Steel melter for forty bucks? Needs a KW dc supply. Also $1 100nS 30KV! Also ALSO!

the resistance of iron is 7x that of copper, the skin depth of iron is also ~1/40 of copper so the resulting resistance gets much higher

that's what the guy in the you tube video did, he also managed to melt aluminium in a graphite crucible

-Lasse

On a sunny day (Wed, 9 Dec 2015 15:42:04 -0800 (PST)) it happened Bill Beaty wrote in :

Yea, some experiments coming up over Christmas I'm sure.

First thing I want to build in is a protection against power failure and then power slowly coming up, was thinking about a big thyristor:

thyristor

• -----------|>|---- load | \ |--||-----\ -- | | button --==-- R

Normally when power rises, the thyristor is off. Press the switch (moment) and C discharges into the thyristor gate and you have power. If power fails then comes back the things stay off. And 20 A thyristors plenty.. but it drops some voltage.

But indeed if I want to add some features then a simple MOSFET in the supply gives better control. There is a long list of experiments, and experiments one should NOT do ammo no. magnesium sheet?

Pity I no longer have that helium neon laser tube. Will think of something:-)

On a sunny day (Wed, 9 Dec 2015 12:12:45 -0800 (PST)) it happened George Herold wrote in :

I have been experimenting with different materials today.

This youtube video (cannot understand the language) has some scope shots:

it shows with those coil spacings the frequency is about 100 kHz, and lowers under load. I have bend the coil turns a bit outward, so probably higher, will measure it later.

Also I ordered (big spending) a carbon crucible:

The smallest one...

I noticed I can get solder to sort of melt by making a loop (one turn), same for putting solder wick in a loop.

Alu strip does not even get hot, it seems the stuff has to be either magnetic, or form some sort of turn. maybe that is why the crucible gets hot???

Carbon rod (from pencil) stays cold, but maybe it is not really carbon. I have one real carbon rod left that I used for magnetic levitation that I do not want to offer.

Real carbon rods seem hard to find, old 1.5 V batteries had those.

Made a crucible from a big iron bolt with 2 nuts on the end, that works. Better use a stone or something to do the experiment on :)

And here is a even cheaper version at 5 MHz:

circuit diagram:

That is a lot like what I did in the sixties, but then with tubes and a real driver (also tubes).

But it shows that it does not have to cost a lot.

I am still looking around on the web what others have done using induction heating. Finding all sorts of interesting things. Of course at 5 MHz or so you need to be aware of any RFI you cause. I killed transistors laying next to it in a box metal that way. But 4 sure a low budget solution.

On a sunny day (Tue, 08 Dec 2015 16:15:43 GMT) it happened Jan Panteltje wrote in :

After some thought and the realization that the heat is generated by current induced in a shorted turn, I got a metal cap from a Bertolli olive oil bottle, mind you remove the plastic washer first, this cap seems to be made of thin aluminum? Good green paint too (hope it is not whatsit? cadmium based), and YES, solder melts in TWO to THREE seconds!

Tomorrow (tm) I will fill that cap with solder and run again. Now how's that for cheap?

Apart from the whole house stinking of burned olive oil and -plastic yes that seal.

3 seconds, my goodness.... And the solder does not even stick to that cap.

Speak of cheap, before paying for carbon crucibles, instead buy blocks of bulk graphite by the pound. Chop it into tiny cups using a power saw and dremel tool. (I haven't tried this yet. But carbon cruicibles are probably just graphite.)

ebay Search: graphite block glass ebay Search: edm graphite

Or, I find $3 for 40mm graphite cup:

On a sunny day (Thu, 10 Dec 2015 14:11:06 -0800 (PST)) it happened Bill Beaty wrote in :

I already ordered one, see my other posting in this thread, but as that takes weeks sometimes to arrive, wanted to test the shorted loop theory.

Need some mechanical temperature control, maybe have a RC servo move the crucible in or out, or simpler move the coil up or down over it.

^ []IR temp meter | [servo }-------[ ] coil \./ crucible with solder something like that perhaps.

Found a better crucible, it is the alu cap that holds the spring from the soldering stand of my LS50 soldering station. :-) That cap is not needed (it never catches any solder anyways), so now tried it with some more pieces of solder scrap I found:

A little more than a minute and a half or two before it all was very fluid, stuck a copper wire in it.. It stays fluid quite long (minutes). Tried to tin some wire with mixed results, this solder was not very clean an 60/40 mixed with silver ROHS stuff, plus some plastic I guess, and dirt.

But it works.

I was sort of expecting as the cup filled up, that the part that forms the 'shorted turn' that creates the heat, to become smaller, and this seems to give an automatic temperature stabilization? I mean if it is full there is no more shorted turns, provided the solder makes good contact. need to really measure current.

Probably not as good as measuring current, but you could make a pick up coil from a few turns of wire and set it next to / near the big coil. I kinda expect the amplitude to drop as you load it.. but I don't know how much.

I've got a ~70MHz RF drive for a Rb bulb and that drops by 1/2 or more when the bulb turns on.

