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LED Light Fixtures for the Home? 101

Posted by Cliff from the replacing-the-burning-filament dept.
HBergeron writes "Despite some exhautive searching I have able to find very little about LED based light fixtures for the home. There are some in marine use, and a spare handful of others come up on a Google search but from all I have read on Slashdot I have to believe there are more out there. I am in the final stages of a home remodel and would very much like to use 'the lighting source of the future' (tm) in a number of places. For one, the bedroom, LEDs could make a nice bedside sconce/reading light, and a red/white option could be just the like for those late night stumbling across the room expeditions. A vanity light seems like another good place. Not to mention energy and bulb replacement savings." While these may not be economical for most people, I'm sure there are a few folks out there who have put these new lights to the test. How well did they stack up to the use of traditional filament lights?
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LED Light Fixtures for the Home? More

LED Light Fixtures for the Home?

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  • LED are as effcient as Incandesent (Score:3, Informative)

    by master_xemu ( 618116 ) on Friday March 07, 2003 @05:50PM (#5462857)
    White LED lights actually are only as effcient as regular incandecset bulbs. If you are looking to save money you are better off going with CF, if you want effciency go with metal halide.
    • i disagree - LED's as light sources have an advantage over most other light sources that you seems to be ignoring - a very fast response time.

      All you need to do to get efficiency out of them is hook 'em up to a little inverter - supplying brief pulses of current with a very low duty cycle at about 10 kHz or so - the light will seem perfectly bright and usable, as the response time for even a white LED to go from off to 100% is nothing compared to the time it takes a human retina to notice that the light is already off.

      Obviously, this is going to save power - the average power usage would be tiny, the intensity of a pulse would not.

      You just can't do that with a incandescent bulb.

      The better LED torches already do this - they practically SIP current from a battery, and a penlight sized torch using a single white LED is enough to read by in an otherwise unlit room - left in one place pointing at the ceiling!

      Plus it lets you get away with another neat trick too - running the LED at a higher peak current then it is rated for, so long as the pulses from the inverter are suitably short, and the average power doesn't exceed the LED's power dissipation rating, you can get even more brightness.

      With a suitable driving circuit, i don't see why LED's can't be used instead of other light sources for most things, as when run pulsed in this fashion they are extremely efficient.

      (The only potential downside is the faint whine the coil in the inverter makes - but this could be removed given careful enough construction.)

  • A couple of places to check out... (Score:5, Informative)

    by Anonymous Coward on Friday March 07, 2003 @05:51PM (#5462864)
    LED light bulbs [ccrane.com]

    LED brass desk lamp [photonlamp.com]

    Several models to choose from [optiled.biz]

  • DC Voltage (Score:4, Informative)

    by Syris ( 129850 ) on Friday March 07, 2003 @05:53PM (#5462896)
    LEDs require a DC voltage and current to run(typically ~3V and 20mA) as opposed to the 120V AC voltage wired to throughout your house.


    You would need some converters as well as LED driver chips to run the 'bulbs' optimally.

    This is all doable; it's just a lot easier to use one of the many, many, many types of incandescent bulbs.

    • Re:DC Voltage (Score:2, Flamebait)

      by pauldy ( 100083 )
      It is a very simple circuit that does this. As a matter of fact it can use up to 4 diodes to make the circuit which could be replaced with LEDs.
      The circut looks like the following excuse the asci art (which would have been bellow if slashdot was worth a crud). You can also use capacitors and zener diodes to smooth out the ripple that is left in the wave giving a truer dc ouput voltage.
    • I don't much about LED's used for lighting, but I know your post is based on the little LED's you use in your little electronics projects. So, lets check out the power; you said 3 volts across the LED with 20mA through it, P=VI=(3V)(0.02A) = 0.06W Compared to a regular 60W bulb, your effeciency is amazing! Your LED consumes 1000 times less power than the traditional bulb....Unless of course you have no idea what you are talking about. I don't know anything about this stuff, so I don't post any BS about it. You should try the same.

  • dansdata letters (Score:5, Interesting)

    by FrenZon ( 65408 ) on Friday March 07, 2003 @05:56PM (#5462932) Homepage
    Dan covers this in one of his more recent letters sections [dansdata.com]. He states that compared to Halogen bulbs, LEDs aren't as efficient, and are best suited to accent lights.

