Can anyone here explain to me why microwave ovens always have their power settings as multiples of some value, e.g. 200/400/800w but never have the ability to set a specific power output, e.g. 425w.
Some GEs claim to use inverters but only for defrosting. I've been wondering why they wouldn't use it for other functions.
http://electronicdesign.com/blog/say-good-bye-last-vacuum-tu...
Using the MHT1003N, manufacturers can use from one to eight of these 250 W units to build a microwave oven with the desired power level. And the magnetron’s 4 kV power supply goes away in place of a supply of 28 to 50 volts. Furthermore, the crude on-off control of the magnetron can be replaced with full variable power control.
However, as far as I know there's no consumer devices containing things like this yet - the only ones I've seen were concept devices from Freescale. This article suggests we won't see them until 2017, and then only in high-end cookers:
http://www.electronicsweekly.com/news/design/the-future-of-m...
You can see this effect if you run a microwave on low power for a short period - sometimes the magnetron will be running for the full duration.
My personal, electronic microwave, has values 125/250/500/750W so not completely exponential (I guess, that's what you meant?).
One thing is, you can always (?) set arbitrary time, so you can compensate to gaps in power settings.
Other thing, maybe electronics are more simple with power settings like these?
When I see exponential settings I would always think of analogy to photography and 'f-stops' [1]. Some devices have exponential settings due to the physical nature of something, but is it the case with microwaves, I don't know.
[0] http://www.firstiraq.com/sites/default/files/products/5002-1...
I have almost no idea how a magnetron actually works.