Induction Cooking Table : IGBT keeping to short !

melting 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.

market, at least with the old formula.

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.

I've done that with steel cookware on a stove, and in a glass casserole in the microwave. The must be covered to help hold in the heat, and let them sit about eight minutes, depending on the thickness of the pasta. In fact, I cooked some medium sized shell pasta in my microwave a few days ago.

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.

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

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.

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.

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?

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.

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 ;)

Actually I have a pretty novel idea I am thinking of trying to implement. A n audio amp with only one output device hopefully, if I can find a fast eno ugh 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 tria c I can use a bridge rectifier and do the same thing with a fast SCR, or ev en 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 you could 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 dam n close. Convertors for VFDs running off three phase mains, with no recitif ication. It was interesting anyway.

I might take a crack at it one day, the problem is designing the trigger ci rcuit, 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 i n my [discouraging] research I found there is another type of class D amp o ut there now, it uses active filters almost instead of analog outputs. The class D part always keeps a pretty constant voltage across the analog devic es keeping their dissipation down. The manufacturer claims efficiency nearl y as high as class D but without the sonic anomalies that those golden ears dudes 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 mentio n my idea except I DID find out that it is unpatentable. If perchance I eve r 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 o n 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 w ould like to do something with it. Maybe I could make a weapon ? I got some microwave parts hanging around for the same reason.

There are couple of transistors for drive the IGBT. replace those transistors and your problem will be solved.

Thanks