    But he says it better than I could.

  • Not as efficient as some claim (Score:4, Informative)

    by photon317 ( 208409 ) on Friday March 07, 2003 @06:02PM (#5462996)

    I did some research on this a while back, with the intent to purchase or build some LED lighting systems. As it turns out, for practical, normal household use, LEDs aren't as efficient as some would have you think. You're better off with some form of flourescent lighting. Where LEDs shine is in spot-lighting situations - such as desk lamps, or small spotlights that go under the bottoms of cabinets to light up counters, and that sort of thing.

    They provide more light per watt of energy consumed to a small focused area than other technologies, which spread their light in all directions and are masked/reflected to give light to only one direction. But for a main light source illuminating a room in all directions, they're somewhere in the same neighboorhood as incandescents in efficiency, and soundly beaten by flourescents.

  • LED only good for low power apps (Score:5, Informative)

    by linuxwrangler ( 582055 ) on Friday March 07, 2003 @06:32PM (#5463303)
    As other posters have mentioned, the lumens/watt for LED is about the same as for standard incandescent. There are a couple of places where LEDs shine (so to speak).

    One is in very low power systems where the LED's output/watt remains fairly constant but the lumens/watt for incandescent is extremely poor. The PALlight flashlight can run in "off" which is actually "very dim" mode for over a year with no problem.

    Another is where you want long life and/or color such as in signal lamps. To explain: the lumens/watt for incandescent goes up dramatically with higher voltage but the lamp life decreases in a similarly dramatic fashion. That's why the bulbs on small flashlights where available power is a limiting factor often last only 4-6 hours compared to a standard bulb at nearly a thousand. Signal lamps are at the other end of the spectrum - they need to last a very long time but do so at the expense of efficiency. In addition, much of the light they produce is filtered out to get the necessary green, yellow or red. LEDs produce just the color you want so there are no filtering losses and they don't need to run at reduced efficiency to give long life.

    LEDs beat flourescent where you need point-sources of light for focused applications like headlights. Some LEDs are now starting to get somewhat above the efficiency of incandescent and you may see them soon in auto headlights (I've seen a couple of prototypes - tiny led and big-a** copper heatsink).

    Finally, LEDs are good in rough-service and high-vibration applications.

    For general use around the house flourescent is far, far more efficient and currently far less expensive (last home LED light I saw was well over $100) and the new flourescents put out a very nice light - far nicer than any LED lamp I've seen. With the exception of a reading lamp my wife owned before we got married, every light in our house is flourescent and it really does make a difference on the power bill.
    • I have two halogen torch lamps reflecting off the ceiling to provide area lighting, 300W beasties, and would love to replace them with flourescents. But every time I have bought a flourescent, desk or floor, it comes nowhere near the quoted equivalent wattage. One flourescent torch lamp is pretty disappointing, its maximum, with both tubes on, is less than the half maximum of the halogen.

      Have you had this problem, and regardless of that answer, do you have any recommendations for flourescent torch lamps or wide area lamps?
      • Since fluorescent lamps are roughly 5x as efficient as incandescents, something around 1/5 the power should yield a similar light level (varying based on phosphor color balance and impact on quantum efficiency). I found a 55-watt CF torchiere [thesustain...illage.com] in the first page of Google results.
      • FWIW, I just got through purchasing today at Home Depot a *150 watt equiv* flourescent light that fits in a standard incandescent screw base. However, it only consumes 42 watts of power (and therefore, can fit in a regular light socket without overloading it) and is estimated for 10,000 hours of life. Price: $10.
      • Have you had this problem, and regardless of that answer, do you have any recommendations for flourescent torch lamps or wide area lamps?

        Yep! When I first started buying CF bulbs, they just didn't seem to produce as much light as their claimed equivalent bulbs. So now I use the next size up for everything. This makes the room brighter than before, and I'm still saving plenty of power.
    • And for those people who suffer from chronic migraine headaches, like myself, flourescent lights are a completely non-option. The flicker they produce is horrible, and I can only be around them for a couple hours without having a headache triggered.

      I'd be very interested in outfitting my house in total LED, saving power form incandescent, and staying away from those horrible flourescent.

