Background
I bought this 8-channel relay module for a project with motors.
Because this is the first time I ever use a relay, I want to try it with an LED.
So I wired up as seen in the attached diagram.
I uploaded the code like in this tutorial.
Problem
When I powered everything up, the LED on the relay does blink as coded.
But the relay itself doesn't "click", changing from NC to NO.
The test LED did light up (bc it's connecting through NO and COM), but it didn't switch off like the indicator LED.
What I have tried
Changing the power supply of Arduino in suspect that current supply is insufficient
Changing the way the test LED is wired
Could you advice me what is the problem?
Should you need more information, please let me know.
You didn't specifically say so, but seems you're trying to power only 1 relay coil, not all 8? That should be ok, they draw 75mA or so iirc. I have the 2 relay equivalent of that, and it's fine with both energised at once.
Presumably you have tried different relays on the board?
Are the relays 5V as in the pic, not say 12V or something?
Alternatively, and this is in any case a better way, take the jumper off and supply separate power to the relay module with the ground to the Arduino removed.
Not quite: you need the jumper off and replace the wire from Arduino 5V to relay Vcc, else the led in the opto-isolator won't work.
Full disclosure: I have never used anything other than a 5V relay, so it's a leap of faith on my part to assume the 5V in the opto-isolator led will switch the 24V in the relay coil circuit.
Personally I'd send the 24V module back seeing as according to the link you gave, you ordered a 5V one.
