Really behind the "eight ball" on this one. But it's still active, so I might add some comments~~~
First off, the flat
copper sheet stock is a very elegant solution. I love it. Having built several "home made" transformers for my models, the wiring was small enough that everything fit so I never pursued things any further in that direction. I may build a couple just to play with the idea. I am "old school" in regards to transformers. I use "fische paper" anywhere something touches the core, the "figure 8" iron in the middle.
Comments now; first off: the insulation paper referred to is called "parchment" paper. Wife has several rolls in the kitchen which may well soon become (several -- 1). When warm weather comes back, it's too cold right now. Since the copper foil is so thin, there may well be a couple or three layers per turn. With the parchment paper between turns.
When I make the wraps on the core, I use a wooden "guide" on each end. A piece of dowel rod split down the middle and glued half on each side. This avoids sharp corners on the first layer of "whatever" copper is used, the most likely place for insulation to fail. I usually make what I need on the wood lathe but the basic idea is to split a piece of dowel.
The other comment is to try a copper foil from a surplus house. I use Marlin P Jones, there are many others. The foil is available in several widths, specifically one inch and half inch. Well, just under that at 25mm and 12mm. My biggest concern is low voltage at a moderately low current, just a few amps. But I need several sources that are electrically isolated. To isolate them magneticaly is acceptable, so long as there is no electrical connection.
Using the foil strips would allow several secondary windings to be wound on a single core. Using the narrow, 12mm, strips would allow me to "stack" more windings on a single core. The end result being one transformer with multiple windings. Instead of multiple transformers having one with multiple windings. Wiring is easy to dress, the cores not so much.
The theory, in my mind anyway, is to take two strips and stick back to back. The parchment paper for insulation on each turn. The 12mm(1/2") strip would make two coils, one on top of the other. Then two more above. All on one core~~~
That's my quarter's worth, here's hoping someone can use the information.
Bill Hudson
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