On Thursday, April 14, 2011 02:51:02 PM John R Pierce wrote:
> switched PC/Server PSU's *so* don't give a bleep about sinusoidal power,
> its not funny. first thing they do is full wave rectify the power to
> DC, then they run that DC through a high frequency (several 100Khz
> usually) oscillator and into a toroidal transformer. they would be
> perfectly happy running off a full squarewave
Actually, a squarewave with the same RMS as a sine wave will full-wave rectify and filter to a lower DC voltage than the sinewave. The supply may or may not be able to deal with that.
To work the math, 120Vac RMS yields a peak voltage for a sinewave of about 170V (Vpeak=Vrms*square-root-of-two); full-wave rectified and filtered that gives 170V DC (with some ripple, depending upon the size of the filter capacitor relative to the current drawn); a squarewave at 120Vac RMS yields a peak voltage of 120V, and a filtered DC of 120V, equal to the filtered DC for an input RMS AC voltage of 84Vac RMS (for a sinewave, Vrms=Vpeak/square-root-of-two); if your power supply can deal with that.....
Also, the odd-order harmonics may create their own havoc in the filtering. So, no, there's more to it than meets the eye.
I are a EE; degree and all..... :-)
But if you don't believe me, please look at:
http://www.opamp-electronics.com/tutorials/measurements_of_ac_magnitude_2_01_03.htm
and come back later....
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