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Thursday, February 28, 2008

Not so easy to run an LED ”bulb” off of a dimmer switch – but here’s how

Feb 28 2008 3:23PM | Permalink |Email this|Comments (73) |

With the feds legislating the end of the incandescent lightbulb by 2011, and compact fluorescent lights (CFLs) being not-so-popular*, I’m eagerly awaiting the advent of inexpensive screw-in replacement high-brightness LEDs (HB LEDs.) It will be a while before they’re readily available at a reasonable price, but it’s likely that dissatisfaction with CFLs will drive LED replacement bulbs into the market sooner rather than later.

But if your house (or product) uses dimmer switches, you’ll have a problem using dc-powered LED bulbs. Dimmer switches consist of a button or dial that sets the firing level for the dimming triac. The lower the setting, the less ac power passed through to the LED bulb (aka, “luminaire”.) But since the LED luminaire has a built-in ac-dc power supply that will try valiantly to hold the ac input to a controlled dc voltage rather than let it rise and fall with the percentage of the ac signal that the dimmer switch passes.

Dimmable LED circuit

NXP has a nice (PDF) reference design based on its SMPS (switched-mode power supply) chip, SSL1523. I saw the demo at the NXP booth at APEC and the LED luminaire responded just as an incandescent lightbulb would. True, luminaires with this capability would probably be more expensive than simpler non-dimming ones, but you’d only have to use these in your mood-lit rooms, and go with straightforward luminaires throughout the rest of the house.

As we get closer to the drop-dead time for incadescents, expect to see LED luminaires become readily available, including some with dimming capability.

*I bought packs of bulbs from both Home Depot and Costco. Most have lasted considerably less than half the lifetime of incandescent bulbs.

Reader Comments

at 2/29/2008 12:36:23 PM, Tom said:
CFLs have lasted less than an incandescent for you? I'm quite surprised. I've used CFLs for years, with bulbs from Philips, Sylvania and GE. All have lasted for at least 2-3 years where an incandescent lasted 3-6 mos. in the same socket. Most CFLs in my home have lasted more like 3-4 years or more. Could the issue be frequent cycling of the CFLs? I use CFLs only in applications where I know the bulbs will be on for at least 20-30 min. at a stretch (like a family room/den). Areas where I use them for short periods like hallways I still use incandescents.

at 2/29/2008 12:40:23 PM, BBowden said:
I'm not sure if you got a bad pack of bulbs or there is something wrong with the power in your house but I purchased CFLs from Costco 3 years ago and I haven't had to replace a single one. The bulbs they are replacing are standard incandesent which have a lifetime of maybe a year

at 2/29/2008 12:56:04 PM, bruce said:
i've also had poor experience with cfl's even in low-usage settings. my kitchen par38 halogens last far longer than cfl's in my garage, as one example. i still want to know what will be done to deal with the mercury that will enter the waste stream in 3 or 5 or whatever many years when these cfl's get tossed in the trash.

at 2/29/2008 1:10:31 PM, Ed Korczynski said:
I bought 12 Philips CFL's over 10 years ago and have used them in standard settings, and 9 still work fine...however, they cost ~$10 each at the time and so we may presume they were made with greater quality. The cheap generic versions out today may die soon. You still get what you pay for.

at 2/29/2008 1:13:28 PM, Nick said:
The first CFL I had in my house just failed on me 2 months ago. But, it was working since 1991, as a kitchen lamp, that gets used every day. So, over 16 years of use saved me money so many times over already.

at 2/29/2008 1:15:53 PM, Joseph said:
Bruce, I have spoken at LED show in SF two weeks ago with the woman who is in charge for the energy program in California and asked her exactly this question. Her answer: the level of mercury that goes from the coal power station is significantly larger than possible environment contamination from CCFL thrown out.

at 2/29/2008 1:24:10 PM, Gene said:
I’ve had CFLs running here for 18 years. I’ve even got high efficiency ballasted CFL pool lights UL approved running since 1991. Reliability is fine. Color has improved and if you want to spend the money they can even look acceptable.

at 2/29/2008 1:27:44 PM, Bill said:
LED lamps will need to get a lot better before I will buy another one. I paid ~$50 for a "70 LED" bulb, it wasn't even bright enough for reading. I found a use for it in my porch, as low level mood lighting. It failed less than a year after I got it. Has anyone spouting LED even tried one out? They will have to get MUCH better than that, or I'll get my incandescents on the black market (which is guaranteed to start up.)