      ~Donald
      • And for those people who suffer from chronic migraine headaches, like myself, flourescent lights are a completely non-option. The flicker they produce is horrible...
        Your problem is not with the fluorescent lamp, it is with the ballast (power supply). A magnetic-ballast bulb is fed directly from the AC line, and input power goes through zero twice per cycle; this gives you the 120 Hz flicker and consequent stroboscopic effect whenever anything is moving across your visual field. An electronic-ballast CF (heft one, if it doesn't feel like it has a chunk of iron in it, it's not a magnetic ballast) may flicker at something like 20,000 Hz or even have a switcher-regulated constant current DC supply. You are very unlikely to notice any problems from one of those, so check 'em out.
        I'd be very interested in outfitting my house in total LED, saving power form incandescent, and staying away from those horrible flourescent.
        LEDs respond even faster to variations in input power than fluorescents; they can be turned on and off at megahertz rates. If the power supply for the LEDs is something simple and stupid like a bridge rectifier feeding a bunch of diodes through a resistor, you will have even more flicker than you have with standard fluorescents. Don't blame the light source, blame the power-supply technology!
        • >You are very unlikely to notice any problems from one of those, so check 'em out.

          Migraine sufferers are even more sensitive to annoying high-pitched noises, which many of the less-than-perfect high-frequency ballasts emit. Plus I want to harm whoever decided to install those bastardly things in my student lounge. As the (volunteer) audio tech there they bring me nothing but pain, inducing their signal into everything. Balanced cables don't help, as it seems to permeate the equipment itself. ARGH! :-)

  • another place... (Score:4, Informative)

    by Dancing Tree ( 536870 ) on Friday March 07, 2003 @06:53PM (#5463492) Homepage
    www.ledtronics.com

    They have lots of light bulbs, strips of leds, etc. as well as a bunch of other neat items (solar lantern, flashlights, flashing safety vests). Some of the household items simply screw into a light socket, others would require some sort of transformer.

  • Comment removed (Score:3, Interesting)

    by account_deleted ( 4530225 ) on Friday March 07, 2003 @06:58PM (#5463548)
    Comment removed based on user account deletion

    • Re:not really what you want, but.. (Score:4, Interesting)

      by Klaruz ( 734 ) on Friday March 07, 2003 @09:44PM (#5464612)
      I found a neat website on this thing:

      http://www.ebtx.com/mech/optolite.html [ebtx.com]

      They sound like the real deal. I'm going to stop by target and grab one. :)
      • That is the single-LED version, which I have (rather, had...).

        Unlike the 3-LED version, this uses expensive watch batteries.

        Pretty durable, lasted about 2 years until the "reflector" cover came unscrewed and the exposed LED fell out a short time later. One nice touch was that the manufactuer put a spare rubber button in the rear battery cover, in case the original wore out or was lost.
    • You don't mention that the EB lights happen to also use 3 N cells, which are much more expensive and harder to find than AAs. None of the LedLensers (The EB lights are rebadged "LEDLenser" lights from a German company named Zweibruder - I think their website is www.zweibruder.de) have DC/DC upconverters, so if they run on AAs or AAAs, they need 3 cells, and for 2AA form factor they must use N cells.

      If you want BRIGHT LED flashlights, look around on http://www.candlepowerforums.com/ - The creations of forum users ElektroLumens, Lambda, McGizmo, dat2zip, and Mr. Bulk are simply incredible. dat2zip sells an excellent drop-in for MiniMags that includes a DC/DC converter circuit and a 1 watt Luxeon LED. (Equivalent to 10-20 of Nichia's best 5mm units.)

  • small applications (Score:2, Interesting)

    by este ( 600616 )
    I've got an old '67 volvo, and I was sick of the old-looking green backlighting in my dash. I replaced all the bulbs with blue LED's, and they look great. Kind of expensive, but they'll last forever. Smaller applications like this seem to be the most useful. though here in Eugene, OR, we've replaced the red and green traffic light bulbs with LED bulbs. Still waiting on yellow, a cost issue mostly.........

