Re: [EE] kapton thickness for transformer

I thought transformer winding tape was usually polyester rather than
polyimide.

David

On Thu, Jan 23, 2025, 08:34 Chuck Olson <[email protected]> wrote:

> 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"
> > >
> > >
> > > Sent with Proton Mail secure email.
> > >
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