Re:A Linux-powered microwave oven
by skykooler on Thursday February 18, 2016 @09:29AM
(#11125925)
Microwave ovens use magnetrons to produce the microwave radiation. Magnetrons cannot be run at anything less than full power. Some microwaves have additional coils in the magnetron that can be connected to increase the power level, but it's limited to the power levels you can get from the various combinations of coils.
For the same reason, running a normal microwave at "50% power" actually means it runs at full power for several seconds, then switches off for several seconds, then repeats. The pulses are so long because starting and stopping are hard on the magnetron.
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Solid-state microwave generators have been developed to replace magnetrons recently, and they can run at variable power.
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...
They are as-yet too expensive for low-end microwaves, IIRC they are around 0.10 per watt in quantity so $100 in parts just for a 1kW oven.
This isn't true, if you get one of the Panasonic microwaves with their "Inverter" feature. It really does run the magnetron at different power levels. It works quite nicely.