    • Re:small applications (Score:4, Informative)

      by pyite ( 140350 ) on Friday March 07, 2003 @09:28PM (#5464537)
      Yea, yellow is usually the last to be replaced (I know this because I do work at police departments and one of the departments' computer guy is a traffic detective). The reason is that it's not on very often and isn't as "important." LEDs offer excellent benefits for red and green though. They have faster response time, translating into more stopping distance at speed. Plus, they are brighter, and you can see it. And they save money in the long run because they don't need to be replaced as often.
      • They have faster response time, translating into more stopping distance at speed

        I cannot imagine that the .05 second faster that the LEDs will light up would add up to reducing stopping distance by more than 2 inches or so. If localities were really interested in saftey they would increase the "on-time" for the yellow light from 3 seconds, back to 5. But no....revenue generated from red light runners is more important than saftey....

        Indeed...perhaps the reason they do not put LEDs for the yellow lights is that in the next few years they plan to get rid of them all together...

        (ok....I know that was offtopic...but that subject is just my pet peeve....so sue me.)
        • Actually, LEDs light up about 1/5 second faster than convential traffic lights, this translates to about 12 feet at 40 mph. That's a significant difference. By me, yellows generally last a fairly long time by design. It kind of sucks though that where you are they're shortening them to catch more people. Now, there are sensors on the lights at certain intersections that identify approaching emergency vehicles and if need be, make the rest of the intersection red and their light green, to make going through as safe as possible.
        • If localities were really interested in saftey they would increase the "on-time" for the yellow light from 3 seconds, back to 5. But no....revenue generated from red light runners is more important than saftey....

          I've lived in states where the lights have long yellows, and I've lived in states where they have short yellows. Drivers quickly adjust for the length of the lights.

          With a longer light, you simply discount the first couple of seconds and ignore it before you start your internal timeout. The same selfish people are going to be running the red light in either situation.

          I've seen no fewer red light runners where the yellows are longer than where they are short.

      • I bought a pair of these and tried them in my brake lights. The problem is, they're so focused, there's a point on the tail light that's too bright, and everywhere else on the tail light, it's quite dark. I need to find a good way to diffuse the light before it hits the plastic cover.

        Reaction time is better. It's supposed to be 200ms better, and you can see the difference.
        • Hm. Have the LED pointing into a curvy mirrorish thing? Sort of like your front lights. It's just a suggestion, and I know nothing about cars.
          • I thought about this, but it would be too invasive to be worth doing. Right now, the LED clusters are interchangable with the light bulbs. If I had the right circle of plastic, it might do the trick.
        • Here's a possibly stupid suggestion.

          How about lightly sanding the LED. The roughed up surface should spread the light better. Maybe you'd end up losing too much light.
          If you don't mind wasting/replacing an LED or two it might be worth a try anyway.
    • You don't want to hear this, I know, but LEDs do have a finite lifetime. Something in the hundreds of thousands of hours, but it is finite, and the LED clocks in the Pearson Airport definately show it. :-(

      Maybe it's just me, but I find the new LED traffic lights cause a night-myopia-like effect in me. If I see one of those at night, a large area surrounding the bulb will be strongly overshadowed by green. Which sucks. :-/

      Perhaps it's just an intensity issue. I don't think it's my eyes, as my opthamologist thinks they're just fine.

  • LEDs are cool, fiber-optic is cooler (Score:5, Interesting)

    by maggard ( 5579 ) <michael@michaelmaggard.com> on Friday March 07, 2003 @07:55PM (#5463941) Homepage Journal
    LED's aren't necessarily the "lighting-of-the-future", actually fiber looks more likely:

    1. Fiber is cheap these days, especially the 2nd rate stuff left over from telecomms and reused for this
    2. One or two centralized light sources can provide all of the lumens needed for a home or office
    3. Those one or two light sources can be optimized for output, their heat vented directly outside or recovered for use in the building, built to be super-efficient, etc.
    4. Maintanence becomes trivial and cheap with the sources placed conveniently, not scattered all over in ceilings, up walls, etc.
    5. The fixtures themselves are very versatile, basically a diffuser of your choice. Want a spot snap on the head for that, want a bulb-look pop on a frosted plastic bulb, same for strips and coils or flat panels
    6. Dimmers on individual feeds are possible with LCD adapters, the same is true for color filtering
    7. No RF noise, no flicker, durable, cool, efficient, fixtures never need replacing, what's not to love?

    Frankly I look forward to having one or two "light boxes" in my attic keeping much of the heat out of my living space (or in the winter pulling it into the HVAC system), only having to replace a few well engineered super-efficient bulbs in a handy box every few years, plugging in a fiber cord instead of a an electrical one for a lamp. LEDs might become a good retrofit for older wired-not-fibered places but for new construction I'm looking to plastic.

