Hello, I have a breadboard, an ESP32, and a relay I want to use. If I provide external power supply to breadboard, 5v on the left (for the relay) and 3.3v on The right (for the ESP), do I have to connect the ground from 5v to the ground of 3.3v in order for the 4 channel relay to work? Thank you. …

External power supply to breadboard

sterretje September 25, 2021, 9:54am 5

If your relay board has optical isolation, you should not connect the grounds.

Topic		Replies	Views
does this connection make sense? General Electronics	18	3587	May 6, 2021
wiring a Relay board with a separate power supply. General Electronics	4	3652	May 6, 2021
Safely connecting a relay board to external power supply General Guidance	18	22112	May 5, 2021
Powering a 4 relay board (120 volt) Motors, Mechanics, Power and CNC	6	1159	May 6, 2021
LeaningTech 4-CH 5V 4 Kanäle Relais Modul an Espressif ESP32 Deutsch	16	3686	May 6, 2021