I am having an annoying issue and any help would be appreciated. I have a NodeMCU connected to an 8 channel relay. I have 3.3v and GND from the Node going to the VCC and GND on the board. I have a 12v 3a power supply stepped down to 5v which is powering both the NodeMCU and then connected to the JD-VCC and GND on the relay board. I can send the board a command for the relay and the relay LED turns on, but the relay doesn't click to send the voltage on to my sprinklers unless I tap on the relay. I thought originally that the relay board was faulty and ordered another one, but this one is doing the same thing. I know I am screwing up something here, I just can't figure it out.
3.3V may not be enough to "trigger" the relay. Try directly connecting 5V to the input (after disconnecting the microcontroller) to see if the relay "clicks" and switches.
Please read the post at the start of any forum , entitled "How to use this Forum".
OR http://forum.arduino.cc/index.php/topic,148850.0.html.
Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Thanks.. Tom...
PS A picture or link to where you purchased the relay board will help, as there are many derivatives of 8ch relay.
DVDdoug:
3.3V may not be enough to "trigger" the relay. Try directly connecting 5V to the input (after disconnecting the microcontroller) to see if the relay "clicks" and switches.
That was the ticket, man thank you so much Doug. I left the ground from the Node in the GND on the relay, but removed the VCC from the Node replaced it with the external and then jumped the other JD-VCC and VCC and it worked like a charm! You rock!
I can't quite figure out what you have done here, but to control these active-low relay modules from an ESP8266, you must connect the "IN"s to your control pins, and "VCC" to 5 V, not 3.3 V as the series combination of the LED and optocoupler LED requires more than 3.3 V to activate. This is perfectly safe as the optocoupler and LED will never apply more than 3.3 V to the pins of the ESP8266.
You then should separately connect "JD-VCC" which is the relay supply and its GND, to a 5 V power supply at the supply terminals where there is a large bypass capacitor - and these connections should be paired all the way. The VCC and "IN"s must also travel together. You do not connect GND to the ESP8266 with them, it goes only as described to the relay supply even if that is the same supply as the ESP8266.