    • And of course, rather than use an artificial light source during the day, you could just pipe in sunlight from outside, filtering out uv as desired.

    • Wouldn't that fiber setup waste a lot of energy when you only want one or two lights on in the house--say when you've got your nightstand light on to read?

      Turning on a powerful central light source seems like an awfully big waste at low utilization. I wonder how designers would get around this.

      Are there any websites that explain a fiber-based central lighting system?

      -AP

  • Color Kinetics (Score:4, Informative)

    by Das Kamikaze ( 17808 ) on Friday March 07, 2003 @08:06PM (#5464025) Homepage
    Color Kinetics [colorkinetics.com] have a number of LED light product lines, both professional and consumer. Their consumer branch, Sauce [cksauce.com] makes an assortment of wands, flashlights and nightlights, while their professional arm has done a number of Huge installations [colorkinetics.com].

    As for prices, I'm sure if you have to ask, you can't afford it...their 4 color intelligent nightlight [cksauce.com] looks relatively cool for $8.
  • White light LEDs are not quite there yet for home use. There are two drawbacks:

    First, as others have noted they are not as efficient as compact fluorescents. Remember that they need low voltage DC so you have transformer losses to factor in.

    Second, the less expensive ones are very, very "blue" in their output and have big dips in the output spectrum. The light is very "harsh".

    Some co-workers follow LED technology for professional reasons (think of a place where spare light bulbs can only be brought up every 3-6 months at $10k/pound transport costs), and passed me some papers that project that they will probably be ready for home use by 2010, and industrial use somewhat before that. They already are starting to dominate in areas where the cost of replacement is high, or where a burn out is a safety hazard.

  • Compact Fluorescent (Score:5, Interesting)

    by Yonder Way ( 603108 ) on Friday March 07, 2003 @09:44PM (#5464615)
    I can't believe I haven't seen it mentioned here yet (maybe I am browsing at too high a threshhold), but compact fluorescent lights are the current way to get the best bang for your buck in home lighting.

    You get roughly a 4:1 amount of light per watt in a compact fluorescent as compared to a conventional incandescent bulb.

    I recently went through my parents house replacing bulbs. I used mostly ~15 watt bulbs (60 watt equivilant) and in a couple of areas where really bright light was needed I used 27 watt bulbs (~100W equiv.)

    There were two fixtures in the hall that used a total of 600W of light originally and now use a total of 60W using compact fluorescent bulbs. The hall is still quite bright, but now use four 15 watt bulbs as opposed to eight 75 watt bulbs.

    It doesn't take a math genius to see that these bulbs pay for themselves relatively quickly via savings in the electric bill. Not only that, but they last a long time. I've been using them for about six years and I've had only *one* bulb die in that timespan (that was a Philips if anyone wants to know).

    Home Depot is selling them pretty cheaply right now. There is no excuse to not buy a pack and try them out. You are totally justified in spending the money for the bulbs up front and put them in now, knowing that if you annualize your costs you are actually saving money.

    These bulbs cannot be used in dimmer type sockets, and other than the really small 9 watt models some of them have a hard time in very small enclosed fixtures.

    You will realize the most immediate savings if you replace bulbs that are in use for extended periods, like driveway lights or hallway lights.
    • It's not just very small enclosed fixtures -- not a single overhead light in my apartment can take a flourescent bulb (of sufficient wattage). At first glance the bulbs don't look that much bigger than their incandescent equivalents, but when you put them side-by-side they are considerably longer (somehow the eye ignores the size of the balast).

      Perhaps more modern fixtures are made with these bulbs in mind, but certainly older ones are not. For these bulbs to really work, we need to start seeing lighting fixtures that are designed specifically for their dimensions. Or better flourescent lamps. If I owned my place I might consider building recessed flourescent lighting (incidentally, Frank Lloyd Wright really liked flourescent lights used this way).

      • Ian, go to Home Depot and take another look at CF bulbs. Like I said, I've been using them for about 6 years now. 6 years ago they were very expensive, had large ballasts, cold color range, flickered when they started up, and of course wouldn't fit in any fixture.

