A Linux-powered microwave oven
A Linux-powered microwave oven
Posted Feb 13, 2016 5:13 UTC (Sat) by luto (guest, #39314)In reply to: A Linux-powered microwave oven by pr1268
Parent article: A Linux-powered microwave oven
Not quite. The Panasonic "inverter" ovens (and their licensees) do a credible job of running at partial power.
Posted Feb 13, 2016 7:45 UTC (Sat)
by pr1268 (guest, #24648)
[Link] (2 responses)
Interesting... I was thinking of inventing a microwave oven with two independently-controlled magnetrons, each with a different thermal power rating (e.g. 400W and 700W). Any combination of running either/both could give three different heating states (approx. 1/3, 2/3, and full power). Running one continuously and the other toggling on/off (partial load) could give even more discrete power levels. Of course, there's the unwritten postulate that the complexity of mechanical devices with n parts is O(n1.5). Or thereabouts. Adding another magnetron would make the microwave oven unnecessarily more complicated. Oh, well...
Posted Feb 17, 2016 23:58 UTC (Wed)
by opalmirror (subscriber, #23465)
[Link] (1 responses)
Posted Feb 20, 2016 22:46 UTC (Sat)
by pr1268 (guest, #24648)
[Link]
Dammit, Jim, I'm a computer scientist, not an electrical engineer with a background in microwave propagation effects! ;-) Of course, my "invention" was just a thought-concept; the scenario you just described succinctly (and graphically) describes why such a microwave oven has not been introduced. Like I said, for n extra parts, O(n1.5) complexity... A sincere thank you for enlightening me. :-)
Posted Feb 16, 2016 16:18 UTC (Tue)
by sdalley (subscriber, #18550)
[Link]
Went back to a more straightforward on-off microwave, which is is still going fine after 3 years.
KISS, indeed.
Partial-power microwave oven
Not quite. The Panasonic "inverter" ovens (and their licensees) do a credible job of running at partial power.
So here you have two magnetrons relatively tightly coupled, resonant at approximately the same frequency, one powered and one unpowered. To me it seems the unpowered magnetron acts as an ideal resonant antenna to receive RF power from the powered magnetron. Even if the unpowered magnetron is connected to an open circuit, I'd expect significant currents and waste heat generation.
If both magnetrons are powered and coherent (same frequency), then synchronization of their output might be tricky - they would have to be in the same phase, or they would be exchanging a lot of power one to the other. The fact one is twice the power of the second could mean the large magnetron may burn up the smaller magnetron or send current back into its power supply.
Maybe you could detune them (different frequencies) and/or use a cavity resonator as a narrow pass filter so that one magnetron isn't very much affected by the other. Cavity resonators would add mass and size and no doubt reduce efficiency by producing still more heat.
Just thinking...
Partial-power microwave oven
Partial-power microwave oven
Cavity resonators would add mass and size and no doubt reduce efficiency by producing still more heat.
A Linux-powered microwave oven