Quantity   Component name
1 × 8042 board https://github.com/kenyapcomau/8042-board
1 × Piezoelectric beeper
1 × Small signal Si NPN transistor
1 × Small signal Si PNP transistor
2 × Small signal Si diode
1 × 33μF electrolytic capacitor See design for calculation
1 × 22kΩ resistor
1 × 47Ω resistor