anyone else with an interest in LED lighting? - Page 1
Forum section: electronics / general

author: slburris
author_rank: Frequent Contributor
timestamp: July 17, 2010, 01:44:23 am
content: I'm looking for others who want to talk about LED lighting.This topic doesn't fit neatly in Lighting groups, nor electronicsgroups, so let me try here....I'm interested in LED lighting both for landscape lighting andfor replacement of incandescent and CFL bulbs in the house.I'm looking at LEDs for two primary reasons, to save energyand to stop having to replace bulbs. For some reason, myelectric company never seems to announce a rate reduction :-)I've been trying various bulbs for a couple of years, but sinceI haven't found anyone else doing the same, I feel I've been experimentingin the blind.Before I ramble on and on, let me ask if anyone on eevblog is interestedin LED lighting and/or has experimented themselves?Scott

author: McPete
author_rank: Regular Contributor
timestamp: July 17, 2010, 01:58:29 am
content: Sure, I'm interested.I useAy-Up lightson my mountain bikes when I hit the trails at night. They're more or less the standard in cycle lighting in Australia, but I do see people with far more powerful systems, and the odd custom-made system too. I've often thought about making myself a more powerful set-up for my road bike, but that hasn't happened just yet. I'd be interested to see what ideas are generated by people with a far greater depth of electronics knowledge.I also employ some of the 3W Jaycar LED MR16 downlight globes in my room, mostly because I despise the orange tinge from the standard halogens, but I find they're a bit lacklustre in terms of intensity and beam angle(a bit too narrow).You my find people on torch/flashlight forums to be pretty handy with this- In my brief wanderings, I've seen some damn impressive little lights appear on those pages.Peter.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 17, 2010, 02:35:00 am
content: I have used 16 ordinary white LEDs as a lamp. It works great but is a little too directional for general use. I'm thinking about using Cree LEDs to make something brighter for general use.Note that the energy savings by using LEDs is more than the efficiency ratings indicate since LEDs can be effectively dimmed and frequently turning them on and off does not wear them out.

author: RayJones
author_rank: Frequent Contributor
timestamp: July 17, 2010, 03:08:52 am
content: Been dabbling with power LED's for quite some time.First driving factor was also for my bike commute to/from work.I first started with 3 x 1W Luxeons on the handlebars.I then moved up to the 3W versions and turned some alloy on the lathe for them, one using a elliptical optic the other a spot.Eventually upgraded those with Cree XR-E's, but was never able to get a suitable elliptical optic.Then I became aware that these LED's can be very glary to oncoming cyclists (bugger the cars), so lashed out and got a Busch & Mueller IQ fly with PROPER optics and a well defined horizontally cutoff beam.But there was a large patch of darkness between the bike and patch on the ground.This has now been updated with the B&M IQ Cyo, and this throws a superb beam without unnecessary light shining into oncoming eyes, and better near field illumination.Now I have moved onto doing solar powered LED spots around the garden, and this has got me now pursuing MPPT technology to keep the batteries efficiently charged. (playing with some firmware right now!)My very infantile web page (in profile) details the woes of some LED spots we bought recently.So yeah, LEDs are certainly the way of the future, and I'd love to get my hands on a Cree XM when they are soon released ....(180 Lumens / Watt)

author: Zero999
author_rank: Super Contributor
timestamp: July 17, 2010, 08:53:30 am
content: Quote from: NiHaoMike on July 17, 2010, 02:35:00 amLEDs are only significantly better than fluorescents when a directional source is required, if you need light to be emitted in all directions, a CFL is superior in just about every way, from efficiency, cost to colour rendering. The only benefits are lifetime but bear in mind that LEDs dim and reduce in efficiency over their life, faster starting and lower temperature operation.QuoteFluorescents can also be dimmed with special ballasts.I know a way to do it using a magnetic ballast, a standard phase control and a couple of other componnets but it's rather inefficient - you're better off with a proper dimming ballast.

