Induction Cooking Table : IGBT keeping to short !

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Actually if they can really penetrate the non-ferrous they can heat the food directly. I gues an upside down microwave or something.

Hell, it might be all the rage range now because your steak heats the pan, not the other way around.

By now you know most of that "Visions" type cookware got recalled right ? The stuff exploded on a few folks and they went back to metal pots and pans.

Funny what it takes to induce common sense sometimes eh ? My Mother had them but got rid of them over that shit. Really, they would probably be alright for boiling and casseroles etc, but I think trying to fry crispy chicken in a glass pan might not be the smartest idea.

But then lead could be put in the glass, or barium. Maybe it would glow or something.

Colored glass I guess in a way could be considered "doped". A study of the various types' reaction to bombardment like this would be intereasting.

 

[cLx]

That Fairchild design note I alluded to in an earlier post discusses
several topologies (including the OP's), all of them based on
resonance principles. The resonant frequency was chosen as 24kHz while
the operating frequency "of the system is set at 28kHz, which is
higher than the resonance frequency, in order to avoid noise generated
within the audio frequency band".

When it was brand new, i've measured the frequency at ~35KHz, modulated by
100Hz (double rectification of the mains' frequency).

See:
http://clx.freeshell.org/view.html?f=Tech/induction/img_0809.jpg
http://clx.freeshell.org/view.html?f=Tech/induction/img_0812.jpg
http://clx.freeshell.org/view.html?f=Tech/induction/img_0813.jpg

 

[William Sommerwerck]

By now you know most of that "Visions" type cookware got recalled,

right? The stuff exploded on a few folks and they went back to metal
pots and pans.

I've been using Corning glassware and Corningware for years, and have never
had a piece break while cooking. Dropping them is a different matter.

 

[[email protected]]

"When it was brand new, i've measured the frequency at ~35KHz, modulated by
100Hz (double rectification of the mains' frequency). "

So they don't bother filtering, like a microwave. Hmmm.

"I've been using Corning glassware and Corningware for years, and have never

had a piece break while cooking. Dropping them is a different matter. "

Visions were different. Some sort of superglass. The commercial showed themmelting a conventional metal pan in their glass pan. I would imagine it was not stainless, IIRC the melting point is quite high compared to aluminum or steel, or cast iron.

But these things didn't just break, they exploded. They are no longer on the market, at least with the old formula.

It is pretty cool to be able to see what you're cooking like that. There was always Pyrex as well. One of the things visions touted was an extremely high thermal mass. In most cases if you wanted to cook say spaghetti, once it came to a boil again with the pasta in the water, you supposedly could shut the heat off and it would cook fully.

 

[William Sommerwerck]

I've been using Corning glassware and Corningware for years, and have

The older stuff was real "Pyrex" [borosilicate glass]. Now they use "soda
glass" and call it "Pyrex". Soda glass will explode if heated unevenly.

I complained about this a few years ago, and was told that the newer glass
was as good. I doubt it.

Several years ago I dropped a Visions baking dish and it shattered like you
wouldn't believe. (I'm still finding the pieces.) Corning paid the postage
to return it, but they never told me what they found (if anything). They
made no offer to replace it.

See the Wikipedia article on Pyrex, section on Composition.

 

[Phil Allison]

"When it was brand new, i've measured the frequency at ~35KHz,
modulated by 100Hz (double rectification of the mains' frequency. "

So they don't bother filtering, like a microwave. Hmmm.


** Microwave ovens have similar line frequency modulation and for the same
reason.

The high voltage PSU is not filtered.

Electronic transformers for 12v halogen lighting are the same too.


.... Phil

 

[Cydrome Leader]

I've been using Corning glassware and Corningware for years, and have never
had a piece break while cooking. Dropping them is a different matter.

beware that anything made in the past some years isn't what it used to be.
it's just some sort of cheapo fake stuff and not the real pyrex as used in
labware.

