Thank you! I wanted to go with the ULN2803A too, but now I`m not sure how to wire it correctly.
I have arduino nano, 5 electromagnets, external 12v powersupply and ULN2803A driver. Here is the pinout for the driver:
Am I correct that I connect arduino outputs to input pins of the driver and output of the driver goes to the electromagnets; to common goes 12v powersupply? Does GND connect to arduino or powersupply?