author: saturation
author_rank: Super Contributor
timestamp: July 17, 2010, 10:58:48 am
content: Yes, have been looking into it myself too. Some words of caution:Many I've used being sold without brand names do not have the operation lifetimes of low voltage, low lumen LED. You are thinking 50k-100k hours life, well maybe but not at the rated lumen ouput, some dim substantially after only several hundred hours, or blow out all together. So be wary of plug in replacements for incadescent or CFL bulbs used in home lighting because LEDs made into arrays still have quirks to ring out.So far, brand names work best, and they often are costly. Sharp, Cree, Luxeon etc., but to get it working as a plug in bulb, cost 2-10x more than an equivalent CFL. If you do the math for cost/hr its may not be worth it to 5 years because the LED bulb say at $60 vs the CFL with ~ lumens costs $5, and the power savings is 1/2 -1/3 of CFL, about 5-6W for LED and 10-15W for CFL.If you ran for 5 years, 365x24 ~ 9000h. So 5W running 24/7 costs = 45 kW.h ~ $4.5. For CFL 15W = 135 kW h = $13.5, diff = $9. If at best case an LED plug in module costs $30, the difference in cost between LED vs CFL here is $30-5 = $25. A breakeven point is at $25/9 = 2.8 periods or ~ 14 years from installation.Assuming $0.10/ kW h.Of course, the longer you run the bulb or the pricier your CFL is, finally the saving will catch up to you sooner. But, so far, I've seen a few high power LED modules not live up to their expected lifespan of 50k hours and give poor light output far within 5 years. Heat is the problem. If the lamp module is exposed to sunlight during the day, the lensing elements could deform or cloud over, or if the heat sink doesn't dissipate what it should because of high ambient temps, or the support electronics needed to drive the LED could fail before the LED itself.http://www.superbrightleds.com/cgi-bin/store/index.cgi?action=DispPage&Page2Disp=%2Fmini-wedge.htmlhttp://ieeexplore.ieee.org/Xplore/login.jsp?url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F4681769%2F4688450%2F04688790.pdf%3Farnumber%3D4688790&authDecision=-203That said, I would unequivocally replace flashlight bulbs or problematic HID technology with LED as the reliability and power consumption of incandescent hand held flashlights are obsolete, HID is too expensive and has 2-3x the power consumption with ~1% the shock vibration tolerance of LED.

author: tecman
author_rank: Frequent Contributor
timestamp: July 17, 2010, 12:39:35 pm
content: LEDs today should not be considered for efficiency. Efficiency of LED lamps beats CFLs by 10% in only the most efficient designs. Most are below CFL efficiency. Issues such as the drive efficiency, heat dissipation and (as mentioned) lighting directionality are issues yet to be resolved. The time will come, but it is not yet. Also despite the potential life of LEDs, other components in the electronics, like caps, will not last the life of the LED.For specialty lighting, they can be great, but for general lighting you are still better off with CFL today. Quite a few articles have been published on the subject (EDN, Electronic Design, Photonics, EETimes) and the general conclusion is that we have not yet reached the point to get excited.Paul

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 17, 2010, 12:57:05 pm
content: Quote from: Hero999 on July 17, 2010, 08:53:30 amIt is possible and there are plenty of Linear application notes on how to do it. But I recall that the amount of dimming is pretty limited (down to maybe 5-10%) as opposed to LEDs that can be dimmed to practically zero.

author: slburris
author_rank: Frequent Contributor
timestamp: July 17, 2010, 02:00:54 pm
content: There seems to be interest, so let me start off with a post about landscape lighting, and I'lldo a separate one about home lighting. I live in the high desert, anything I gethas to operate at temperatures between about 5F and 115F.I have a typical lighting installation, 12V, with lights that take MR16 bulbs, and othersthat have 11w wedge base bulbs. All these bulbs are cheap, but invariably one or morebulbs has burned out, so it seems I'm forever doing light bulb maintenance. Also,on long runs of wire, the fixtures near the end are a bit dimmer than the ones nearthe transformer due to voltage drop. When you add up the power, there's asignificant wattage being consumed here.Aha! A perfect job for LEDs I thought a couple years ago. So my search began.First of all, any of those "Solar Powered" landscape lighting thingies are absolutejunk. No reason to even look at them. Everyone's idea of "high intensity" LED didn'tmatch up with mine. Luxeons were available, but I couldn't find landscape lightswhich used them. Well I could, made by someone in China, but not in quantitiesa normal human could order.So I started down the road of spinning my own PCB with an LT buck constantcurrent chip driving a Luxeon star. Then I picked up some conventionalfixtures with the idea of gutting them and replacing the insides with LEDs.The electronics worked, but getting the thermal design to work in thefixtures was a huge problem. I shelved the idea and waited for somethingmore mainstream to develop.Then about a year ago, when I was in Lowe's (a chain home improvement store here in theUS), I passed a landscape light with the magic words "3 watt LED" on the box.I stopped to look, and found this:http://www.lowes.com/pd_284339-2121-WT-S41_0_It's a Portfolio LED flood light (even though the website says 110, the stores haveit in 12v). I think Portfolio is a house brand of Lowes, so I don't know if this ismade for them or a relabeling of another brand. So far, these have worked like acharm. They don't care about polarity, and they are regulated so they aren'tpicky about the line voltage. None has failed yet. The light is very white, whichis fine for landscape applications, but would be annoying in the house. No informationotherwise about color temperature or lumens. At about 4W, they replace the 20WMR16 fixtures I used to have. So 5 fixtures for the power of one original!I looked at drop in MR16 LED replacements, but at the time didn't see onesthat were bright enough or seemed to have a sane thermal design. There seemto be better ones now, but they are close to the cost of this fixture, so I tendto just buy the fixtures right now.But a year is a long time in LED terms. Where's the competition?I'm still looking for a bigger floodlight, something like a wall washer.See attached picture. But something with a few high intensity LEDs,not 160 LEDs for a paltry 240 lumens like this light:http://www.deslamps.co.uk/85-watt-led-garden-flood-light-p-5162.htmlSigh, maybe I need to go back to building my own light.Scott

