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LED lamps vs fluorescent lamps?

Discussion in 'General Electronics Chat' started by Flyback, Sep 8, 2013.

  1. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi again Flyback,

    I've seen Lumens per watt output go up over the years for white power LED's. So i dont know where you are getting this info from. Maybe i am not understanding you or something.

    But even more striking, back in the 1980's i could not even start to build an LED flashlight because all that was available were basically indicator light LED's, which got brighter later in the 80's but still not a very nice flashlight component. Made nice indicators, but that's about it.
    And go back to circa 1975 and all i saw were pretty dim indicator light LED's like red, with many applications still using those silly neon glow lamps :) As an example, i worked for a company that made numerical displays out of hundreds of neon bulbs yet LED's were available. Why would they need to do that if the LED's were already bright enough to use? And they still took 20ma, not 2ma or 0.2ma, so the efficiency must have gotten better somewhere along the line.

    Maybe the advances are not as big today, but i suspect they are still working on it.
     
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  2. Flyback

    Flyback Well-Known Member

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    Indeed so, -in 2007 I started work for a company who were enthralled that the Cambridge University Gallium Nitride dept in UK had stated in all the main newspapers that in three years time they would have LEDs available for the mass market which would be at least 300% more efficient then the LEDs currently existent at that time (2008).
    This obviously never happened.
    It seems to me that LEDs have hit the end-stop.
    The only thing we get increased now for LEDs is marketing spin.
    Even wiki contradicts itself over CFL vs LED......look under CFL then LED and you find contradictory statements.

    What I do know for sure is....
    LEDs have unfortunate directional properties, need big heatsinks, and are more expensive than flu.

    I am told that its easier to build a 10 Watt offline led light bulb without using electrolytic capacitors than it is for CFL....but im looking into this.

    Also, in USA, mains is only 110VAC.....I sometimes wonder if when rectified into a smoothing capacitor, -is that enough voltage to properly and efficiently drive a CFL?.....I don't think so....I reckon in USA, maybe LEDs are therefore better than CFL....especially if not much smoothing capacitance is used and the DC (post rectifier bus) dips significantly below 100V say.
     
  3. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Flyback, I asked you yesterday to stop posting stuff about LED's. I asked you to sleep on it. And think about before posting more nonsense..

    Since you will not heed me or listen I will give you a little fact:

    Osram's little Duris E3 is a 100mW LED that manages to push 7 to 8 Lumens @ 110 Degrees viewing angle..... Just a properly designed PCB according to Osrams guidelines is necessary for them to work up to 50000 Hours.

    Designed specifically to replace Fluorescent tubes...

    Stop talking crap. Or otherwise get up to speed with the latest LED offerings. Forget what you "saw" or were "taught". Things have changed rapidly lately.

    Thats all I can say.

    Regards,
    tvtech
     
    Last edited: Sep 11, 2013
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  4. dave

    Dave New Member

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  5. ronv

    ronv Well-Known Member Most Helpful Member

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    The only thing keeping me in CFls is cost. I have a lot of 65w can lights. For some reason they are expensive. Maybe the temperature issues require a larger heat sink.

    Interesting read on the history:

    http://www.fairchildsemi.com/Assets...lobal-Power-Usage-and-Cleaner-Environment.pdf
     
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  6. Flyback

    Flyback Well-Known Member

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    Well, Thanks for info on Duris E3 TVtech.
    It shows, due to so much marketing hype out there, you have to come to a forum to cut to the chase and find things like that out.
    Anyway, I believe those lumens you speak of are in the zenith......the 120 degree angle is where the lumens falls to half of that..from the way I interpret the datasheet
    http://www.farnell.com/datasheets/1514325.pdf

    Ronv, thanks for article, but see page 1 and the graph there...thus they (Fairchild) show the impressive increase in led lumens that occurred between 1960 and 1999....this is utterly and entirely irrelevant to the state of play in power led technology, which took off post 1999.
    Its these unfortunate "spinning" of information which leads to so much false knowledge on leds.......that graph should not be in that document....Fairchild want to increase their led driver sales....and are using a irrelevant graph to do it.
     
  7. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    The irrelevant part is your posts, you are the only person ever mentioning power LED's - and even you didn't mention them until very late in the thread.

    LED lighting generally doesn't use power LED's, just stacked small LED's - which surely you're fully aware of, as you claim to be having some made, and despite your condemnation of paralleling LED's are doing exactly that.
     
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  8. tvtech

    tvtech Well-Known Member Most Helpful Member

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    Off Topic so post deleted by me.
     
    Last edited: Sep 12, 2013
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  9. Flyback

    Flyback Well-Known Member

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    I think LED light bulbs try and use fewer , higher power leds.
    LED floresent tube replacements probably use many smaller leds.
    "Low sales volume" led lights try and use as few leds as possible, so if the power is high, then they use higher power leds.
    LED streetlights almost certainly use power leds.
    LED car headlights use power leds.
    LED TV's many small leds.
    Nigel Goodwins panel light = many smaller leds.

    ...so theres still quite a few power leds used....a very significant part of the market.
     
  10. ronv

    ronv Well-Known Member Most Helpful Member

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    Flyback,
    You sound like a young American, always wanting instant gratification. :)
    But give them some years and someone will come up with another material or something that increases power. There are many parts to technology improvement. Many road lead to profit.
    In the meantime I'm stuck with my CFLs in a can.
     
