Re:Microwave Oven Diagnostics with Indian Snack Food
by joezydeco on Saturday February 28, 2015 @02:24PM
(#9124696)
"Did you know that if you take apart microwave ovens, there is a really great ceramic magnet inside of the magnetron?"
There is also beryllium oxide in the ceramic insulators of most magnetrons. If the insulator cracks or is broken, that dust is highly toxic if inhaled.
If you want a nice magnet, there are safer ways to get one. Leave the magnetrons alone.
Re:Microwave Oven Diagnostics with Indian Snack Food
by cellularmitosis on Saturday February 28, 2015 @03:20PM
(#9124890)
Anytime I see someone mention hacking on magnetrons, I feel it my duty to remind us that the back of your eyeballs don't have pain receptors. If you were to power up thatagnetron outside of the microwave and point it at your face, it's possible you'd blind yourself before you even realized you were in danger.
Re:Microwave Oven Diagnostics with Indian Snack Food
by weland on Sunday March 01, 2015 @09:54AM
(#9127200)
Just wanted to add something. Itching is the first sign. If you feel itching in your eyes, turn the damn thing off immediately. I nearly blinded myself when I was an idiot undergrad. Kids, take the idiot adult's advice and don't play with it before you understand the theory and working principles extremely well.
Re:Microwave Oven Diagnostics with Indian Snack Food
by stenl on Saturday February 28, 2015 @04:24PM
(#9125113)
And the front (cornea) has more pain receptors per surface area than any other part of your body. Not that this would necessarily help prevent cataracts if you expose your eyes to a magnetron.
Re:Microwave Oven Diagnostics with Indian Snack Food
by bjelkeman-again on Sunday March 01, 2015 @03:22AM
(#9126436)
I didn't realise this until I had laser surgery to correct a cornea problem. Oh dear, two days in a dark room on morfin, before I could even think straight again, no fun. But now I can see better again.
Re:Microwave Oven Diagnostics with Indian Snack Food
by 13 on Saturday February 28, 2015 @11:01PM
(#9125995)
It's also a problem that there is no blood flow through your lenses. If you heat them via microwave radiation, they're going to stay hot for an alarmingly long time.
Re:Microwave Oven Diagnostics with Indian Snack Food
by foobarian on Saturday February 28, 2015 @02:59PM
(#9124821)
No doubt the material is toxic, but it doesn't seem breaking it would create a whole lot of dust, similar to any other ceramic. You'd have to machine or sand it.
Re:Microwave Oven Diagnostics with Indian Snack Food
by x0x0 on Saturday February 28, 2015 @07:35PM
(#9125596)
I read the Beryllium oxide page and found this interesting note:
Formation of BeO from beryllium and oxygen releases the highest energy per
mass of reactants for any chemical reaction, close to 24 MJ/kg [1]
and this comment would be incomplete w/o sharing the findings of my wikipedia browsing which lead to making plasma in microwaves with grapes. https://www.youtube.com/watch?v=RwTjsRt0Fzo
Re:Microwave Oven Diagnostics with Indian Snack Food
by cmurf on Monday March 02, 2015 @12:42AM
(#9130475)
When I was 12 I disassembled a microwave, unplugged from the wall, and got electrocuted. Not the visible kind like from static or from an outlet, but... I don't know how to describe it. Inside was a boxed case the size of a Kleenex cube, and my hand, palm side, just got sucked right on it like a magnet and bam I nearly passed out and fell off the chair. That was the end of playing with microwaves for me.
edit: nevermind, didn't realize they kept the 'plate spinners' on during the experiment. The rings in the appalam are artifacts from rotating an anti-node through the food. would have to do something different to get equal heating using ~two points vs. a line
Re:Microwave Oven Diagnostics with Indian Snack Food
by SomeCallMeTim on Saturday February 28, 2015 @04:49PM
(#9125185)
Like a slow-speed random orbit sander? :) [1] Some of the dead areas looked too big for even that to help, and it would mean the maximum plate size would be smaller. Hmm...
OK, I'm going to say that the right answer is to move the microwave source linearly (or change how it's aimed? Or otherwise change its focus) at a frequency that would maximize even coverage of the heating area based on the rotation speed of the turntable.
