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As makers, we’ve all experienced LEDs. We use them to make throwies, blink them with Arduinos, and mix them to make nearly any color imaginable. We love them because they are cheap (well, some of them), useful, fun, and typically operate at low voltages. Just like us makers, manufacturers are coming up with new ways to use LED lights in products. From computer screens to car headlights, LEDs are rapidly starting to take over leaving incandescent, and even fluorescent, lights in the past.  In this new Maker Press book LED Lighting – A Primer to Lighting the Future, author Sal Cangeloso shines a light on LEDs.

Recently, O’Reilly publicist Mary Rotman caught up with Sal Cangeloso to find out what the big deal is about LED lighting, and how it can change (and is currently changing!) our future.

Why is LED lighting so important right now?
LED lighting is important right now because it is at, or at the very least near, a transition point. The technology already makes sense for use in businesses and continuous-use scenarios and very soon it will make sense in the majority of lighting. This includes the standard, screw-in socket that is used in every building in the country. It might not be a transition that everyone is thinking about actively, but it has major implications for energy use and environmental initiatives. Additionally it’s a really interesting example of how technology changes over time and it results in a noticeable change in our lives.

When did you start getting interested in LED lighting?
I’ve been following the industry on and off for a number of years now. Initially I was intrigued by what LED lighting could offer, but dismayed by the prices and the performance of early LED lamps. All the while, I was never happy with CFL bulbs. So over the years I heard people have the same complaints I had about efficient CFL bulbs while watching LEDs getting better and cheaper. I started to foresee a major transition happening around 2012 and started researching. Ultimately, my research showed my timing was a bit optimistic, but it’s now clear that a change is coming.

Are there any notable companies using LED lighting exclusively?
Lots of companies are making the switch to LED lighting. Some of the most notable include Facebook’s use of “smart lighting” by Redwood Systems in one of their data centers and Walmart’s transition to LED retrofits. Other interesting transitions are happening in government usage–New York City is testing out LED street lamps in some areas–and then high profile projects, like the Empire State Building’s switch to Philips LED fixtures earlier this year.

What are the major challenges that electronics companies are running into with LED lighting?
Companies have been hitting all sorts of hurdles with LED lighting. The two biggest are cooling and cost. The simple fact is that LED’s don’t like high temperatures, it shortens their lives and limits how bright they can get. So designing 75- and 100 watt-equivalent bulbs has been a challenge. The issue of cost is really simple: people expect their lighting to be inexpensive. So even though LED bulbs save money over time (because of the power they save) people just won’t spend $25 on a bulb.  Initial costs have dropped and will continue to do so, but they need to get lower before we see mass adoption.

How can LED lighting change the future?
I’ll try not to get carried away here, but LED lighting will save billions on power and will slow down the production of CFLs, which have mercury in them and are a pain to dispose of. They are also convenient–bulbs tend to be rated for about 25 years, so you won’t have to get back on that step ladder again too soon. Also, new LED lights are starting to look really good, so hopefully they will make people happier with their indoor lighting.

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  • John F. Bramfeld

    I disagree that people don’t want to pay $25 for an LED bulb. There may be some like that, but I won’t pay $25 for a bulb not knowing what its color rendition will be like. Incandescent light is a known quantity. LED’s often look terrible, and even compact florescents vary widely and color temperature is an insufficient guide.

    • sal cangeloso

      That’s a fair point. I was referring to the mass market, where people generally recoil at the thought of a bulb that is over $10. And it’s understandable – bulbs have been cheap for a long time and people have homes with lots of light sources.

      Color temperature is not a perfect solution, and color accuracy (generally measured in CRI) is even worse. There are efforts to improve on these fronts though and certain manufacturers are very big into light quality.

  • Tommy Phillips

    Yeah, frankly, I will believe that LED lighting is ready for the home when I see it.

    If LED manufacturers want to get people on board, they should commit to not repeat the mistakes of CFL:

    1. Don’t promise ultra-long lifetimes until the devices really will last. I replaced a lot of CFL bulbs well before their promised lifetime. All of them in my house, in fact. They didn’t last much longer than incandescent bulbs, though they cost a lot more when I bought them. And it doesn’t matter to a consumer which component fails. A failure is a failure, whether it is a solder joint, a resistor, or the LED proper.

