Mosquitoes are found all throughout the planet and pose a serious threat to humanity. Eliminating these "devils" by electricity would be a wonderful method to exact revenge. This is the purpose of a mosquito swatter bat. Let's study the construction of its electronic circuit. Mr. Max Tunnel requested the concept.
Mosquitoes Are Tough to Get Rid Of
Even though they are really small mosquitoes can multiply like crazy, and no matter how hard we try to get rid of them, they just keep coming back in huge numbers.
Today, there are tons of products available to help us deal with these annoying bugs. You can find everything from sprays to coils and mats that you have to light up. Most of these solutions use chemicals that either scare away or kill mosquitoes because they are toxic.
It's important to remember that if these chemicals can hurt insects, they might not be great for humans either, even if the effects are smaller. Over time using these chemicals could lead to some serious health issues.
Using a Swatter Bat to Fight Mosquitoes
On a cooler note, there's a way to zap mosquitoes using electricity, which means you don’t have to use any chemicals, and it’s a clean way to deal with them.
The electric swatter looks like a tennis racket, making it fun to swat at these pesky bugs and get back at them.
The mosquito zapper is shown in the diagram, and heres how it works:
The setup uses a blocking oscillator similar to what you find in joule thief circuits where a single transistor and a center-tapped transformer work together to create steady oscillations in the two parts of the transformer.
Circuit Working
The way the circuit works is mainly affected by how R1, the preset, and C1 interact which together control the oscillation frequency. R1 is really important because it helps keep the transistor within safe limits while you adjust the preset.
In this setup, TR1 is shown as a small ferrite core transformer made using the tiniest EE type ferrite core that you can find.
The coil is carefully wound to work with a 3V DC power supply making it suitable for a 3V battery pack that you can easily create by connecting two AAA batteries in series.
When you turn on the power to the circuit, both the transistor and the center-tapped transformer start oscillating at a high frequency almost right away. This oscillation allows the battery current to flow through the winding of TR1 in a push-pull manner.
This quick switching creates a high voltage across the secondary winding of TR1, which, based on the winding design, could reach about 200V.
To boost this voltage even more so it can create a flying spark, a charge pump circuit using a Cockcroft-Walton ladder network is added at the output of TR1.
This clever network raises the voltage from the transformer to around 600V.
The increased high voltage is then converted and sent through a bridge rectifier, where it gets properly rectified and boosted by a 2uF/1KV capacitor.
As long as the output terminals across the 2uF capacitor are kept apart by a certain distance, the high voltage energy stored in the capacitor stays inactive and doesnt discharge, keeping it ready for use.
When the terminals are positioned at a relatively short distance from one another, approximately a few millimeters apart, the potential energy stored in the 2uF capacitor becomes sufficiently potent to overcome the air gap, resulting in an arc that manifests as a fleeting spark traversing the space between the terminals.
This phenomenon occurs momentarily, ceasing until the capacitor has fully recharged, at which point it is capable of producing yet another spark. This process continues in a repetitive cycle, provided that the distance between the terminals remains within the threshold that allows for high-voltage saturation.
In the context of a mosquito swatter the terminals of the 2uF capacitor are strategically connected to the internal and external layers of the metal mesh that constitutes the bat.
These metal meshes are intricately woven and securely positioned over a robust plastic frame ensuring that they are maintained at a certain distance apart. This specific spacing is crucial as it prevents the high-voltage spark from arcing across the meshes while the device is in a standby state.
However, the moment the swatter is brought down upon a fly or mosquito, the insect effectively bridges the gap between the mesh layers, thereby providing a pathway for the high voltage to flow through it.
This interaction produces a sharp crackling sound and a visible spark as the electrical current passes through the insect resulting in its instantaneous demise.
Making the Ferrite Core Transformer
The diagram for the mosquito zapper explained here includes a small transformerless charging circuit. This circuit can connect to the main power supply, which helps charge a 3V rechargeable battery. This is especially helpful when the battery stops generating enough voltage to zap mosquitoes effectively.
You can find details about the winding specifications for TR1 in the next image.
Core: EE19/8/5
Commercial Circuit for Mosquito Zappers
The construction specifications of a high voltage generating circuit, which is typically found inside all commercial or Chinese mosquito zapper or mosquito racket devices, are covered in the part that follows.
How the circuit for this electric mosquito racket operates
I chose to share the story here since I thought it was easy to read and rather intriguing. It was first posted on one of the Chinese electronic sites.
The high-frequency oscillator, which is made up of the transistor VT1 and the step-up transformer T, is activated using the 3V DC supply when the power switch SA is pressed. This results in a high-frequency alternating current of around 18 kHz, which is increased by T to roughly 500V.
Then, a ladder network consisting of three 1N4007 diodes and capacitors C1–C3 is used to further increase this high voltage, which ranges at 500V.
A high voltage PPC capacitor at the very end of the ladder network stores the approximately 1500V that is obtained by stepping the T output to around three times its initial value.
After then, the stepped-up 1500V is connected to the mosquito racket net, which is now equipped with this high voltage. Any mosquito that attempts to pass through the racket net is immediately electrocuted by the high voltage discharge from the PPC capacitor.
The overall layout incorporates an LED, which is used to show the circuits' ON and OFF states as well as the battery's remaining power. The LED's brightness is controlled by the series resistor R1, which may be adjusted to suit personal preferences and extend battery life.
Selection of components
The 2N5609, an NPN BJT with a current carrying capability of about 1 amp, is the oscillator transistor employed in this Chinese mosquito zapper circuit; nevertheless other comparable models, which include the 8050, 2N2222, D880, etc., may be tested as well in place of what was originally used in the schematic.
The diodes can be of the 1N4007 kind, although a rapid recovery would be more effective, consequently you can also try swapping them out for BA159 or FR107 type fast diodes. The LED may be any 3mm small 20mA type of LED. Resistors with a 1/8 watt rating or even a ¼ watt rating can be utilized without any problems.
Only PPC kinds with a minimum rating of 630V are permitted for the capacitors.
The High Voltage Transformer Construction Process
Should it be possible 2E19 type ferrite cores and the corresponding plastic bobbin are used in its construction.
L1 is made up of around 22 rounds of φ0.22mm enameled copper or magnet wire.
L2 is similarly coiled with approximately 8 rounds of φ0.22mm enameled copper wire or magnet wire.
Lastly, L3, the secondary winding, contains about 1400 turns and is made of enameled copper wire with a φ0.08mm diameter.
The mosquito bat circuit mentioned above may additionally be employed to electrify different types of insects using another appropriate configuration. For instance, this design might be used with a mesh covering a dish that contains insect or mosquito bait, and this could draw mosquitoes.
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