at 2/29/2008 1:39:55 PM, Profazmat said:
Get 'incandescents on the black market'! The 'liberals' and 'environment-Nazis' will turn us all into 'criminals'. Maybe the Feds need to install an incandescent lamp sensor 'wall' at the south border along with the people wall! (for those who might miss it: all sarcasm)

at 2/29/2008 1:59:23 PM, Jerry said:
What are we supposed to do with our expensive chandeliers, throw them in the dumpster? I hope the govt is not really serious about this phase out idea!

at 2/29/2008 2:09:08 PM, W17053 said:
With my experience, CFLs don't want to start when they get cold - you probably can't use them as a porch light in cold weather, or in the 'fridge (you need an incandescent, or maybe LED). What about the oven light? As another commenter mentioned, they don't last long when used on-and-off. They won't work long in a closet, but will run 'forever' if left on.

at 2/29/2008 2:16:50 PM, JTK said:
The cheap no-name CFLs I bought lasted about as long as the dollar-store incandescents. But, the 2 cases of Sylvania CFLs I found at Lowes are still going strong. My electric use is about half of what it was a year ago.

at 2/29/2008 2:48:11 PM, TXranger said:
The isssue with short lived CFL's and LED bulbs can usually be traced to temperature issues. Incandescent bulbs are just glass and metal and can handle a huge temperature range. But CFL's and LED's have tiny switch mode power supplies in the base. These sensitive electronics begin to age quickly at 50 Deg C or so. They simply cannot be expected to last in unventilated can housings or other places where no air can flow past the bulb. It's worst when the bulb is installed base-up. I have used them in ordinary table lamps and ceiling fans for years with excellent life. (Lacking a filament, they are tolerant of vibration, making them really attractive for undimmed ceiling fan lights.) The low temperature start issues can also be traced to the electronics in the base...

at 2/29/2008 3:27:16 PM, LEDJunkie said:
I liked the comment about Chandeliers, I imagine the candle people talking about new-fangled electricity the same way. 1. LEDs are no where near the brightness limits, it is only efficiency that is limiting. We have been experimenting with 100 watt LEDs that are dangerously bright. Say goodbye to your night vision for a few days if you aren''t careful. The goal is to make them more efficient than alternatives, which is pretty close to happening now, but efficiency is the limiting factor. 2. As quantities increase to a few billion units a year, you will see the prices plummet. That will in turn increase the demand. Amazing how technology isn''t in that equation except peripherally. 3. I personally will welcome a three color LED lamp for my Cheap Chandelier which seems to burn out right before I actually plan on inviting people over. Having a lamp that simulates flickering flames or bright lights when needed will be great and having it last 40,000 hours (to half brightness, not burn out!) will be even better.

at 2/29/2008 3:29:45 PM, MDskeptic said:
Has anyone experienced very high base temperatures when a CFL fails? I had one fail in a range hood while I was out of the room. I did not realize the lamp had failed until my wife smelled it burning. It got so hot the base insulation bubbled and melted. If this had occurred in a normal lamp socket I believe it would have started a fire. Since then I have refused to use any more CFLs.

at 2/29/2008 6:52:01 PM, Tom said:
Ms. Conner, please get your facts straight before printing something quite wrong. You say that the incandescent bulb sales will end 2011. That's wrong. I did a little searching and a phase out of incandescents begins 2012 and is complete by 2014 in the US except for some applications. Taken from Wikipedia: "Many of these state efforts became moot when the federal Clean Energy Act of 2007[5] was signed into law on December 19, 2007. This legislation effectively banned (by January 2014) incandescent bulbs that produce 310 - 2600 lumens of light. Bulbs outside this range (roughly, light bulbs currently less than 40 Watts or more than 150 Watts) are exempt from the ban. Also exempt are several classes of specialty lights, including appliance lamps, "rough service" bulbs, 3-way, colored lamps, and plant lights." The [5] footnote refers to the information taken from a U.S. News and World Report article on the subject, the Dec. 17, 2007 issue. I found the article and that's where they indeed sourced the information. So please, to the "conservatives" out there that are always being victimized by those "liberals", take solace that you won't be thrown in the klink until 2014. Between now and then you can look for other ways to be frightened and abused.

