Is this water in the toroidal trafo ?

OK, the resistance of the windings drops more voltage than I expected, so using just a light bulb in series is not so wasteful. The only remaining advantage of starting with a lower supply voltage might be safety, but if you're careful then it should be ok either way.

Or you could short circuit the secondary of each trafo and put all of the primaries in series, with a resistance (bulb, etc.) also in series, and connect the whole lot to the 220VAC. The heating may not be identical in the different trafos, but otherwise I think it should work.

Chris

I have just noticed that Lostgallifreyan also suggested this.

Ah, I see what you're thinking now. I suggested the microwave oven/light bulb in response to this: "The sun has not shown itself for days, and is not expected to the coming days.

I am now looking for a suitable secondhand mini oven at ebay and such places."

I was not proposing it to compete with the technique of passing current through the windings - it was intended as an alternative to getting an oven from ebay.

Regarding effectiveness, how do you know it is far less effective? Have you dried toroids by passing current through them? Intuitively, I would also think current through the toroid to raise its temperature would be more effective at drying it than raising ambient temperature, but I have no experience with doing the former, so I can't estimate how much more effective it would be. That's why I ask.

But there has to be something to observe, so it is not clear what you have in mind.

Ed

ehsjr wrote in news:M%nzi.5167$6h3.2320@trndny05:

Past experience. :) What I do is look at anything, it might not reveal a useful point at the time, but anything recalled later when searching for clues or ideas helps. The various times I've tried to dry stuff in any way, the one common flaw was in extracting vapour from a confined space. Even with the fan, a working microwave can have vapour condensing on the walls, and it won't insulate against heat very well, it wasn't built with that in mind, as the contents absorb energy directly and heat doesn't get out to the walls that easily, let alone beyond them. That set of observations led me to think a microwave case would be good as a slow drier only, and even then, dependent on low ambient humidity and a lot of local heat for extreme drying.

If I needed an extreme drier in a self-contained case I'd probably buy a cheap portable dehumidifier and put in in a small cupboard with the stuff to be dried in front of its fan. I've got one and tried it, it's astonishing, far better than heat alone, and with far less energy used too.

Chris Jones wrote in news: snipped-for-privacy@corp.supernews.com:

:)

The nice thing about the linked primaries is that each provides limiting resistance for the other(s). Even with just two, both would have to fail to become dangerous, although there is a need to isolate the whole rig on a plastic shelf or something similar.

No. Just leave them in the vacuum. The water will diffuse out.

robert

The microwave idea is a option.

It gave me a other idea. The microwave is to a certain level prepared for small explosions. This means you can use it as a safety box for experiments. And still watch what is going on.

(I wrote the following before, but the message seems to be lost, so sorry if this is a duplicate)

I just did a experiment with a aquarium pump as vacuum pump. Put the aquarium pump INSIDE a plastic bag. Lead the blowing air tube and the power cord out of the bag. Seal the bag by winding wire around the plastic, tube and powercord. Then i put a foam tennisball in the plastic bag. And let the pump suck the air out. It works :-) But unknown what percentage of the air is sucked out. Here are two pictures, before and after the pumping.

It seems to work ! I put a trafo in the bag. After 2 hours of continuous pumping, no ON-OFF sequence. Picture 3 and 4 show the start and after 2 hours result:

It is a easy way. Aquarimum punp is not expensive, and can be found at secondhand markets even cheaper. A plastic bag is also cheap. And you do not need a real airtight seal. In my experiment air is pumped out all the time. This must mean somewhere air is coming in.