LED Lighting As Cheap As CFLs Invented 553
mcgrew writes "New Scientist reports that a British team has overcome the obstacles to cheap LED lighting, and that LED lamps as cheap as CFLs will be on the market in five years. Quoting: 'Gallium nitride cannot be grown on silicon like other solid-state electronic components because it shrinks at twice the rate of silicon as it cools. Crystals of GaN must be grown at 1000C, so by the time a new LED made on silicon has cooled, it has already cracked, rendering the devices unusable. One solution is to grow the LEDs on sapphire, which shrinks and cools at much the same rate as GaN. But the expense is too great to be commercially competitive. Now Colin Humphreys's team at the University of Cambridge has discovered a simple solution to the shrinkage problem. They included layers of aluminium gallium nitride in their LED design... These LEDs can be grown on silicon as so many other electronics components are. ... A 15-centimetre silicon wafer costs just $15 and can accommodate 150,000 LEDs making the cost per unit tiny.'"
Re:If they are still not dimmable they still suck (Score:5, Informative)
I've not used the commercial LED light bulbs, but standard LEDs dim just fine (at least to a point). I see no obstacle that would stop the bulbs from dimming too.
In fact, a very quick check on the bulbs available at Amazon indicates that they do dim. Is there a dimming problem that you're aware of that's not made clear in the Amazon reviews?
Re:Clap on? (Score:5, Informative)
They won't work with the clapper.
Cheap automated switching devices like the clapper and some timers include the bulb as a resistance element in the switching circuit. They count on the bulb acting almost like a short when the light is off. This works with incandescent bulbs, since the resistance of the filament is very low when it is cold. CFL and LED bulbs act exactly the opposite way. They are almost an open circuit when off. With no current flow, the automated switch is unpowered.
There are switches that will work with these types of bulbs, but they generally cost more.
Re:If they are still not dimmable they still suck (Score:1, Informative)
You can trivially dim LEDs using PWM, which is more or less the same method used by regular dimmer switches. An LED light which was as simple as a chain of LEDs designed to run off rectified 110VAC/240VAC should work fine with a regular dimmer.
Re:My first experience with LED lighting... (Score:5, Informative)
Don't lose hope yet. For one thing, a 40 watt incandescant (you didn't specify if what you were replacing was incandescant or CFL) is damned dim to start with. When I used incandescants, the lowest watt bulb I used was usually a 100 watt (60s in closets and in the basement where there's one every fifteen feet), and used 3 way 250 watt bulbs for reading.
A 40 watt CFL would be damned bright, I don't know if I've ever seen one. Most of my lamps have 27 watt twirley tubes. They vary in intensity, in color, in startup time, and some grow brighter the longer they're on. The one on the front porch won't light if the temperature gets below 0F, the back porch light has lit every time. It's also dimmer and bluer.
I'm looking forward to these, but when I finally buy one, I'm not going to pick one that says "equivalent to a sixty watt incandescant", I'm going to get one that says it's equivalent to 100 watts, just to be sure.
Re:If they are still not dimmable they still suck (Score:3, Informative)
Actually, you should be able to use a standard dimmer switch on these things. Unless someone is doing something I've never seen before, there's no logic in them, just the diode and a resistor. Maybe a capacitor if they were really ambitious.
I'd expect control with an LED to be much better than an incandescent, because the fact that the 'light emitting' voltage stays relatively constant between the on state and off state, so you should get better effective rangability and control.
Yes, I'm a control systems geek. :P
Re:If they are still not dimmable they still suck (Score:5, Informative)
It's hard to take you seriously when you don't know about a SINGLE component in the system.
First, LEDs are definitely variable in a non-binary sense. Anyone who has ever used an LED in pretty much any application ever can tell you that light output can be changed by altering the current.
Second, a dimmer isn't a variable resistor. It cuts the AC waveform, reducing the current available to an incandescent light bulb.
Pulse width modulation is definitely NOT the only way to vary the light output of an LED.
Re:Solar panels too? (Score:5, Informative)
Looks likely. Cambridge are researching that too, e.g. both fields are covered by the following grant application.
