Tutorial: Use your MCU to turn stuff on or off

Tutorial: Learn how to use digitalWrite from your Arduino, Teensys or ESP32's to turn on or off small components like and LED or 120 VAC devices like lights and fans using common relays. In this tutorial you will learn the commands, and see how to implement digitalWrite.
Other useful tutorials
Temperature sensor shootout: • Temperature sensor sho...
Using 7-segment LED's: • Using 7-segment displa...
Writing and reading to SD cards: • Tutorial: Writing and ...
Saving settings even during MCU power down: • Tutorial: How to save ...
Getting those darn TFT LCD displays to work: • Tutorial: Getting TFT ...
Writing analog signals/voltages: • Tutorial: Use analogWr...
Using digital sensors: • Tutorial: Use digitalR...
Using analog sensors: • Tutorial: Use analogRe...
Talking to your Arduino: • Tutorial: How to talk ...
Some fun projects to build
Build a 3D printer filament meter: • Build a 3D printer fil...
Homemade motorized table saw fence • DIY motorized table sa...
High"er" res homemade Thermal Camera for $100: • DIY high-er res Therma...
DIY Garage Parking Assistant: • DIY Garage Parking As...