When product testers said 'it had a real buzz about it'...

Post #301,295 by Meerkat 12/20/08 6:27:11 PM Reply	When product testers said 'it had a real buzz about it'... ...marketing probably said "Excellent! It'll sell by the truckload! Ship it!" "but.. the buzz.." "The buzz! The hype! It's what we need! SHIP IT! NOW!" Ahem. Anyway, I did a quick bit of research - there are some microwaves that have proper variable power - Panasonic Marketing Guff here: http://www.panasonic...wave/inverter.asp They said I was gullible ... and I believed them
Post #301,299 by Ashton 12/21/08 12:37:21 AM Reply	Cute.. 'designed via Chaos theory' ! (Who wouldn't?) Love. It. An inverter yet, lighter and throttle-able; stand corrected. Expensive too, I wot. (Love to see a schematic of the PS.. fat chance.) Were I to embark on becoming a fish chef (as, with some tricks, it seems that µwaves can do very well with our edible piscine friends) -- might even spring for one of these. Thanks for the research. Probably though, more mundane use here: reheat tea, speed up epoxy curing, disposal of Repo body parts ... the usual stuff. Where do I get my decal? Â Powered by Chaos Â
Post #301,301 by Meerkat 12/21/08 7:16:10 AM Reply	Mundane uses First my microwave to a T (or tea), I think. I'd say ninety-nine percent of the time I use it for defrosting. The other one percent is at christmas when I melt chocolate to make Rocky Road for my co-workers :) They said I was gullible ... and I believed them
Post #301,303 by Another Scott 12/21/08 10:13:15 AM Reply	I'm pretty sure it's just marketing. That is, it's not especially new technology. It was described in a paper in 1991, unless I'm mistaken. http://ieeexplore.ie...085575.pdf?temp=x Development of compact inverter power supply for microwave oven Kako, H.; Nakagawa, T.; Narita, R. Consumer Electronics, IEEE Transactions on Volume 37, Issue 3, Aug 1991 Page(s):611 - 616 Digital Object Identifier 10.1109/30.85575 Summary: The development of a novel inverter power supply for a microwave oven is described. Due to its operation at a high frequency using a fast switching device, an IGBT (insulated-gate bipolar transistor), the power supply has been made light and compact. It weighs about one-fifth of the conventional ferro-resonant unit. Adopting the inverter power supply with a new control IC has made it possible to realize a new microwave oven featuring a power control function and high output power. (If you want a copy, let me know.) I assume it hasn't been used on most consumer microwave ovens simply because it's more expensive than switching the tube on or off. Cheers, Scott.
Post #301,326 by Ashton 12/21/08 10:04:26 PM Reply	Re: I'm pretty sure it's just marketing. Maybe the IGBT was a lot more expensive then (maybe also less reliable?) Now the reduction in shipping cost may factor in '08. Thought you were a ChE, not EE I? I'm wondering though, if the 'throttling', while reducing power through the magnetron -- might just dump the excess resistively. That's the sort of thing marketing, even if they understood the implications (sure..) would willingly gloss-over. Either way, it must have an interesting power factor.. minor, unless everyone had one. Damn, nothing is simple (again.) If the paper has techno details, diagrams, would appreciate a copy. Maybe it will go into what happens to the plasma in the magnetron, whether fil. voltage/current are also reduced..? and like that. (A few cohorts time-shared at Varian, developing klystrons and 'other'; RF is interesting stuff, but to grok to fullness one needs to be more conversant than I, with Mr. Maxwell's, 'transverse modes in waveguides' and related arcanery.)
Post #301,328 by static 12/21/08 10:15:17 PM Reply	It sounds like they just shorten the cycle time. A non-"variable-power" microwave obviously cycles on-off for a few seconds at a time. From looking at the excerpt above, they use a PWM system to vary the power to the magnetron. This means on-off cycles of a fraction of a second. :-) Wade.
Post #301,443 by Another Scott 12/23/08 8:09:43 PM Reply	I found a copy. (Yeah, I'm a EE. It's in my genes, I think. :-) The paper's about 380 kB. (I keep forgetting to bring it home.) Assuming I don't forget tomorrow, should I send a copy to your VOM address? I haven't studied it in detail, but it seems to have a good description of the way the circuit works (along with a couple of simplified schematics). It talks about 2 power levels (600 W and 700 W), but I don't see a reason why those would be magic values (but again I haven't read it closely). Cheers, Scott.
Post #301,465 by Ashton 12/24/08 5:25:59 AM Reply	Yes, please --> vom The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins, all of them imaginary. -- H.L. Mencken
Post #301,510 by Another Scott 12/24/08 6:53:37 PM Reply	Sent.
Post #301,511 by Ashton 12/24/08 7:42:50 PM Reply	ACK/NAK .pdf nicely legible. Will send my reading of its tea leaves and trade-offs, anon. Hmmm '91 then ... actual product in '08? Must be a story there. Thanks much.. schematics: EE-mantras.
Post #301,512 by Another Scott 12/24/08 7:48:19 PM Reply	I think they're different companies. The paper was by folks at Toshiba. I doubt that it was so unique that other microwave oven manufacturers couldn't have come up with their own versions if they chose. Have fun! Cheers, Scott.

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