Tim wrote: I've been told that one shouldn't plug anything using a ferroresonant transformer into a UPS. Perhaps someone who knows more about the characteristics of ferroresonant transformers (and UPSes) can explain why, or refute the claim. I haven't tried it, because the only thing I have (*) containing a ferroresonant transformer *is* my UPS, and there's no point plugging that into itself. Although just a few days ago a friend who shall remain nameless was talking about playing around with two old, decommisioned UPSes. He pluged each one into the other to see what the frequency of the resulting on/off osciallation would be (about two seconds as it turned out). Eric (*) The only modern thing, anyhow. Did DEC use ferroresonant transformers in any of their machines?