March 2011
Why do most laptops, cell phones, etc., have relatively large transformers to convert AC power to the proper DC voltage, but the Amazon Kindle only has a small adapter that seems to have no space for the traditional transformer?
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The linear type wallwarts operated on line frequency of 60 cycles, and even though they only have 3-6 parts, these had to be large to handle the current and squelch ripple. What you are looking at are the newer units which are switch mode type supplies, operating in the 100-200 kilocycle range. Even though they may have 40 or so parts, these parts due to surface mount technology, and the high frequency, can be much smaller and lighter. These supplies also provide a stable voltage of more current and less load droop than their older linear cousins.
