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Electric insect zapper (killer)

     Electric insect killer kills flying insects using high-voltage grid. To attract insects to the grid it is using UV lamp.
The electric grid of insect killer is made up of two bare wires. They are wrapped around four plastic columns as in Figure 1. The wires should be glued or melted to the columns. The columns should have cuts to hold the wire in the proper position.
It must generate sufficient voltage to discharge inti insect body when it is approaching the grid. Insect exoskeleton acts as insulation and therefore must be sufficiently high voltage. Some cheap factory binder used voltage 620V DC (2x amplitude of mains), but then sometimes even the insects is crawling on the grid and it does not kill it. Supply at Fig. 2 creates voltage around 1240V (4x amplitude of mains). This voltage reliably kill insects of all sizes.
Insects are attracted to UV light with a wavelength of 365nm. In cheap factory production electric insect zappers there's often only a 25W incandescent UV lamp. It does produce almost no UV radiation (it can't - it's only an incandescent), and practically can not attract insects. Therefore, I have used a 4W UV fluorescent lamp (may be even more powerful) that produces a sufficient amount of radiation at 365nm. To operate this fluorescent lamp you can use either ballast from energy saving lamps (even broken), fluorescent connects to the place where it was connected to the original tube. Thus the "UV Compact fluorescent" is made. It can alse be screwed into the factory insect zapper where originally was the incandescent bulb. Today, you can buy energy saving bulb very cheap, so this seems like a good deal. The second option is to use the classic circuit with conventional magnetic ballast a starter. Both parts are shown in Fig. 3. (Update: now it is possible to buy a UV Compact fluorescent). UV lamp is positioned in the center of grid. The whole device is made so that it prevents the accidental contact with the high voltage grid, either by its position (near the ceiling), or better by using outer protective cage as in factory produced units.
     You may also like the Electric insect zapper (killer) II.

     Warning! There's a dangerous high voltage in the grid. Grid supply is not isolated from the mains. Before handling the device you must disconnect it from the mains and discharge capacitors! Everything you do at your own risk.

Fig. 1 - Homemade bug zapper grid construction.

Fig. 2 - Insect zapper high voltage power supply.

Fig. 3
1) Using the electronic ballast from energy saving bulb to operate the UV tube.
2) Operating the UV fluorescent tube (black light tube) using conventional ballast and starter.