Arduino_hw

Arduino diode

• 1N4148

Arduino transistor

• BC327 - PNP
• BC337 - NPN
• https://forum.arduino.cc/t/universal-pnp-and-pnp-transistors-bjt-for-atmega328-based-arduinos-what-to-buy

How to use buzzer correct way

Stephane reveal it here - use 10 kΩ resistor from pin, PNP transistor, 220 Ω from +5V and antiparalel diode.