H I
someone can explain me how can i connect/controll an electric motor at 220V [or any other equipment that use 220V AC]?
thanks
If you just want to turn something AC on and off, a solid state relay is easy, but a bit expensive.
Get the SSR that is rated to switch 220V and more than your load.
The good thing about these is that the 220V is optically isolated (no electrical connection) form your Arduino.
Mark Allen from the Machine Project in Los Angeles has a good diagram of one... just change where it says "Basic Stamp" ( what is that anyway? 
) to a "Arduino".
Straight relays are also good, but they will eventually wear out form contact sparking. You'll need a transistor driver circuit (also try googling "relay driver").
The bad thing about using regular relays is that if you make a wiring mistake, you might run 220V into your Arduino. 
If you want speed control of the motor.. that's nmore complicated. The above two solutions are just for straight on/off control.
How to connect a relay is also shown on page 40 of this (excellent!) document.
THANKS for all...
i look Mark Allen Machine Project - QUESTION: which ground of scheme have to connect to arduino board?
i wold like to avoid that arduino receive 220V[!][...]
H I
keep the AC power ground away from the Arduino circuitry...