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Re: Request for help with air core transformer/power transfer system



Original poster: David Speck <dave@xxxxxxxxxxxxxxxx>

Dave and list,
Thanks very much to all who responded to my query about transmitting a little power through glass with analyses both simple and complex.


I have to admit to getting more than a little sentimental (or is it just mental?) around the holiday season, and I want to make a nice show scene inside an old (150 years!) glass terrarium jar. I have some small LED Christmas lights that I'd like to light inside the jar, but because of the age and value of the container, I'd rather not ruin it by drilling it. With my luck, it would break just as I finished the hole, anyway.
It would also be neat to lift the scene off its pedestal and have the nephews and nieces try to figure out how the lights were being powered.
There isn't time to experiment with the multi kHz arrangements, but I might take a stab at the doubled E/I core system. I only need a few volts inside the jar, so I don't think I'd need a lot of turns inside.
I think I'll try a couple of scrap transformers from MWO control boards. I must have 50 of them from salvaged ovens laying around. I'll see what kind of secondary voltages I can get with a 1/4" separation. I suspect that a larger core set where the width of the pole pieces is larger than the interposed gap would be a more efficient setup, but my space is a bit limited. Just have to give it a try.
Best wishes for a happy and healthy holiday season.
Dave


Tesla list wrote:

Original poster: "Dave Halliday" <dh@xxxxxxxxxxxxxx>

I would try two filament transformers with an E+I core system. Pop the I
lamination off and place them face to face.

Is there a reason you cannot go through the glass?  Drilling glass is
very doable. Use brass "hobby" tube as your bit and use 600 grit
abrasive powder and water (with a bit of soap) as the cutter - build a
dam out of toothpaste to contain the slurry.  Use a drill press and feed
very very _very_ slowly.  You can then use any manner of electrical
feed-through.