kai,

thanks for all the insight, I think that you really solved my problem with the suggestion of that class II transformer (I didn't knew about these things), I'll look for one of these!

When I said about safety standards in commercial products was in the sense that the device will be made for my personal use, so the damage is limited to the device and myself :-)

by the way, do you have some online reference for that transformer? I'm googling but not finding a datasheet or reference part number, only mentions of use in other products.

orlando