Of Wall Warts & Wall Transformers

Published:2013/10/31 22:10:00 Author:lynne | Keyword: Wall Warts, Wall Transformer | From:SeekIC

With all the recent mania on capacitor limited power adapters at electroschematics.com, the Wall Wart seems to be the neglected power source. Wall warts are small, convenient and have transformer isolation. With line isolation they are free from ground fault shock hazard. The power level and output voltage is ideal for most experimentation, and difficult to specify or obtain “X” capacitors are not required. It has been suggested that wall transformers were coined “wall warts” because they often take up 2 or 3 positions in a power outlet strip, but I say it is simply because they protrude from the wall like a “wart.” The name is simply a humorous alliteration. Voltage regulation Voltage regulation (no load to full load) for AC adapters ranges from 12 to 34%. For DC adapters, it is roughly double that or 32 to 80%. This may be seen in the regulation data. The DC adapters have inferior regulation due to the peak detection effect of the input filter capacitor—this is not a serious issue because nothing really operates at no-load, not does anything actually work on AC without rectifiers. For frame of reference (because % regulation tends to be confusing), 0% is perfect and 100% indicates that the voltage drops to half when loaded. Just keep in mind that wall warts tend to be sloppy and the equipment to which it is connected is designed to accept double the specified input voltage safely. For experimentation, I like the AC versions because I can connect a voltage doubler rectifier to get much higher voltages. Also, if connected to half-wave rectifiers, I can easily obtain ±voltages.



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