Another (more limited) possibility is a way to mount a fixed spoon that could stir soup or other appropriate liquids while the bowl turned.
Re:Microwave Oven Diagnostics with Indian Snack Food
by chris_va on Saturday February 28, 2015 @03:41PM
(#9124969)
This is actually a fun way to measure the speed of light. You can measure the wavelength by looking at the distance between the bubbles. That plus the operating frequency of the microwave will give you the phase velocity.
Re:Microwave Oven Diagnostics with Indian Snack Food
by anigbrowl on Saturday February 28, 2015 @05:59PM
(#9125375)
I got rid of mine several years ago and have never once found myself thinking 'gee, I wish I still had a microwave.' You know what takes up less space, saves money, and provides constant utility, which most American kitchens don't have? An electric kettle. The most appliance-happy country on earth (except maybe Japan) and you still boil water on the stove like it's 1815.
Re:Microwave Oven Diagnostics with Indian Snack Food
by jedberg on Saturday February 28, 2015 @08:03PM
(#9125643)
Electric kettle? Having an Asian wife, I have learned there is an even better choice, a countertop hot water boiler. It boils the water and then keeps it hot in a super insulated container so the energy use is really low and you always have hot water ready for tea, so you don't have to wait!
We unplugged it once to take to an ice rink and it was still hot hours later.
Re:Microwave Oven Diagnostics with Indian Snack Food
by anigbrowl on Saturday February 28, 2015 @10:32PM
(#9125941)
Funny, my wife's Asian too and I know the exact thing you mean. We like being able to tote the kettle around rather than having the bring the container to it, though. I agree it's more energy efficient.
Re:Microwave Oven Diagnostics with Indian Snack Food
by washadjeffmad on Sunday March 01, 2015 @03:07PM
(#9128650)
Since realizing most people only have coffee makers and microwaves and are missing out on tools to simplify making great tea, I've made it a habit of giving out airports (dewar flask pump liquid dispensers) as gifts to everyone I know along with some tea-making utilities, like the IngenuiTEA. Water stays piping hot all day, no power needed beyond the initial boil.
Also, am East Asian, can verify: it's pretty uncommon to find a household without a rice cooker, a portable butane grill, or a Zojirushi.
Re:Microwave Oven Diagnostics with Indian Snack Food
by anigbrowl on Saturday February 28, 2015 @06:33PM
(#9125456)
I have a toaster oven for that, but since I cook 6 days out of the week unless I've very busy it's that big a deal. I got sick of the uneven heating and other well-known microwave problems and realized the only things I ever used it for were soup and popcorn, both of which are just as easy to do in a pot.
Re:Microwave Oven Diagnostics with Indian Snack Food
by snarkulosity on Saturday February 28, 2015 @06:36PM
(#9125467)
I've heard that electric kettles don't work as well in the US as in (say) England because our mains voltage is much lower -- and I guess a transformer would be too bulky.
Re:Microwave Oven Diagnostics with Indian Snack Food
by jarvist on Saturday February 28, 2015 @07:13PM
(#9125547)
I think this is probably true - in the UK (and EU) our kettles are 3 kW, maxing out our 230 V / 13 A plug/sockets.
American plugs always seemed relatively anaemic (and scary dangerous - where are the switches? where is the Earth? though the EU are also typically unswitched), though you do get to have less bulky mobile phone chargers as a result!
Re:Microwave Oven Diagnostics with Indian Snack Food
by weaksauce on Saturday February 28, 2015 @07:51PM
(#9125626)
> (and scary dangerous - where are the switches? where is the Earth? though the EU are also typically unswitched)
well the bottom prong on a cord is the ground and anything that is not a wallwort is polarized nowadays so that the neutral and hot are always on the right wire.
by switched you mean it has a fuse in the plug? if so that's not something that america does. we have 15A circuits going to different parts of the house and if there is a possibility of water immersion there will be a GFCI circuit breaker or outlet installed to protect all downstream outlets. overall it works well enough that there aren't a massive number of deaths caused by it. usually you have do something exceptional to be electrocuted.
edit: the kettle I have is 1500 Watts and at 120 volts it's ~12A of current.
