Microwave power

output

NT

Microwave ovens are rated on INPUT power as they are AC residential connected consumer devices, and what they draw from the wall is what matters and has to be declared.

The actual beam energy inside is NOT what is declared.

Now for a microwave transmitter, the story is different. They are rated on what they DELIVER to the antenna.

Output, at least in the U.S. The ratings label makes that clear--a

1kW unit typically draws ~1.3-ish kW.

Cheers, James Arthur

My point is that the rating label MUST declare what gets used from the AC line.

IF it *also* declares output, OK, but the consumed power is what is required to be stated.

Food producers probably guess that customers are able to multiply or add times that are in fractional minutes (e.g. when cooking 2 dinners at the same time, or when cooking part of a package when applicable), but are unable to do so when given minutes and seconds to work with.

Of course everything would be much easier when both the instructions and the oven worked with times in seconds only, at least up to some duration where a minute more or less does not really matter.

That would be a fair assumption, assuming intelligent consumers and microwave oven user interface designers. However, I fear that is not the case. Microwave oven dinners in a box are for lazy consumers, such as myself. These require minimal preparation (open box, puncture plastic film cover, nuke, and serve. The most difficult part of the procedure is finding the cooking time and adjusting it for the power level of the microwave oven. Adding a units conversion step to this simplified procedure would normally be considered an un-necessary impediment. So far, the microwave dinner producers have not seen the necessary unit conversion to be a problem and have ignored what would otherwise require a lawsuit to solve. One could easily claim that they were confused by the conversion step, which caused them to over or under cook dinner, which then poisoned the entire family. I've come close to destroying the oven when I accidentally overcooked a yam:

Nope. It's still possible to do it wrong. What's needed is a microwave oven with a built in RFID or bar code reader, that would automatically set the cooking time and power level. Extra credit for having the oven puncture the plastic film. Just toss in the frozen dinner, punch the "cook" button, and go back to reading Usenet news.

Of course, such anomalies require a conspiracy theory to explain. In this case, there are two:

During the 1970's, one of my first consulting jobs was to working on automated cafeteria machinery. Basically, a vending machine with a built in microwave oven to dispense heated items. The plan was to eventually introduce the concept into the home. I'll spare you the details but suffice to say that the pilot program was a flop. The problem was that the housewives in the test, did not consider a fully automated cooking process to be cooking. The problem was also recognized by the microwave dinner producers which resulting in requiring some trivial addition, such as adding butter, or procedure, such as stirring the half heated dinner.

The other conspiracy involves increasing eye contact time. The longer the consumer looks at a package, the more likely they are to remember it, and hopefully purchase it again in the future. So, the colors, text, instructions, and layout are designed to be slightly confusing, which requires a closer look to read and understand. I found a Nissin Chow Mein noodle dinner, that has red lettering on a black background. I need a magnifier and bright lighting in order to read it. Fortunately, they also include translations in Spanish and international hieroglyphic icons:

Anyway, it would be trivial to change the cooking instructions to minutes and seconds or to include 1/4th, 1/2, and 3/4th minute buttons on the microwave oven. Why haven't they done it?

--
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

I usually ignore one line comments because they offer little of value. However, I'll make an exception today because I feel the need for a rant.

Please tell that to an attorney experienced in product liability lawsuits. In the past, you could assume that a reasonable person, of average intelligence, would be expected to do the arithmetic without a calculator. With the progressive and rapid deterioration of the American educational system, I suspect that this assumption is no longer valid. In our litigation happy society, giving someone instructions in how to do something exposes them to responsibility and liability for that persons actions. It doesn't matter if the instructions are good, bad, or indifferent, if the buyer does something stupid, it's still legally actionable. If I sell you something, and you misuse it, I am at fault because I failed to inform you that overcooking a meal, might produce acrylamide, which when ingested, has been known to cause cancer. This is why products now include more warning labels than instructions for use, and why user manuals (if they exist) are written for the lowest possible form of educated life. So, yes they do need to have everything explained, not because they don't know how to do it, but to protect against any potential product liability litigation for failing to provide the necessary instructions.

--
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

The best way to cook with a microwave without worries of power differences is to use a reduced duty cycle and cook longer.

The heat more evenly distributes through the target medium as well.

It takes a bit of time to get used to it, , and longer to cook the food as it were, but the food product is definitely better.

snip

I simply place a disclaimer on miy packaging.

