
I bought this transformer about a year ago for my German sewing machine (230 V, 85 W, 50 Hz) to run it in the US (110 V, 60 Hz). So far it works like a charm. I've used it for quite a few sewing projects over the past year and was worried whether the 60 Hz/50 Hz difference would be an issue, but everything seems to be running just fine. Investing twenty bucks in a transformer allowed me to keep using my familiar sewing machine instead of buying and learning how to use a new one, so it was well worth it.
Addendum April 2011: After three years of use now, it still works fine and I haven't had to replace any fuses yet. But you have to be aware of the wattage on the appliances you are plugging into it. I just saw some of the reviews with lower ratings on this item saying it doesn't work, starts smoking, fuses blow immediately etc. Please be aware that this transformer is limited to 200 Watts only, and you probably don't want to max that out either to stay on the safe side. Find out how many Watts you are plugging into it before you turn it on and keep in mind 200 is fairly low. If you have larger wattage items you will need to invest your money into a transformer that can handle that.
You can probably safely run the following items using this transformer: clock radio, electric blanket, laptop, a small TV, radio, VCR/DVD, Xbox, PS2, Wii. You may hit the limit and ask for trouble with desktop computers, Hi-Fi equipment, Xbox 360, PS3, LCD or plasma TVs you may want to get a 500W transformer for those. You will almost certainly blow the fuses if you try to run: any sort of kitchen appliance, power tools, vacuum cleaner, hair dryer, iron. You need something much more heavy duty for those items.

I bought a couple of these on moving from London to NYC, and they work fine. My one complaint would be that the clearance below the UK plug socket is not huge, so the cord coming out the bottom of the plug has to bend sharply to avoid the surface the transformer rests on. It's not a big issue though, and we've been using them for a couple of months with no problems. Don't throw away the replacement fuses that come with it, though; I've already had to replace one of them.
Buy Power Bright VC200W Voltage Transformer 200 Watt Step Up/Down converter 110/120 Volt - 220/240 Volt Now
Got this to power an old computer from the 90s; it was a UK version so it needed a 220V to function.
The setup is very simple; just keep an eye on the input current, unless you wanna cause problems (there is a selector in the back, it goes from 110 to 220V, so you cover the whole globe).
The unit itself is noiseless; you hear no buzzing at all; if you touch it while on is cold, and has a very minimal buzzing that you can just feel if you put your hand on the top of the unit.
I kept it on, powering the computer (which uses about 100W), for a couple of hours, and had no issues. I saw many negative comments but they were made by people not very tech savvy....you need to know the basics of the power load that you can apply to a transformer, otherwise you will just overload it and burn it.
This will be enough to power anything that is below 150W and 10A; don't use it with higher power consumption items or you will overload it.
The cons are the weight; which is out of this world, if you are planning to travel and put it in your bag, and the very short power cable. Also keep in mind that the 220V plug in the front is very flimsy; so use care when you plug something in or unplug it.
Read Best Reviews of Power Bright VC200W Voltage Transformer 200 Watt Step Up/Down converter 110/120 Volt - 220/240 Volt Here
After reading reviews on bad experiences with the transformers, I decided to buy this 200W transformer even though my sewing machine takes up 100W theoretically. (Do P (Watts)=I (max current of your device) *V (your device voltage 110V/220V... ))
It's been nearly two months now and it has worked fine for me. So I'm quite pleased with it.
Latest update (12 March 2013): Recently I found out that the speed of my sewing machine increased quite a bit. I'm not sure if this is related to the transformer. It makes the sewing machine shake quite a bit even if I pressed the pedal very gently.
Want Power Bright VC200W Voltage Transformer 200 Watt Step Up/Down converter 110/120 Volt - 220/240 Volt Discount?
i bought it for my sewing machine and is doing an excellent job, small and not heavy, it's what I needed
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