HW-622 ESP8266 Relay Board
USB to Serial
Configuration (old format, will be converted to new template when applied)
DYI ESP8266 relay with external optoisolated button. Requires an external power supply. The input from the switch is opto-isolated so the 5V can be used directly to supply the switch. Unfortunately, it appears that many cevices do not have the 0V connected on the input. A connection needs to be made from the 0V on the supply to the 0V on the signal input.