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Electronic Mosquito Repellent

Updated: May 2, 2020

Components Required:


generate an ultrasound wave whose frequency ranges from 20kHz – 38kHz. Ultrasound waves of these frequencies will help to scare the mosquitoes away.


The working principle of the project is quite simple. As soon as we power ON the circuit by closing the switch the 555 timer IC is turned ON. As the capacitor (C1) is initially uncharged hence it’s voltage is zero and the trigger pin of the 555 timers is also zero. The resistors Ra and Rb are responsible for charging the capacitor (C1). The voltage at the trigger pin is less than the capacitor voltage hence it causes a change in timer output. When the supply is turned ON the capacitor (C1) starts discharging through R(B). This process continues until the voltage comes back to the original state. This results in an output signal that is 38kHz. The resultant signal is sent to the piezo buzzer which will be used to generate the ultrasound wave that will scare away the mosquitoes. The output frequency can also be varied by using the potentiometer present in the circuit.


There are some applications of this circuit. Two of them are listed below:

  1. If this circuit is modified, by generating a signal of a specific signal, it can be used to repel other insects too.

  2. This circuit can be used as a simple buzzer alarm circuit.


Although this circuit is simple and works good but still it has some limitations. Some of its limitations are given below:

  1. This circuit will work efficiently if the population of mosquitos is not very large.

  2. A lot of frequency settings are required to tune it to give the maximum output.

  3. Ultrasound signals, when leaving the source, take a path that is 45 degrees to the source. So, if there is any obstacle in the way of these signals, they will divert their path.

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