        The very cheapest ones that they sell at Home Depot today have only been around for about a year or two. They start right up without flickering, have a smaller ballast, they are relatively CHEAP ($7 for a three pack of bulbs on a sale day today, vs. $22 I paid for an individual bulb 6 years ago).

        The 9 watt bulbs are probably smaller than your average 60 watt incandescent in external dimensions.

        CF's fit great into lamps now. They also fit great into driveway lights, courtesy lights by the front door, etc. They also work very well in cieling fans.

        As for brightness, I have a desk lamp that is rated for no more than a 45 watt bulb (incandescent) that now has a 27 watt CF bulb which is the functional equiv of a 100W incandescent. Very bright! Earlier on I was so smitten with the savings of CF bulbs that I was putting 27 watt bulbs everywhere. But now I use mostly ~15W bulbs because they are still plenty bright (just as bright as the bulbs they replace, usually) and because right now they are the cheapest. In more decorative fixtures that use multiple bulbs, or where space is tight (like you mention) I've been using the super compact 9W bulbs with great success. The 9W bulbs are a bit dim for general room lighting but most of the time that I use these, there are 3 to 5 bulbs in the single fixture anyway.

        That said, you concerns have already been largely addressed by the industry. Get thee to Home Depot and try out the latest & greatest designs.
        • They start right up without flickering, have a smaller ballast, they are relatively CHEAP ($7 for a three pack of bulbs on a sale day today, vs. $22 I paid for an individual bulb 6 years ago).

          Here in southern california, the cost of the bulbs is subsidized by the utility companies. The nice 27 watt ones are about 3$.

        • I have a number of different brands. My experiences:
          • Lights of America lamps are very cheaply built, and the 3-way ballasts destroy themselves when the bulb starts to die. The bulb is supposed to be replaceable, but if the ballast is dead you have to buy a whole new unit.
          • I bought some "Eco-Bulbs" (Feit Electric, made in China) and they all croaked in less than a year of relatively undemanding use (though many starts). The dead units were the folded-tube, frosted-plastic cover type, but the one I took the cover off of for better cooling lived no longer than the others. I have a naked spiral tube unit of the same brand (13 W) in a desk lamp, but it does not have enough hours on it to get any idea of the longevity.
          Them's my experiences; your mileage may vary.
      • I've found a few (again, at Home Depot) that are small enough to fit even the tighter tolerance fixtures. But you can only get them up to 75 watt equivalence - the 100 and 150 are just too big.

        What I'd like to see is a 3-way CF bulb that's reasonable in size. They're too tall for most lamps.
    • All fluorescent bulbs have dangerous amounts of mercury in them. Be very careful when handling fluorescent bulbs of all types--you may end up saving money and energy but at the expense of contaminating your living space with deadly mercury.

      Kris
      • Your average fluorescent bulb has less mercury than your average thermometer.

        Your average compact fluorescent has far less mercury than your average fluorescent.

        So for God's sake, please stop taking your temperature before you die!
    • one other side benefit you didn't mention. I have a ceiling fan in the living room that would go thru 40w fan light-bulbs like they grew on trees. I would replace at least 1-2 a month and these were supposed to be suited for fans and withstand heavy vibration. COuld never figure out what was causing the problem, vibration or burnout or power surges. I finally got sick of it and got those 15w lightbulbs in Home Depot abut 5-6 months ago. Yeah, they cost about 4 times as much, but I'm not constantly having to run to the store to get more lightbulbs as not one of them has burnt out yet. And if this keeps up, I won't have to replace them for a long time coming, thus saving me time and money and unnecessary aggravation.
    • I wonder...can you use these compact fluorescents in the fridge?
      • I haven't tried it. I imagine it would work but when they are cold they tend to take a few seconds to start up (when I say cold, I mean like 40 degrees (F) or less).

        The fridge would probably be the very last place I put a CF, just because it is going to yield the least benefit (this is a light that is only ever on a few seconds at a time).

        I think it is best to start with lights that are on the longest, and work your way down from there.
  • On a whim last year, I bought an Ledtronic 9-led 4500K Incand White bulb [netdisty.net]
    at a fire sale at my local alternative energy shop. It uses
    approximately 0.6-1.2W of power, and produces light equivilant to a 15W
    incandescent bulb.

    But that said, it's sitting here on my desk, not in a socket. Why? When you turn it on, the light flickers and
    whines (my guess is it's about a 60-hz flicker/whine, like an old TV);
    and I have not found a good place to put such a dim bulb (perhaps when
    I install my outdoor lights or build the shed in the back).