author: slburris
author_rank: Frequent Contributor
timestamp: July 17, 2010, 02:26:43 pm
content: Here are some pictures of the Portfolio LED floodlight.The first picture is the business end of the light. Looks like3 1-watt LEDs. I removed the screws and found it was a metalbacked PCB. The PCB presses up against a a metal plate and poweris provided through a hole in the middle.The second picture shows the inside of the fixture. The regulatingcircuit is enclosed in the black heat shrink tubing. The hand is mine :-)Scott

author: Zero999
author_rank: Super Contributor
timestamp: July 17, 2010, 03:19:50 pm
content: Quote from: tecman on July 17, 2010, 12:39:35 pmTrue.http://en.wikipedia.org/wiki/Lighting_efficiency#Lighting_efficiencyFluroscent 15.63% maximum, including ballast.LED 22% maximum, not including power supply.Note that this is very misleading, the figure for the fluorescent is including the ballast but the figure for the LED is taken from a Cree datasheet which doesn't include the power supply!The efficiency figures given for LEDs including the power supply and fitting are generally worse than fluorescents. Also bear in mind that a fluorescent will be replaced more often than the LED so you'll get more life at high-efficiency.I recommend an light unless it's a replacement for a halogen or is for an inaccessible area which will make replacement inconvenient.

author: slburris
author_rank: Frequent Contributor
timestamp: July 17, 2010, 04:23:29 pm
content: OK, on to LED house lighting.First off, I'm not a big fan of CFLs. Although they have improveddramatically in the last few years, they still have somesignificant drawbacks for me. Let's see why:-- They don't do well at low temperatures-- Take a while to come to full brightness. And yes I've testedthe "instant-on" versions. They start up with morebrightness than normal CFLs, but still take time tofull brightness.-- They are fragile. The glass breaks and exposes youto nasty stuff-- They don't like being turned on and offI have two little girls at home, so I can't put CFL's withintheir reach. And my youngest likes to flick lights on and off,causing CFLs out of her reach to have short lives. Both ofthese are concerns for incandescent bulbs as well tosome extent.Then this morning, I went to switch on a light, there was a snapand smoke with that lovely burnt ballast smell. A Feit ElectricCFL bites the dust. I'm going to shop for an LED replacement today.On to the LED story. Originally, I got some noname bulbs off ofEbay. Multiple LEDs, no UL marking. I tried them and they didn'tput out much light and were distinctly blue in color. Absolute junk.So I instituted a new rule. I won't buy anything unless I can find outthe lumen output and the color temperature. That's helpedquite a bit.The first halfway decent bulb I found was a Lights of AmericaPAR38 bulb at Sam's Club. Oddly, this bulb isn't on either Samsor LofA's website.It's a 11w 429 lumen bulb with a 4100K color temperature.Not bad, still it's a bit white for general applications, but workswell in kitchen recessed lights. I've attached some pictures ofthis bulb. Ordinary incandescents have a 2700K color temperature.Recently, some mainstream companies have put bulbs on the market,namely GE, Philips, and Feit Electric. These are still quite expensive, but I've trieda few and will give you my impressions.The best light I've found so far is the Feit PAR38/HP/LED:http://www.amazon.com/Feit-Electric-PAR38-HP-LED/dp/B002Q8H99YIt's 16w, 710 lumens, with a 3000K color temperature. Unfortunately it's $60.I have one (and only one) and love it. Color looks very incandescent like.Also unfortunately, it's not dimmable (most LED bulbs are not).Next bulb I got was a Philips 5w bulb (photo attached) that was about 230 lumensand 5 watts. 3100K color temp. It's still expensive at $25. I put it ina desk lamp my daughters use. Quite cool to the touch and the glass part isthick. So far, no one has broken it.Then out of nowhere, Home Depot introduced a light that dramatically undercutsthe existing players:http://www.homedepot.com/h_d1/N-5yc1vZ1xhc/R-202188260/h_d2/ProductDisplay?catalogId=10053It's 429 lumens, 8.6w at a 3000K color temperature for $19.95. And it's DIMMABLE!I have several of these and they are indeed a decent 40w bulb replacement.They aren't as directional as most bulbs (good!). I've heard Philips is coming out witha 60w bulb, but I assume it will have a premium price. Hope this bulbwill pressure the other guys to reduce their prices, and if a 60w version of the bulbcomes out, I'm there!Still on the list to tackle, the flame shaped candelabra bulbs and bathroom fixture lighting.The quest continues. Anyone else found decent (or great) LED bulbs?Scott

