I am trying to use an arduino uno to power some 12V dc motors through a 5v 4 channel relay board. I have the arduino set up and it is switching the relays from the pins. Now I just need to get power to the motors, but I dont want to have two power supplies.
I have a 12v 5A power adapter and I want to solder two wires to the DC jack on the arduino to provide high voltage to the high voltage motor side of the relay powering both the board and the motors from one common source. This doesn't seem common at all and I figure there must be a reason. Is there a reason why it wouldn't work?
You will damage the barrel jack doing that - it is not rated for that much current.
Instead, make a Y cable with the common end at the supply and a leg going to each device.
CrossRoads:
You will damage the barrel jack doing that - it is not rated for that much current.
Instead, make a Y cable with the common end at the supply and a leg going to each device.
The motors I am using are very small and I dont think the jack will ever see the full 5A, maybe 1.5 tops. The leads on the motors are smaller than the posts connecting the jack to the board.
I have attached my attempt at a drawing. I would like to be able to keep the plug on the adapter since I want to package all of this in a box and power it form the wall.
You can do that - I'd still recommend a splitter cable for ease of maintenance.
What coil current is needed? Unless it's really low, you'll need a transistor to sink the coil current. Don't forget a diode across the coil too.
The relay is actually a sainsmart module designed for this purpose, so I think it has all that stuff built in. I could be wrong though, what do you think?
Opto-isolated inputs"