    But this is an early generation bulb, so I expect the flickering to go away with a later generation.

  • The reason LEDs seem so bright is that they are essentially a point source of light, and they generally are designed for small viewing angles.

    It would take quite a number of LEDs to match even a dim light bulb.

    The reason LEDs are considered so efficient is that their light output is based on the current through, rather than the voltage through them.

    Inefficiencies are introduced in the circuit used to power the LEDs. In most small circuits one would use a simple resister to limit the current. This resister typically wastes 2-3 times the energy that the LED itself consumes. This isn't an issue since one LED and resister should consume less than one tenth of a watt.

    Cheap LED light bulbs for home use might use a simple resister scheme. If so, they will consume nearly as much energy as an equivilant incandescent bulb, and let off as much heat.

    A truly efficient LED light bulb will have several high-output LEDs, and a small, 90%+ efficient switching current regulator. Such a bulb should still be more efficient than current lights. This can be shown by how little energy is given off by other (non visible light) forms of radiation, such as infrared light and heat.

    -Adam
    • Stupid question:
      Why don't they build just one giant LED instead of creating arrays of 10 or so LEDs?

      • They do (Score:3, Interesting)

        by Andy Dodd ( 701 )
        http://www.luxeon.com/

        Currently the largest LED is Luxeon's 5 watt emitter, which gives off around 100-120 lumens. No one has been able to manufacture anything larger easily yet. There's a rumored 10W LED coming from another company, although its light output is specced as LESS than Lumileds' Luxeons (i.e. it's less than half as efficient.)

        5W units are $40/each in small quantities, dropping to $24 or so each in larger quantities (100+) They are VERY hard to obtain.

  • I built them myself and they are great. (Score:4, Informative)

    by jakedata ( 585566 ) on Saturday March 08, 2003 @09:20AM (#5466606)
    I have an off-grid camp and desired safe and efficient lighting. I loathe fluorescent light.

    So I have a small (300 ma) solar panel charging a 12 Volt gel cell that I salvaged from a UPS.

    Rather than use resistors or a dc-dc converter, I wired the LEDs in series. I made strings of 5 LEDs and wired the strings in parallel. (think christmas lights) Peak voltage on my circuit can be > 14.8v

    Hints:
    The light was extremely white/blue so I made some yellow strings and mixed them in. Cheaper that way too.

    I used a cheap wirewound potentiometer as a dimmer because it was too bright for night reading.

    I made the electrical connections into a self-supporting frame for the LEDs rather than using a backing material. That means the clear LEDs and fine wires disappear into the background. When it is off it is nearly invisible.

    The LEDs I used (Hewlett packard, purchased from Newark Electronics) are extremely focused and directional. It took some careful aiming of the individual elements to get a good spread. You might consider a diffusor.

    Good luck, and I will be happy to answer questions if you have any.

    Next time I make some, I am going to make seperate red, green and blue circuits so I can tune the color balance.

    -j
  • OK, not for everyone or every room. LED christmas lights, hidden behind a strip of molding near the ceiling. Done wrong, very tacky. Done right (maybe with a light defuser?), it would be no-fuss or maintenance for decades.

    On sale, a string of 100 went for $6 USD at WalMart in January. Now...probably $20.

  • Paint those walls with light (Score:3, Interesting)

    by rich_r ( 655226 ) <rich@NospAm.multijoy.co.uk> on Saturday March 08, 2003 @01:28PM (#5467488) Homepage
    Using these [pulsarlight.com]!

    Using them in the venue I work in and they really do look great!

    YMMV on whether they're appropriate for your home application though! I would suggest, however, if you are going down the hardcore-lots-of-new-fixtures-everywhere route that you consider using fixtures that talk DMX [usitt.org], which'll make life a darn sight easier when you want your rooms to slowly change colour over the day!

  • Not LED's, but we like our Microsuns (Score:4, Informative)

    by dpbsmith ( 263124 ) on Saturday March 08, 2003 @04:47PM (#5468445) Homepage
    Not LEDs, but I thought I'd mention that we currently have three Microsun [microsun.com] HID metal-halide lamps in our house and are very happy with them.

