This circuit is used to exterminate bugs. This circuit needs high voltage but low current to do that. To attract the flying bugs this circuit use lamp. But be careful, these device exterminate all bugs, although that are useful and friendly bugs.
This circuit uses the principle of voltage quadruple which supplies a direct current output voltage which is four times the peak value of the alternating-current input voltage. To prevent damage to circuit, we use R1 and R2 that limiting the current.To exterminate the bigger bugs we use larger capacitor.