You made my point exactly.
The function of this circuit is not explicitly stated
duh = "obviously" (if you find it offensive then ignore it. I don't think there's any thing wrong with using it when it is appropriate and this is one of those times)
If you know what the OP is trying to do then go ahead and solve the post. Otherwise , ask the OP what he is trying to do so we can figure out what the problem is.
The OP needs to forget the schematic and simply tell us exactly WHAT he is trying to do. That should be obvious. I don't know what your problem is but it is pointless to discuss a schematic if you don't know what the DESIGN CRITERIA is. So far, that is unknown. You admit yourself you are making assumptions. I am not being an ass. I am being practical. Maybe you should find out what the OP is trying to do before calling someone an ass.
The only way for a newbie to learn what mistakes are obvious is to simply tell them straight out that it is obvious you cannot do something. How else are they going to learn that ?
Obvously you can't switch a relay that is being used to do the switching. The OP said it didn't work when he connected the battery. We don't know what that means , yet.
@OP ,
Thank you for the explanation . Can you please explain the problem ?
From what I can see, the idea is that when the 5V adaptor is NOT present, the arduino is powered through the N.C. contacts and when the adaptor IS powered, the arduino is powered through the N.O. contacts.
I am still not clear on what the problem is . Can you please explain the problem ?
Also, do you have a DMM (digital multimeter ? Please measure all the voltages and post them. Also, please post a link for the relay.
Please state the problem you are having.