at 2/29/2008 7:26:06 PM, ERP said:
It seems that longevity of CFLs has decreased over the last three years, probably as the volume increases and the manufacturers cut more corners. But the real problem with CFLs is that they''re full of mercury, so I''m eager to see them replaced by LEDs.

at 3/1/2008 4:55:12 AM, MJM said:
"But the real problem with CFLs is that they''re full of mercury, so I''m eager to see them replaced by LEDs." Umm, aren't LED's made from Gallium-Arsenide? Does anyone know the effects of dumping that into landfills across the country?

at 3/2/2008 2:16:07 PM, Loophole said:
Time to install 150W bulbs throughout the house (with dimmers of course :) True, try to find a CFL that is the size of a small mains powered teardrop bulb - good luck!

at 3/3/2008 12:58:16 AM, LED bulb lifetimes said:
I have replaced GU10 20W spots in my home office with LED (in the UK our mains is 240v). However, out of 6 bought less than 2 years ago, 2 have failed and one has grown dim - less than half the brightness of a new one. I expect that they will improve over the next couple of years, but LED bulbs are not yet ready for the mainstream, in my experience.

at 3/3/2008 11:31:42 AM, Jonathan Williams said:
Just think of the brisk sales in incandescent bulbs as we approach the deadline. I can't see how our Congress can get any more stupid. What ever happened to free markets? As the price of 'juice' goes up, motivation to use energy more efficiently increases as well. I have certainly relamped mnay fixtures in my house with CFL, but I want that to be my decision, not some do-goodin' meddler inside the Beltway.

at 3/4/2008 2:24:59 PM, Dictate said:
You dont have a choice, do what we say or go to your room! Remember, we are smarter then all of you.

at 3/5/2008 9:19:34 AM, Bill said:
Here in Wisconsin, incandescents provide heat as well as light. A room lit up with incandescents feels warmer.. because it is! So I'll get some 150W 'heaters' for the great room. ;-)

at 3/10/2008 1:05:07 PM, GaAs vs mercury said:
MJM, white LEDs use a blue or violet GaN LED. If you dumped a GaAs red LED into a landfill, it would sit there for a long, long time. If you incinerate it at an extreme temperature, a minute amount of arsenic would be released. I would be surprised if all the arsenic ever used to make LEDs was even a fraction of the arsenic that is ingested worldwide from naturally occurring groundwater contamination. Or the amount of arsenic leached from pressure-treated lumber.

at 3/10/2008 6:20:14 PM, Gallium is rare and expensive said:
Invest in Gallium stocks. Gallium is a rare and expensive metal. I can''t wait to see what happens to the cost of LEDs when we start to use Gallium for general lighting. Even if they aren''t as efficient as LEDS, OLEDs will probably end up far less expensive, especially since they don''t need complex optics and heatsinking.

at 3/13/2008 2:32:39 PM, engineer said:
It is not true that LEDs need a DC supply. They can be simply driven using a bridge rectifier and capacitor as the current limiter. Of course this only works for a fixed frequency supply, but it will work with dimmers, since they are a form of PWM, but controlling the amount of the sine wave during which they are on.

at 3/13/2008 3:10:05 PM, Mr. Blue said:
I have used CFLs since 1991, but only for lamps that are on for more than 10 or 20 minutes at a time (not the laundry room, closet, garage, etc.) with great success. I have also used one CFL outdoors (on a dusk-to-dawn porch lamp), but I bought the "porch lamp" type that can start in cold weather. I -am- using some LED lights now, but only as night-lights and accent lighting.

at 3/13/2008 3:49:47 PM, Robert Salasidis said:
My experience with CFLs is that they will last < specified life expectancy if in an enclosed environment where heat becomes an issue. In that case, as smaller wattage bulb may help.

at 3/13/2008 4:16:13 PM, Radman said:
Uh, so I''m supposed to put a bunch of unshielded switching power supplies in my recording studio? And for the carbon-obsessed, let''s see you replace those coal plants with nice, clean, nukes. Remember that cheap coal-fired electricity, if eliminated, would bankrupt American industry and electricity consumers.

at 3/14/2008 6:46:59 AM, John L said:
I have to comment about CFLs, I have found that the 40 watt replacements are the fastest and first to blow. Typical for my household in on/off site such as a bathroom, maybe 4 to 5 months. However in the bedroom nightstand where these bulbs are on longer than an hour at a time, so far about 18months and still going. But it's not the electronics that dies it's the filaments, YES there are 2 filaments, that usually burns out. I have taken many of these CFTs apart, disassemble the eletronics and hook them up to as much as a 40 watt long fluorescent and be able to run that bulb for months on end. The problem is the surge currents in the filaments that burn the filaments out. I don't see this as a problem on the higher wattage lamps though?

