Running an empty microwave oven

most with glass rotating trays will run, the glass absorbs enough rays to heat up slightly but wont smoke anything.

might ruin your electric bill budget though. ;-))

shakle the damm bird to the cage/perch

or teach the bird to climb inside to warm itself up. ;-P

break it?

or a build up of microwaves over a certain level?

concerned one of my pet parrots will switch it on! (Seriously, they do stuff like that)

he meets. "Good day, Mr. British, thank you to accept me in Your nice country", but the person interrupts and says: "I am not British, I'm Chinese."

Mr. British for to let my family and me stay here... " Again, he's interrupted before finishing his sentence. "I no be British, I be Turk!"

you for letting me come to your beautiful country." ... "I'm not British, I'm Kosavon."

forever.

when

(one

that

with

well normally in order to cuase an explosion you have to have a combustable material that burns very quickly, the force comes from the fact that the burnt material wich is oxidesed takes up a great deal more volume and until it expands is under great pressure. in an empty oven there is no combustables.

they always seem to try something to see if it blows up and if it doesnt then they make sure it does, its often a caravan or microwave oven that gets blown up.

magnetron and draw more power from it than it expects. I didn't agree or disagree, I know nothing about that sort of thing.

It cant 'draw' more power from it unless that power actualy goes somewhere, however it can put the magnetron under more stress, the voltages and current may be higher even though the power is actually less, ie they are out of phase and hence arnt both high at the same time.

but theres actually not that much to a magnetron, theres a central cathode wich is like a rod with a heater inside, and a circular anode around this with slots in, all in a vacuum and also not surprisngly a strong magnet. The power is picked up via a piece of wire inbetween one of the slots. The anode is what gets hot due to current flowing and is attatched to a quite large heatsink with great number of fins wich has a fan blowing on it.

theres not a great deal to go wrong, its simplicity is its strength, the same basic design was used 60 years ago, it could lose the vacuum of course, or the insulation could fail, or the heater could break, or the magnet could lose its strength but most of the parts are designed to work at a high temperature, its just metal and glass, its not like silicon wich self destructs at 200'c.

The transformer does actually limit the current anyway.

Colin =^.^=

WEll, almost right... (and your 'normally' does apply, so what you say is true, but there's more! )

All you need is pressure, not a combustable substance.

In the case of the balls that 'exploded' were they to have a 'strong' outter shell, and a high moisture content inside, the moisture could easily convert to steam and build up pressure until the outer shell failed--an explosion... It would not be difficult to build up a hundred PSI of steam pressure, and that would result in a rather large 'bang'!

combustable

takes

no

aha yes the Boiling liquid expanding vapour explosions didnt think of that at the time, but I did think enough to say normally lol, bit like eggs that explode when you put them in a microwave without first making a hole in them, although its not all that exciting.

Colin =^.^=

Once upon a time whilst visiting the in-laws in Germany, my wife reheated some hard boiled eggs in their shells in the microwave by placing an egg in a glass tumbler and then a slightly larger one over the first 'in case they pop'. They were then placed on the table for 'früstück'. A full two minutes later an egg exploded covering not only us, but the ceiling, drapes and nick nak display shelves with egg. A frantic clean up campaign started as was had a little over a hour to restore the dining room to its pristine condition before the mother-in-law returned. We can laugh about it now, but we never have told the in-laws about it. One day when my father-in-law has to change a light bulb (long-life of course) he might find a bit of dried egg and wonder....

They're cleverer than you think. One escaped, and flew from tree to tree waiting for me to chase after him. Came back the following day by himself, after flying for miles all over the place.

--
http://www.petersparrots.com    http://www.insanevideoclips.com   
http://www.petersphotos.com

It said, "Insert disk #3," but only two will fit!

yep, we give humans way too much in the way of exclusive ability to think and reason. & dont forget, some of these other critters have had eons of evolutionary expertise in dealing with the occasional problems of human interference! and they win too! we seem to be ruthless killers for no reasons at all!

release of grey parrots from zoo in NY city awhile back, they migrated east to connecticut, began habitating/building HUGE stick nests around (what else) telephone poles cross arms, complete with transformers and 14 KV feed thru lines!

30-40 birds per nest, quite a probem for power crews! of course, animal rights folks went nuts when they had to start removing them!. u can read articles abt in news archives. quite interesting

:-))

waiting for me to chase after him. Came back the following day by himself, after flying for miles all over the place.

to

overheating,

I'm

person

you

British,

--
http://www.petersparrots.com    http://www.insanevideoclips.com   
http://www.petersphotos.com

The ant can lift 50 times its own weight, can pull 30 times its own weight, and
always falls over on its right side when intoxicated.

When in doubt, read about what manufacturers have done about the empty oven problem.

Some patents: "Oven protective device"

"Electronic oven protection circuit"

"System for sensing the presence of a load in an oven cavity of a microwave cooking appliance"

There are probably other patents.

Basically, there is a directional coupler VSWR (voltage standing wave ratio) detector or other scheme for detecting if the oven is empty, which senses the high reflected power produces by an empty oven and shuts it down.

