Hi Everyone, looking for some help with a relay module rated for 12vdc.
https://www.ebay.co.uk/itm/12V-1-Channel-Relay-Module-Opto-Isolated-board-for-Arduino-and-MCU-projects/151932550208?hash=item235fe2bc40:g:6mcAAOSw4HVWDVxJ
^^^ This is the relay I have...
Basically when i give it a high (12vdc) signal, the relay will not turn on, the indicator LED appears dim and doesnt turn on the relay. The jumper is in the correct position for the high signal.
Any suggestions as to what could be wrong??
I'm not powering it via arduino, as its 12v.
I have tried connecting it to turn on a small 5v led, but no such luck.
Would appreciate any advice.
Many thanks,
Jack 
Give a link to exact the relay You use, not the whole shop.
Post the wiring You use.
Hi @railroader
I have posted the link to the specific item on ebay - not the whole shop???.
I have used a 12v power supply rated at 1.4amps. I have then used another branch of the + side of the 12v as the signal into the relay.
Many thanks,
I see 4 different presentations.
Post a wiring diagram of Your setup.
1- The relay board need power. In your case 12volts.
2- The relay board need a trigger signal. From what I understand, your trigger signal is a branch of the 12v in the trigger port.
3- The Load side can be left unconnected for now. You will ear it tick when it change state.
About 1. Power means 12 volts and ground on the board (this is to power the board not to eventually power the load).
About 2. Usually only a couple of mA are required to trigger the relay. 5-10 mA should be enough and the voltage doesnt matter. Any digital pin of a 5v Arduino can provide 5mA. You can put a resistor in serie to limit the current. Since you just seem to test for now. Touching the trigger pin with a +12volts line will work but it is not good practice.
About 3. When 2 work, you can hook up whatever load you want 
And yes a diagram would be much better for explanations.
Hi, here is a schematic which is the same as my setup - and I have added on the signal jumper from the 12v pin.
Read the text down on the relay. it says SRD-05VDC-SL-C.
That relay is a 5 volt relay. Applying 12 volt might destroy it.
This relay is identical to mine, apart from mine is 12v not 5v. I was unable to find an image of a 12v one
Okey. Connecting the "signal" to +12 or GND would activate the relay. Else the unit is out of order.
Ok, that's strange as its brand new, just arrived from ebay. Any suggestions for why the led would be showing as dim?
Many thanks for your help @railroader
Is your board standing on a conducting table? Probably not but maybe you have a unwanted connection under it?
Investigate the surface mounted resistors. There is a resistor in serie with the signal pin. Measure it! Maybe it is badly soldered or has a way too high value.
do you have 12v and ground connected to the right hand side terminals?
green led should be on to indicate power available.
forget left hand side connections for now
@bluejets - yes they are connected to the right hand side. I have just contacted the ebay seller and they believe it may be faulty, as do I, so they are sending a new one out. Hopefully that can solve the issue.
This topic was automatically closed 120 days after the last reply. New replies are no longer allowed.