Review on 💡 High-Quality Power Relay Module for Raspberry Pi 4 3 2 Model B B+ A+ by Mark Cole

This product worked after I spent some time fiddling around (thanks to Jon H for providing the GPIO numbers). By default, the GPIO pins must be pulled LOW to turn the relays on and HIGH to turn them off. I've used the RPi.GPIO library with Python with no problems. I could argue that there should have been documentation BUT as there are different ways to use the Raspberry Pi (Python, Java etc) I understand why nothing was included as they differ just to explain John's review X : Relay 1 - Use GPIO26 in Python (labeled P25 on the board) Relay 2 - Use GPIO20 in Python (labeled P28 on the board) Relay 3 - Use GPIO21 in Python (labeled P29 on the board)