Improving the performance of Electric Flyswatters

When I got a electric flyswatter from a friend I remembered some websites back in 2006 describing the modification of these devices in order to increase output voltage. These involved removing two resistors, which improved matters just a wee bit. I decided to take more drastic steps and to use all available space in the handle to hold extra capacitors that would form a tripler circuit. Very simple: 1 kilovolt in, 3 kV out.

This first swatter had a blue handle with a grid of thick wires that would carry the high voltage alternatingly. Once an insect touches the two polarities it gets zapped. The original zapper failed to provide proper results, only the smallest of flies would be killed, the phat shit flies would be stunned but continue their buzzing annoyance a short time later. So I increased the battery voltage. At 5 volts I fried the transistor, so that was out. Then I decided to use a tripler, consisting of four diodes and four capacitors. After some experimentation with power transistors I found a nice one, the 2SD2012. I slipstreamed a few parts in a Farnell order at work so I procured the diodes and capacitors. My junkbox didn't have the capacitors with the required rating, 2 kV. I also didn't have enough diodes, so I settled for the fast RPG02-20. I kludged the parts together and switched on my power supply. I was rewarded with no less than 3.2 kV! Not bad for a Chinese quality product! The quality was so good that the racket started arcing with loud bangs between the wires where they were connected in the frame. I had to pry the thing apart to resolder everything...

Then someone else came to me with another one. This was just plain broken, and I threw it out. Time for some drastic measures! I went to buy ten of the things for only 2 euros each. Good thing I didn't use them first because as it turned out the transistor was driven heavily into conduction due to the decision of the Chinese to use only equal value resistors for the LED and the base of the transistor. The output voltage was a measly 390 V, and a long burst would have killed the transistor. And depleted the batteries. Changing the base resistor to 560 ohms produced an even lower voltage, 250 V. It turned out that the Chinese used two 1N4007 diodes in series, effectively destroying any efficiency at the oscillator frequency of several kilohertz. So I just broke off the part of the PCB and connected my tripler. Bam! With my bench power supply turned up to 3.2 V I almost hit 3 kV! Then rewiring the LED as it didn't line up anymore with its hole in the handle and putting the screws back in and I was done. With fresh batteries output is a healthy 3 kV which drops down to about 2 kV when they are empty.

The results with the grid are no less than impressive! Mosquitos that just have been feasting on my blood and recover on the wall now don't get transformed into a large red stain. Slowly moving the racket towards the pest causes it to fly against the wires and explode! Its legs get stuck to the wires and the body just shoots away! Un-fucking-believable!!! The fat shit flies also don't stand a chance!

Some design remarks: the very first swatter, with a "Vapona" sticker, and the blue noname one both had a grid racket. This means that you can touch the high voltage. In unmodified form it's not that bad, but the souped-up version may be lethal. 3 kV is not something to play with. More recent devices, like the "Catcher" swatter have a cage-like design, which has a mesh grid sandwiched between two grids with larger holes. This means that the high voltage can't be touched anymore so it's a bit safer. Drawback is that fat flies won't fit through the holes, but maybe it works just fine. I haven't tried it yet. The high voltage itself of course remains dangerous. While not immediately deadly it may very well be in a worst case scenario so whatever you do, be careful!

















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