thinking this unmarked component was an AC transformer I fried it while measuring it by supplying it with 220V AC current. It appears that it's a DC to DC converter, probably 2x15V. I need the exact same one, not an equivalent one. Please help me identify the manufacturer and specific model from this photo. enter image description here

  • \$\begingroup\$ What makes you think it is a DC to DC converter, specifically a 2x15V one? What has it come out of? Why can't it be an equivalent part? \$\endgroup\$ – Oli Glaser Sep 16 '12 at 4:08
  • \$\begingroup\$ Chop into it and see what's inside. There's not much we'll be able to tell you based on just the dimensions. If it's unmarked, you're pretty much on your own. It sure looks like a transformer to me. \$\endgroup\$ – Connor Wolf Sep 16 '12 at 7:49
  • \$\begingroup\$ Also, is it possible you just applied the 220V to the wrong winding (i.e. the output, instead of the input)? \$\endgroup\$ – Connor Wolf Sep 16 '12 at 7:50
  • \$\begingroup\$ A friend who has notions of electronics told me it was a DC to DC. Before that an electronic engineer told me to supply it with 220V and measure it in DC and that it could be a 15 + 15V. It doesn’t matter what went wrong, now it’s fried and the only way to identify it are the dimensions as they are known from the manufacturer and distributors. I can cut it open but what would it tell ? \$\endgroup\$ – WaterBearer Sep 16 '12 at 12:01
  • 1
    \$\begingroup\$ Cutting it open will reveal if it's a transformer or a converter. You said it's burned, no? Then it won't matter if you cut it open or throw it away, curiosity (your reason for asking) will be satisfied. Do note the conditional there. I, for one, agree with Fake Name. \$\endgroup\$ – Vlad Sep 16 '12 at 17:47

This is an AC transformer, other than that it would be hard to figure out its specs without the circuit it came from, especially from a fired one. In the futre it is best to make as many measurements as possible in the circuit before removing it.

Aslo cutting it open may not have made a difference in testintg its resistance. If it was fried you may not have been able to determine its resistance anyway.

Why I believe it is an AC transformer, for a transformer to work, the current in one coil has to somehow make current flow in the other coil and the circuit it's connected to. A DC current in one coil will make a magnetic field on the other coil, but a magnetic field by itself won't drive any electrons around. A CHANGING magnetic field, however, does create an electric force which will accelerate those electrons in the other coil into carrying a current. This process is described by Faraday's law of induction. You get a changing field from an AC current, since the current which makes the field is changing.


I'm not sure the diameter of the wires will be too helpful, normally the diameter would indicate how much current it handles (thicker = more.)

However the ratio of the winding of the wire is very helpful. As a last ditch effort you could try to determine how many times the wire is wrapped around on each side. Also, since it seems you are really interested in possibly replacing this (as opposed to just being curious,) you could post some pictures of the device it came from and what the device is and does; and we can probably help you get it working again.

enter image description here

I looked up a few videos for you about transformers,

  1. Animated transformer video, this is slow with long pauses but seems informative.
  2. How Transformers Work
  3. DIY Build a transformer, you possibly could rebuild your transformer.

With this information, plus the incoming voltage of the device, you should be able to calculate the output voltage. This wont be easy, you will have to get a fairly accurate count of the number of windings on each side.

For example if the input side has 100 and the output side has 50, the ration is 2:1, so if the input voltage RMS is 10vAc, then the output should be 5vAc. Anyone reading this, please correct me if I'm wrong.

You may also try a distributor like Mouser and try to find one with the exact dimensions, but my guess is that there will be many different voltages that match that size.

  • \$\begingroup\$ So what's the visible difference between an AC and a DC transformer ? and a AC/DC ? From the dimensions its power should be 2.5W. I know something can be deduced from the diameter of the wires but dunno what or how. I contacted a dozen of manufacturers, no luck yet. \$\endgroup\$ – WaterBearer Sep 29 '12 at 4:40
  • \$\begingroup\$ @user2534 a DC/DC transformer will need more then two wires coupled inductively, two sets of wires wrapped together around a core will always be AC. \$\endgroup\$ – Kortuk Sep 29 '12 at 13:12
  • \$\begingroup\$ @user2534 see my update. \$\endgroup\$ – Garrett Fogerlie Sep 29 '12 at 17:59
  • \$\begingroup\$ How many turns is it likely to have ? if a thousand then I won't bother. Also how do I separate the windings from the core ? (I think they are around the centre of an "8") \$\endgroup\$ – WaterBearer Sep 29 '12 at 20:45
  • \$\begingroup\$ @user2534 From the picture I'm sure its thousands. You would have to carefully cut it up. I've never done it myself, so I don't know for sure. \$\endgroup\$ – Garrett Fogerlie Sep 29 '12 at 21:26

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