Using universal interfacing platforms has always helped us. From Wi-Fi or Bluetooth like communication protocols to data exchange and charging platforms like USB, we have reduced the dependencies on specific brands. Now you can charge a Samsung phone with a Nokia USB charger or charge an iphone with a local USB charger. But what counts here as a difference is the power requirement of the gadget and interestingly, even though USB is a universal platform, there can be some serious variations in the efficiencies and power wattage. Ken Shirriff has done quite an amazing task in taking out some of the most sold USB chargers available and has tested for some of the most critical measures of wattage, efficiency and ability to filter inputs.He has also used a spectrum analyzer and shown the results in form of images. To satisfy some extra curious people, teardowns are also shown in this post.