George H.

Ooo, can you destroy aluminum using liquid solder? Mercury or gallium will turn aluminum into gray powder. LMI liquid-metal embrittlement. But I think it has to "wet" the oxide-free Al first, like molten zinc does. Perhaps tin/lead won't do it.

Generally the first time you mill or cut a graphite block at home is the last.

Nasty fine black dust everywhere, and it dulls saw blades.

I do lathe down graphite welding/cutting rods to make small crucibles, but I would seriously rather buy them.

SWMBO will scold you and give you two supervised weeks of being Dr. Bunsen HoneyDo, if she ever saw what happens when you dry machine graphite without it being wet or near a serious collection system.

Steve

On a sunny day (Fri, 11 Dec 2015 12:49:07 -0800 (PST)) it happened Bill Beaty wrote in :

Yes, I did notice the alu crucible has somehow become weaker, I pressed it and it was easier to bend, i.e. it collapsed :-) had to bend it back in shape again. A carbon one is ordered (3 $).

Any next test will have to be above something to catch molten solder in. Talking about molten solder, of course (:-)) I tipped it over at some point while lowering the coil around it, and a whole bunch of fiery sparks appeared as molten solder shorted turns in the coil. I switched off very fast.. No damage done apart from cleaning the coil an filling up the crucible again. But all that is just normal procedure no?

:-)

On a sunny day (Fri, 11 Dec 2015 14:18:45 -0800 (PST)) it happened snipped-for-privacy@gmail.com wrote in :

Yea, for 2$39 inclusive shipping of course:

And then you can melt even hotter things, like maybe GOLD?

Heating should not affect the nucleus until you pass millions of degrees.

I doubt that your RF has a wavelength short enough to interact with the nucleus either!

Clifford Heath.

While looking for things to melt I came across my Thorium welding rod collection. These are a bit [radio] active on the Geiger counter.

One question that came up is: Will decay rate change in a RF (heating) field?

So to see if I could measure this easily (without high power RF messing up my Geiger counter) I uses a Zns scintillation screen to try to see if there were any flashes from those rods. Unfortunately after spending half an hour in the near dark bathroom I did not see any flashes...

Should be alpha, say Helium ions...

Thorium welding rods, Thorium lamp mantles, you know,

But: Tests: Thorium welding rods do not heat up in the coil... And heating them up still does not show any light flashes on the screen.

Should try that Geiger counter again.

And that, was only part of all alien Xperiments today.

I have also recorded some movies that I did not have time to watch, RED [2] one of them, it stands for ... Maybe I should watch it,. Maybe

mm Suggestions? OK, no forget it. ;-)

Can guess

Probably tungsten TIG rods, with ?1% thorium. Not very hot when compared to the powder from burned lantern mantels.

Once I had someone try to cut a TIG thorium rod with an oxy torch, thinking to avoid radioactive grindings. Uh, no. SUDDEN BIG YELLOW CLOUD of tungsten oxide smoke. Mmmm, smells like alpha particles.

Actually we dropped everything, rolled up all the big overhead doors while fleeing outside.

Practiced habit: breathing outward continuously while fleeing. Only take a breath far upwind, to check whether you're out of the plume. Learned during the bygone age of big opaque clouds of bus engine exhaust, also fireworks, also cooking experiments involving dry chili peppers in overheated wok oil (an invisible tear-gas.)

On a sunny day (Sun, 13 Dec 2015 23:23:43 -0800 (PST)) it happened Bill Beaty wrote in :

Yes I use that technique when soldering, the fumes seem to come after me sometimes... [1] Anyways, thanks for the warning, will leave those rods alone for a while. The big copper coil is by now somewhat colored copper getting darker. MOSFETs stay very cool, body temperature or less. Quite satisfied with this thing.

[1] especially when burning insulation of transformer wire, I have read these fumes are poisonous. Those people who use thin transformer wire for prototyping use that, I do not want that.

Wanted to test some more things, and looking forward to baking some eggs, and maybe fish, made a spiral coil, as many of you suspect it was ever since I was abducted and the aliens .. but that is an other story, anyways their math goes like this: I took length of the copper tubing in existing coil, (1 meter ) and as litz wire was way too expensive, even on ebay, I used 2 heavy gauche wires in parallel of the same length.

. Anyways, smoke! hey but the coil did not get hot, where does this smoke come from? I tested it on the PCB for thermal insulation, as before. Well picked up the peeseebee, and it was freaking hot, turned it over:

OK, that explains it, seems copper works too on a spiral coil! Who would have thought that? In case you think of soldering that way, not sure the components like it. it is not very even either. So, mm BAD burn, all the way through to my glass table, glass still OK:

After setting the exhaust fan to maximum, and it still smells, and mind you this happens in just a second! these kind of things,

testing without the PCB, and with a steel spoon if it would burn water: The alien calculations worked:

I bet you could charge your iPhone in seconds with that..

--sp

--
Best regards,  
Spehro Pefhany 
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