at 3/14/2008 8:05:09 AM, Mike Bibby said:
Joseph wrote: "the woman who is in charge for the energy program in California [said] the level of mercury that goes from the coal power station is significantly larger than possible environment contamination from CCFL thrown out." Surely no-one ever believes anything claimed by officials any more? I admit that living for 10 years under a government of blatant liars (UK) may have coloured my views, but I now always start with the assumption that they are lying to me until proven otherwise!

at 3/14/2008 8:09:01 AM, Mike Bibby said:
W17053 wrote: "they don't last long when used on-and-off. They won't work long in a closet, but will run 'forever' if left on." Another one I don't believe! I've tried it, and the BEST life I've achieved - left on all the time, never switched off - is 5000 hours NOT the 8000 to 10,000 claimed!.

at 3/14/2008 8:18:29 AM, JB said:
Funny that happens in your household Ms. Conners. I bought my house 3 years ago and the first thing I did was replace all incandescents with CFL lights. The only place where I have replaced 1 bulb after 2 years of use is in my laundry room, because of frequent on/off cycling. I'm still running all the others for 3 years, and these are all cheap Costco bundles. And for those worried about candelabras, I have one at the main entrance of my house, and they also make CFLs for that. Granted they are not everywhere, but I ordered from a specialty store. Big difference in power consumption (and heat generated) and I get the same light output.

at 3/14/2008 9:19:55 AM, Bill-G said:
There is a modified dimmer technique - so called "Mark-X". The dimmer is limited to 50%-100% (plus off) and the electronic ballast measures the input's dim level and doubles it. This way, the ballast stills gets enough power for it to work.

at 3/17/2008 3:02:52 AM, Darren Holdstock said:
Wallplug efficiencies aside, the unfortunate truth is that CFLs give out a terrible quality light that's no good for reading, working, or being in an environment where one wishes to distinguish colours. They're not as bright as they're claimed as well (a 60 W incandescent looks much brighter than a 60 W-equivalent CFL). And they interfere with my FM radio. I'll be stocking up on low-voltage halogens then... CFLs are great in principle, deeply flawed in practice.

at 3/17/2008 7:15:36 AM, pgdion said:
I've bought off brand CFL's and had very poor performance from them. Most only lasted a few months, one went out as soon as I turned it on. The name brand ones perform very well however. I only buy Sylvania or GE now and they last a very long time, perform well in warm and cold areas, have a pleasant light output, and are very efficient (actually much more efficient than the current LED bulbs are). I've placed them everywhere in my house except the one room downstairs where I still have floods so I can dim them for TV watching. The electric bill dropped lots of dollars. CFL's are a very good choice and offer a somewhat warm natural light, another area LEDS fall way short in right now (they make very good flashlights though).

at 3/18/2008 11:58:50 AM, PaulR said:
Even Sylvania reliability is sometimes lousy. We just bought a couple of the the 20 packs of 4 ft. bulbs for our plant, and nearly 1/2 had one problem or another, right out of the box. I also find that inexpensive ($20-$25) 4 ft. FL fixtures (such as from True Value, Lowes, Wally World, etc.) sometimes die before the bulbs (or with them). Some "savings"! How can that be "green"?

at 3/18/2008 12:06:14 PM, PaulR said:
Someone should ask that "official" if the mercury emission figures still hold if you use actual FL lifetime vs. claimed? Don't get me wrong, I still use a lot of FL and CFL lighting, but switch to incandescent in the winter for the same "heating" reasons mentioned above. A gov't mandated switch makes about as much sense as the mandated use of ethanol. (And just how many more people in 3rd world countries have DIED of starvation due to the resultant increase in world food prices, caused by the diversion of cropland to "fuel-land"?)

at 3/18/2008 12:12:11 PM, Dave said:
The failure mode in current LEDs - rapid dimming - is due to manufacturers not including transient suppression in the PSU. LED's won't stand for brief overvoltages (up to 1.5kV switching spikes allowed here in the UK). Where do they get 21W CFL = 100W incandescent? It simply isn't true - and it shows! A current CFL is about 3.5 times more efficient than a conventional incandescent (and that's only after a 10 minute warm-up period). In Northern Europe, during the darker 9 months of the year, the heat from a lamp contributes to the house heating. So my boiler will work harder when I have efficient lighting...

