Clap Switch

Introduction: Clap Switch

Are you tired of getting up just to flip the switch to turn off/no an appliance?,or tired of searching for a switch in the dark?.why not make a clap switch.
What is a Clap switch? A clap -switch circuit is a sound base sensitive circuit, It was invented by R Carlile, Stevens, and E Dale Reamer on 20th February 1996. The operation of the circuit is simple, a Clap and the appliances turns on. Clap again and it turns off. The condenser microphone picks up the sound of your claps or any form of sound produced.
The 555 is a Timer IC, is one of the main component ,It is used in the monostable mode in this circuit , which has only one stable state {Note: we also have astable and bistable modes}. It gets back to its original state when an external clock pulse is given to the monostable oscillator. Similarly, when the 555 timer get an oscillating wave at input (trigger) pin 2, it enters a stable state, and the LED at output pin 3 is used to dictate the output in the form of light..
The condenser mic is another 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.


Components required
>555 Timer IC
>Two BC547 Transistor
>Resistor {1k, 4.7k, 47k, 100ohms, 330ohms}
[ Let R=47k and 100uF=C for calculating the light duration, by applying the formula that will be given later.]
>Capacitor {Two 0.1uF, 100uF}
>Condenser microphone
>9v battery

Step 1:

Get the required components as listed above.

Step 2: NOTE:

Take note of the following while making the connection of the different components.
> The Electret Condenser Microphone [ENM]: this is a type of condenser microphone transducer, the Mic. has polarity ie -ve (negative) and +ve (positive) terminal, at the base of the Mic. the terminal with marks is the ground (-ve) will the plane looking part is the input (+ve).
>The BC547 transistor: it's has polarity show in the diagram.
pin1=collector, pin2=base, pin3= emitter.
>The 555 timer: as mentioned earlier, it is used in the monostable mode. To get the proper numbering of the timer, place the timer with the pointer, dot (cut) facing up. From the the top left, the numbers are 1-4 and from the base right 5-8. The duration of the light can be calculated by applying the formula; T pulse = 1.1 x RxC.

Step 3: Step to Step Guidance:

Connect the electrical components as shown in the circuit diagram.

> Place the collector (pin 1 of the transistor) to the base (pin 2) of the second BC547 transistor and the emitter of the first to the circuit -ve.
> From the base of the first transistor, connect the 4.7k to the -ve of the circuit and the microphone to the direction to the +ve from the same base.
>Connect the emitter (pin3) of the second transistor to the circuits -ve. Note: the emitter of the two transistor are all connected to the -ve of the battery direction.
>From the base of the second transistor connect 1k resistor to the +ve of the circuit, while from the collector of thesame transistor connect 330 ohms to the +ve and from the junction between the collector and the 330 transistor connect 0.1uF to pin 2 of the 555 timer IC.
>Connect pin1of the 555 timer to the -ve the circuit, connect 4 and 8 of the 555 timer together to the +ve side of the circuit, pin 7 and 6 should be connected together, from that Junction connect 47k resistor to the +ve the circuit, from the same junction connect 100uF. From pin5 connect 0.1uF and join the two capacitor {is the 100uF and 0.1uF} to the -ve of the circuit.
> From the pin3 (output of the 555 timer) connect 100 ohms and from the resistor connect the LED, with the larger leg of the LED to the -ve while the shorter to that resistor

Step 4: Possible Trouble Shorting Tips:

1. If the transistor get hot without the LED displaying when you clap, check and make sure the Mic. polarity is connected aright.
2. Or check the polarity of the LED. Note, the longer leg of the LED is the positive terminal, while the shorter is the negative.
3. If it still doesn't work, check your general connection and make sure it is the same with the circuit diagram.
[From Inventive Genius, we wish you the very best of learning and exploit].

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