author: slburris
author_rank: Frequent Contributor
timestamp: July 17, 2010, 04:30:16 pm
content: Here's a pic of the Home Depot Eco-Smart bulb.I forgot to mention in the previous message that the Feit Electric bulbis quite heavy. So heavy in fact that I'm a little concerned that therecessed can will not hold it up. Clearly Feit has done its thermalengineering, but still....Scott

author: saturation
author_rank: Super Contributor
timestamp: July 17, 2010, 04:41:12 pm
content: As LED's deteriorate the color spectra shifts as well as lumens drops, when you see bluish tinged LEDs that are supposed to be white, those are dying or defective. Unlike bulbs, they are unlikely to simply burn out.If you have these LED bulbs exposed to desert sun for now over a year, it may have a the color shift it starts to deteriorate. But you need to compare it against a virgin bulb, since there is some shift in all 'white' LEDs so you get its like new signature.

author: saturation
author_rank: Super Contributor
timestamp: July 17, 2010, 04:49:34 pm
content: My only concern for these LED bulb products is who makes the LED, at this stage of the game, the LED supplier is key to the quality of the LED, the final assembly will determine how long the LED will function.The only bulb I think I would buy are those made by Sharp, as the LED and the assembly are their own design.http://sharp-world.com/corporate/news/090611_2.htmlEach bulb can be remote controlled and run $70,each.Quote from: slburris on July 17, 2010, 04:30:16 pm

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 17, 2010, 08:24:19 pm
content: Quote from: Hero999 on July 17, 2010, 03:19:50 pmA good regulator can get about 95% efficiency, or an overall efficiency of 20.9%. Even if it's only 90%, it would be 19.8% overall. Still better than fluorescent.Also note that while fluorescents are broad light sources, LEDs are near point sources. Whether that is good or bad depends on your application. If you need light in only one area, LED definitely wins.QuoteLEDs can be turned on and off a lot without wearing them out, solving your problem. In addition, if you turn off LEDs for short times that fluorescents would normally be left on, LEDs get an efficiency advantage.Another advantage of LEDs is safety. In addition to having little or no fragile glass, the operating voltage is over 2 orders of magnitude lower. Some fluorescent inverters supply as much as a few kV for starting, while a common white LED runs on about 3.6V. Combine that with low voltage supply to the regulator (12v from solar battery array, etc.) and it would be much safer than fluorescent near water or outdoors. I'm in the process of building a UV light for my turtle aquarium and the main problem is ensuring safety. (I couldn't find a reasonably priced Luxeon-style deep UV LED, so I'm stuck with a CCFL tube I originally bought to find leaks in air conditioning plumbing.)

