Ebay funny

Michael A. Terrell wrote on 2013-01-21 06:41 MET:

With the primary center tap it should be possible to use this transformer at either 110V or 220V.

--
MfG / Regards 
Friedrich Lobenstock

Impossible to tell if it is center tapped, the third pin might be unused, it doesn't say

but it has such important information as: blue and red design :)

-Lasse

Where did it mention a tap? One of the three terminals could be used strictly for orientation.

What's a "Heedle"? Are they some kind of "Electalcrl" thingy? It has five of them!

Very patriotic colors. And it provides proper separation of the "red and

blue states", as the secessionists would like. :)

Paul

Did you read the label? It looks like fifth generation babbelfish.

Michael A. Terrell wrote on 2013-01-21 23:00 MET:

It could but it usually is if there is a terminal.

--
MfG / Regards 
Friedrich Lobenstock

I've seen lots of PC mounted transformers with an indexing pin so that assmblers don't install them backwards. A lot with a single 120V primary.

So its a 110V transformer. If you see a car in an advertisement they are not going to sell you the exact car from the picture but another one that made its way to your local dealership. So the license plate may be different. The same goes for the color unless its a Ford.

--
Failure does not prove something is impossible, failure simply 
indicates you are not using the right tools... 
nico@nctdevpuntnl (punt=.) 
--------------------------------------------------------------

How can you be sure, when the vendor doesn't take the time to state that the photo is wrong? I see a lot of equipment marked for 240 but advertised as 120 from Chinese vendors. Am I to believe that every Chinese vendor knows the difference, or even cares? Ones who name their store "%^%&*electronics" then list more pet supplies & women's clothes than electroncs, are really experts in electronics.

"Can be used in kinds of machine tools, electric appliance in machinery equipment or lamp for a voltage transform tool."

The Chinglish at least IMPLIES that it's a

240 primary center tapped for 120/240 use.

With a bridge and cap about 12VDC or 6 if you use the 240 primary on 120.

How do you suppose these would do on a HIPOT test?

Hard to see from the photo, but I don't see the two wires at the that should be present at the center tap.

'Voltage transform tool' is what any transformer does..

It would do great. It's a split bobbin design.

Best regards, Spehro Pefhany

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"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

I was more worried about shorts within the windings and to the core, crappy enamel or sheathing between core and enameled wire.

I've got trust issues with import stuff.

I got some hongkong stuff that was Ok but I've also got some that was utter crap, cold solder joints, bad solder joints severe flux corrosion, etc. Just plain nasty.

The flea market nature of this seller worries me too.

I'd dissect one for sure.

Did you notice that at least on the top of the core stack part of the top layer is missing?

Oh, that's certainly possible. Not usually a safety issue.

The core is separated from the winding by the bobbin- if the bobbin is badly designed or made from an unsuitable material it could be dangerous. That product may be made for domestic China use, so anything is possible. Possibly it is sub-standard for domestic use-- I don't see the usual domestic certification on the label.

The product looks like total hand-made garbage to me, I'd not buy it in 100 years. Not cheap either.

This Tamura one:

Is 3.83 in 10's and has UL/CSA and is rated at 2.4VA, and has two primaries and two secondaries. It's multiple-sourced. I've gotten very good versions from China (with UL/CSA) in 10K or so quantity.

You can get some very good stuff from Asia, but the guys who make good stuff are not usually interesting in small quantity sales like even a few thousand pieces, and the guys who do small quantity sales are often not very quality conscious (or even honest, sometimes).

Would you ever use a mains transformer bereft of ANY certifications?

There's a significant market price difference between a transformer with UL/CSA and a junk one- typically ALL the materials are pedigree on the former, including such things as the plastic used to mold the bobbin, the wire, all insulating tapes used, core materials etc.

That doesn't bother me as much as the crap PVC electrical tape (rather than mylar or glass fiber) and the crappy soldering on the pins. Not to mention the label that looks like it's been picked off badly and replaced.

That's a really inefficient use of copper.

--

John Larkin Highland Technology Inc

jlarkin at highlandtechnology dot com

Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

I am looking for a small transformer to convert 12 VDC to 90 VDC at around 10 mA output from the inverter. It looks like I am going to have to wind one.

With seperate sections on the bobbin? They should do OK.

I've used standard ISDN transformers for low-power converters like that, T2 here.

I'm getting about 120 volts at TP15.

You could maybe do a boost converter if you don't need isolation. A standard center-tapped inductor gets you a 2:1 step-up advantage there.

--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom timing and laser controllers 
Photonics and fiberoptic TTL data links 
VME  analog, thermocouple, LVDT, synchro, tachometer 
Multichannel arbitrary waveform generators

I dealt with a Japanese instrument maker years ago, and they used lighter wire for the half of the primary that would only be used for

240V. Of course they moved to off-line switchers way before it was fashionable in consumer goods (saving a case pin and avoiding having to deal with 100/200 as well as 120/240).

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com