My second Instructable on remote control using Arduino, Bluetooth, and a relay. The first Instructable in this series was designed using the serial communication software PuTTY for turning off and on the remote device from your computer. This one will be quite similar in the setup of the project but we will be using the Volthaus Lab Bluetooth Controller Android phone app for control. The Bluetooth Controller App was designed using the MIT App Inventor and the source code is available below so you can import it into your own MIT App Inventor account console to adapt it to your needs if you wish to extend its capabilities, or just study how it works.
Check it out at:
https://www.instructables.com/id/Remote-Control-Bluetooth-Arduino-Android/
QUICK LINK-All project files here