These devices have been around for a while. They're basically a bat/racket/racquet that has an electrified grid that zaps bugs when they pass near it. The units tend to run from two AA cells and have a very simple step-up circuit involving an initial transformer stage and then a short multiplier to charge the main capacitor to a high voltage. When an insect makes contact with two layers of the grid the capacitor discharges through it.
Two things surprised me about this design. the location of the NPN transistor in the transformer circuit and the unusual two section rectifier/multiplier that charges the main capacitor. Particularly unusual is the choice of different capacitor values for the two lower stages of the multiplier. I would guess it might be to optimise efficiency or to keep the cost to the minimum.
The older bats used to have open rows of alternate polarity wires, but the newer ones use a sandwich of three meshes and insulating layers. I would guess it's actually a lot easier to make them this way, and also results in a slightly safer and stronger bat.
The boost circuit isn't really designed for continuous operation, although the switching transistor only reached a temperature of 50C in normal use.
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