author: Zero999
author_rank: Super Contributor
timestamp: July 17, 2010, 08:58:53 pm
content: Quote from: slburris on July 17, 2010, 04:23:29 pmAll those points are perfectly valid.One note about them being fragile: you can buy compact fluorescents with a double glass envelope, they're more rugged and if the actual fluorescent lamp inside breaks you won't be exposed to any nasty stuff. There are also tubes designed for use in food preparation areas and are designed not to shatter.By the way, the only real hazard of a fluorescent is the is broken glass and high voltage (assuming it's on when it breaks), as with a normal incandescent. There's only a tiny amount of mercury in there, a truly microscopic amount and being exposed to a 22W broken tube is probably well below the safe daily exposure level, even for a small child. Second to the glass and high voltage there's the phosphor which is poisonous if eaten but I think the broken glass will do far more damage to your digestive tract so it's not an issue.QuoteDon't put any bulb with in their reach, unless it doesn't get hot enough to burn them and is not mains powered. If you want LEDs get the sort which run from a 12V transformer, you can buy 12V fluorescents too but I wouldn't recommend them as they contain a high voltage inverter circuit: although it's current limited so is safer than mains, it's still pretty nasty, LEDs are entirely extra low voltage which is inherently safe.Quote from: NiHaoMike on July 17, 2010, 08:24:19 pmI think that's a bit optimistic for a small SMPs run off the mains.The LEDs on the datasheet referenced to by Wikipedia are naked so would need to be suitably enclosed which will result in a further drop in efficiency, so you're probably looking at at total efficiency of between 17.8% to 18.8% efficiency. Yes you're right, it's still more efficient than a fluorescent but it probably comes at a price.QuoteYes, even if you have a cheaper LED which is only 10% efficient, if you need a direct light source it's better than trying to focus a fluorescent which results in a loss.QuoteI'm sure you know this but this is negated when run off the mains because the converter will normally not be isolated.QuoteAs far as I'm aware CCFL tubes aren't the most efficient fluorescents.Fluorescents tend to be better for UV because they work by producing short wavelength UVC and the shorter the wavelengh is, the less power is wasted in the phosphor converting it to the desired wavelength. There again, you probably need a direct light source which is might be negated by the fact that LEDs are better at this.If you go with fluorescents then get the unfiltered blacklights if you can, the sort which appear white when unlit, not deep violet/black. Unfiltered is better because there's less loss and visible blue and violet is also good for reptiles.Don't worry about the high voltage, it's very low current, 5mA at most, much lower than hot cathode fluorescents and as it's high frequency the only hazard is burns but it's so low current, it won't be anywhere near as bad as a hot halogen lamp.

author: slburris
author_rank: Frequent Contributor
timestamp: August 19, 2010, 03:42:31 am
content: So on the landscape lighting front, I've got two things on the frontburner. First, Home Depot is carrying two new LED floodlights from Malibuwhich claim 7watts of LED power. The Malibu site doesn't seem to have thesemodels on it at all and I haven't been able to find any real specs.There are two lights with part numbers 8401-9613-01 and 8401-9513-01.Pics of the two lights below.I have seen it lit up in the stores and it seems pretty decent.I think I'll pick one up and compare it to the Lowe's Portfolio LED lightsI already have (which are 3 watts).Next, I've ordered a 10watt LED on a heatsink and a 10 watt constantcurrent driver board from China. No idea what I'm really getting :-)I'll post pics when they arrive.Scott

author: dimlow
author_rank: Frequent Contributor
timestamp: September 22, 2010, 09:58:55 am
content: Has anyone used thesehttp://www.ledcentre.uk.com/235-230v-led-lighting.htmlled spots, I'm renting my house and the previous owner seemed to love spots, these 50watt spots are in every room and they mostly are fitted in banks of 4. In the dining room there are 8 x 50watt spots, I hate them and i don't much like the electric bill for these. There are a total of 40 x 50w spot lamp bulbs in this house thats 2000 Watts of lighting, im not too pleased with this as i have kids and they love to leave the lights on. Replacing all these spot lamps with leds will be expensive but im thinking i will save money by replacing them with LED lighting. What are your views?

author: Zero999
author_rank: Super Contributor
timestamp: September 22, 2010, 11:23:52 am
content: Their claim of it only using 4W of power but giving the same amount of light as a 40W halogen seems very optimistic. I think it will probably be equivalent to a 15W halogen, 20W at best.

