You are exactly right about the 110/220 "switch" KVS. It don't exist and it makes no sense to have one on a UPS.

Q: about . What's the issue here? The amount of current the UPS will draw through the converter? The phase difference? The crappy waveform output of the converter?

The waveform, unless you use a bulky transformer-based converter like http://www.stayonline.com/transformers/3092.asp.

There is also a slight chance that the UPS unit will not accept the 50Hz frequency and will switch to battery power immediately...

So, have you checked whether your stuff will accept 220v/50hz? All of the electronic gadgets I've purchased in the last few years will. If so, all you need is (as noted above) a cheap plug adapter and away you go.

Okay: some new data.... :)

I did check a few of the power bricks for my gizmos. The digital still camera and the digital camcorder(both Canons) will accept 110-240v 50/60Hz. So I'm good there using just an adapter to get the prongs to fit the wall sockets.

The laptop and the DVD player only accept 110v. I have a couple 3rd party batteries for the player whose chargers accept 110-240v. I'll just run the DVD player off these batteries and then charge them up in BKK for the flight home.

That leaves the laptop. Its' a work laptop so I may just chance it and run it off the travel transformer and see how it goes. Part of the reason it is coming with is to be able to respond to problems back at the ranch if need be.

The comment by studentff that many UPSes don't put out a pure sine wave got my interest up. So today I borrowed a oscilloscope and had a look-see. Oh my gawd was that an eye-opener. Those of you that have access to a scope take a look at your UPSes when it is on battery....and I plug my servers into that!! I don't look at my bigger 1500w models but the little 500w ones like I was planning on taking to BKK was just plane ugly.

Can't seem to replicate the waveform here without the text formatter trashing it but picture three steps on a stairway and you have it. No smooth curves just three step up and three down. It went from a steady 0v for ~1/300th of a sec then immediately to 55v for another 1/300s and then up to 110v for 1/300th and back down to 55v.... No smooth transition between just very quick jumps. and even then it would overshoot the plateau voltage by 50%.

I'm no electronics person so possibly that stepped output is the "norm" for some power supplies but I'll certainly be more selective about what I plug into a UPS....

Can't you just expense an iGo Juice or something?