component which opposes the flow of current or prevents excess leakage of current in the circuit when required.
• Capacitors – 0.1 µF * 2 (C1), 4.7 µF(C2): A capacitor is a passive component that stores a small amount of charge.
• Microphone – M1: A microphone is similar to an amplifier.
• BC 547 – T2
• Diode 1N4004 -d1: A diode is an electronic component that acts similarly to a regulator or a switch.
• Light Emitting Diode – d2: An LED is used to radiate light when it is power supplied

Clap Switch Circuit Diagram

The entire function of the clap switch is based on CD 4017 IC and NE 555 IC.

IC 555 is a Timer IC

It is similar to an oscillator like monostable, which has only one stable state. It gets back to its original state when an external clock pulse is given to a monostable oscillator. Similarly, when 555 timer generates an oscillating wave at output pin 3 it enters a stable state, in order to get back to its normal an external trigger is applied.

CD 4017

It is a CMOS divider or a counter IC. On receiving an external clock signal it turns ON (say all together 10 lights) all the lights in a sequential manner. It consists of input pins 3 in number and output pins 10 in number and a GND – ground pin as shown below

Input Pins

The followings are the input pins used in 4017 decad counter ic

• Reset (P 15): This pin helps to reset the position back to zero. Suppose if you want the counter to count till 3, after the 3rd signal the reset pin goes back to zero.
• Clock pin ( P 14): It is an input clock signal pin that goes high when the circuit is in the working stage.
• Clock Inhibit Pin (Pin 13): This pin controls the counter pin by turning it ON and OFF. When Pin13 is set high it means counter if turned off, and when pin13 is set low it means the counter is turned on.

Output Pins

The followings are the output pins used in 4017 decad counter ic

• Output Pins (0 to 9): These pins process the task sequentially and provide an output at pin3 (let us assume we are using only pin 3 out pf 10 output pins).
• Carry Out Pin ( Pin 12): The connect many CD4017 IC together.

Clap Switch Working

Assume a human standing closer to the mic and clapping. This mic takes the sound energy and converts it into an electrical signal and gives this input to the clap switch circuit at transistor T2. This signal in return triggers IC1 ( 555 Timer) pin2. We can theoretically calculate the output clock signal status using the following formula

T = 1.1 * R 5* C 4

The output which is a clock signal from IC1 (pin3) is given as input to CD 4017 IC (pin 14). Now CD 4017 IC starts counting from “0” until pin 14 goes high. On receiving input signal on the first clap, Q1 gets activated, LED 1 (d1) starts glowing. The switch circuit is controlled by a relay and the output is obtained from pin2. Similarly, on receiving another clap, pin4 gets activated and LED2(d2) if connected glows and LED1 stops glowing, likewise, this process continues.

Advantages

The following are the advantages of clap switch

• Automatically controls lights within a specified range by clapping action
• It is an advantageous technology for mobility-impaired person
• Reliable
• Cost is low
• It provides good output efficiency.

Disadvantages

The following are the disadvantages of clap switch

• It is cumbersome compared to traditional control switch
• The filter should be added in the circuit compulsorily for working.

Applications

The following are the applications of clap switch

• Air conditions
• Tv
• Motor, etc.

FAQs

1). Who invented the clap switch?

R Carlile, Stevens, and E Dale Reamer invented a clap switch on 20th Feb 1996.

2). What is a clap off and clap on?

It is a concept which controls (turns on or off) the light or electronic appliances by clapping action.

3). Name two main applications of Clap Switch?

The two main applications are

• Fans
• Light.

4). Why is it called a 555 timer?

It is similar to oscillator like monostable, which has only one stable state. It gets back to its original state when an external clock pulse is given to a monostable oscillator. Similarly, when 555 timer generates an oscillating wave at output pin 3 it enters a stable state, in order to get back to its normal an external trigger is applied.

5). Is the Clapper a fire hazard?

No, the Clapper is not a fire hazard

6). What is the principle of a clap switch?

Clap switch converts sound energy into electrical pulses and uses these electrical pulses as input to the circuit and provides an output in order to control light appliances.

7). Define a switch?

A switch is an electronic device that is used to connect or disconnect the power supply to the circuit.

A clap switch is an electronic device that works based on clapping action, it converts sound energy into electrical pulses and proved these electrical pulses as input to the control circuit for controlling the light appliances. The main advantage of this technology is that it is very much helpful for a mobility-impaired person. 555 IC and CD4017 IC are two main components of this circuit.