I'm using a arduino mega and a 16 channel relay module and when I trigger pins of the relay module to turn on via arduino the LEDs on the board light properly but the relays do not click and they do not switch power on. I have 12v power supply running to the board and 5v power and ground running from board to arduino. I thought maybe the board was bad even though it's new but I tried a second board and a 8 channel board with the same results
8-channel relay boards and 16-chanel relay boards can be totally different.
And both can have different ways of connecting to Arduino.
Post a link to your relay modules.
Leo..
On the and channel board I hooked 5v and ground to arduino and pin 1 of relay board to pin 37 on arduino.. when I send digital write low the led on board turn on on relay 1 but no click... that board does not have 12 input like the 16 channel board does... I really need the 16 channel board to work I was only trying a simple 3 wire set up in the 8 channel one just to see if it worked and it didnt.
You have posted a link to a 24volt relay board.
I only know 16-channel Sainsmart boards with a design flaw.
Hard to read the diagram, but this board seems to be designed by the same noob.
You can get this board working with a 24volt supply, and run the Arduino from it at the same time.
Because it has an onboard 5volt DC/DC converter.
Don't expect opto isolation (safety) from this board.
I would only use it for low voltage switching.
Post a link to your 8-channel board.
They usually do have opto isolation.
Leo..
It says 24v but the 2 external input pins say 12v and ground and I'm only switching 12v relays with these relays. I'm using this board to turn on other 12v relays. When I ordered them I did not notice they were 24v until I just pulled up the link to send to you... are you thinking that the eternal power connector needs to be 24c not 12?
They probably use the same bare boards to manufacture these modules.
Look at the printing on the relays.
12volt or 24volt.
Leo..
Looked at relay they are 24v I didn't have a 24v power supply handy to check to see if it fixed the problem but I did have a 18v drill battery so I hooked it to it and they started clicking away thank you so much for your help with me over looking something so simple and stupid.. and also explains why the 8 channel wasn't working straight off arduino because it has 12v relays on it... I didn't even look when ordering just say works with arduino so I ordered them.... lesson learned for next time
The board might work on an old 19volt laptop supply.
Plenty of them in the thrift shop.
Leo..