Electronics > Projects, Designs, and Technical Stuff
Power Supply Line Filter with Trifilar Windings
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duak:
Hmmm, the measured values are lower than I would expect.  It would then make sense that Apple had to use two stages to meet requirements.  Having participated in EMI testing, it would be interesting to see the test spectra.

I checked some of the parts in my collection and see they're all in the mH range.  I understand that because the line/mains currents cancelling, the core can have greater permeability giving a greater inductance without worrying about saturation.   I see that the later assembly has a greater inductance so perhaps the design was simplified with a component change.
JDW:
But as I said in my previous post, the part number labels on (1) & (2) are exactly the same (look at the photos), despite one being a trifilar and the other a bifilar. How would you explain that?
Phoenix:

--- Quote from: JDW on March 09, 2020, 09:47:00 pm ---How would you explain that?

--- End quote ---

Same potting box, different custom wound choke.
JDW:

--- Quote from: Phoenix on March 09, 2020, 10:38:29 pm ---
--- Quote from: JDW on March 09, 2020, 09:47:00 pm ---How would you explain that?

--- End quote ---
Same potting box, different custom wound choke.

--- End quote ---

I could have guessed that but didn't because it seems too odd to me that all those numbers on that label merely refer to a "potting box" instead of referring to what that component really is.
duak:
Welcome to production land.  Bills of Material (BOMs) and part numbers.  Buy parts, make parts, programmed parts, assemblies, subassemblies, ECRs and ECOs, Deviation Permits, running changes, versions and revisions, etc., etc...  I hear that in aviation, the paperwork can be heavier than the part.

Sometimes the part number you see isn't for the whole thing.  EPROMs for instance, have the original manufacturers' numbers on them but it's the contents that make them special.  The auto industry has no end of parts that can't be properly identified by the obvious part number.  A part may have a raw forging number but may be machined and heat treated differently.
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