construction of insect repellant circuit

ALL IN ONE REPELLENT CIRCUIT :Insects, mosquito, lizards and dog

10:23 pm Posted by Tittu Thomas


Now i am going to introduce you an All in one Repellent circuit.
Ya i mean it, by using this circuit you can keep nasty insects, Mosquitoes, lizards, and dogs away.

Lets look the PRINCIPLE of this circuit:-

This circuit works under the Principle of Ultrasonics. As you may know, we can’t hear Ultrasonic sounds but animals or insects like Mosquitoes, bees, lizards and even dog can hear Ultrasonic sounds well.

How this repellent circuit keeps Insects, lizards, Mosquitos and Dogs away?

As i mentioned above, they can hear Ultrasonic sonic sound well at a particular Frequency range. Above that, they may get IRRITATED continuously. That’s how this repellent circuit works.

all in one repellent circuit

The ALL in one REPELLENT CIRCUIT mainly consisting of a 555 timer, Frequency determining network, and a buzzer.

The 555(NE555) timer is wired here as an ASTABLE MULTIVIBRATOR, which will generate Square waves continuously upon the power supply of 12V.

The output Voltage from pin3 of NE555 is given directly to a Buzzer by a COUPLING capacitor C2.

The Frequency determining Network is one of the Important part of this all in one repellent circuit. It consists of two Resistors R1, R2 and a capacitor C.
They determines the Frequency of the circuit.

Each our prey’s (Mosquitoes, Lizards, Insects and Dog) requires separate Frequencies to get REPELLED. So we have to tune this Frequency Network. The tuning is made possible by selecting a Variable Resistor R1, R2, and C

By giving the supply Voltage of 12V the Buzzer will vibrate at the predetermined Frequency (By Frequency determining Network)
You can Try our Frequency Determining Tool to calculate the Frequency:-


Here is the list of components required to wire up this CIRCUIT.

IC1 – NE555

C1 – 0.01μF

C2 –
12V Battery

*The value of R1, R2 and C is not listed Because it is different for Each REPELLENTS.

Value of R1, R2 and C.

For repelling Mosquitoes:-

R1 – 10K
R2 – 10K
C – 1nF

For Repelling Lizards

R1 – 1K
R2 – 20K
C – 1nF

For Repelling Dogs

R1 – 10K
R2 – 1K
C – 1nF

Why I can’t Hear the Output of all in one repellent circuit?

You can’t hear the output of this circuit. Because the output generated from Buzzer is in the Frequency range of Ultrasonic. Ultrasonic sounds are situated far away from the audible sounds in Frequency chart. That is why we can’t hear it.

How to check the output, whether all in one REPELLENT circuit works?

It is pretty easy to check the output of this circuit, you can use an LED or a multimeter to check whether their is any output Voltage at pin3 of NE555.



Here is the circuit diagram of an ultrasonic mosquito repeller.The circuit is based on the theory that insects like mosquito can be repelled by using sound frequencies in the ultrasonic (above 20KHz) range.The circuit is nothing but a PLL IC CMOS 4047 wired as an oscillator working at 22KHz.A complementary symmetry amplifier consisting of four transistor is used to amplify the sound.The piezo buzzer converts the output of amplifier to ultrasonic sound that can be heard by the insects.

Circuit diagram with Parts list.



32 thoughts on “construction of insect repellant circuit

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