Details of Grant [epsrc.ac.uk]
Re:My first experience with LED lighting... (Score:3, Informative)
If you properly "dispose" of them (aka "recycle"), you can reuse just about every part of them except the small PCB in the base, and even that you can strip for the metals.
So yeah, they have a tiny blob of mercury in them - Of which, when properly recycled, 99.999% should end up in a new bulb.
Re:What about the production? (Score:5, Informative)
Re:My first experience with LED lighting... (Score:5, Informative)
How so? Recently, in my local walmart, GE started selling Par20 LED bulbs that were supposed to be 40-50 watt equivalent but for 7 watts produced 200 lumens. That's 28.5 lumens per watt.
My Feit Electric (Costco) 13w CFLs (60 watt equivalent) produce about 800 lumens. That's 61 lumens per watt.
A 60w incandescent makes around 700-850, depending on brand. Using the 800 as a comparison, thats 13.3 watts per lumen.
LEDs may have the potential to be more efficient than CFLs, but it doesnt look like they automatically are. Or am I missing something?
Re:My first experience with LED lighting... (Score:3, Informative)
'A 40W incandescent is an excellent light source - brighter than a pretty big fire or the largest candle known to man.'
In home lighting isn't rated against candles or big fires (unless you are looking for mood lighting) its compared to daylight.
'a typical domestic living room is nicely illuminated by 3-4 35W tungsten halogen lamps'
Yeah, I'm sure 110w of HALOGEN would be reasonably bright. But we were referring to indoor lighting. The gas in the bulb would be argon.
Ok, let's get this thread straightened out. (Score:5, Informative)
(1) LEDs can in fact be dimmed by running less current through them, however their power efficiency drops, which negates the whole purpose of LED lighting. The most efficient way to dim an LED is to strobe it on faster than the human eye can detect By varying with fraction of the on/off cycle that the LED is on, the human eye perceives this as "dimmer". The number of photons averaged over a second is reduced, but for the milliseconds the LED is on it is at full brightness.
(2) Incandescent bulb dimmers are almost never been rheostats, not since maybe the 1920s. The problem is efficiency again. Imagine a certain current flowing through the light bulb and the rheostat; the power dissipated in each device is then proportional to the resistance. When the rheostat is at equal resistance to the light bulb, it is dissipating as much power as the light bulb is! A 100 watt light bulb at 50% of the normal RMS current dissipates 25 watts, which means your rheostat is getting as hot as a small soldering iron. You'd need a massive heatsink to handle this.
Therefore for many years, dimmers were not very practical. The best dimmers were actually transformers, but they were extremely bulky. They were mainly used in theaters and fancy restaurants to soften the shock of the prices on the menu by relief at being able to find them at all.
With the creation of the solid state silicon controlled rectifier (scr), it is possible to do a trick with incandescent bulbs that is rather like the LED strobing trick. What you do is you take the sine wave power and you clip out the parts of the waveform on either side of the peak. So rather than having power delivered to light bulb all the time, the light bulb is only powered for a fraction of the cycle. The difference is that an incandescent filament glows because it is hot; it does not flicker on and off.
Now with respect LED light bulbs, I'm not sure about what circuitry they contain, but they do contain circuitry. If you just plugged enough LEDs in series to plug straight into AC, they'd flicker at a very noticeable 60Hz. If you put a full wave rectifier into the circuit, they'd flicker at 120Hz, which might be fast enough you wouldn't notice the flickering. You'd certainly be able to use the a solid state dimmer to dim such as circuit, but flickering might be noticeable.
There are relatively simple tricks you could use to maybe double the frequency, in which case you probably would not be able to perceive the flicker. On the other hand, there might be fancier circuits that know how to do the right thing. One of the problems with LEDs is that they age, their brightness varies. If the LED bulb achieves its white color by using several different colors, you need a compensating circuit to maintain the original color.
Of course you could use white LEDs, but most of the bright ones are very harsh; I've seen warm white LEDs advertised, but I've never had one.
So there you go, the straight facts on dimming that every geek should know.
Re:If they are still not dimmable they still suck (Score:5, Informative)
Actually, you should be able to use a standard dimmer switch on these things. Unless someone is doing something I've never seen before, there's no logic in them, just the diode and a resistor. Maybe a capacitor if they were really ambitious.
