Below is a simple clap switch circuit for electronics amateurs which could turn on & off a bulb, Fan, Radio and so on., through the noise of clap. The sound of clap will be captured by a tiny mic which is indicated through a biasing resistor R1 within the circuit. The mic transforms sound influx into electrical pulses, that is additionally amplified by Q1. Transistor Q1 is employed as common emitter circuit to boost poor signals caught by the mic. Amplified result through the collector of transistor Q1 is fed back to the Bistable Multivibrator circuit generally known as flip-flop circuit.
How Clap Switch Works
Flip flop circuit is built through the use of a couple of Transistor, within our circuit Q2&Q3. Inside a flip-flop circuit, at any given time just one transistor triggers while the other remains cutoff and once it receives a trigger pulse coming from external source subsequently 1st transistor gets switched off and 2nd transistor is activated, therefore output of transistor will either be logic-0 or logic-1 plus it continues to be in a single status 0 or 1 until receives trigger pulse from a clap sound.
The pulse wave from a clap, which is converted as a trigger for the bistable flip-flop tends to make variations towards the output status which is contributory (opposite). End result of flip-flop, which can be in the reduced current state may not be able to push a relay so we employ a current amplifier circuit through the use of Q4 this is a common emitter circuit. The trigger from Q4 is linked to a Relay (Electromagnetic switch) that operates similar to a mechanical switch so it gets to be feasible for hooking up various other electrical equipment.
The relay contact is actually coupled to the mains power line and therefore it switches on/off just about any electrical appliance attached right through this relay.
Simple Clap Switch Part List:-
Resistors
R1=15 KΩ, R5,R6=1.5 KΩ
R2, R11, R12 = 2.2 MΩ, R13=2.2 KΩ
R3 = 270 KΩ, R4=3.3 KΩ
R7, R8 = 10 KΩ, R9, R10 = 27 KΩ
Capacitors
C1 = 1000 µf/16v
C2 = .01µf, C3, C4 = .047µf
Semi Conductors
Q1, Q2, Q3 = BC548
D2, D3, D4 = IN4148
D1, D5 = IN4007, Q4 = BC368
Sundries
T1 = 12v/500mA Transformer
Mic = Condenser Microphone
K1 = 12V Relay, B1= Bulb or Load
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