[ccomer1955]

I've never tried to make a bucking transformer box for my radios, but I saw these on EBay and wondered if they could be adapted as bucking transformers to step down my 121v at the socket to closer to the voltage my old radios were made for?
I'm guessing amps and other considerations would make that impossible, but these are cheap.

http://www.ebay.com/itm/110V-12V-AC-60W-...5d3455d93d

[Mondial]

Don't think it will work. That looks like an electronic switching inverter, not an old fashioned copper and iron transformer. There is no mention of waveshape, harmonics or phase of the output.

Even if the output was a true sine wave and the phase was controlled so as to be able to subtract from the AC line voltage, there would still be the problem of RFI. Most of that type of switching supply will put out loads of RF noise and harmonics, which will be picked up by the radio you are trying to operate.

[ccomer1955]

Figured, but thanks.

[morzh]

Seems like a high freq transfomer for LEDs.

That won't do.

[codefox1]

An extra 6 volts or so will not unusually distress a typical 10 or 115 volt series set. You can probably replace a 35XXX with a 50XXX output or a 35XXX with 50XXX rectifier if pinout is same to lighten the load. Buckeroos are old school iron 12 volt or whatever you can scrounge or fit. Agree, up to date wall warts are probably not what the doctor ordered.

[morzh]

I have a wall wart that would do.
It is a simple 60Hz transformer and bridge rect to charge booster packs.
Some of them are OK but need to know what is inside to be sure.

[Arran]

It may use a mains transformer on the inside, but there just isn't enough information to tell, it does appear to have a metal case which most switchers would not have, it also lists the input line frequency which many switchers do not care about. At $2.54, and free shipping, you could buy one and find out, just remember that it's Chinese and it's rated at 60 watts, so assume that it's good up to 45-50 watts without burning up. I have no need of such things, I have a bin full of power cubes/wall warts that are from the era before China junk electronics.
Regards
Arran

[morzh]

http://www.displayplus.net/news/articleV...dxno=37881

Arran

Those are called electronic transformers for a reason.
SET02B is one of them, listed in this article where they tested LED drivers.

[Arran]

Article or not, inverter or not, if it's made in China it's made to fail. Why they need to get an inverter involved for a 110 to 12 volt AC power supply is beyond me, but being China built it's almost guaranteed to be trash can bound, the fact that it does not even have a manufacturer's name tells you something. I would just salvage a proper mains transformer from something else if you want one to lower line voltage by using the low voltage secondary.
Speaking of line voltage in the case of an AC/DC series string set they were designed around a working voltage of 117 vac, I don't know where this 110 volt idea came from, the only true 110 volt mains they had was DC mains, which likely does not exist anymore anywhere.
In an AC/DC series string set you usually have three 12.6 volt tubes, a 50 volt, and a 35 volt which comes to 122.8. If it's something less it will have a resistor in series with the tube filaments to make it add up to 117 volts, where you could easily add a larger power resistor to make it add up to 121 volts or whatever your line voltage is. A few volts extra on the B+ side does not matter much.
Regards
Arran

[morzh]

>>>Why they need to get an inverter involved for a 110 to 12 volt AC power supply is beyond me...

Because it is small, so it can output more amps at less size. High frequency is the key word.

>>being China built it's almost guaranteed to be trash can bound,

Not true, most manufacturing today is in China, Foxconn who builds for Apple certainly does not build trash, or Huawei, or....depends on whom they build for. And where do you think all those dimmers and GFCI outlets made? I haven't had many failed.

>>>the fact that it does not even have a manufacturer's name tells you something.
No...it does not. But the fact that it has a name (SET02B) that made it in a white paper means I could likely trace it if I wanted to. But even if I do not.....cheap stuff is cheap stuff and it serves its purpose.

I am not even sure why we are discussing "Chinese vs non-Chinese" when many traditional transformers of a good quality (have two output ones in my radios) are made in China today, but this was not the point.

The point was, a High Frequency Transformer CANNOT be used for bucking purposes with 60Hz MAINS transformer, and this is what was communicated to Ccomer by Mondial and myself, so when you said "At $2.54, and free shipping, you could buy one and find out", why even say that, when it is not going to work anyway, Chinese or Red Blooded American?

[Arran]

Mike;
Foxconn products function well,at least for the short term, because they are partnered with a U.S company, but the no name export stuff often is trash from the get go. Some would differ with you on Apple products, some consider it overpriced garbage from brand new, which is likely based on personal bias against Apple itself, but I digress.
None the less I'm not sure whether you could use the fact that Foxconn (Hon Hai) manufactures for Apple is a good measure of product quality since the majority of Apple products are marketed as fashion accessories intended to be replaced or traded in within a few years for the latest and greatest model. My definition of whether something is trash can bound or not is whether it lasts more then five years, which is something that many China made goods are incapable of. This does not mean that they won't last five or six of course, but is there anyone out there that uses an Iphone I or II anymore? If you look at their company website they are actually a Taiwanese company, not a China state owned company, so that may explain why Apple, Dell, and some others deal with them. But then again so is Lelon and they make lousy capacitors.

http://www.foxconn.com/

As for Huawai, that company is run by a retired general from the Chinese People's Liberation Army, therefore he is a party insider. So they can pretty much infringe on any other company's patents without consequence, and get whatever financing they want from a China state bank. Unlike a Taiwan based company it's just about impossible to sue a company with party connections in China, there are no independent courts. I won't comment on the quality of their products but since they don't have to invest much in R&D it's possible that they may throw more into better materials and quality control, though I would not hang my hat on it.
No doubt the one making these cheap halogen light transformers is made by a similar sort of company, though one of a lower standing then Huawai, no doubt using stolen designs. The same sort of outfits also pedal crap electrolytic capacitors, the more honest ones have some mystery brand printed on them, the dishonest ones sell outright counterfeits. This was in part responsible for the capacitor plague between 2004-06. This is why you can't really trust the specs that they mark on products with these direct from China sales, I've even heard of them selling counterfeit LM317s when the real ones are $.50 each!
I have noticed that unlike many American firms many of the Japanese ones often go out of their way to avoid manufacturing their products in China, they seem to prefer Malaysia, Indonesia, Singapore, and even Thailand over China. I think that the intellectual property theft may be part of the reason but I'm sure that quality control and the lack of independent courts may also weigh in. I think as time goes by you will see more and more electronics come from India as well, which would definitely be an improvement.
Regards
Arran

P.S GFIs and light dimmers fail all the time, though they don't usually fail in a shower of sparks, they just stop working or make lots of RF noise.

[codefox1]

Ancient TV's used VBOT's in tube Televisions. Useless unless possibly as a choke or copper scrap.