Thread: Power Surge
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  #7  
Old August 30th 03, 06:45 AM
w_tom
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Others have summarized your answer. Some numbers. A
switching power supply first ups the 120 VAC to about 300
volts DC (and yes, those 300 volts did hurt). Then it
oscillates that 300 DC voltage through a transformer,
rectifies it, and creates the +5, +3.3, + 12 etc. Notice the
so many transitions. 120 VAC to 300 VDC to various low
voltage AC to regulated 3.3, 5, and 12 DC.

With all those transitions, it becomes easy to take a widely
varying, AC input voltage to create a noise free, galvanically
isolated, robust, and well regulated DC voltage.

Vanguard wrote:
If the voltage drops on the input side but you still have the
same power demands on the output side and where you must maintain
the same voltage requirements with the same demand for current,
how does the power supply make up for the deficiency in input
voltage?