Hello friends, this post provides you a simple mini project of clap switch. This clap switch mini project is useful for operating electric equipment like fan, bulb, radio etc. by using clap sound. For getting the sound of clap we will use a small microphone in this mini project as shown in clap switch circuit diagram below.
Construction of Clap Switch
We have used a microphone which converts sound wave into an electric signal. This electric signal from the microphone is then amplified by using a transistor Q1 as shown in circuit diagram. Transistor Q1 is used in common emitter mode. The output of transistor i.e. signal from the collector of the transistor is then fed to the flip-flop circuit which is also known as bistable multivibrator circuit.
Transistors Q2 and Q3 are used to make a flip-flop circuit. We know that in a flip-flop circuit only one transistor is conducted and other is in cut off. Now when this second transistor gets a trigger pulse from outside it will be in conduction mode and the first transistor will be cut off. Therefore the output of the flip-flop will be always either 1 or 0.
|Resistor||Capacitor||Semi Conductors||Other Components|
|R1=15KO, R3=270KO, R4=3.3KO R5,R6=1.5KO R7,R8=10KO, R9,R10=27KO R13=2.2KO R2,R11,R12=2.2MO,||C1=1000µf/16v
|Q1,Q2,Q3= BC548D2,D3,D4= IN 4148D1,D5=IN 4007,
|T1=12v/500mA Transformer,Mic= Condenser Microphone,
K1= 12V Relay, B1= Bulb or Load
Working of Clap Switch
Working principle of clap switch circuit is based on the above discussion. In this clap switch, circuit clap is acting as a pulse for the flip-flop circuit. For example, suppose initially output is high (i.e. on state), when clap sound is generated output becomes 0 and the equipment connected to the output of clap switch circuit will be in off state. Thus by generating clap sound, the output get reversed.
The output of flip-flop circuit is unable to drive the relay circuit. Therefore we have to use an amplifier for amplifying the current. To overcome this problem we have used a current amplifier by using a transistor Q4 in common emitter mode. Thus the output of this current amplifier is sufficient to operate the electromagnetic relay which is used to connect the electrical equipment to the clap switch circuit.
The basic use of a relay is that we can connect or disconnect the electrical equipment from the supply. Therefore we have to use a relay in power line as shown in circuit diagram.
Tip: Following figure shows the pin configuration of mic that we are using in our clap switch circuit.
Here terminal ‘b’ is connected to the ground and terminal ‘a’ is connected to the supply through a resistor as shown in circuit diagram.