New power MOSFET makes solid state microwave oven possible: In German:
It tsays 'Midea' will make a 600W microwave oven with these MOSFETs, about same efficiency as a normal one, but switchmode power suplly, so probably a lot lighter.
The MOSFET specs:
"Internally matched." Bummer. That makes it a lot less useful for broadband/time domain use.
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Magnetron-1624974.html
The ratings are for a linear amp. I wonder if the oven is going to do that, or if they're running it class C (and how badly matched it is when you do that).
Our microwave oven uses a switcher supply (at least it proudly proclaims that it does), and magnetrons seem to be pretty damn cheap and reliable these days. For that matter a magnetron is a small fraction of the mass of a microwave oven -- the transformer is a good part of it, but much of the rest is case and fan etc. Somehow I think it'll be a while before we'll see solid state microwaves everywhere.
-- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
Jan Panteltje schrieb:
But a very effective cooling of these MOSFETS will be necessary to get out about 200 W of thermal (and wasted) energy.
Bye
2000M20228&fromPage=3Dtax s
of
have a at work that has stick that says it is a switcher, haven't lifted it but the only different I see is that it has a very noisy fan that runs for quite a while after it is done
-Lasse
But what % of the cost? Unlike semiconductors, the price of mechanical parts like magnatrons do not rapidly fall with large volumes.
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If I were to replace my 1200W microwave with a 50% solid state one, Ignoring everything else, I'd need 2400W / 28Vdd = 86Amps. That has its own set of challenges.
There are microwave ovens with switching power supplies and no heavy transformer (Panasonic, for example). Weight is dominated by the metal housing and glass turntable.
Of course they do (and have). They have fallen by orders of magnitude in real terms. That's how ovens have dropped from maybe $10K in real terms to (in some cases)
RF semiconductors are way spendy. Maybe Freescale is making some that'll be cost effective in a microwave, even after you figure out how to make that cheap 50A supply.
Maybe not.
-- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
And the allowable operating temperature is not nearly as high as the magnetron's, making the heatsink far less efficient per CFM of air blown over it.
What's the bottom-basement consumer price on a 1kW computer supply these days? $50 at best? There goes your whole budget, without even buying a single RF transistor to use that low-voltage supply. Unless they're going for exceptionally small size (unlikely given the heatsink requirements??), I don't see this becoming competitive!
Tim
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No, it's not for the basement boys. It's for the over paid, under worked, don't get out much person that thinks the world owes them, even more.
Seems to be a lot of them in the Bank, Gov. and federal reserve business.
Jamie
of
Compared the price of a MRF454 with a 6146B 30 years ago? Or today? :-)
Tim.
For sure an Escalade needs a microwave (as well as an ice maker, gun safe and a chest freezer) but I can't see them getting to 1500W easily with transistors.
Best regards, Spehro Pefhany
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At one of the CES eons ago, some company from France was demonstrating a hot water tap for use in a car. The hot water would come out of tap on the dash. Needless to say, this never made it to market.
I do some road trips, and I sometimes want hot coffee in the middle of nowhere. I was in a truck stop and found a 12V coffee maker. In actual operation, it was terrible. It pulled so much power out of the battery that you had to keep the engine running. Even then, a few cups took about half an hour.
So I wonder what is the most efficient way to boil water from a 12V 15A source (180 watts).
For heating water in the boonies, there is little substitute for a stove. Esbit, naptha, etc.
..so one uses 6 or so in parallel for the gallon of RF to cook corn for buttered fluff?
On a sunny day (Mon, 25 Jun 2012 21:32:00 -0400) it happened Spehro Pefhany wrote in :
Thing may get cheaper when using 2 strings of 5 at 24 volt in parallel. No switcher...
1 coaxial fan to pull 1 kW of heat out, total cost in China 20 $ :-) The heat can actually be used in a combi.It would also make a great WiFi amplifier :-)
?On a sunny day (Mon, 25 Jun 2012 21:14:51 -0700) it happened miso wrote in :
I had a litle gas burner (with camping gas tank) to make rice in the boonies. One day I got a new gas tank, and after it drilled the hole it would no longer close, left it in an empty area to gass out, OH PLEASE do not smoke here, leaking gass tank! I am still alive.... I prefer electricity over gasses any time, at least I know hot to handle that.
er
business.
Most efficient? Maybe some sort of heat engine to get it to ~60C and simple I^2*R heating to 100C? Not the cheapest though. :^)
George H.
Brings back memories of pumping up a Coleman petrol (gasoline) stove at a campsite and hearing a little "pssweee..." noise just as I was about to light it. The tank had rusted through and developed a pinhole.
...and the time I cross-threaded the carbide chamber on an acetylene bicycle lamp and then lit it before realising my mistake....
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That calls for a combo, convection/microwave oven. :-)
Mikek
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