MIT invents light-bulb that is more energy friendly over LED

Discussion in 'Frontpage news' started by Hilbert Hagedoorn, Jan 13, 2016.

  1. Hilbert Hagedoorn

    Hilbert Hagedoorn Don Vito Corleone Staff Member

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  2. Kaarme

    Kaarme Ancient Guru

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    Let me guess: They still only last a single year in regular use, and if you drop them from the amazing height of 10cm, the filament will be broken and the whole thing rendered useless?

    Energy saving wasn't the only thing first fluorescent and then led lights gave us. Anybody just a bit older has a childhood and even later full of moments of a light bulb suddenly going out in a room and needing changing. They were also very ordinary items to be bought from supermarkets in multi-packs. These days lights last forever in comparison.
     
  3. BLEH!

    BLEH! Ancient Guru

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    I still use incandescent light bulbs, stocked up before the nanny-state EU banned them. Give more natural light than LEDs/fluorescents and don't give me headaches because of the flicker. The 150W I use in the "big light" is like turning the sun on!
     
  4. wavetrex

    wavetrex Maha Guru

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    You do realize that modern fluorescent and LED lamps "flicker" at frequencies above 50Khz, that is 50.000 or more pulses per second.

    Unless you are from another dimension in which time flows 1000 times slower, you won't be able to perceive such a high frequency. Basically anything over 60-70Hz (and in case of some really sensitive people over 100Hz) is registered as "continuous". That is why TV's and Monitors have 60 Hz refresh frequency, and advanced models 120-144, but that's WAY more than sufficient.

    But hey, good luck with your 150W filament bulbs. I enjoy my FULL-LED house for a few years already :)
     

  5. Brisse

    Brisse Active Member

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    LED lamps don't have to flicker. It depends on how the circuit is designed. There's PWM circuits that cause flicker (depending on the switching frequency) and then there are constant current circuits that don't cause any flicker. If you buy the really cheap stuff, you can expect the former. The latter costs more. You get what you pay for. Also, some LED lamps have really good colour reproduction, while the cheap stuff is horrible. Again, you get what you pay for. Please don't bash LED technology just because you only experienced the cheap stuff, okay?

    Florescent is still the best performance per dollar though, even after you factor in lifespan and electricity bill. Only big downside is that they contain toxic mercury that will be released if you accidentally break it.
     
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  6. mbk1969

    mbk1969 Ancient Guru

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    And that process of bulb going out is immortalized in culture (at least in cinema)...
     
  7. scatman839

    scatman839 Ancient Guru

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    Not too much an issue though, unless you're breaking lots of bulbs directly under your face and inhaling deeply.
     
  8. schmidtbag

    schmidtbag Ancient Guru

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    Agreed - the amount of mercury in modern bulbs is almost negligible. In fact, one of the reasons modern fluorescent bulbs take so long to reach full brightness is because of how little mercury is put in them these days. I'm sure eating salmon and tuna on a regular basis is more likely to poison you of mercury than a single fluorescent lamp.

    Mercury overall is a lot more demonized than it should be. At least one isotope of it is safe enough that you can stick your bare hands in it for extended periods of time without risking any danger.
     
  9. Brisse

    Brisse Active Member

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    I assume you are both toxicologists then, since you consider yourselves qualified to give such advice. In some cases it is safer to demonize than not, especially when it comes to household items used by mostly clueless people. Does your son, daughter, mom, dad, aunt, uncle etc. know how to properly dispose of a broken florescent light and how to properly ventilate the room afterwards? Maybe one out of a hundred persons know, but what about the rest? By demonizing the issue we might actually get them to care about it, which could potentially save lives.

    Ask yourselves this:
    What do we have to win by demonizing the issue?
    What do we have to win from actively doing the opposite, like you guys/gals are doing?

    Answer to the second question is: Nothing... So what you are doing is pointless!
     
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  10. scatman839

    scatman839 Ancient Guru

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    Haha wow, remind me not to talk to you again.

    But feel free to read http://www.nhs.uk/chq/Pages/854.aspx?CategoryID=87

    http://ec.europa.eu/health/scientif.../mercury-cfl/l-3/2-release-health-effects.htm

     
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  11. schmidtbag

    schmidtbag Ancient Guru

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    I agree that you are better off demonizing something that is inevitably hazardous. I think it is very important to take hazards seriously. My point, though, is there's no point in freaking out over a broken fluorescent bulb. Just as there's no point in freaking out over drinking a lot of alcohol once in a while, or standing under a smoke detector for a long time (smoke detectors are radioactive).