    Microsun makes table and floor lamps that are nice-looking pieces of furniture, mostly of wood. Not cheap but not out of line for "nice furniture." They incorporate a "gearpack'" which holds a 68-watt E17N metal-halide HID bulb and two conventional 25-watt incandescent bulbs.

    The company claims "more than 300 watts [sic] [sigh...] of crisp white light, yet uses less than half the energy to do so." I think the claim is reasonable. The bulb package, annoyingly, does not state the light output in lumens, but such bulbs typically seem to have an output of about 5000 lumens. (The 25-watt bulbs, of course, don't add very much light but are just there to warm up and smooth out the spectrum).

    That is, of course, not nearly as energy-efficient as fluorescent. However, most of the compact fluorescents we've tried really have fairly unpleasant color balance AND just don't put out much light.

    These lamps put out a LOT of light and the color balance is quite pleasant. And they just look "normal," small bright sources of light inside a lampshade that light up the room just the way traditional lamps do.

    Nothing revolutionary here, just nice, bright, ready-made, energy-efficient lighting with no "geekiness."

  • On a recent science or medical info radio program,
    it was said that:

    - rates of breast cancer in women may be linked
    to the amount of time they work in artificial
    lighting (eg office flouro's)

    The research found that women who work at night,
    presumably in artificial lighting, have higher
    rates of breast cancer.

    Blind women have much lower rates of breast
    cancer.

    'don't know if it matter -which- type of
    lighting they're experiencing, but it might
    be good to know... ie -before- choosing
    a lighting system technology for the home.

    I don't have a link to the original Danish
    research work, but here's a German link:

    www.labournet.de/diskussion/arbeitsalltag/gh/bru st krebs.html

    Other links are available; cf:

    Google("breast cancer" artificial lighting blind rates)
  • You should check out the Luxeon Star LED. It is a little larger than the average LED but has the light output of 20-25 smaller 5mm LED bulbs. They even make drivers for it that simply require you to attach the emmiter. So I would suggest checking out the Luxeon Star site. http://www.lumileds.com/luxeon/products/products_i ndex.html

    • More on Luxeons (Score:4, Informative)

      by Andy Dodd ( 701 ) <atd7NO@SPAMcornell.edu> on Monday March 10, 2003 @09:56AM (#5476120) Homepage
      Go to http://www.candlepowerforums.com/ - It's the closest thing you can get to a "Luxeon Star User Group" :) - There are a lot of flashlight modders there that use LOTS of Luxeons in their projects. People have started using Luxeons elsewhere, too. (One guy on the forums builds Luxeon-based replacement dome light modules using 1W white LS units + a DC/DC converter circuit he designed himself.)

      Very little in the terms of line-powered lights, but people are starting to experiment (very carefully...) in that area.
  • LEDs are indeed the light of the future.
    I.e. they aren't the best choice for light today,
    however they have been improving at close to what Moore's law predicts,
    so perhaps in 10 years, they will be the ultimate light source.
    Today however, they are still too expensive (90 dollars vs 90 cents for a standard bulb) and only a little more efficent.

    Last year the light/power breakdown was something like this:
    Lumens/Watt Light Source
    100-190 low pressure Sodium (HID)
    50-150 High pressure Sodium (HID)
    60-140 Metal Halides (HID)
    20-60 mercury vapor (HID)
    85-95 32 watt T8 fluorescent
    60-65 standard F40T12 cool white fluorescent
    48-60 compact fluorescents
    45-55 Super bright Red/Orange LED
    35-45 Super bright Green LED
    20 T3 tubular halogen
    15-25 bright white LED
    5-25 Halogen
    17 standard 100 watt incandescent
    6 incandescent night light bulb (7w)
    <6w incandescent flashlight bulbs

    The best choice for the home today is almost certainly the cool white tube fluorescent, with an all electronic balast.
    They don't "whine" or flicker like the older fluorescent lights,
    the tubes cost about $2.00 US, they are near the top in efficiency, and the last for years.
    The down side is that they require special fixtures, and they flicker more than incandencances, which is a problem for some people.

    Compact flourescents are the next best choice,
    but they don't have "instant on" which can be annoying for some rooms.
    In my kitchen, I have an old 3 socket fixture.
    I use two compact flourecents and a long life incandescent and it works well.

    Yes, this is the third time I've made essentially the same post, what's your point?

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