at 3/19/2008 7:49:32 AM, PaulR said:
I see ol' Tom hasn't answered my last question. Dave: Is it likely that a lot of the premature failures in FL's and CFL's are due to lack of spike supression in the electronic ballasts? Maybe I'd be smart to pick up some heavy duty surge suppression outlet strips next time I see 'em on closeout somewhere, take the guts out & insert them in those AC circuits I have which are dedicated (or at least mainly) lighting circuits? It'd be a pain, but less so, and less cost, than having to replace (in particular) FL fixtures often. Incidentally, I agree with you that many CFL's are overrated in terms of useful brightness. This is especially true in areas where the lights are on for under 10 minutes, as you point out. Ditto for an older CFL. All you have to do is run a CFL = Incandescent side by side. (Ok, true that some incandescents, such as some of the long life types, have lowish light outputs compared to std. incandescents.)

at 3/19/2008 7:59:45 AM, PaulR said:
I'm not amused by the suggestion that one should just run a smaller CFL bulb in enclosed fixtures. Maybe this is ok if you are <= 20 years old, or, if you have lots of $$ to install more fixtures. (Another not so green proposal!) For those of us over 50, we want (need) MORE light, not less! I guess we have to hope there are a lot more advances in the LED's, which is where this discussion all sort of started... (Gov't mandated creativity - yeah.)

at 3/22/2008 6:34:35 PM, Lazy Bones said:
When I first started using CFLs in the 1990s, I had a lot of early failures. Especially form a brand called “Lights of America”. More recent purchases, however, have been both cheaper and much longer lasting.

at 4/21/2008 7:11:38 AM, Chris PE said:
Overall CFLs work OK for me, but I will ONLY use them in "utility" areas like hallways ,laundry room and porch. Other than that I have a good stock of lightbulbs and nobody in a free country will tell me what to use for my lightning.On my last visit to Poland (who is the best manufacturer of filament bulbs in the world - you can actually see thick sturdy filament) I bought about 200 of them in various filament power.They are 220V ,so you get a half of light , they burn cooler and last about 15-20 years.CFLs are deadly for your vision and contain poisonus vapors....that's how green and smart we grow. We save sooooo much and then we run a dryer that takes 26000 BTU two times a day.Somewhere we have to get smart and think.

at 4/22/2008 1:09:11 AM, CH said:
Most problems with the CFL and LED lamps is the power supplies in them. Most manufacturers cut to the bone on the components costs here. Generally, most cfl tubes and LEDs are the same, so the only areas that vary are the power supplies. Usually saving a few pence using a lower temperature rated part is more important than giving the user a longer lifetime. You probably find the ones tested to give a lifetime rating have been built in the lab from quality components, not from production stock. The only way to improve the lifetimes is to have a continuous assessment standard, so production parts are randomly tested to check they are still the same quality.

at 4/22/2008 1:27:28 AM, CH said:
John L is right, there are filaments in every form of fluorescent lamp. They heat the gas inside the tube until it ionises and an electrical current can flow through it. The light given off this way is normally heavy in UV, so a phosphor coating is put inside the tube to convert the UV into visible light. It's the quality and composition of these phosphors that dictates the colour temperature of the fitting. I could design a power supply for a filament lamp that would last for years, but it would cost a damn site more than people would be willing to pay. Unfortuantely, we are all very good at wanting long life and high quality at a very low cost, and these things never really go together.

at 5/27/2008 2:12:50 PM, PaulR said:
I just had another "Lights of America" fixture, bought not even a couple years ago, fail on me. Virtually all my shop lighting is on separate lighting circuits - doesn''t seem to help.

at 5/27/2008 3:17:38 PM, MRC said:
I've had 100W equivalent CFLs blow the 2nd or 3rd time I switched them on. I've also had them last for years. The most puzzling thing I've had happen is in my bathroom fixture, which is 5 lights controlled by the same switch. I consistently have two sockets that pop CFLs. They don't last more than a couple of months. Yet the other bulbs in that fixture have been working for 3+years. I think it must be inductive spikes from bad contact in the aluminum lamp sockets. One of these days I'll try some bulb grease and see if it helps. Till then I live with 3 bulbs :)

at 6/27/2008 1:54:25 PM, ano said:
You might want to check out the fairly new LED bulbs from CREE, like the LR6. You can get them for under $100 and they are very bright, and they light instantly unlike a CFL, plus no mercury. Yes, that is expensive, but they have a life of 20 years and I measure that they consume only about 9 watts. And they are dimmable.