You can even tell from the color of the stuff that it's nothing more than
melted bottles and windows.

 

[Cydrome Leader]

The older stuff was real "Pyrex" [borosilicate glass]. Now they use "soda
glass" and call it "Pyrex". Soda glass will explode if heated unevenly.

I complained about this a few years ago, and was told that the newer glass
was as good. I doubt it.

Several years ago I dropped a Visions baking dish and it shattered like you
wouldn't believe. (I'm still finding the pieces.) Corning paid the postage

I wattched a Visions lid from the large pasta pot get dropped recently
onto a wooden floor.

I would not doubt there was more energy stored in that lid than just it
falling into the ground. It din't break, it became hundreds of pieces, but
sharp ones unlike a windshield.

We noticed that those 1980s white corningware plates with the yellow
printing on the edges were unbreakable when new, but became extremely
brittle over the years. They seemed to heat in the microwave oven, so
maybe that has something to do with it.

The extra plates and bowls from the set that never really saw use can
survive a kitchen floor drop test. The rest just shatter.

to return it, but they never told me what they found (if anything). They
made no offer to replace it.

Did you send it to the real corning or the fake place called "world
cookware" or something like that that now just licenses the corning name?

 

[William Sommerwerck]

Corning paid the postage to return it, but they never told me

Did you send it to the real Corning or the fake place called "World
Kitchen."

The latter.

It's not actually fake. According to the Wikipedia article, World Kitchen
was originally Corning's Consumer Products division.

I'm bothered by companies buying up trademarks, then applying them to
products that have no connection with the trademark's original usage. Pyrex
is a good example of this bad practice. So is Accutron. Modern Accutron
watches do not use a tuning fork.

 

[cLx]

** Microwave ovens have similar line frequency modulation and for the same
reason.
The high voltage PSU is not filtered.
Electronic transformers for 12v halogen lighting are the same too.

No big DC filter capacitors means you'll not have huge peaks two times by
mains cycle. Better power factor, in fact, it's almost itselfs a PFC

 

[[email protected]]

Actually I have a pretty novel idea I am thinking of trying to implement. An audio amp with only one output device hopefully, if I can find a fast enough triac type device (a few kinds would work). Would advance the phase of the triggering pulses according to input and switch off automatically when the HF power cycles. No filters or even rectifiers. If I can't do it a triac I can use a bridge rectifier and do the same thing with a fast SCR, or even a tansistor. The only advantage to a transistor though is that it would be switching off at zero crossing all the time. Still no filters.

It would have all the problems of a class D amp but less components and youcould probably use slower output device(s) or a higher frequency.

I almost decided to patent it but I found some things that are just too damn close. Convertors for VFDs running off three phase mains, with no recitification. It was interesting anyway.

I might take a crack at it one day, the problem is designing the trigger circuit, there is not going to be a chip that'll do what I want - yet.

But we are talking more efficient than class D if I can pull it off. Also in my [discouraging] research I found there is another type of class D amp out there now, it uses active filters almost instead of analog outputs. The class D part always keeps a pretty constant voltage across the analog devices keeping their dissipation down. The manufacturer claims efficiency nearly as high as class D but without the sonic anomalies that those golden earsdudes can hear.

The days of linear operation may really be at an end. Don't even bother to rectify or filter ? Chop chop chop, nary a watt dissipated.

Enough commentary now, we can start a thread for that. I would never mention my idea except I DID find out that it is unpatentable. If perchance I ever do build the thing I will get a provisional patent and see which way the wind blows. It's only a hundred bucks.

Of course I think in that case every Eurasian engineer out there will look at it and by the time I get to market there will be three products like it,two challenges to the patent and more legal bills than I could ever make on one product.

Such is life. I need to look for something even wierder to build.

Speaking of which, I happen to own one of those induction cooketops and I would like to do something with it. Maybe I could make a weapon ? I got somemicrowave parts hanging around for the same reason.