author: Simon
author_rank: Unknown
timestamp: September 22, 2010, 11:52:03 am
content: Quote from: Hero999 on July 17, 2010, 08:53:30 amI beg to differ on the colour rendering, I've not used Led lights except for my little head lamp but I despise the fluorescent lights that emit 2700K of colour temperature because this is totally unnatural and is actually yellow and our eyes can just about ajust to make it white but it actually makes me drowsy particularly in winter, I've tried 5000K bulbs and they are a bit bluish but 3500-4200 is spot on. the catch is try and find a bloody bulb that has on the box it's colour temperature ! I call this a big rip off because i then have to go to a specialist bulb supplier who will charge 10X the costs of a crappy "standard" 2700K bulb for one that does produce white light.I've had comments about how horrible my 5000k bulb is (you will see it tonight actually when you come round as it's in Dad's living room) and how blue it is. I know it maybe a bit blue but i think a lot of it is about what you get used to and for someone walking into a house in the evening expecting to find a light on is also expecting it to be the light he/she is used to and is "ready for it" so being confronted with a 5000K bulb when unconsciously already being ready for 2700K does kind of rock things.Of course looking at a 2700k versus a 5000k (and you can do that tonight too) you see a big difference.

author: PetrosA
author_rank: Frequent Contributor
timestamp: September 22, 2010, 12:08:21 pm
content: I get asked about LED lighting a lot as an electrician. My honest response is that it's almost, but not quite there yet and is still in the outrageously expensive experimental phase (CFL went through this stage in the 1980s and early 1990s). Commercial CFL (bi-pin base bulbs) tend to be much better quality with better CRI scores than what's available to most homeowners, so generally don't recommend people use the screw-in type in the house except for areas like basements, closets or outside lights. Recessed and track lighting in the US is almost all designed for the (now obsolete) incandescent reflector bulbs or halogen PAR bulbs. In some cases the R style CFL bulbs work OK as long as they don't need to be dimmed. LED replacements are getting better, but very few have a lumen output even close to halogen, so customers see a huge negative difference there.I have found one company making an LED replacement that comes close, but the price is astronomical, making it really appropriate only in a commercial setting. The units are very well heat sinked and have cooling fans that run whenever the "bulb" is on. The PAR30 long neck replacement gives 850 lumens (compared to approx. 1130 for a 75W PAR30 and 600 for a 50W PAR30) but uses 20 watts, so you have to take that into consideration. The beam spread is not bad, but doesn't match a wide flood spread (60 degree) that a halogen gives. The price is well over $100 each for these bulbs.www.solaislighting.com

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 22, 2010, 01:15:17 pm
content: quite interesting topic as i'm in the middle of home ceiling and lighting renovation. but i wonder, how much ~12W led should i used to exchange with one 25W light bulb similar to in the picture to get the same brightness? i'm going to put the led or the bulb in downlighting fixture, so it will be directional for both anyway. any idea? thanx.ps: i have to edit to get the clearer picture.

author: slburris
author_rank: Frequent Contributor
timestamp: September 22, 2010, 02:02:59 pm
content: Quote from: PetrosA on September 22, 2010, 12:08:21 pm$100 is way overpriced now. If you live in the US, Home Depot has just introduced aPAR38 bulb, 18 watts, 850 lumens, 3000K color temp, for $45. And it's *dimmable*!This price blows away a non-dimmable Feit Electric bulb I've seen around$70 for about 700 lumens. Check out:http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&productId=202324426&langId=-1&catalogId=10053I haven't gotten one yet to try it out. They also now have a 729 lumen bulbPAR 30 for $40. Eco Smart is a Home Depot house brand. Their LED bulbs are made for them byLighting Science Group (http://lsgc.com/).HD just cut the price on their 429 lumen bulb to $18.47. It looks like their aggressivepricing is starting to have an effect on the other players. I've seen Feit Electric'sbulbs drop by 30% in price recently. Philips, Sylvania, and GE bulbs are stilloverpriced relative to the competition.It looks like the major players have gotten with the program as well, as I'm seeingmore and more packages labeled with both lumens and color temperature, bothvital to making a decision about a bulb.The pricing is still high enough that I'm only replacing high use bulbs that myfamily can't seem to remember to turn off, as well as difficult to replace bulbs(high ceilings, etc.).Scott

