Comment by tambre
4 days ago
I'm surprised no one has mentioned inverter microwaves. Unlike plain old regular microwaves where power settings just adjust the time that the magnetron is running at full blast the inverter ones can actually change the power of the magnetron. Makes it tons easier to cook food evenly and calmly. Never am I buying again one without.
It's kinda hard to find them though. Most manufacturers hardly list this but Bosch seems to have inverters in most of their mid and higher-end ones. My favourite is the Bosch BFL634GB1. Bosch BFL7221B1 was a huge downgrade due to the shitty touch screen and wheel along with a multi-second boot time.
This explains a lot, American microwaves have these settings for different types of food etc, it seems most people throw something in and just 'nuke it'. European microwave ovens on the other hand, have a setting for different wattages (90W up to 720W 'Max' in my case), which, combined with instructions in the recipe or on the box, provide the right setting for this particular food.
Are you sure that European microwaves actually use continuous power at those wattages and not also "simulate" the wattage by using short bursts of a fixed power?
Some have inverters for continuous power adjusting, others turn on and off the magnetron.
In any case, all that I have ever used have 2 dials, one for power and one for time (and a button to allow to chain multiple time intervals, each with a different power level). I have always used only these 2 dials and I have never used any other buttons that may exist for preset programs.
For many years I have used microwave ovens only for reheating food. Now I consider that I was stupid and I cook all the food that I eat in a microwave oven, from raw ingredients.
This is much better than by traditional means, because it is much faster and perfectly reproducible. Moreover, cooking in a microwave oven removes the need for continuous or periodic stirring that is required in many traditional cooking methods, because the microwave-cooked food is homogeneous (without lumps etc.) even with no stirring, if the time and power level are chosen correctly.
They switch the magnetron on and off, unless they have inverters I guess. I have seen the two knob ones (and I prefer these) and the fancy ones, which all have cryptic user interfaces and usually no manual next to them.
American microwaves almost always have a fairly easy way to change the power level, it's just nobody bothers to use it.
Rtings has a post saying that they aren't effective: https://www.rtings.com/microwave/learn/research/microwave-in...
Curious to hear more about your personal experience
Read that and got to this ludicrous claim:
> The inverter models are marginally better at converting the total power they draw from an outlet (the apparent power) to useful work (the active power). However, your residential electricity bill is calculated based on active power use, so an inverter microwave won't save you any money.
If any power company has the ability, much less the inclination, to not charge you for your appliances waste heat that would be news to me.
This is referring to active vs reactive power and the concept of power factor [1]. You're still paying for all the real energy consumed (including waste heat). Inverter microwaves tend to have a higher power factor than traditional models (measured data [2]). Residential electricity bills are based on active energy (kWh), not apparent power or reactive components, so a better power factor by itself doesn’t lower your bill. We’ll take a look at the article to clarify it.
[1] https://en.wikipedia.org/wiki/Power_factor [2] https://www.rtings.com/assets/pages/hRDTskis/power-factors-l...
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I’m trying to figure out how they misinterpreted things to come up with that statement. Maybe they are mixing up start-up draw and constant draw? Idk
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Wow that's wild. I usually consider Rtings pretty reliable so that's a big surprise to me.
Could they be talking about power factor? Still doesn't make sense anyway.
I've found inverter microwaves for example useful when making porridge. A traditional one at 50% power blasting at full for 5 seconds makes it boil over, but on an inverter microwave 50% continuous heats it evenly and consistently such that it doesn't boil over. Sure you may be able to lower the traditional one so it does it even shorter steps but then it takes longer to get done or the result might be rather poor due to the inconsistent heating steps.
I also could never get traditional ones to heat potatoes well. Scalding hot on the outside, cold on the inside. With inverter ones it's simpler: just a lower power setting for longer.
I wonder why microwaves can't work like modern radio transmitters. Magnetrons generate ~2.4 GHz radio waves using resonance and a strong magnetic field acting on free electron orbits. That was necessary in the 1940s for radar transmitters. But today, solid state electronics generate 2.4 GHz (and higher) waves without any trouble - cf. WiFi and Bluetooth hardware. I'm not the first to have this question, and it looks like there is some ongoing work. https://www.digikey.com/en/blog/will-the-microwave-ovens-mag...
