Electronic – Does signal ground have to be connected to actual ground

ground

Does signal ground have to be connected to actual ground, or does it simply need to be a common node? I have a number of "floating grounds" in my schematic (denoted by the upside-down triangle) and also actual grounds (on Arduino; denoted by lines slanted to the left). I assume they are distinct, and I'm guessing I have to connect all of the signal grounds together but I don't know if they need to also be connected to "earth" ground.

Best Answer

You have to connect all grounds together. Unless you're pulling 120VAC or 240VAC, you should have no need to connect those to "earth" ground.