at 7/7/2008 1:38:48 PM, Scott Roberts said:
I have had CFL''s in an unheated poultry building in N.Dakota run 1-2 years at a stretch. In the house, one in the basement had been going non-stop for 3+ year. They are great for utility lighting but crap for on/off cycling. We grew up with incandecants, and still prefer the warmth, both visually and thermally. Besides, whatever happened to KISS?

at 7/7/2008 3:58:25 PM, David PL said:
Incandescent light bulbs can last for a very long time. At least one in my house seems to be 30 years old. On the other hand, I have had to replace many CFLs. Many CFLs are still going. I am willing to replace IL with CFLs where there is no dimmer involved, and am looking forward to the day that leds can handle the required level of illumination required- as opposed to mere brightness. But they need to work with dimmers.

at 7/8/2008 9:09:04 PM, Jeff said:
I have been using some CFL's in my house for nearly NINE years, in applications where they are turned on-off two-three times a day, and in two CONTINUOUSLY on applications (outdoor light). I have no idea what is wrong with your power, or your bulbs or both.

at 7/29/2008 7:43:34 AM, Odd Man Theory said:
In the future we may all be genetically engineered to see a far broader spectrum than we do today, so there will be no need for artificial lighting at all.

at 7/29/2008 7:48:23 AM, Craig Leman said:
I imagine it maybe a better option to redesign the dimmer switch, won't be quite as mass produced will it.

at 7/29/2008 8:46:58 AM, lcsjk said:
Joseph wrote: "the woman who is in charge for the energy program in California [said] the level of mercury that goes from the coal power station is significantly larger than possible environment contamination from CCFL thrown out." Good point perhaps, but the real issue is not that one offsets the other. The real problem will be the localized contamination from landfills that slowly leach into our ground water system along with rivers and streams. The coal power plant is very localized and can take steps to reduce or eliminate leakage. Landfills are much more of a problem.

at 8/10/2008 5:33:15 PM, Ken said:
I recently swapped out all my incandescent bulbs with both CFL's and LED's. Here's my real world experience: Whereas most of my CFL's have lasted for several years, I did have a couple that surprised me by failing after a couple months. Those were definitely the odd ones. I suspect that as new manufacturers are getting in on the game, some are not manufacturing to the highest standard. I'll admit that I bought a mix of "big name" CFL's as well as some from names I've never heard of. I don't remember which ones made the bulbs that failed quickly. But in my experience, over all the CFL's I bought, they seem to last several years. I can't tell you exactly how long, because it's been about 3 years for a few of them and 1 year for most of them. As for LED's, I didn't do as much research as I thought I needed before I bought them, and I paid the price. 1st off, you must be VERY careful about the warmth of the light. The warmer lights are dimmer than the same powered bright white bulbs. I wasted some money because the seller wasn't clear on how warm the light was... my wife hated them, they were too cool. That was wasted money. 2nd, this is probably more important, get the "high discharge" or "high brightness" LED's. For these bulbs, a 3W would have a cluster of 3 x 1W HD LED's, a 7W would have a cluster of 7 x 1W HD LED's, etc... Do not get the other LED bulbs, no matter how cheap!!! they are a waste of money. I bought several of those, and sadly, I can't find a use for them. So when comparing a bulb with 120 LED's or 7 of the 1W HD LED's, the 7 LED bulb is superior. I know, you'd think more LED's is better, but not so, the quality of the LED is more important. Lastly, most sellers of the HD LED bulbs over estimate the incandescent equivalent. However many lumens they say it has, subtract 50 because you will be buying a warm light, then compare it to your own chart of lumens/incandescent wattage. The HD LED light bulbs, in my opinion are acceptable and will take the place of CFL's in time, but unless you buy the right bulb, you will make an expensive mistake. Having bought a few of these HD LED bulbs, I can tell you that I like them, and none have burnt out in the past year. Whether they last the 50,000 hours they promise, will take a few more years for me to figure out.