"This product is for novelty use only" "Utilize for whatever means at your own risk"

There. Now I do not even need ANY instructions.

Instead of an age window on the box, one can declare a minimum IQ requisite with the disclaimer. Hehehehee!

The proper solution would probably be to specify the number of (kilo)Joules required to heat the dinner, and to have a kiloJoule scale on the microwave as well. A typical cooled microwave dinner would require around 200kJ to heat, frozen dinner around 450kJ. Within the usual range of microwave oven power that could be converted to time by dividing it by the power output of the oven. (of course you cannot heat a dinner by applying 10W for 20000 seconds)

A microprocessor-controlled oven could have a switchable setpoint that can be in seconds or in kJ. When the oven output is 1000W these are the same. A lower-power oven would heat longer to get to the same kJ. A clever oven would even have adjustable power output (usually by applying some duty cycle) and would re-calculate the heating time to arrive at the same kJ.

It probably depends on the target audience. Microwave dinners are not targeted at the housewive cooking for a family. That has to be considered when doing panel tests.

I have the same problem... especially black printing on a dark colored background (often blue or red) is difficult to read in the kitchen light. The printing is often blurry and small. Fortunately I have been using the microwave for so long that I can guess the heating time from some basic properties of the product:

- weight

- is it deepfrozen or cooled

- does it merely have to be heated or is there some cooking to be done

My oven even has two automatic modes (that I never use)

- "auto reheat" - put a plate of prepared dinner in the oven without any cover and it will heat the dinner until a certain level of steam is detected.

- "temperature setpoint" - insert a sensor (pin) in the food and the oven will stop when it reaches a temperature that has been set

That mirrors the "instant cake" experiences from the 50s.

It was perfectly possible to put all the (dried) ingredients in a packet, just add water and heat (or whatever it is you do to make cakes). But the market researchers found that the housewives didn't like "complete" products. Instead they preferred adding an egg, since that made them feel they were "cooking".

cooking should be specified in kilojoules,

time is a guess based on a typical oven, time for the same result will vary depending on the mains voltage, age of the magnetron, model of oven etc...

--
This email has not been checked by half-arsed antivirus software

Maybe in the 50s. But now, at least here the "bread baking machines" are quite popular. You just put in some "bread mix" and water, and start the machine. About 3 hours later, a freshly baked load of bread comes out. All the processing is done by the machine.

Dunno where you get that - recipes and cooking instructions on the packet usually indicate several cooking times for different output powers.

You can ruin a lot of food not knowing that rating.

Of course the input power must also be indicated on the specifications label.

the front states the microwave output power, the rear rating label the mains power consumption.

A nuke rated 850W is almost certain to be output power. 850W input would be a rare low power thing, 850W output is in the range of common output powers.

NT

You can still buy "Betty Crocker" instant cake mix, apparently. Googling for it revealed

which is pretty much what my father told me as a kid.

Why? In a design done today, a digital timer is just a microcontroller with software. It can do anything without noticable difference in cost.

My Philips microwave has a time setting with just + and - button and when pressing + it increases the time in increasing steps. The display is in minutes/seconds.

00:05 00:10 00:15 00:20 00:25 00:30 00:40 00:50 01:00 01:15 01:30 01:45 02:00 02:30 03:00 03:30 04:00 04:30 05:00 05:30 06:00 07:00 08:00 etc (step remains at 1 minute)

It also has 3 memories that I have set to 02:00 03:30 and a low power mode for thawing frozen bread. The memory setting can be used as a quick starting point so 05:00 is just "recall memory 2" and then + + +

This of course is all implemented in some microcontroller, not in static digital circuitry.

I wrote another followup based on that idea.

There usually are some different times for different power levels of the oven like 600W 750W 850W and one quickly finds out what figure to look for, so even when the oven indicates 700W but is a bit inefficient or degraded over time, one can still use the 600W figures.

Anyway, getting really tasty and attractive food out of a microwave is not easy. I use mine only for defrosting frozen bread, to cook rice and vegetables, or to heat simple canned foods. Anything "fatty" like meat will just become a shapeless mess.

Essentially, they say something like "when using a 1200W microwave".

Since the difference between what they consume and what they produce isn't much, it does not matter much.

What THEY are doing is giving the cook a reference point, because years ago the were only 800W and they are way better now, but weaker jobs are still available.

Next thing you'll be telling me is that blow dryers are rated for output wattage.