I'm using an Arduino Uno with a Sainsmart Ethernet shield and a DF Robot shield on top. When I've got it plugged into the USB supply (to my mac), it works - connects to network, testing a sensor updates accordingly in the web xml data. When I plug it into the dc power supply, however, I get a light on the main board and a faint light on the relay shield - nothing on the ethernet shield. I'm using an - ac/dc adapter output 9v dc, 650mA.
I imagine the issue is related to my project using 3 shields instead of the combined ardunio/ethernet board in the tutorial. This is my first project, so i'm still getting oriented... anyone have thoughts on what type of power supply i need to use?