Re:Microwave Oven Diagnostics with Indian Snack Food
by jdhzzz on Sunday March 01, 2015 @07:40AM
(#9126844)
Kitchen and dining room circuits are required to be 20 A and GFCI in the US so you could up the wattage if need be. I doubt such a thing exists, though.
Re:Microwave Oven Diagnostics with Indian Snack Food
by DiabloD3 on Sunday March 01, 2015 @12:26PM
(#9127945)
They are NOW required to be that, but a lot of legacy circuits are still 15A, and some even don't have GFCI (GFCI only became a requirement in the late 70s/early 80s in the kitchen, bathroom, and anywhere else that can conceivably be near water.
This has spread to AFCI (arc fault instead of ground fault) being put in every bedroom as a requirement as well.
If your house doesn't have GFCI and AFCI everywhere, they're required, you proobably should start retrofitting your sockets.
All of that said, you can use temporary use 1800W devices on 15A legally without tripping the breaker.
Re:Microwave Oven Diagnostics with Indian Snack Food
by gambiting on Sunday March 01, 2015 @04:34AM
(#9126532)
It has absolutely nothing to do with use of transformers. Sockets in US and in UK are fused at approximately 13Amps for safety reasons. And 110V at 13amps is 1430W, while 230V at 13 amps is 2990W. You can make a kettle which uses only 1430W of power, but it would take much longer to boil water than a 3kW kettle would. You could raise the voltage to any number you like,but if the socket is fused at 13A you are not going to draw any more power out.
Re:Microwave Oven Diagnostics with Indian Snack Food
by anigbrowl on Saturday February 28, 2015 @07:58PM
(#9125638)
Letting it cool down so I can have the thrill of boiling it again.
Seriously, tea, coffee (15-20 cups in a typical day, between two of us), plus cooking. It's often faster to boil water in the kettle and then pour it into a pot and switch on the gas than to boil it from cold in the pot.
Re:Microwave Oven Diagnostics with Indian Snack Food
by x0x0 on Saturday February 28, 2015 @07:20PM
(#9125568)
A kettle plus a toaster oven strictly dominates microwaves and toasters, particularly for things like reheating pizza or cooking chicken breasts. Toaster ovens also get hot much quicker than an oven, making them far more convenient to use.
Re:Microwave Oven Diagnostics with Indian Snack Food
by lfowles on Saturday February 28, 2015 @09:04PM
(#9125753)
Recently moved into a house without a microwave, but we do have a toaster oven, so it evens out. I often wish I had a teeny tiny microwave to melt a stick of butter quickly though.
Re:Microwave Oven Diagnostics with Indian Snack Food
by dbbolton on Saturday February 28, 2015 @06:52PM
(#9125505)
My microwave has a feature that when you press the "Start" button without entering a time, it just runs for 30 seconds on high.
One time I hit the start button and it started running based on the value of the clock (e.g. it was 4:23pm and the oven kicked on and counted down from 4 minutes and 23 seconds).
I suppose it could have been a weird coincidence, but my partner is very strict about leaving "unused time" on the microwave and obsessively hits the Clear button. Plus it seems unlikely that there would be that much unused time left (it's usually a few seconds), or that I happened to use the microwave exactly when the unused time synced up with the clock.
Re:Microwave Oven Diagnostics with Indian Snack Food
by latcampbell on Saturday February 28, 2015 @05:01PM
(#9125214)
I make appalams in microwave too and have the same uneven cooking problem - putting them vertically seems to help. Here is a commercial product that says so too. https://www.papadumexpress.com
Re:Microwave Oven Diagnostics with Indian Snack Food
by anonetal on Saturday February 28, 2015 @06:25PM
(#9125433)
xkcd had a nice what-if on this recently (http://what-if.xkcd.com/131/). He points to the way ice and water react to microwave radiation as one of the main culprits for uneven heating (of frozen stuff).
Re:Microwave Oven Diagnostics with Indian Snack Food
by jpalomaki on Sunday March 01, 2015 @05:55AM
(#9126681)
Previously I've seen similar tests done with oatmeal and sugar. Put oatmeal on plate and then sprinkle sugar on top. The purpose of the oatmeal is to insulate. The sugar should get brown on those places where the microwaves hit.
