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

Well, it works.

The heatsinks were busted off the board as the solder down stakes broke free, at the PCB, can be reflowed with no problem or damage past that.

The think resonates at 100kHz with 12 volts in and no load. I was able to heat up drill bits, coins and other junk with no problems. Frequency drifted upto 160kHz with some materials.

With no load, the copper tube does heat up quite a bit, the caps stay cool and part number checks show they are in fact PP induction cooktop caps.

Will play some more with a scope and larger power supply and maybe water or air cooling for the coil. With so few turns winding up some litz wire would be pretty easy too.

The board is dead simple. If I saw it at hamfest, I'd have haggled to $20 or $25 tops, but whatever. It's fun so far.

Glass will melt in a microwave oven. So, probably an induction heater works too. However, it won't start from cold.

I heard about accidental glass-melting in home microwave ovens. So I tracked this down and duplicated the effect. It requires a "trigger," either a small particle of carbon etc. which heats up a tiny spot. Or, just use a torch to get it started. See:

Glass is an electrolytic conductor, and must be pre-heated to just below visible red glow. This frees up the ions, so any current-loops induced by high voltage will begin to couple some watts into the glass. At a certain temperature, the induction heater might offset the natural radiant cooling, so the temperature then rises exponentially until the conductive glass pool is absorbing a large portion of the magnetron output.

Also, red "lava rock" from under bushes, it will melt into black lava if torch-heated and then microwaved. Put it atop a tiny inverted ceramic flower pot.

In the microwave oven, martini glasses with gold-plated rims will self-start. Apparently the metal creates a large enough hot-spot that small patches of ionic conductivity take off and spread.

-wbeaty

Hah! Might work, but also might need a cooling jacket. Turn down the DC supply voltage. Also, might need a tesla coil "vacuum tester" to ignite the tube. Better: wind a copper-tube coupling-coil around the induction coil, then connect the ends to the CO2 tube's existing terminals. But, will AC high-freq give same effects as DC which the tube expects?

I noticed that during airplane trips, always my creativity would peak about

20min into the flight, then slowly decrease. I always carry a blank book to record the resulting spew of ideas. (Do others know about this? It was the origin of mechanical maglev demo, the high speed copper pipes machine.)

Years later I heard an archeology lecture: Apache tribal shamen would mark certain caves with a special glyph symbol, and those "secret holy caves" turned out to be always radioactive. A pre-Columbian radiation symbol. Radon sources. Supposedly they convert meditation into visionary experience.

So, do cosmic rays cause altered mental states? Nikola Tesla said yes, after sticking his head in the beam many hundreds of times. (That explains so much!)

As the aircraft rises, the local cosmic ray flux goes to a peak. 5mi altitude has very significant ionizing radiation (your geiger counter will roar, fifty counts per second for a small GM tube.)

I have some orange radioactive dinner plates. But I haven't tried attaching them to my head like headphones. Maybe we need muons and far gammas, not just yellow uranium compounds. I will stay with cross-country plane trips for my periodic whole-head gamma dose.

The ultrasound beam passes right through tissues, and probably creates a serious hotspot on bone surfaces. Yeesh. Also, burns in 3D cannot be rapidly cooled like skin surface burns. The "cooking" may last for many seconds, unstoppable.

"I pray nightly that I never suffer an internal burn." - Nikola Tesla

Also on eBay, search 2000W induction. But 220VAC. Maybe works fine at 1

20V, and 500 watts output>

Perhaps use a layer of RTV silicone caulk as a match? Or perhaps epoxy? Something with sound velocity between ceramic PZT and water.

Excellent!

Also, focus your beam down to diffraction-limited spot, metal mirrors or lens made from ?melted PE? or epoxy, in a glass sphere-flask with some mold-release spray? Never tried it.

Also, produce controlled low-power cavitation using a microbubble generator to provide initial "seed cavities," so no need to over-drive the water to produce spontaneous cavitation like a hydrogen bubble chamber.

Those ultrasonic humidifiers and "Mist Makers" run at a little above 1MHz. Just stick a scope probe in the water, and it produces enough mV to see the drive period. I aim these upwards in the aquarium, with a block of steel a few inches above, and when the separation is right, a nodal pattern of thin bubble-regions appears. Either it's cavitation, or it's just node-trapping the existing micro-bubbles in the water, and then growing them via degassing effect. Also, aim the beam to cross a meter-wide aquarium and strike a piece of thermal-colors liquid crystal sheet. You can write on the sheet by moving the distant transducer.

