Re: [EE] kapton thickness for transformer

Forgot the link to the November 1976 issue of QST with the Ugly
Duckling article :

https://www.worldradiohistory.com/Archive-DX/QST/60s/QST-1976-11.pdf

Best Regards,
Chuck, WB9KZY

On Thu, Jan 23, 2025 at 6:47 AM Chuck Olson <[email protected]> wrote:
>
> I only rewound one transformer, never wound one from scratch.  Lew
> McCoy had an article in November 1976 QST on the "Ugly Duckling" where
> he rewound an old TV set transformer for a low voltage (18 volt)
> output (can you say E I ?).  He left the primary alone and also the
> insulation over the primary.  The secondary windings were gauged by
> the number of turns on the 5 volt winding.
>
> My victim was a non-working Knightkit tube amp (KG-240 ?)  - it still
> works but it buzzes and the laminations do kinda warm up :)
>
> In these modern times I'd consider a design for a 3D printed plastic
> bobbin - usually the primary and secondary are two windings side by
> side separated by plastic - check the data for Tamura (or other
> brands) of transformers for ideas.
>
> If this is a toroid, yikes, good luck on that !
>
> There is a book on tubebooks.org on transformer design:
>
> http://www.tubebooks.org/Books/Lee_1955_Electronic_Transformers_and_Circuits.pdf
>
> Best Regards,
> Chuck, WB9KZY
>
>
> On Wed, Jan 22, 2025 at 10:53 PM madscientistatlarge
> <[email protected]> wrote:
> >
> > I'm building a large isolation transformer (1KW+-) on a laminated steel core.  How much kapton is typically used for insulation between the windings and the core, i.e. how many 1 mil layers (or 2 or 5 mill is also available).?  I know that surviving power spikes requires planning for 10KV+ surges.  I'm thinking 4 or 5 layers at 1 mill thickness?  Lets say the voltage is 250V (I'll also be using the output in series with the outlet to get "220" V).  I'm in the U.S. so power line is about 127V (they keep creeping it up to increase power levels).  Thank you.
> >
> >
> >
> >
> > "Human beings are the only creatures on earth that claim a god, and the only living thing that behaves like it hasn't got one.  Does the world belong to no one but you?"  The Lobster in "The rum diary"
> >
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