Also note that the middle adapter sense pin is much smaller than the pins, unlike the Magsafe 2. The connector below is an older Magsafe notice the slightly different shape compared to the Magsafe 2 above. I had a Magsafe cable that malfunctioned, burning the power pins as you can see in the photo below, so I figured I'd tear it down and see what's inside. The pins are arranged symmetrically, so the connector can be plugged in either way.
