Automatic sensing power systems and methods

[Subject] The electric power constitution system which solves simultaneously the problem of the problem of being insufficient and transient-voltage serge of a plug mouth, and a noise is offered. [Solution means] The AC*DC regulator which transforms AC electric power into DC electric power, If DC electric power is received from an AC*DC regulator, it consists of DC*DC regulators which can change DC power level dynamically and an electrical machinery and apparatus is connected to an automatic electric power detection system, The demand electric power of an electrical machinery and apparatus is determined automatically, it changes into DC power level of which electric power was required, and electric power is outputted to this electrical machinery and apparatus. [Selection figure] Fig. 11