Mosquito Repeller

We usually get irritated when mosquito bite.When mosquito bites we also get fever at sometimes.We cannot do our work with concentration ,in a place where mosquito are present.This mosquito repeller will make your home and work place mosquito free environment.

Step 1: Components Required

IC

• IC 555

Resistor

• 820Ω
• 1.5KΩ

IC BASE

• 8 Pin IC Base

Capacitor

• 0.01μF
• 0.1μF

BUZZER

• Buzzer

PCB

• General Purpose PCB

Connectors

• 2 Pin screw terminal---------2

Power Supply

• 5V Charger Board from MOBILE Charger and you can use any type of charger board

Step 2: Materials Required

Calling Bell Box

I had taken my home calling bell box which was not in working condition.So,i choose to enclose the Mosquito Repeller circuit with this calling bell box.

Step 3: Principle Behind Mosquito Repellent Circuit

Human beings can hear sound in the range of 20 Hz to 20 kHz. Sound of any frequency above 20 kHz is termed as ultrasonic sound. Several animals like cats, dogs, insects, mosquitoes have the feature of being able to hear this ultrasonic sound. In mosquitoes, this feature is attributed to the presence of sensory structures in their antennae. Usually ultrasound is transmitted by male mosquitoes and received by female mosquitoes. However after breeding, female mosquitoes generally avoid the ultrasound and this fact can be used to produce ultrasound in a range similar to that produced by male mosquitoes and repel away the mosquitoes. The ultrasound produces a stress on the antennae of the mosquitoes and repels them away.

In other words, a simple circuit is designed which can produce ultrasound in the frequency range of 36 kHz, which can scare away mosquitoes.

Step 4: Schematic Diagram

Step 5: Designing the 555 Oscillator

The basic idea behind developing the circuit is to use a buzzer to produce ultrasound. The buzzer is driven by an oscillator circuit. Here, we are using a 555 Timer based astable multivibrator circuit as the oscillator circuit.

Designing the circuit involves designing an astable multivibrator circuit. Generally, frequency of output signal produced by a 555 astable multivibrator is given by:
F = 1.44((Ra+Rb*2)*C)

Here Ra is the value of resistor between pin 7 and Vcc, Rb is value of resistor between pins 7 and 6 and C is value of capacitor between pin 6 and ground.

Let C = 0.01 microFarad

F = 36 kHz

Let Duty Cycle, D = 60% (It is not possible to get 555 timers to produce signal with 50% duty cycle.

Formula to Calculate Ra and Rb Resistors

Ra = 1.44(2D-1)/(F*C)

And Rb=1.44(1-D)/(F*C)

Substituting values of C, F and D, we get

Ra = 0.818 K Ohms, i.e. 818Ohms and Rb=1.52KOhms

Thus, we can use a resistor of 820Ohms and another resistor of 1.5 K.

The another capacitor at 5th terminal of IC555 is used to terminate the 5th terminal.Because in order to avoid any noise in frequency and also we need not use 5th terminal of IC555 so,we generally connect this terminal to ground with 0.1uF capacitor.

Step 6: Frequency Testing

Testing the output frequency of IC555.The Frequency is 36 KHz,you can see in the above picture.

Step 7: Assembling the Oscillator Circuit in a PCB

I had soldered the Mosquito Repeller circuit in a General Purpose PCB according to the schematic diagram

Step 8: Assembling the Mosquito Repeller

Step 9: And Finally

I had finished assembling the mosquito repeller and i plug into 230V AC socket.Now it is ready to work.Enjoy the mosquito free environment.

Comments

[sanjumajisujay1998]

Please tell me the voltage of the capacitor...........

[annpalaya]

can i add a fuse?

[Rajkumar2506]

Probably you don't need it.If you wish to protect the circuit from high voltage you can add it.But the fuse need to have a proper rating.

[igggy17]

did it, but not working

how to test output?

[Rajkumar2506]

You can't hear that sound of mosquito repeller because the sound is in ultrasonic range.But you can test the output.To test it disconnect the buzzer,take a multimeter.Turn it in AC voltage measurement.Keep the probes of multimeter at the output that is,the two point terminals where the buzzer is connected.If it shows the reading of AC voltage,your circuit is working.You can also test it in another way.Take a frequency meter.Connect the probes of frequency meter in the output of circuit.If the frequency is above than 20Khz.Your mosquito repeller will work.It will take some days to show its effect on mosquito.You can notice the difference in day by day.

[igggy17]

I know that I can't hear this sound :-)

Have very small AC output 0,1. Is it OK?

[Rajkumar2506]

Yes it is ok.Since the IC555 is generating AC signal.The AC signal generated will be a square wave.So the square wave is a digital signal.The digital signal will have amplitude 1's and 0's.It is to be taken as,1 is equal to 5V and 0 is equal to Ground, that is 0V.If you want to extend the effect of mosquito repeller till some coverage distance.You can increase the output voltage of IC555.It can be done by as follows

IC 555 has maximum supply voltage till 15V.You can use 12V power supply instead of 5V supply.By doing this,will increase the output voltage of IC 555.

[igggy17]

I found a mistake. 3th pin of ic555 was not connect. I fixed it, but now I can hear it. Strong sound. Even neighbors can hear it :)))

Not good frequency.

[Rajkumar2506]

You might have used incorrect resistor and capacitor values.See the schematic diagram for values of components used.you should use buzzer.Did you opened up digital watch ever.You will find a buzzer if you opened it.The buzzer will be like a round plate.This type of buzzer you should use.

[igggy17]

I used this

resistors and capacitors are ok

[Rajkumar2506]

You had used 5 Band resistor.Use 4 band resistor.

[igggy17]

4 or 5 band

what is the difference?

value are 1.5 kohm and 820 ohm

[Rajkumar2506]

Did you used 0.01μF capacitor at 2nd terminal?

[igggy17]

need help

where this go?

[Rajkumar2506]

This jumper wire connects 8th and 4th pin of IC 555

[rafununu]

This is supposed to imit males flying noise and reppels females already gravid (pregnant) that got what they wanted and that's enough, too much is too much.

[Rajkumar2506]

What do you mean by too much is too much.I can't understand what you are saying.Can you say it again clearly.

[dzehner2]

So does this work only on female mosquitoes or does it work on males too? Very intriguing!

[Rajkumar2506]

you need not care about male mosquito,because female mosquito only bites.

[nemob]

too bad this doesn't work