Rumor: oxygenated water full of alcohol or methane will, during cavitation, produce acoustic pulses during high pressure part of the cycle. A tiny diesel engine! Is that familiar and known?

Heh, that's where I should look up the micro-diesel engine. Try making a micro-combustion-powered acoustic "laser," where the "stimulated emission" is collapsing cavitation bubbles full of flammable gas mixture?

On a sunny day (Thu, 3 Dec 2015 00:40:59 -0800 (PST)) it happened Bill Beaty wrote in :

Now that is a new idea for an altitude based bomb trigger... Only had coffee just now at zero altitude... :-)

I will stay with my Sennheiser HD201, cheap and decent headphones. Professor Sennheiser died a few years ago, so get one while you can.

In fact I keep that radiation stuff well packed away and only take it out for experiments. Things like radioactive watch hands etc can easily crack and the dust inhaled. The reason I made it to this age is probably that I always have been a bit careful.

I know airline pilots get a lot of rad dose.. They still seem to get old though.

On a sunny day (Thu, 3 Dec 2015 00:24:02 -0800 (PST)) it happened Bill Beaty wrote in :

PS

Here:

something like that it was.

Tracking is pretty easy to start on glass with any sort of arc across the surface.

Hey Cydrome, what did you use as a power supply, (and how much current?) My son has been trying to heat treat metal (knifes) with a blow torch and I think he needs hotter.

George H.

I've got a Dayton arc welder in the barn...? ("DC" and AC) Or is that too big? GH

get some fire bricks and build something like this:

-Lasse

Yeah, he bought what looks like the small one of these,

for ~$100, (I think)... We've got a lot of wood.

George H.

On a sunny day (Thu, 3 Dec 2015 00:24:02 -0800 (PST)) it happened Bill Beaty wrote in :

PS, inductive heater board arrived.

Do not have proper size (6 mm) tubing around. So far testing the MOSFETs with a multimeter seems OK. Maybe later I will run it without cooling, bit busy now. The screws were too long for the holes in the copper pilars, and the threads damaged, but it _just_ fits. I also spaced the turns in the coil so these do not short each other. Maybe weekend.

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

OK, follow up, could not resist testing:

This is the item:

This is the test setup:

Using 3 of these set to 8 V in series:

Works very nice, that is a backplate for a D connector for a PC that I use as mall for D connectors...

No unexpected fireworks, no strange things, but I was very careful... I tried solder wick with solder, that does not get hot. I tried solder by itself and that does not melt, need a metal or carbon container for a solder pot I'd think, But great value for money, really cool gadget, 24 V battery on boat and you have 24 V cooking too. (different coil) to bake eggs or fish, without converter, better efficiency.

Fun:-)

Thanks, I order one of these too, (but I still don't know how I'll power it.) Does it take the whole 20A at 24v? (I've got a 20V 10A supply.) I like the idea of two car batteries in series... "Sorry honey no car today, we're induction heating"

Maybe with a current meter in series?

George H.

On a sunny day (Wed, 9 Dec 2015 10:01:19 -0800 (PST)) it happened George Herold wrote in :

I think not, but of course it depends on the load. I left out the amp meter as I was worried the extra lead resistance would drop the voltage too low. Maybe you did see the youtube video of the guy who blew one up?

So this is my take:

1) Check the copper pillars on the board, the screws are too long, or the thread in those too short, replace or cut so it actually is fixed to the board, avoid bad contacts. 2) Create spacing between the turns of the coil, mine were packed close and touching, else you get shorted turns. 3) Do not use a slow ramp power supply, I switch on supply and _then_ connect the circuit. 4) Do not start it with a load already in the coil, as then it may not start oscillating and blow a MOSFET. 2 11.1 V RC lipos should work too.

Yes, contemplating how to build this into some box I ordered this:

cannot make it for that money, see circuit diagram at bottom page.

Yup, that all makes sense.

Wow that is cheap. I've got some old Hoyt galvanometer/ ammeters. I was thinking a current shunt acorss one... but the 5 milli ohm shunt is a dollar or two.

George H.