Nope. LED fixtures on an Edison base incorporate ballasts, just like CFLs, and incandescent dimmers do not work well with any ballast. You are probably making the incorrect assumption that an incandescent dimmer just takes a sine wave with a ~ 170 V peak and outputs a sine wave with a lower peak. It would indeed be easy to create a dimmable ballast if that were the case. But instead these things just cut out portions of the wave creating all kinds of nasties on the house current. This is because it is cheaper to do, and all you need to do to dim an incandescent is to reduce it's average current consumption.
There are a number of solutions to this problem. The one that's most likely to happen is that a new type of dimmer will be created which does something sane for ballasts like reduce the peak voltage, and labeling will be created for both such dimmers and the CFL and LED light bulbs with compatible ballasts. Another solution would be to simply put the dimming entirely within the ballast itself, then the switch would just send a message to the bulb via radio or another out-of-band channel to the bulb circuitry to dim. But while this would be more efficient, this is not going to happen in today's fragmented home automation market without a government mandate, or at least the threat of a government mandate, to standardize.
PS There already are dimmable CFLs and CFL compatible dimmers, I have some in my house. They are not perfect, and both cost 2x as much as conventional CFLs and incandescent only dimmers; and there is no branding to tell the consumer they are compatible. This means you need to do a lot of frustrating web research before you buy the things. I also bought one bright LED Edison base lightbulb to satisfy my curiosity and it was both very expensive and non-dimmable.
PS2 My biggest frustration with buying lighting on the web is that no one shows you a spectral diagram of the light output of the bulbs. If there are any lighting web retailers reading this, please do this and you will win some early adopter business and appear expert in the eyes of even those who don't know what they are looking at. Use, trademark and reasonably license compatibility marks and you will make a killing.
Comment removed (Score:2, Informative)
Re:Whoopie for cold light! (Score:3, Informative)
If they can cluster LEDs in a way that simulates natural light (ie, a few at one frequency, a few at another frequency, etc) then I don't see how it's impossible... impossible for a single diode, perhaps..
Re:Big advancement (Score:3, Informative)
Re:What about the production? (Score:5, Informative)
More mercury from coal plants used to power incandescent bulbs, 100% of it lost to the environment. Look at whole life, not just one part.
Re:Whoopie for cold light! (Score:5, Informative)
LEDs have almost nothing to do with antennas, aside from the fact that both emit EM radiation. Specifically, there is no oscillator in the LED. The photons are a direct result of the diode band gap -- each electron-hole pair combining emits one photon with energy equal to the electron charge times the forward voltage (ie a 3V forward voltage LED emits photons with 3eV of energy, aka blue visible light). The Wikipedia page [wikipedia.org] has a fuller explanation.
The reason LEDs produce weird light is that their spectrum is a sharp band, as opposed to the broad hump of a black body. This can be fixed (somewhat) by using a phophor to shift some of that frequency (most white LEDs), but the usual techniques for that leave a gap between the LED emission and the phosphor emission. Better, though more expensive, is combining enough different color LEDs that the narrow individual bands blend together to simulate the blackbody output. Eventually, that will get cheap enough to be common, and then you'll see LEDs in common usage as lighting.
Wrong bulbs (Score:5, Informative)
You're buying the wrong bulbs then. Mine are at full brightness instantaneously.
Re:My first experience with LED lighting... (Score:2, Informative)
I believe you're thinking of the "inverse square law" and it applies to all light sources.
Re:We need lumens ratings (Score:3, Informative)
Especially as color temperature doesn't really tell the story where LEDs and fluorescents are concerned. While incandescent lights are thermal emitters with smooth color spectra, the others are composed of several sharp peaks at different wavelengths, a conditition which doesn't reduce to a single color temperature. It's also much of the reason why the light seems somewhat harsh and unnatural.
Re:What about the production? (Score:5, Informative)
Quit buying crap CFL and just rig your place with T5HO linear fluorescent.
One 54 watt bulb is all I need to light my living room or my kitchen, and it's 5,000 lumens INSTANTLY, no warm-up.
And they grow GREAT sweet basil and catnip and peppers.
