Mosquitos are annoying especially while sleeping so most people use chemicals because the chemicals are high efficiency. But using often chemicals no good for everyone. This project “Mosquito Repellent Circuit using 555 Timer” generates a high-frequency sound ( 20 kHz to 40kHz ) wave that mosquitoes do not like. According to the theory of scientists found that Mosquitoes do not like high-frequency sound waves. So, it flies away because this sound interferes with its flying.
This electronic mosquito repellent circuit is easy to build but is kind of hard to adjust on the exact sound frequency which will repel the mosquitoes.
The heart of this circuit is a NE555 Timer IC. The IC possesses an oscillation frequency ranging from 670 to 680 Hz. Here, this NE555 timer acts as an astable multivibrator An astable multivibrator is a free-running oscillator that switches continuously between its two unstable states. With no external signal applied, the transistors alternately switch from cutoff to saturation state at a frequency that RC time constants of the coupling circuit determine. If these time constants are equal (R and C are equal) then a square wave will generate with a frequency of 1/1.4 RxC. Hence, an astable multivibrator is also a pulse generator or a square wave generator.
Hardware Components
The following components are required to make Mosquito Repellent Circuit.
| S. No | Components | Value | Qty |
|---|---|---|---|
| 1. | Resistor | 1K | 1 |
| 2. | IC | NE555 Timer | 1 |
| 3. | Piezo Buzzer | 1 | |
| 4. | Ceramic Capacitor | 0.1uF | 1 |
| 5. | Variable Resistor | 10k | 1 |
| 6. | 9v Battery | 1 |
555 Timer IC Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 555 Timer IC
Mosquito Repellent Circuit
Working Explanation
In this circuit, we are using a timer IC in A-stable mode in order to produce frequencies at 40KHz. We have connected Buzzer at the output (PIN 3) of the 555 timer IC so that a sound of desired frequency can be generated. Here, we need a high-frequency Piezo buzzer, so that a high-frequency sound can be generated. You will not be able to hear the sound generated by the circuit as it is beyond the audible range.
We can calculate the value of resistors and capacitors to produce oscillation of 40KHz frequency by given formulae:
F = 1.44 / ((R1+R2*2)*C)
Applications
- It can be used in any kind of setup such as homes, offices & hospitals to protect people from ailments related to mosquito bites.