author: slburris
author_rank: Frequent Contributor
timestamp: September 22, 2010, 02:18:11 pm
content: Quote from: shafri on September 22, 2010, 01:15:17 pmLooking at wikipedia, a 25w CFL is about equivalent to a 75w incandescent bulb,so somewhere around 1100 lumens.My experience is that for downlighting applications, you can go a little smalleron lumens for the same light. I assume that's because none of the light is emitted intothe fixture and wasted -- it all goes downward.I'd look for something between 700 and 800 lumens as a replacement, butthere's nothing like trying it for yourself.Scott

author: slburris
author_rank: Frequent Contributor
timestamp: September 22, 2010, 02:30:17 pm
content: I did purchase the larger of the two new landscape lighting fixturesI mentioned a few posts ago in this thread. I like it! It's significantlybrighter than my previous lighting and seems to be holding up well.Inside the house, I'm struggling to find lights for two applications.The first is a nightlight which is a ball with a rice paper shade.It came with a 7w CFL, which is OK, but too bright for myintended use. I've been looking for an LED replacement witha candelabra base (E12 in the US).The best I've been able to come up with so far is this50 lumen 2 watt bulb from Osram Sylvania:I've also been searching for lights for a bathroom fixture that lookskinda like this:I've tried my favorite Home Depot 40w LED replacement bulb, but it's toodirectional for this fixture. I've also found that it has a different dimming curvethan the incandescent bulbs. So if you mix the bulb types then dim them,you'll have one kind of bulb going out far before the other. Should have beenobvious in retrospect, but I didn't think of it.Scott

author: Simon
author_rank: Unknown
timestamp: September 22, 2010, 04:37:45 pm
content: I think bulb wattages should be abolished as the main characteristic as today it is totally meaningless. Lumens should take the place of watts (which can still be mentioned) and the colour temperature should be on the packaging and bulb by law. I get the impression that higher temp bulbs do not appear to make as much light which may be why 2700K (yellow) is preferred by manufacturers as it dupes the users into thinking more useful light is being made than there really is. I had to use a 20W 5000K CFL in my 4 sq metre bedroom to be happy with the amount of light !

author: slburris
author_rank: Frequent Contributor
timestamp: September 22, 2010, 04:48:21 pm
content: http://en.wikipedia.org/wiki/Incandescent_light_bulbhas a table with incandescent light bulb wattages and lumen output.I refer to it frequently when trying to estimate what kind of LED bulbcould replace something. This is for 120v systems -- I don't know howthis should be adjusted for 240v areas.The table is about 2/3rd's down the article.There's also a claim made that incandescent bulbs are *less* efficient(in terms of lumens/watt) at higher voltages.Scott

author: Simon
author_rank: Unknown
timestamp: September 22, 2010, 05:17:56 pm
content: Quote from: slburris on September 22, 2010, 04:48:21 pmwell from why I've seen it's actually a case of "x" volts per watt of light, the more watts you want the longer the tube and the higher the voltage needed to get it going. of course the table still ignores colour temperature which is important as while we can ajust to a certain range of light colours (our brain will do an automatic white balance - literally) we see colours differently and will be more sensitive to a certain colour (green I believe)

author: PetrosA
author_rank: Frequent Contributor
timestamp: September 23, 2010, 03:23:21 am
content: The 2700 Kelvin goal is more to make the color attractive to consumers who are used to incandescent bulbs. There's also something to be said for matching the color of all the bulbs in a house.While there are fluorescent bulbs capable of a high CRI that match 5000K and 6500K (they are available for graphic's purposes) they cost a lot more because of the gases that have to be mixed to provide a fuller spectrum. Many CFL and LED lights have too little spectrum to have a decent CRI and while you might think that your eyes balance the color out, they really don't, because they can't - there's just too little information to see all the colors. There are LEDs designed for use in gallery lighting, but you won't touch them for $100.A few of you have mentioned difficulty trying to find LEDs with the right throw of light - this is one of the biggest challenges for LED designers. There is a huge difference in the spread between incandescent, CFL and FL, but LEDs are another beast altogether. They have a hugely directional beam spread which works great for flashlights and headlamps and somewhat ok in dense lighting strips designed to bounce light off of reflective surfaces, but they don't work so well for replacing room lighting. They also have different cutoff characteristics from either CFL, FL or incandescent (the lumens drop off much faster with LED than other types of light). There are still lots of hurdles to get over with LED.Efficiency of incandescent bulbs drops non-linearly when voltage drops which is one of the common arguments against dimmer switches and lifespan of bulbs is reduced drastically at higher than nominal voltages. At half the rated voltage of a given bulb, you may actually only be getting 25% of the light output. On the other hand, at 95% of nominal voltage, you may get better than 50X the expected life out of the bulb, which again changes the equation. So while it may be a more power efficient plan to swap the bulbs out each time you want less light, the dimmer may be reducing your consumption of bulbs to such a large extent that it offsets the losses in power efficiency.The bottom line is that incandescent is the one type of light source that doesn't violate the KISS principle and price reflects that. LED has a good chance to compete, but it needs a lot of work yet.