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  11. audioguru

    audioguru Well-Known Member Most Helpful Member

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    Today it was raining like crazy and very windy. A street light leaned then dropped slowly to the ground, lighted.
    It has about 20 or 30 high power white LEDs. There is a pretty big finned heatsink on top.
    They have almost finished replacing all the high pressure sodium (orange light) street lights in my city.
     
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  12. Flyback

    Flyback Well-Known Member

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    That's interesting, -It would be interesting to know if the driver SMPS was up in the head, or down in the base where its cooler and easier to replace. -if its up in the head, does it comprise electrolytic capacitors?
    Also, is there a complex led pcb arrangement so that each group of leds points in a slightly different direction so as to avoid the streetlight acting like a downlight?
     
  13. audioguru

    audioguru Well-Known Member Most Helpful Member

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    The high power LEDs in the street light are all pointing directly downward but have a wide angle beam.
    The electrical workers who disconnected it to make it safe said that each street light has its own RF modem. The antenna on each light is about 5 inches long (12.5cm) so they receive at about 1.2GHz.
     
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  14. Flyback

    Flyback Well-Known Member

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    http://www.leafnut.com/how.do

    ..it'll be like the "leafnut" streetlighting system....incidentally, note that they (Harvard) specialise in streetlighting, and most of their streetlamps are fluorescent, or HID....not LED....
    http://www.leafnut.com/products.do
    ....even their dimmable streetlights are mostly HID or fluorescent.

    I am starting to seriously doubt the genuinity of a lot of the marketing hype that I am hearing about LEDs.
     
    Last edited: Sep 12, 2013
  15. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi again,

    I dont know about street lights, but for home lighting i would hate to have to give up my LED's now that i've had them. I would never go back to the fluorescent tubes as those things really bite, but i might be able to go to the curly bulbs as i did find some in "Cool White" on the web. I might actually try one of these bulbs anyway just to compare with the 120vac LED bulbs.
    I did have a few curly's blow out already but i also have one that has lasted a few years now. Not sure why the big difference.
    There are some health and environment risks however because of the mercury. If the bulb breaks, the mercury gets out. At around 5mg, that's enough to contaminate about 6000 gallons of water.

    Here in the US, at least in my area, we have 120vac line power and that can power a fluor with no problem. What happens though is that sometimes the line drops to nearly 100vac or lower and that causes a problem with some fluor tube start up, as they just sit there and blink on and off trying to turn on. This happens mostly in the summer time and even yesterday it dipped down to around 100vac for a while.
    The curly bulbs have a different drive circuit though so they work a lot better than the old tube+ballast that we used to see. I could never use them because of this problem, or at least not over the entire summer months.
     
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  16. audioguru

    audioguru Well-Known Member Most Helpful Member

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    The dumbos who designed the elevated highway in Toronto used fluorescent light tubes. Then they found that they didn't work in winter when it is cold.
    They used sodium vapour or metal hydride lights after that for many years.

    The new LED street lights are good.

    This morning I went to see the LED streetlight that got blown down. The pole was on the ground but the LED lighting part WAS GONE! Stolen? Not by me.
     
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  17. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi again,

    I should have also mentioned that i also like to promote LED's over other types of lighting because i believe that LED's will improve as the user base increases even more than if the user base did not increase. In other words, if manufacturers see that more and more people are using LED's then they are going to be more prone to try to improve them and reduce cost, and that's to us as consumers a great benefit.

    But that's not all. I also believe that LED's are the lighting of the future in that eventually they will be the best over all other types. To me it is just a matter of time and as above, interest. This could turn out to be a blunder in say 50 years if someone somewhere comes up with a better way to improve some other type of lighting or even a new invention. But from what it looks like right now in this present day and age circa year 2013, it still looks like LED's will get better and eventually take over. So i see it as a good bet that doesnt cost me too much. I have invested very little for what i got right now, and i do actively try to persuade others to do the same. I dont have a commercial interest in any company that makes or uses LED's at the moment, but i do have personal interest in that i hope they get better and cost less in the future. If not as much for me, at least for the coming generations.
     
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  18. tvtech

    tvtech Well-Known Member Most Helpful Member

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    LED's are the future MrAl

    Good PCB and/or cooling design is essential for their success though.

    All the best,
    tvtech
     
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  19. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    You need to be quicker next time! :p
     
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  20. RODALCO

    RODALCO Well-Known Member

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    Interesting discussion is going on here. I have two LED traffic lights. The LED's are 4 in parrallel and then in series with a controlled driver circuit. ( these came out of the bin at work - ex car v. pole crash ) Will take some photo's if anyone is interested. These are 5 mil LED's.
    Also I got two LED Street lights, they have large Aluminium heat sinks and complex controller boards, these look like high power LED's. One cluster of about 28 of these LED's works very well and is extremely bright. Will do a current measurement on it and will post back.
    Will attempt to work out why the other cluster failed.
    LED's have improved enormously over the last 15 years or so. I still have some red , green and orange LED's bought in the mid 1970's. Compare these with the new 4000 to 10000 mCd LED's they look like glowing dots and they are very dim.
    I must say that the older LED's took more abuse in the case of excess current than the new LED's which pop a lot easier.
     
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  21. Flyback

    Flyback Well-Known Member

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    Thanks for the info, this is interesting....do you mean 4 parallel strings of 4-leds-in-series?
    -And may i ask did you say there are current limiting resistors in each series string?
    Also, please advise -was there a manufacturer name?
    It'd be great to see a pic of the led streetlight heatsink....I just bet its a real hulk of a heatsink.
     

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