at 8/15/2008 12:41:30 PM, Martin said:
I liked the CFL idea so much when I got my first Philips CFL back in Europe some 18 years ago. But my recent experience with CFLs sold in California (Costco, Safeway etc.) is very poor. Since I apraise recycling I still keep all the bad bulbs to be properly disposed. And the box is now overflowing :-(

at 8/20/2008 5:56:58 AM, Pat Wilkerson said:
I bought some incandescent lamps a few years back that were sold as "cryptonite" bulbs. They sold for $2.12 ea. and were advertised to last for 10,000 hours. They lasted for over 2 years in my porch light sockets. I had previously put regular namebrand incandesent lamps in those sockets and they burned out in less than 2 months. I have been unable to locate those light bulbs for purchase since that time. Has anyone else hear of or used that lamps? I think maybe they work so well that they quit manufacturing them. I tryed the CFLs in the same application and they lasted less than 6 months.

at 8/21/2008 2:02:30 AM, rmorris said:
using IKEA branded CFLs in UK - had no problems reliability wise using them in standard light fittings ( ie non - enclosed room / hallway lights ). Can remember only 1 failure and that was a bulb which had been left on for days at a time due to a problem with the light switch. But the light quality is less pleasing, and the start up delay from cold annoys especially if used for hall / landing use so I mix with incandescents as apppropriate. Also if visible they aren''t as aesthetically pleasing - even with the ''lightbulb'' shaped ones you can still see the ''real'' bulb inside although the ''globe'' shapes are okay.

at 9/3/2008 5:44:10 AM, BL USA said:
Did they find a way to remove mercury from the CFLs yet? Think LEDs were just flagged because of Cadmium usage or some other nasty! Fix one thing and break another!!!

at 9/3/2008 10:57:54 AM, Buzz said:
Purchased (14) non-dimmable CFLs form Home Depot. (2)burnt out within (2) months; the rest have lasted about 15 months so far. Purchased (12) dimmable CFLs on-line. One burnt out within three weeks; the rest have lasted about five months to date.

at 9/14/2008 2:36:01 PM, Eric said:
Avnet, Arrow, other distributors, and NXP themselves have been trumpeting this NXP dimmable LED luminary reference design. That's all well and good, except where is the actual design? All I can find is the glossy blurb linked above. A reference design should have schematics and a BOM at the very least, but all the glossy has is a block diagram.

at 10/15/2008 8:55:51 AM, Butch said:
Does anyone know why if I put a CFL in a socket controlled by a motion detector it flickers in the off position and works correctly in the on position?

at 10/28/2008 5:56:36 PM, ABC123 said:
Re Butch's Flicker problem. The motion detectors light is turned on by a triac. Typically a capacitor of say 100nF can be found across the triac for EMI suppression. This cap conducts sufficient (leakage) current for the CFL / LED bulb to turn on, all be it for only a couple of switching cycles, hence the flicker.

at 11/3/2008 9:12:49 AM, Chasm said:
I replaced many of the incandescents in my house with CFLs almost two years ago, and I have not experienced any failures. I have five CFLs in recessed ceiling fixtures (pointing downward) with no problems. I have CFLs in two ceiling fans that were operating most of the summer, also with no failures. One outdoor "bug lamp" CFL, a number of standard table lamps, and eight CFLs in two bathroom mirror fixtures (horizontal mount). No failures to date. All of them come up to full brightness in a matter of a couple of seconds except the outdoor "bug lamp" which takes about a minute or so regardless of ambient temperature. So in summary, my experience has been quite positive. I even think the quality of light is fine. I do have to say that I believe your recent "tear down" analysis to be flawed, at least the reason for it. You state that you received many comments that complained of CFL failures like you experienced. I just read every comment here, and I count 16 positive comments regarding CFL performance and only 7 negative comments that indicate failures. The rest of the comments were about otherh issues.

at 11/3/2008 1:40:23 PM, jmas said:
My experience with CFL's has been that they don't like heat. After opening several up, it is not surprising given the number of general purpose components stuffed into the base along with a circuit board that did not seem very heat tolerant. One of the first things noticed were several overheated (cold solder) connections. Unless high temperature circuits are incorporated the CFL will have to remain the choice for table lamps and open air fixtures.