    2. Don’t lie about brightness. You have to discount CFL brightness by about one standard size. If it says it’s a 75-watt equivalent, it will run pretty close to the brightness of a 60-watt incandescent. If you are replacing a 75-watt bulb, you want a 100-watt-equivalent CFL.

    3. Get the color balance right. We like the color of incandescent lighting. See if you can get the devices bright enough without flooding us with blue.

    • sal cangeloso

      Good points all around. I think a lot of people in the lighting community sort of want to just forget the whole CFL thing and act like it didn’t happen. A lot of consumer were turned off by their experience with these and are hesitant to make another change. I’m confident that things will be better with LEDs, but it’s going to take some time to win people over, which is totally understandable.

    • Dan Koss

      Hi Tommy,
      I am in a field where I specify lighting for a lot of industrial applications and have learned a LOT about CFL bulbs and lighting in general. I had a lot of the same concerns you mention and dug pretty deep into things to figure out how to avoid the same issues you mention. Here’s what I learned:
      1. The spiral bulbs that we all think of as CFL bulbs are really only a retrofit. This is important b/c the manufacturers are doing a lot of work in the same space as an incandescent bulb. A true CFL bulb has separate ballast and are usually a lot more robust than the retrofit kind.
      2. CFLs have electronic ballasts that are sensitive to power quality. This is true for both retrofit and OEM CFL. Surges and sags in voltage will shorten the life of both the lamp and the ballast. CFLs will hate it if the lights dim when your AC kicks on.
      3. Switching will also shorten the life just like an incandescent. Fluorescent lamp life is determined by plugging in a ton of lamps and leaving them on until 50% of them burn out. However long it took for the 50% to die is the determined lamp life. If you switch the lamps on and off a lot the lamps won’t last as long. This is especially true for “instant start” type lamps. To instantly start the lamp the ballast hits it w/ a very large voltage spike. That spike burns up some of the gasses in the lamp and shortens the life. “Program Start” lamps are better than “instant start” b/c they still hit the lamp a little harder to start it but they don’t hit it w/ an entire bus.
      4. Wattage is a horrible way to measure brightness. Look for the rated lumens. Lumens are a measure of light out of the lamp. There is a whole lot to learn about lumens and where they are lost but it’s a much better start then wattage. This applies to CFL and LED! A lumen is a lumen.
      5. Another deceiving thing about brightness is color. (again, CFL and LED) For the same lumen output a “cooler” color will appear brighter to the human eye. That’s why the first CFL lamps were usually very “cool”, they were perceived as being brighter. The measurement for color is in Kelvins. The higher the Kelvin the cooler the color. The typical incandescent is about 2500K to 3000K. The only reason we prefer that color is because we have grown accustomed to it. Sunlight is well above 10,000K for reference. Typically the higher the Kelvin rating the better the color rendering. The Color Rendering Index (CRI) is only supposed to be used for comparing the color rendering ability of lamps of the same Kelvin rating. That’s not very useful but there isn’t a widely accepted alternative yet. There are plenty of people working on it like Sal mentioned. If you give yourself a change to get used to a 3500K lamp you will probably find you will prefer it to 2500K. That’s personal preference though. You can find both LED and CFL in lower color temps.
      To summarize; Retrofits are only band aides to avoid replacing the fixture, power quality is important, excessive switching is bad, lumens = bright, watts = power and $, look for Kelvin ratings if you don’t like blue, take CRI with a grain of salt, and finally CFL isn’t always the best solution but LED has a ways to go and the standard incandescent toaster light is rarely the best solution.

      • sal cangeloso

        Ha, awesome summary. Totally nailed it.

      • Bruce

        Thanks Dan. Lots of great info in your comment, except the part about color temperature of sunlight “Sunlight is well above 10,000K for reference.” Direct sunlight is typically assumed to be 5,750K, though NASA puts it at 5,878K ( ). Still, thank you.

  • nzc (@ngvrnd)

    Further, I recently bought some chandelier-base LED bulbs, and found after installing them that there was noticeable flicker. Waving my hand in front of them, I see strobed images. I hate that in fluorescents, and I don’t like it any more in LEDS. That’s another thing that stops me from getting on the bandwagon — until I can be sure there’ll be no flicker, I shan’t be buying any more.