Re:What about the production? (Score:5, Informative)
When you break a lamp, the state of Maine [maine.gov] says "The next time you replace a lamp, consider putting a drop cloth on the floor so that any accidental breakage can be easily cleaned up. If consumers remain concerned regarding safety, they may consider not utilizing fluorescent lamps in situations where they could easily be broken. Consumers may also consider avoiding CFL usage in bedrooms or carpeted areas frequented by infants, small children, or pregnant women. "
Here's what the EPA says to do if a CFL bulb breaks in your home [epa.gov]:
Before Clean-up: Air Out the Room
Clean-Up Steps for Hard Surfaces
Clean-up Steps for Carpeting or Rug
Clean-up Steps for Clothing, Bedding and Other Soft Materials
Disposal of Clean-up Materials
Please research before spreading FUD! (Score:3, Informative)
BZZZT, *WRONG*!!!
According to Energystar.gov: [energystar.gov]
Re:My first experience with LED lighting... (Score:3, Informative)
"you would need active cooling for a 300 watt halogen."
I'm calling bullshit. I've got a 300w halogen floodlamp. I don't see any fans on it. It's a shell, two ceramic sockets, a reflector, and a cord. I don't see ACTIVE ANYTHING in here.
Re:Ok, let's get this thread straightened out. (Score:3, Informative)
>Now with respect LED light bulbs, I'm not sure about what circuitry they contain, but they do contain circuitry. If you just plugged enough LEDs in series to plug straight into AC, they'd flicker at a very noticeable 60Hz. If you put a full wave rectifier into the circuit, they'd flicker at 120Hz, which might be fast enough you wouldn't notice the flickering.
Speaking as someone who designs LED drivers for illumination, and as such, who has spent tens of hours ripping apart competitors' LED lighting systems, I'm amazed and depressed at how many off-line LED systems use only a single diode and cap as rectification. The *nice* ones use full bridges.
There are good solutions: regulated rectification, current-limited LED drivers. We make them. They cost forty cents more than the full wave rectification design, and fifty cents more than the diode/cap half-wave design.
Guess which ones are selling like hotcakes and which ones consumers aren't buying?
Warm LED's look quite nice. A cool white LED with a similarly-rated red LED beside it, looks even nicer.
Re:My first experience with LED lighting... (Score:3, Informative)
A 40-watt CFL is about like a 150-watt incandescent. Here's a link [1000bulbs.com] to a really bright "compact" fluorescent. It's over a foot long.
Re:We need lumens ratings (Score:5, Informative)
Re:What about the production? (Score:3, Informative)
(Yes, this is a [citation needed] moment, I apologize.)
Re:What about the production? (Score:3, Informative)
I know you're joking, but that's what I actually grow with T5HO. [photobucket.com]
Pot only gets cloned and starting veg under fluorescent, then it's HID all the way.
GaN on Si commercially available (Score:2, Informative)
Actually sapphire substrates surprisingly are not that expensive.
I'm not sure why this press release is considered news.
Gallium is NOT in short supply (Score:5, Informative)
Never has been, and probably never will be.
Indium and Gallium Sustainability â" September 2007 Update [indium.com]
Re:Wrong bulbs (Score:4, Informative)
Re:Wrong bulbs (Score:5, Informative)
Re:What about the production? (Score:4, Informative)
I suggest you look up their recommendations for cleaning up a standard incandescent bulb for comparison.
I looked and didn't find anything. Care to provide a link?
As far as land fill problems, putting them in the land fill puts less mercury in the enviroment then using an incandescent bulb. Assuming your power come from coal, and not a clean alternative like nuclear.
The concern here is spot concentration -- what goes into the landfills tends quickly to go into the groundwater. If you've got a coal plant 150 miles away, you're not going to be getting much of it. Here's a link [mercuryexposure.org] that says mercury in landfills is a bigger problem than mercury in the air.
Re:What about the production? (Score:5, Informative)
I'm calling bullshit.
The largest T5HO bulb only uses 54w of power, two of those would be 108, plus ballast which in reality should be far, FAR more efficient than that, should use no more than 125w of power.
My 4-lamp T5HO system uses 230w according to Kill-A-Watt, that's 216w in light bulbs plus 14w energy conversion loss in the ballast. I toss out 20,000 lumens.