Learn by Destroying(tm) or this should be tested by Mythbusters:

About 15 years ago, I was drawn into a discussion about what bad things might happen if the oven were to run empty. Opinions varied ranging from nothing to planetary destruction. I wasn't sure but based on my RF experience, I guessed(tm) that it would be either a huge increase in voltage across the magnetron, or a huge increase in current through the magnetron. I placed my bet on some kind of arcing, but didn't offer any specific location.

Three allegedly functional junk microwave ovens were purchased from the local thrift shop for about $20/ea. When the owners of the store found out what we were doing, she threw in three more ovens that had various defects which made them unsellable, but were allegedly able to heat water.

I don't have time right now for the whole story, so I'll just summarize. Every oven acted or failed differently. As I vaguely recall:

- One immediately shut itself off and would not restart until I unplugged the power cord. My guess(tm) is I tripped an overcurrent breaker.

- One turned itself off after about 30 seconds by blowing a fuse.

- One made a noise indicating the something had blown up inside, but continued to run. After about 1 minute, there was another noise followed by smell of burning electronics.

- One arced over some burned food on the waveguide window. I removed the window and tried again. This time it arced intermittently inside the waveguide near the window for about 15 minutes. There was a hint that something electrical was burning inside, so we turned it off.

- One had some mechanical damage to the case, which caused some arcing outside of the cooking area. Since that meant that we might have high levels of RF leaking from the oven, we terminated the test early.

I have photos of the ovens and list of makers and models. I'm too lazy/busy to find them right now. Suffice to say that there were no fires, explosions, implosions, lightning bolts, ball lightning, toxic discharges or devastating EMP. In most cases, the fuse or breaker tripped, which is easily replaced or reset. Someone did an autopsy on

3 of the ovens and found one shorted magnetron and two blown Hi-V diodes. The ovens that seemed to have burning electronic were not inspected.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Jeff Liebermann wrote on 12/12/2017 2:26 PM:

Jeff, you are a trip!

--

Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

Microwave ovens use magnetrons, not klystrons. When power is applied to the magnetron, it is pretty independent of the RF load, you apply a couple thousand Volts minus to the cathode, and the anode is grounded. But, due to the magnetic field, the electrons spiral outward instead of just heading straight outward radially to the anode. Passing the resonant cavities repeatedly during that spiral path builds the RF resonance.

The oven chamber develops standing waves. If there is nothing to absorb the RF, it is reflected back into the magnetron, and the anode runs hotter. I think the thermal switch on the anode is more to cover the condition where the fan motor has seized up than no food in the oven, but may handle both to some extent.

Jon

tore

He is having too much fun - Ban Jeff!

(thanks, Jeff!!)

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup) 
                      John's Jukes Ltd. 
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 
          (604)872-5757 (Pinballs, Jukes, Video Games) 
                      www.flippers.com 
        "Old pinballers never die, they just flip out."

I live in an apartment complex, and a lot of microwave ovens have been thrown away; and most of them were perfectly OK after they were cleaned up. Same pattern with vacuum cleaners. A number of people are pigs.

I got four Dysons off freecycle (because they're infamous for falling to bits). Put all the faulty parts into one, then the other three work :-)

--
In the first few days of the Olympics the Rumanians took gold, silver, bronze, copper, lead and anything else they could get their bloody hands on.

About 60 years ago a couple of men started a grocery store with one store. Their idea was to make 5 fast penneys instead of one slow nickle. That turned into the Food Lion chain of stores. Made lots of people in a small town of about 20,000 people millionairs. I was a stock boy during part of that time and remember going to almost every item in the store (with others) and marking down each item. This was before bar codes and every item had to be hand marked. In that town and several small towns around there are several Food Lion stores, Wallmart, and two other stores toget groceries at as their main item. The A@P, Winn-Dixie chains folded years ago.

Depending on the item, it is often better to stock many low dollar/ profit items and a few high dollar items.

People are funny. A fellow I knew sold items at a farmers market. One day he tried to sell cantalopes for $ .25 and not selling many, he marked that out and put up a sign of 3/$ 1.00. Sold almost all of them at that price even though they cost more.

I found this at a local market: When I accosted a stocking clerk to point out the problem, he failed to see what was wrong. When I dragged over a manager, it took about

15 seconds for his brain to engage and see the problem. He later mentioned that it was like that for at least 2 days and nobody noticed.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Winn-Dixie went through bankruptcy, but they didn't fold. In fact, by local Winn-Dixie store was a 'Sweetbay' that had been a Food Lion store that was sold out with all the others to Sweetbay, in the region.

Just depends who the "You" is!! "You", the customer or "You", the retailer!! ;-)

--
Daniel 

The three Ages of Man .... 

1.     Man believes in Santa Claus!! 
2.     Man does not believe in Santa Claus!! 
3.     Man IS Santa Clause!!

I y e

If he needs to make $50 a sale to run his shop, then making less than th= at for te cheap shit is pointless.

s r l

ll

How stupid do you have to be not to be able to fit these things yourself= ? Do you pay an electrician to change a lightbulb too?

f

You have to cater for whoever lives nearby. If it's a council estate, g= o set up business elsewhere or be prepared to make f*ck all.

. s a

le

n

No, they just like a brand new car and have more money than sense.

.

he

ew

ss

I o

de

You only made more as he gave you them free.

-- =

Helpdesk: Click on the 'my computer' icon on the left of the screen. Customer: Your left or my left?