Twisting and Turning Your Way Out of EMI Problems

That would have brought the Drain end of the Primary winding right next to the safety barrier, with the Secondary ground end (which is usually connected to the chassis) directly across the isolation boundary. With this winding arrangement, we would have a healthy dose of CM noise injected directly into the chassis/earth. 

Obviously, a few 12V turns were still leftover after the 5V foil winding got completed, and these were simply wound tightly around the inner 5V foil. 

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