this post was submitted on 19 Aug 2023
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In a transformer, why are both coils apart from each other? Wouldn't make more sense to have the ferrite core (tube shape), wind the primary coil around that and then wind the secondary coil on top of the primary? So that the magnetic fields are as close to each other as possible?

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[–] [email protected] 8 points 10 months ago

That does actually exist, it's called a toroidal transformer. Instead of a tube shape though it's a donut shaped piece of ferrite with the primary and secondary wound one on top of the other. The different types have different use cases though, as far as I remember the toroidal ones have higher leakage current. Marco Reps has a good video on his YouTube channel where he explains some of the differences if you're interested, although he mainly focuses on what's important for precision electronics.

[–] [email protected] 6 points 10 months ago

I'm not sure I understand your proposed solution, but the ferrite core guides the magnetic flux, there are very few losses, and both circuits are perfectly electrically insulated from each other. How would your solution be an improvement?

[–] [email protected] 4 points 10 months ago
  1. Insulation. Physically separating the two sides makes sure there are no issues.
  2. The difference in magnetic fields distance is fairly irrelevant with a core that is really good at "conducting" magnetic fields.
[–] [email protected] 3 points 10 months ago

The coils in EI-core transformers are all wound around the middle leg. My last build had five separated coils: primary, 520V, 80V, 25V, 6,5V.

[–] [email protected] 2 points 10 months ago
[–] [email protected] 0 points 10 months ago (1 children)

It's all about the lines bro, the lines.

[–] [email protected] 2 points 10 months ago

Charlie Sheen has entered the chat