There are these types of mosquito killer racket are easily available in market at some 150 rupees.
This consist an electric fence in the bat portion which has 5000-10,000 volts passing through them. This is not only mosquito repellent, it’s insect zapper. When a mosquito gets in contact the high voltage burns it. The inner circuit consists of battery, a charging unit, and a HV inverter circuit, which I’m going to describe here.
Coil turns will be as described in text and not the one indicated in this tmage.
The circuit consists of a flyback topology transformer driven by a general NPN transistor 2SD965. The feedback coil of transformer is of 10 turns, the primary is of 40 turns and the output or secondary coil is of 450 turns. When this circuit is run by 3Volts, the transformer generates about 2000-4000 volts at zero load, and the output is then coupled 3 times by using 3 IN4007 diodes and suitable capacitors, thus reaching our need of 5000-10,000 volts.
Note: All diodes used in circuit are IN4007 diode, The transistor is 2SD965, and can’t be replaced by BC548, The transformer should be ferrite core.
Below an actual circuit board found in mosquito zapper rackets.