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 shootout  
Using 7-segment LED's:    • Using 7-segment display LED's  
Writing and reading to SD cards:    • Tutorial: Writing and reading to SD c...  
Saving settings even during MCU power down:    • Tutorial: How to save settings to MCU...  
Getting those darn TFT LCD displays to work:    • Tutorial: Getting TFT LCD displays wo...  
Writing analog signals/voltages:    • Tutorial: Use analogWrite to vary spe...  
Using digital sensors:    • Tutorial: Use digitalRead to monitor ...  
Using analog sensors:    • Tutorial: Use analogRead to monitor a...  
Talking to your Arduino:    • Tutorial: How to talk to your Arduino...  

Some fun projects to build
Build a 3D printer filament meter:    • Build a 3D printer filament meter  
Homemade motorized table saw fence    • DIY motorized table saw fence  
High"er" res homemade Thermal Camera for $100:    • DIY high-er res Thermal Camera for $100  
DIY Garage Parking Assistant:    • DIY Garage  Parking Assistant