Hello Jarda, there are various possibilities to talk about power like musical power, sinus power or effective power. The sinus power means the peak-to-peak value. If you take this power (500 W) and divide the squareroot of 2 from it like this

500W / SQR(2),

then the effektive power is about 354 Watt.
It's not a 'perpetuum mobile' - it's the blind power of a magnetical spool captured and released by the pump effect of an electrical capacity.

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Greetings from Frankfurt (Germany),
Sheriff ;-)

[This message has been edited by Sheriff (edited 02-25-2005).]