David, manufacturers make relay shields for the Arduino that work on the I/O pins. Also, most models can sink/source 40mA to my knowledge. See my post on compatibility Development Kit Limitations - How to Determine Compatibility .
David, manufacturers make relay shields for the Arduino that work on the I/O pins. Also, most models can sink/source 40mA to my knowledge. See my post on compatibility Development Kit Limitations - How to Determine Compatibility .