enter image description hereI salvaged this a transformer from a small 12v battery charger, it has 8 pins, four on one side have continuity one with the other, four on the other are two separate circuits, hope someone can help identify it and how to determine input and output, thanks

  • 1
    \$\begingroup\$ well, it's a transformer, with multiple windings. That's as much info you gave us - and that's all we can tell you. It's probably a custom-made thing for something like a flyback voltage regulator, and pretty much useless unless you want to build one that is similar in current and voltage as your original device was. \$\endgroup\$ Aug 6, 2020 at 10:59
  • \$\begingroup\$ Welcome to EE.SE! This appears to be a reverse engineering, modification, or repair question. Please be aware that such questions must involve specific troubleshooting steps and demonstrate a good understanding of the underlying design of the device being discussed, so that you can ask specific, focused questions that can be answered concisely. Otherwise, the question is far too broad. More information can be found here: Is asking how to fix a faulty circuit on topic?. \$\endgroup\$
    – Dave Tweed
    Aug 6, 2020 at 11:02
  • \$\begingroup\$ As the core material looks like ferrite, assume it's a high frequency transformer from a SMPS so you can't even apply low voltage 50Hz to the windings to see what it does. \$\endgroup\$
    – user16324
    Aug 6, 2020 at 11:42
  • \$\begingroup\$ Get waveform generator, apply 10-100kHz signal to one winding and measure the others to find out relative turn ratios. I'd repeat this process a few times to be sure. Then use an LCR meter to measure the inductance of each winding. Using the turns ratio from before you can then solve for Al of the core using Al*N^2 = L. OR you can just make your own. I guarantee you will spend more time messing with this one than it takes to design a brand new one. \$\endgroup\$
    – Stiddily
    Aug 6, 2020 at 12:09

1 Answer 1


If I wanted a transformer for a flyback converter, I'd probably go the Premier magnetics and they make dozens (possibly hundreds) and they are all different and look generally like these: -

enter image description here

The one on the left looks similar to yours but, it's a semi-custom made device with different winding ratios and different thicknesses of copper wire to suit a specific application such as these: -

enter image description here

And, if you clicked on the top link (DC to DC converters) you'd find a PDF document that lists about 50 variants.

If you clicked on the 2nd link (Off-line power converters) there are 8 sub-PDF documents listing designs numbering into the hundreds I would say so, there's no chance that your transformer can be recognized for what it is on this basis because: -

$$\boxed{\text{It's a custom made transformer for a specific customer}}$$

Even if you measured the inductances and wire resistances and recognized the polarity inversions between the individual coils you would still not know what maximum current to drive the primary with because the ferrite material would be largely unknown and also the operating frequency. You could take a stab at things and you might get lucky. Or, you do the sensible thing when wanting to make a flyback or forward converter and, that sensible thing is: -

$$\boxed{\text{Design it yourself}}$$

Throw away those transformers because they're worth absolutely nothing to nobody.


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