Your 100w incandescent only at most pumps 12-1800 lumens.
So either you bought some bullshit lighting or you're talking out of your ass.
Re:What about the production? (Score:4, Informative)
1) They are nearly a perfect point light source.
2) They light output is typically very directional.
But when you try to illuminate a room with one, you have to spread out this concentrated beam so much that it's not nearly as bright as your first impressions might make you think.
Re:If they are still not dimmable they still suck (Score:3, Informative)
PWM works fine as long as the oscillating frequency is above what the visual system can respond to (IAAVN ... I am a visual neuroscientist). The maximum frequency that the visual system responds to depends greatly on a large number of parameters, including contrast levels, and individual sensitivities, but, generally, the upper limit is about 150 Hz.
If your intention is to draw attention, then 5-to-10 Hz is excellent for this.
If your intention is to make even illumuniation, then oscillating at or above 200 Hz is certain to not appear to flicker.
These days, fewer and fewer people recall the horror of using a CRT computer monitor at 60 Hz refresh. It is painful. Seizure-inducing. But increase the refresh rate on a CRT to 85 Hz and most people don't see the flickering anymore. Increase it to 160 Hz, and it is nearly undetectable even in a laboratory setting. That's for a light that essentially goes full-on to full-off.
For light sources that are modulating at less extreme levels (like most LCD monitors, where each pixel is essentially constant in light output as long as the image does not change) a much lower refresh rate is necessary. 60 Hz is just fine.
The most recent laptops that have LED illumination are, unfortunately, modulating brightness with a typically 60 Hz PWM driver. This makes it much more like a CRT because the light source is pulsing on and off. I can see my laptop flicker easily, but it's only milding annoying (120 Hz, and it would not have been an issue -- and the thing is, a 120 Hz PWM driver isn't any harder to design than a 60 Hz one).
For a bike light, where you are using the illumination to see where you are going, I would recommend at least 100 Hz, if not 200 Hz. Do you have a choice in PWM drivers, or are you designing you own?
clean alternative like nuclear (Score:3, Informative)
Nuclear power isn't clean.
Falcon
Re:What about the production? (Score:3, Informative)
So it looks like the real mercury is from mercury vapor and from mercury that's already in the food chain.
Re:Retina Sear (Score:5, Informative)
A pointless tip for anyone:
Don't you hate it, in the middle of the night you have to have a piss. So you get up and can quite easily make you way to the toilet just by ambient light. You flick the light switch in the WC and do your thing. You finish and then switch the light off. Instantly you are thrown into total darkness. You stumble your way back to bed, hitting your shins and stepping on as many things as possible on your way. What can you do?
A simple solution is to close one eye before turning on the light. Keep this eye closed tight as long as the light is on. After you switch the light off, open your eye. You can still see quite well in the ambient light again with the eye you had closed as it did not adjust to the brightness of the light.
Re:What about the production? (Score:5, Informative)
BULL-fucking-SHIT. The ~3 MILLIgrams of Hg in a CFL are in an entirely inorganic metal amalgam form [patentstorm.us]. Stop pulling wacky pseudoscience scare tactic shit out of your ass and claiming it as truth.
Re:What about the production? (Score:3, Informative)
Manufacturers are moving from CCFLs to LEDs for laptops primarily because of power issues - lower power consumption == better battery life.
Re:What about the production? (Score:5, Informative)
Inorganic mercury in the environment (wether it's by burning coal at power plants or from light bulbs) eventually reaches soils, which get wet with water, and as most of the water on land eventually does, washes into aquatic systems (water cycle).
Microorganisms in the aquatic environment then convert it to methylmercury (what he was talking about).
After that, it's the same old story you already know: Aquatic system is contaminated so the mercury (actually methylmercury) bioaccumulates its way up the food chain until it gets to the humans who eat the fish. The higher up the food chain the carnivore is, the more toxic their exposure is. This should be of personal concern to you if you are a whale, shark, big fish (like tuna) or human.
It really doesn't matter what type of mercury is in those bulbs.
All forms of it that get into the environment do eventually turn into the very type that hurts us most.
Re:Wrong bulbs (Score:4, Informative)