bhoughto@pima.intel.com (Blair P. Houghton) (12/13/90)
The Jan. '91 issue of The Institute (the IEEE's newsprint newsletter) arrived today, and synchronicity of synchronicities, there's a story on p. 6 (hidden as filler under the headline "Intel's Newest Supercomputer" (no plug intended :)) about how GE has just improved the electrical efficiency of halogen lamps. They give the envelope an infrared-reflective coating. No details on what it is, but it's probably just a half-wave-gel thing. This reflects much of the heat back onto the filament, keeping it incandescent-hot, saving the electrical energy that would have been radiated. Since it works only on infrared radiation, it doesn't affect the lumens in the visible spectrum. They claim an energy savings of 60 percent. --Blair "I'm impressed."
phil@brahms.amd.com (Phil Ngai) (12/14/90)
In article <1348@inews.intel.com> bhoughto@pima.intel.com (Blair P. Houghton) writes: |GE has just improved the electrical efficiency of halogen lamps. |They give the envelope an infrared-reflective coating. No details This is great. Any relationship to the shortage of MR-16 50 Watt bulbs? You can't buy one for love or money here in the SF Bay area. (no doubt thanks to the Taiwanese dumping those low cost low voltage halogen track lights on the market without warning GE) --
ih@udel.edu (Charlie Ih) (12/14/90)
In article <1348@inews.intel.com> bhoughto@pima.intel.com (Blair P. Houghton) writes: >The Jan. '91 issue of The Institute (the IEEE's newsprint .... >GE has just improved the electrical efficiency of halogen lamps. >They give the envelope an infrared-reflective coating. ... > .... This reflects much of the heat back onto the filament, keeping >it incandescent-hot, saving the electrical energy .... >....... Since it works only on infrared radiation, >it doesn't affect the lumens in the visible spectrum. I have been thinking about this for a long time. I am glad somebody have made it. 60% energy saving (even more) is possible. Actually the IR coating can improve the color balance of the light. Can anybody tell me if this is already a product on the market or where I can find more information. Thanks in advance. Charles S. Ih
gordonl@microsoft.UUCP (Gordon LETWIN) (12/28/90)
Some folks have posted that they'd wondered why halogen bulbs weren't coated with IR reflectors to improve efficiency before now. The problem was finding a coating which could take the heat (and of course which was also transparent to visable light). Natually, the technique only works on bulbs with the proper shape, but most halogen bulbs are cylinderical. The article that I saw showed a guy holding the bulb itself - a bit larger than a peanut - in one hand, and an ordinary looking PAR reflector "bulb" in the other. Presumably the halogen bulb mounts inside the PAR thing (those cone-shaped bulbs you see in outdoor fixtures) for this application. The blurb didn't say. gordon letwin
dunphy@col.hp.com (Dan Dunphy) (01/05/91)
>/ col:sci.electronics / schuster@cup.portal.com (Michael Alan Schuster) / 4:41 pm Nov 29, 1990 / >>The halogen cycle not only prevents rapid loss of filament >>material, it repairs minor flaws in the filament and prevents >>hot-spots due to these flaws. >> >>Halogen lamps burn out (barring some extensive flaw) only >>when one of the non-tungsten parts fails (the filament supports >>weaken from temperature cycling, the way the filament would >>if it weren't for the halogen cycle). > > >What's the principle behind the "krypton" flashlight bulbs being sold >now, and market as "70% brighter" than the standard type? >---------- I suspect they use a principle similar to halogen. I just tried my first. They are a lot brighter.
dunphy@col.hp.com (Dan Dunphy) (01/05/91)
I used a halogen (H4) with a modulator in my motorcycle for a long time. The decrease in tempeature caused a significant tungsten deposit to form on the inside of the quartz envelope. There was a significant hole in the low beam pool of light in front of the bike. I believe a dimmer defeats the halogen cycle.
charless@cory.Berkeley.EDU (Charles R. Sullivan) (01/07/91)
In article <16120020@col.hp.com> dunphy@col.hp.com (Dan Dunphy) writes: >>/ col:sci.electronics / schuster@cup.portal.com (Michael Alan Schuster) / 4:41 pm Nov 29, 1990 / >> >>What's the principle behind the "krypton" flashlight bulbs being sold >>now, and market as "70% brighter" than the standard type? >>---------- >I suspect they use a principle similar to halogen. I just >tried my first. They are a lot brighter. I don't know if Krypton bulbs use a halogen cycle too, but the idea of the krypton is that it is a heavier gas than the usual fill gas, and so retards the evaporation of tungsten more, and I think has lower thermal conductivity. You can take the benifits of this as longer life or higher efficiency, depending on what temperature you design the filament to operate at. Charlie Sullivan charless@cory.berkeley.edu
bhoughto@pima.intel.com (Blair P. Houghton) (01/07/91)
In article <16120021@col.hp.com> dunphy@col.hp.com (Dan Dunphy) writes: >The decrease in tempeature caused a significant >tungsten deposit to form on the inside of the quartz envelope. [...] >I believe a dimmer defeats the halogen cycle. I would expect so, as the rate of deposition is proportional to the fourth power of the temperature; so, where the vaporous tungsten ends up would be very much affected by the power dissipation. --Blair "This holds true for the deposition of cats, too."
bhoughto@hopi.intel.com (Blair P. Houghton) (01/08/91)
In article <1634@inews.intel.com> bhoughto@pima.intel.com (Blair P. Houghton) writes: >[...]the rate of deposition is proportional >to the fourth power of the temperature; so, where the vaporous >tungsten ends up would be very much affected by the power >dissipation. I forgot to mention that I bought Mom one of these things for Xmas, and the directions in hers (mine didn't have this) mentioned that when the light appears less bright than usual you should run it at full power for a couple of hours. So, the manufacturers are aware of this phenomenon. (Their English, however, could do with some brushing-up; as I was assembling the thing Mom was reading the directions, and she was thoroughly confused since the passage was written "...if the lamp should never seem to lose brightness...") --Blair "Quoth the raven, 'Not for more!'"
leland@cbnewse.att.com (leland.m.kornhaus) (01/09/91)
I hate to start a new thread about lights, but here it goes... Today I saw a room that had florescent lighting ith dimmer switches controlling the florescent bulbs. How is this done? Would it be done before the ballasts? Does it work by Pulse Width Modulation? There was absolutely NO flicker that I could see. Any answers? Enquiring minds want to know.
strong@tc.fluke.COM (Norm Strong) (01/18/91)
In article <10040@pasteur.Berkeley.EDU> charless@cory.Berkeley.EDU writes: }In article <16120020@col.hp.com> dunphy@col.hp.com (Dan Dunphy) writes: }>>/ col:sci.electronics / schuster@cup.portal.com (Michael Alan Schuster) / 4:41 pm Nov 29, 1990 / }>> }>>What's the principle behind the "krypton" flashlight bulbs being sold }>>now, and market as "70% brighter" than the standard type? }>>---------- }>I suspect they use a principle similar to halogen. I just }>tried my first. They are a lot brighter. } }I don't know if Krypton bulbs use a halogen cycle too, but the idea of the }krypton is that it is a heavier gas than the usual fill gas, and so retards }the evaporation of tungsten more, and I think has lower thermal conductivity. }You can take the benifits of this as longer life or higher efficiency, depending }on what temperature you design the filament to operate at. Xenon is even heavier, and has the additional advantage of being a lot cheaper. So where does that leave your argument? -- Norm Strong (strong@tc.fluke.com) 2528 31st S. Seattle WA 98144