I have an arduino board, and I would to turn a different, completely isolated circuit, on and off. Actually, I will be running 230V to another device, and then control whether it is on or off, with the arduino.
http://www.powerswitchtail.com/Pages/default.aspx I have been looking a bit at these, and it looks interesting. The problem is, shipping to Europe means they become quite expensive.
So how can I make one myself? Do I need to build some kind of relay? What components can actually handle sending 230V through it, but be controlled from arduino's 5V?