    • nzc (@ngvrnd)

      Phillips, I think they were.

  • Eugene

    I started to replace all light bulbs that are going out with Philips LED bulbs (the ones with yellow elements, which actually emit white color). I’m very happy with these light bulbs. No flicker, the light is pleasant, and I get a kick out of ability to touch working light bulb without burning myself. ;-) I don’t know the reliability yet, since I started the process 6 month ago, and none of the Phillips light bulbs went out yet. The other kinds of LED bulbs I got from Costco didn’t last long, so at this point I’m only going to buy Phillips bulbs. I had the same reliability problems with CFLs that the other reader mentioned, so I’m hoping that Phillips LEDs will fare better.

    • sal cangeloso

      I found the Philips to be a great choice, specifically the 12.5W AmbientLED. It’s a reasonable price and I’m happy with the performance. I’ve probably only got a few hundred hours on mine, but they are holding up nicely. I’d be curious to know the brand on the ones that burned out prematurely if you remember it.

  • Randy Pyter

    I work for a company in an industry that has been using LEDs as indicators for over 20 years and has lately gotten into projects using LEDs to provide actual lighting. The through hole type T1, T 1-3/4, (3mm & 5mm) and the smaller surface mount parts draw only 20 mA of current and have a light ouput of 2 to 200 milli candela (mcd). A 60 watt incandescant light bulb has a light output of 500 candela and the light is omni directional while LEDs always have a specified viewing angle and the light is actually emitted in a “beam”. Most of todays lights or bulbs available to consumers using these small LEDs in multiples in a lame attempt to get meaningful light output.

    The only wat to get usefull light from LEDs is to use multiples of 1/4 watt (75 mA), 1/2 watt (150 mA) or higher power devices. A 1/4 watt LED may have an output of 25 candela and a 1/2 watt 50 candela or so leading one to believe that ten 1/2 watt parts could replace a 60 watt light bulb. The problem is that the light emitted from LEDs is so directional. The lens can be diffused but then the light ouput is lessened. Philips, Cree, and other major companies have high powered engineers working on this and there will be usable products released and the prices will continue to fall.

    There is really no such thing as a white LED. Huh? A white LED is really a blue LED with phosphor on the lens. If you examine a white LED you will notice a yellowish or reddish tint to the lens. The type and quantity of the phosphor determines the color temperature by filtering the blue light. White LEDs are either cool, neutral, or warm white. The cool white LEDs are normally brighter than the warm white probably due to a lesser amount of filtering. The warm LEDs are more like the sun and incandescant bulbs that we all love.

    I hope this was helpful.

  • Dan Koss

    Thanks Sal! Great stuff.
    One other point on LED that I’m watching carefully is lamp life. It is only calculated at this point and is defined as when the LED dims to 70% of it’s original lumen output. How is anyone supposed to know 70% of lumen output after 5, 10 or 15 years? Unless the lamps (or drivers most likely) fail completely nobody will know when to replace them.

    • sal cangeloso

      Thanks Dan!

      That number, the L70, is the standard for the lifetime of the bulb. It basically says that after 25,000 hours the bulb will be at 70% of its original brightness. After that point it should continue to operate, until the LEDs or electronics give out. You don’t have to replace it at that point, but you’ll see a noticeable difference. And, you’re right, there is no good way to tell when a bulb is at 70% (or 80% or 50%…) unless you have some sort of measurement tool. This might not matter to some people, but others will probably wonder if they got their money’s worth!

      Some high-tech lighting systems will have lamp tracking, so you’ll be able to mark down install days, run time, power consumption, etc. but that’s just for big commercial installations so far. Home automation should be able to tackle it before too long.

      Regarding lifetime – There isn’t testing for how long a lamp will last, but the degradation of LEDs over time is linear, so you can do the math and figure out the expected brightness level after x hours of operation.

  • Pingback: MAKE | LED Lighting – A Primer to Lighting the Future « ElectraLED Blog()

  • mrmarkjackson

    LED Lighting is definitely ready for the home, we’ve written a guide here on how best to install an LED lighting system at home which includes what the potential advantages are.

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