I recently bought a little Radio Shack wallwart power supply, equipped with two parallel-blade AC power terminals (with no ground blade) and a 6 VDC output wire pair. As you would expect, one of the blades is slightly wider than the other (implying that this is the neutral or return line), conforming to the convention of the typical NEMA 15 Amp female power receptacle. Since the AC power blades are located near one edge of the wallwart, you can plug the wallwart into a receptacle and the bulk of the wallwart body hangs to one side of the receptacle. Unfortunately, when you try to plug in a second wallwart, the bulk of the wallwart body prevents you from plugging it in, and the larger AC power blade prevents you from facing this second wallwart opposite the first one. My question is, why does this appliance have a polarized blade power connector? I am assuming that the input power pins go directly to the primary of a transformer, so why should we worry about which side is "high" or "return"? Could wallwarts be designed using identical power blades, allowing the option of a 180-degree rotation installation? Ed Price [email protected] WB6WSN NARTE Certified EMC Engineer & Technician Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Is Our Specialty
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