Because transistors for generating even very low microwaves like 2.4GHz are extremely expensive comparatively speaking, and don't produce much power. They're good, though, because you can produce very precisely tuned and modulated signals and very precisely controlled output powers - as long as they're less than a couple of watts.
A cavity magnetron is a block of metal with some holes drilled in, two bits of glass glued on, and all the air sucked out. They're hard to tune to exact frequencies and hard to regulate to exact powers, and modulation is as you've already discovered kind of limited to just turning them on and off - but they're extremely cheap to make, last a very long time, and require minimal support circuitry to generate double-digit kilowatts of RF.
You don't need to be cock on frequency to heat up a pie.
Now there are gallium nitride microwave transistors that can produce very high microwave power at very high efficiency. So that is no longer a limitation.
Microwave ovens with such transistors have been demonstrated, which have the advantage of modulating the microwaves in such a way as to achieve a more uniform heating throughout the oven, than can be achieved with the fixed-frequency magnetrons.
At least for now, such microwave ovens with transistors might be encountered only in some professional applications, because these transistors together with the associated control circuits remain much more expensive than magnetrons.
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Ah, thanks, good to know. I thought solid state power electronics had come down in price more than they apparently did. I guess it's high frequency plus high power that's still expensive. For not so high frequencies (< 1 MHz), mass production for ubiquitous switched-mode power supplies and electric cars has surely brought down the price.
(Side note, modern very high power radio transmitters might also still use some vacuum tube technology - my latest information is that there's a slow transition going on)
Magnetrons are cheap, reliable, and work well enough. Their one and only job is to produce energy at about 2.4GHz, and to make a lot of it. You merely put in electricity and through the magic of geometry you get RF out.
A transistorized solution is, simply, inappropriate. The RF section alone will cost more than an entire microwave off the shelf, and plus that you need all the control circuitry and high speed crap to generate a 2.4GHz tone. Not to mention that putting kilowatts through silicon creates a much higher risk of catastrophic failure: transistors blowing out into a plume of plasma and such.
You're asking why we haven't reinvented the wheel. There's simply no improvement to be had.
You want high power RF in a given frequency band, you want a magnetron. It's just a lump of iron with some wires. You don't need any electronics. At all.
I love inverter microwaves so much. I got a cheap one at Target for maybe $100 or so. I almost never use full power, typically I go for 50% or 60%. Food heats through evenly, every time.
I try and tell friends about it and they all think I am crazy. I've had more luck with induction cook tops, probably because there is more general buzz around them.
I really with Alex on Technology Connections would do a video on inverter microwaves to get the word out!
Why would it make a significant difference? On/off modulation intuitively seems likely to have the same effect.
Isn't that just the power % option? I don't think mine is fancy but I can adjust the power %
Unless you have an inverter microwave it simply adjusts the % of the time that the magnetron is turned on. So at 50% you will have the magnetron at full blast 700W for 5 seconds and then 5 seconds off (or similar timestemps). On older microwaves you may be able to hear the magnetron cycling between being on and off.
I have a new microwave and can definitely hear the magnetron cycling, but it's a fairly subtle difference in sound.
I want a variable power ("inverter") microwave with two rotary knob. One for power, and one for timing.
I hate every microwave I have ever had the displeasure to operate during my lifetime, except the old stuff witn the teo mechanical knobs.
With a rotary encoder we can get second precision and minute granularity at the same time.
Is that time for a Kickstarter?
I had until now (in Europe, for somewhat more than the last 2 decades) a couple of Panasonic microwave ovens.
Both of them match your description. They had some other buttons, which I have never used. Besides the 2 rotary knobs, I use 3 buttons: start, stop and a button for chaining multiple time intervals, each with a different power level.
I cook all the food that I eat in the microwave oven, from raw ingredients.
Breville BMO850BSS
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