    The gain is to not unnecessarily panic. Panic is what makes the world stop, and when you're panicking over something literally petty light a modern broken fluorescent bulb, you are doing yourself and everyone around you more harm than good. I'm not saying to treat mercury as though it's no big deal, because it is. But if you're going to demonize a few milligrams of a toxic and dense vapor, where do you draw the line? Should we induce vomiting for eating a couple apple seeds or cherry pits? Should agencies like the FDA prohibit meat from being cooked well-done? Should we stop putting chlorine in our drinking water?
     
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  12. Brisse

    Brisse Active Member

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    Yea, maybe it sounded exaggerated at first and I don't want that. I'm just asking for some common sense respect towards the stuff, especially those who have children living amongst them.

    Imagine if a family has a big basket full of loose florescent bulbs lying in it and the basket is standing on a shelf. What if a child accidentally bumps into it and suddenly you have the entire floor full of glass shards contaminated with mercury, and the child is crawling around in it. Parents should be aware of these risks.
     
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  13. JJayzX

    JJayzX Master Guru

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    You get flicker from the mains, which in EU is 50Hz, in US it's 60Hz. You see it on crappy or failing bulbs, you can sometimes hear it too.
     
  14. nick0323

    nick0323 Master Guru

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    I'm on Philips LED bulbs for my room, 6w each, can't go wrong really and the warranty is good.
     
  15. Brisse

    Brisse Active Member

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    LED's are feed with low voltage direct current so they need a driver circuit in them that lowers the voltage and converts AC to DC. The output to the LED itself is regulated either with pulse width modulation (PWM) or some kind of constant current regulation. PWM causes high frequency flicker while constant current should be flicker free if it's done properly.

    As for incandescent light bulbs, they don't flicker nearly as much as you might expect because the electric current isn't converted directly into light. It only serves to heat up the filament, and the heat is what actually makes the filament glow. Heat changes are slow compared to the changes in current. The filament doesn't drop to room temperature in between each peak. This means it gives plenty of light even when the voltage is at zero in between the peaks. You might see some flicker when they are close to their end of life though, just like you said.

    Edit: Also, I'd just like to point out that it doesn't flicker at mains frequency, but at twice the mains frequency, so in europe 100hz and in us 120hz. Every cycle has two peaks and both will add heat to the filament.
     
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  16. Backstabak

    Backstabak Master Guru

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    Nope, LED is powered by DC. Some (cheap ones) just use pwm with given duty cycle because CW just produces enough heat to actually changes the properties of the LED.

    Also the sound you described is probably a faulty coil. There is nothing else that can buzz in LED or halogen lights.

    Anyway no one can conciously precieve the frequency of this flicker. If you think you do, it's just psychological.
     
  17. Lavcat

    Lavcat Master Guru

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    I won't argue theory, however I recently had a buzz in my halogen desk lamp that was definitely coming from the bulb or reflector. The transformer is two feet away.

    Reseating the bulb solved the problem and made the lamp perfectly quiet again.
     
  18. Fox2232

    Fox2232 Ancient Guru

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    From economical standpoint LED is most economical and not toxic at all.

    CCFL lights can be pretty energy efficient, but not those small bulbs, only big tubes are energy efficient. And cost wise CCFL is in normal household less cost efficient than incandescent.
    Because while they can deliver same amount of light, they are more expensive and die in between 500~5000 hours based on use. That's sad part of CCFL. What many people saved on energy they paid to company making them.

    Strobe? I have LEDs everywhere. I took cellphone in 240fps mode. And and only 1 out of 4 types did not strobe over time. But thing is, that none goes completely dark between strobes.
    It takes up to 3 seconds to go completely dark for usual LED used in light. What cellphone camera catches is actually dimming by maybe 10~20%.

    Is it possible to notice such strobe? Yes, LED has to have weak output of light not to burn-in into your eye much. And you have to notice it with peripheral vision as that is much more sensitive to light changes.

    Side note, technologies used in LED lights differ. Oldest one I have is using plain unregulated AC 230V. It is Corn Type, 1/2 of AC cycle powers 1/2 of LEDs and 2nd half of AC cycle powers remaining LED connected in opposite polarity.
     

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