mosquitos coming to you. It uses IC CD4047 to control the buzzer timing utilizing resistor and capacitor. When the voltage passing through the transistor, the buzzer would sound.
Variable resistor R1 : 10K ohm
Polar capacitor C2 : 4.7 nF/16V
Capacitor C3 : 22uF
IC1 : CD4047
NPN transistor Q1-Q2 BC547
PNP transistor Q3-Q4 BC557
Buzzer K1 : Tweeter 8 ohm
Power supply : 12V