Re:Microwave Oven Diagnostics with Indian Snack Food
by officialjunk on Sunday March 01, 2015 @01:41AM
(#9126287)
of course not. you're right, i should be more general an say any electric dipole, but what i was trying to point out was that microwaves don't directly radiate heat and instead vibrate/rotate certain molecules. so, heat sensitive paper isn't going to work, unless there's some that have dye that will interact with a microwave.
There is also beryllium oxide in the ceramic insulators of most magnetrons. If the insulator cracks or is broken, that dust is highly toxic if inhaled.
If you want a nice magnet, there are safer ways to get one. Leave the magnetrons alone.
http://en.wikipedia.org/wiki/Beryllium_oxide#Safety
If you're doing anything with it wear gloves; if you even might snap or machine it, you need to work in a fume chamber.
[1] http://en.wikipedia.org/wiki/Beryllium_oxide#Safety
I assume this article was posted because it was mentioned in XKCD[0] , which also ends on the grape plasma tangent.
[0]: https://what-if.xkcd.com/131/
I'm guessing 30 seconds is too much for these. (Although you can kind of see that my hotspots match #1 in the original article)
Hooray science!
edit: nevermind, didn't realize they kept the 'plate spinners' on during the experiment. The rings in the appalam are artifacts from rotating an anti-node through the food. would have to do something different to get equal heating using ~two points vs. a line
OK, I'm going to say that the right answer is to move the microwave source linearly (or change how it's aimed? Or otherwise change its focus) at a frequency that would maximize even coverage of the heating area based on the rotation speed of the turntable.
Another (more limited) possibility is a way to mount a fixed spoon that could stir soup or other appropriate liquids while the bowl turned.
[1] https://en.wikipedia.org/wiki/Random_orbital_sander
We unplugged it once to take to an ice rink and it was still hot hours later.
Also, am East Asian, can verify: it's pretty uncommon to find a household without a rice cooker, a portable butane grill, or a Zojirushi.
American plugs always seemed relatively anaemic (and scary dangerous - where are the switches? where is the Earth? though the EU are also typically unswitched), though you do get to have less bulky mobile phone chargers as a result!
well the bottom prong on a cord is the ground and anything that is not a wallwort is polarized nowadays so that the neutral and hot are always on the right wire.
by switched you mean it has a fuse in the plug? if so that's not something that america does. we have 15A circuits going to different parts of the house and if there is a possibility of water immersion there will be a GFCI circuit breaker or outlet installed to protect all downstream outlets. overall it works well enough that there aren't a massive number of deaths caused by it. usually you have do something exceptional to be electrocuted.
edit: the kettle I have is 1500 Watts and at 120 volts it's ~12A of current.
http://m.alibaba.com/product/1462287490/UK-Type-13A-1-Gang-P...
This has spread to AFCI (arc fault instead of ground fault) being put in every bedroom as a requirement as well.
If your house doesn't have GFCI and AFCI everywhere, they're required, you proobably should start retrofitting your sockets.
All of that said, you can use temporary use 1800W devices on 15A legally without tripping the breaker.
Seriously, tea, coffee (15-20 cups in a typical day, between two of us), plus cooking. It's often faster to boil water in the kettle and then pour it into a pot and switch on the gas than to boil it from cold in the pot.
One time I hit the start button and it started running based on the value of the clock (e.g. it was 4:23pm and the oven kicked on and counted down from 4 minutes and 23 seconds).
I suppose it could have been a weird coincidence, but my partner is very strict about leaving "unused time" on the microwave and obsessively hits the Clear button. Plus it seems unlikely that there would be that much unused time left (it's usually a few seconds), or that I happened to use the microwave exactly when the unused time synced up with the clock.
The same here. She gets really mad about that. I can't really blame her, since I am am just the same about a bunch of other stuff.
My microwave is my most visible clock in my apt (small sf sub). Whens its paused it doesnt show the time and just constantly blinks.
But even for heating flat items (such as Naan) I haven't noticed any uneven heating with my giant Panasonic microwave.