at 11/3/2008 1:40:58 PM, jmas said:
My experience with CFL's has been that they don't like heat. After opening several up, it is not surprising given the number of general purpose components stuffed into the base along with a circuit board that did not seem very heat tolerant. One of the first things noticed were several overheated (cold solder) connections. Unless high temperature circuits are incorporated the CFL will have to remain the choice for table lamps and open air fixtures.

at 12/5/2008 9:40:17 PM, ronw said:
To Butch and ABC123, Butch is partially right about the 100nf capacitor, but the real culprit is the power the motion detector logic is designed to steal through the controlled load. The motion detector is in series with the lamp, just like a switch is. The CFL (and probably the LED types as well are each presenting a fairly high load impedance (input) in series with a fairly high load impedance, (but nonetheless a current source through the motion detector), dividing the AC such that each sees a good portion of it. As the motion detector (or dimmer, electronic timer, etc.) is used to seeing the entire line voltage, this makes little difference to it. However, it''s ideal for the CFL inverter/ballast. The flicker is the bridge rectifier and capacitor in the CFL input circuit charging until the starting circuits can start the mercury vapor arc, whereupon the much lower impedance arc draws the capacitor-stored voltage down extinguishing itself, over and over.

at 1/10/2009 8:59:31 PM, Sandy said:
Jerry, I think the LEDs have improved a lot since you posted back in February - thank goodness! I''d been reading a blog called LEDinsider.typepad.com and was learning about the improvements. That led me to www.Eaglelight.com and Amazon where I bought a bunch of LEDs and they''re plenty bright enough. I also got some great LED flashlights and colored lights that I love. They had candelabra bulbs too so Jerry I think our chandeliers are going to be saved! Let me know any other great sources but I was very happy with LEDinsider and Eaglelight.com. Sandy

at 1/10/2009 11:07:11 PM, Rain said:
ELECOSN announces its 5W dimmable LED Bulb with features: •The users can use inncandescent lamp dimming controller and halogen lamp electronic transformer to do the dimming, not need to have the specific LED dimming controller •The dimming functions are integrated into the LED driver, not need additional Signal Pins (PWM Dimming Controller) for dimming. The bulb can keep only two pins that is exactly the same as traditional halogen bulbs. •What the users should do is just to connect the bulb to traditional electronic transformer, which is used by halogen lamp, and incandescent bulb controller •NO lower lifecycle Liquid Electrolyte Capacitors applied in the drivers, so the lifecycle of the LED Driver is the same with the LEDs, that guaranteed the extremely long use life of the bulb •Our 4.2W EverBright is the only LED Lamp that can replace 50W Halogen MR-16 Lamps with similar brightness, and the payback from the saving power bill is only 6 months in condition that the bulb are 24hrs turned on. Most of other LED Lamps from other providers are not able to replace the 50W halogen lamps because of the insufficient brightness Its website is elecosn.com

at 1/20/2009 12:59:17 AM, Travis said:
I read that engineering students at Kettering U are working on ways to dim LEDs. I hope they figure something out because a dimmable LED bulb would be so much more versatile to use. Also, I heard that if you dim a non-dimmable bulb, you can burn out the LED. Is that right? I bought some nice LEDs from eaglelight (Thanks Sandy). The LED lights are worth the money but they''re expensive and I would hate to ruin them by putting them on a dimmer.

at 2/12/2009 8:52:24 AM, Aaron Dalton said:
It's not dimmable, but you and your readers might be interested in the new Pharox LED bulb just profiled at 1GreenProduct.com Requires just 4 watts of energy to replace a 40-watt incandescent. Prices on this latest generation of LED bulbs are getting more reasonable too... - Aaron Dalton, Editor, 1GreenProduct.com

at 2/12/2009 1:43:16 PM, Dana said:
'Engineer' said that all that's needed is a bridge rectifier and current-limiting capacitor. This is true for a sine wave, but real power lines are loaded with sharp transient spikes (especially if used with a phase-control dimmer), resulting in extremely high peak currents through the LED. This kind of treatment drastically shortens life. A much better solution would be a current limiting inductor, if we were willing to pay for it.

at 2/13/2009 1:10:15 PM, JRT said:
Re: Engineer & LED power supply In addition to the series capacitor ballast, it is probably a good idea to also add a shunt capacitor across the output of the rectifier bridge. This should be a small value ceramic with a low ESR. Remember to use 120 Hz when figuring the value. This should protect that LED from line noise. A choke in series with the rectifier bridge input would also do the job but it would be larger and would dissipate some power.

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