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 23, 2010, 04:55:47 am
content: There's halogen (technically just another kind of incandescent) which offers an even better spectrum and slightly higher efficiency, but can't be dimmed very much.And yes, incandescent lights (regular or halogen) are generally less efficient at higher voltage ratings, particularly at low wattages. It has to do with the thickness of the filament and the operating temperatures. There used to be a "high efficiency" incandescent bulb that had a series diode as a cheap way to reduce voltage (thereby allowing the filament to be thicker and hotter), but it has since disappeared due to CFLs."Broadband white" LEDs (UV LED with RGB phosphors or blue LED with RG phosphors) exist, but I do not know of a source for them. They are used mostly in high quality LCD displays.One application where incandescent will always be the clear winner is infrared heat. (I have used reflector incandescents to stay warm during the winter.) They use much less power than any space heater and even heat pumps have difficulty matching the efficiency if all that's needed is a spot of heat.

author: Simon
author_rank: Unknown
timestamp: September 23, 2010, 06:44:18 am
content: 2700K is far too low, it is essentially yellow but you eye adjusts, try playing with colour temperature in photography to see what I mean, when we used to use film you just could not use outdoor film under CFL's without filters or specific film. 3500K is getting closer, but I can assure you that incandescents DO NOT put out 2700K, infact no end of people complain that they cannot see well under CFL's and I heard of someone looking for an incandescent bulb for some elderly people because they could not see to read under the CFL lighting, I explained about colour temperature and suggested she find a CFL of more "normal" colour temp. I do now seriously doubt the efficiency of CFL's ok they are better than incandescents but no where near as good as the manufacturers claim, again going back to my experience in photography, do you realize just how sensitive our eyes are and what a huge range (dynamic range) of brightnesses it can handle, the ratio is well over 1:1000 I believe (try using an SLR camera indoors and then going out into a sunny day and see the settings change required), so it's easy to say that a 20W CFL is equivalent to a 100W incandescent, it's not ! I think the problem with my 5000K bulb is that it puts out pretty much 5000K only so does not as you say cover the full spectrum, but 2700K is just as bad on that band, really it's a case of what colour (literally) do you want your lighting. When I do need more bulbs I'll go for 3500K, 2700K ones just send me to sleep particularly in the winter and yes it's medically proven and some people really have an issue with it, that's how bad those damn things are.on the original topic though I would like to get into led lighting and may well convert my whole house some day, it also makes it very easy to power from a 12/24V battery that was charged by a solar panel

author: Zero999
author_rank: Super Contributor
timestamp: September 23, 2010, 07:36:33 am
content: I dislike 5000K for room lighting, it just looks bluish grey and the light isn't full spectrum or anywhere near bright enough to simulate daylight.Incandescent is better, halogen probably the best. I don't really like 2700K CFLs but it's acceptable. I've never tried 3500k in my house but I know it's what's used in offices and I'm not sure if I'd like it.By the way, I noticed at your dad's house that the 5000k bulb was dimmer than the 2700k: is it because it's a lower wattage? I would generally expect a 2700K lamp to be brighter than a 5000K lamp of the same power level because the eyes are less sensitive to blue, there again blue phosphors will be more efficient because there's less of change in wavelength from the UV emitted by the mercury arc.

author: Simon
author_rank: Unknown
timestamp: September 23, 2010, 11:40:46 am
content: the 5000K light is 20W the 2700k is 18W and is in a smaller area. like you say the 5000k looks not so bright and bodied as it's not emitting a full spectrum but then neither is the 2700K as it doesn't go much above. like I said I think some of it is physiological you don't expect the 5000 light. I was using one of those 5000K lights in my 4 sq metre room and that looked ok but that say's alot about the real efficiency of CFL's as in that room 40-60W incandescent will do the same job. I had some 3500K strip lights and they were good.the cfl in the bathroom is 4200K not so stark but yea I'd stick to 3500 as a general recomendation