Light bulb efficiency exhibit updated with LED bulb option

It seems like tinkerers are always being tapped to build or repair exhibit hardware. This time around it’s [Dino’s] turn. He’s been asked to alter a light bulb efficiency demo so that it includes an LED option.

The idea here is that you crank a generator to power different types of light bulbs. There’s an ammeter built in, but possibly the best feedback is knowing how hard you have to crank to illuminate the most inefficient choice. As it stands there is a toggle switch to choose between incandescent and CFL bulbs. [Dino’s] solution is to use a three-position rotary switch. He removes the toggle switch and replaces it with a socket for the LED bulb. A new location for the rotary switch is chosen and he does a bit of work to get it mounted securely. If you haven’t worked with this type of switch before he takes the time in the video after the break to explain how they work.

30 thoughts on “Light bulb efficiency exhibit updated with LED bulb option

  1. There’s a gaping flaw in these sort of demostrations, and it’s the fact that a person is a poor judge of brightness and color.

    Put simply, the LED/CFL bulb can be up to 1/3 dimmer before you’d notice it by simply switching on different bulbs, and since you can’t accurately estimate the power you’re putting into the bulb – as tangible as turning a handle is – you’re effectively blind to see the difference.

    They could cheat by putting in a 60 Watt bulb and a 5 Watt LED, which don’t produce similiar amounts of light despite the advertisements, and you’d feel that yes, turning 5 Watts feels much lighter than turning 60 Watts, but other than that it tells you absolutely nothing.

    1. And the biggest difference here is between the CFL and the LED, where the falsity of the test really comes on.

      Because the CFL would need several minutes, even 10 minutes of turning before it reaches full brightness. The LED is on instantly, so it would seem that a feeble 5-7 Watt LED is able to outperform a 15-20 Watt CFL, while in reality the CFL is at least as efficient and usually more efficient than the cheap LED bulb.

      1. aside from the brightness, comparing various light sources has never been apples-to-apples.

        Color temperature/wavelength curve/color rendering index, lumens-per-watt, delivered output, heat-radiation, photometrics, and shit tonnes of application considerations.

        The snippet yesterday where the guy stopped using his halogen (MR16 it looked like) downlights in favor of an RGB strip seemed like a poor decision despite the benefits of the computer controlled effects. Warm white light (2700kelvin) is much more pleasurable to work under than the cold white LEDs (4-6000k). also, the amount of light that actually made it to his desk from the LEDs was nowhere near what he was getting from the halogens, even if with the same total wattage. Buying higher quality MR16 lamps would have extended their lamp life, Osram MR-16s typically last half a year when left on 24/7.

  2. Gee, electricity must be expensive in the US if it costs over $300 a year to run a 60 watt bulb 3 hours a day – $335 / (60/1000)*3*365 = $5 a kilowatt hour! I DON’T THINK SO…. more leftist global warming propaganda?

    1. Whoa! the left wing apologists come out from under their rocks – now WHO is the troll colecoman1982? Not I, I am a simple electrical engineer who gets sick of people making ludicrous claims to suit their ideology. Tony – you make a good point in that he doesn’t give enough information but it is a demo of 3 different light sources and he CLEARLY points to the lamps and mentions the cost of running those lamps – now that would have to be a 1000 watt lamp to run up that cost – and he DOES indicate how long it runs and that it is over a year. No way in the world are LED lamps (that are generally available) are 1/6th the power of an incandescent lamp (for the same luminosity). In addition when talking about the running cost of any item you MUST amortise the up front capital cost calculated in present worth – CPLs are 10 times the price of an incandescent and LEDs are 100 times the price. That price comparison he gave was clearly intended to give the impression that incandescents are MUCH more expensive to run that the other two, and the truth is they are not – in fact it has been shown that in cold climates CFLs can be more expensive to run than incandescents because heating has then to come from other sources. I have no doubt that eventually solid state lighting will drop in cost enough to make them competitive – that point is still a long way off.

      1. Unless your house is seriously leaky with paper thin walls, 3000 W is enough power to make it into a sauna. In fact actual sauna heaters are in the 3000-6000 Watt range.

        The energy need of an average sized house is 25000 kWh for one year. Three fifths of this energy is used for heating. That gives you an average heating power of 1700 Watts.

      2. Simple is right, engineer I’m not so sure of.

        A half-decent engineer would write better, not jump to conclusions, and do a little research.

        Your writing: use paragraphs. There’s a big key with ‘Enter’ written on it. Use it.

        He doesn’t give any information as to what the paper is describing, and merely points to each bulb as describing the costs. Yes, he could have done it better. Note he doesn’t give the bulb wattages, so you can’t calculate their costs.

        That said, the ratios between the running costs of each bulbs are correct; CFL is cheaper to run than incandescent, and LED cheaper again. That difference is the point he (and the generator he is upgrading) is trying to make.

        While he only describes running costs and not total, the prices of CFLs have dropped so much it matters little; they can repay themselves in a matter of months. LEDs will follow the same path, and with a possible lifespan of over 20 years will be even better.

        The lefties are at it again… No they’re not. Most bans were introduced by conservative governments, that’s certainly the case in Australia.

        In the US efforts started in 2007 (y’know when that leftie Bush was running things), and California was first to sign legislation – that would be the other well-known leftie Arnold Schwarzenegger.

        China is stopping production of incandescents anyway, what needs a ban when you can’t buy them?

        The ‘but they provide heating’ is a well-refuted furphy. Most of the energy goes into heating up the roof itself, and escapes there.

        Any advantage gained in lower Winter heating costs is more than offset be increased cooling in Summer – cooling is much more expensive than heating. Even in cold environments there is a small energy saving with switching to CFLs.

        You could drop the guy a note of his blog asking for details, or spew out a few more random half-truths. Your choice.

      3. @Dax: dunno about you, but I switch my heating off in Summer. And most of Spring. Autumn too.

        How big does my AC need to be to deal with 3000W of heat from the lights?

        With CFL (or LED) I have less heat for the air conditioning to deal with. Obvious really.

      4. –“@Dax: dunno about you, but I switch my heating off in Summer. And most of Spring. Autumn too.”

        I turn off my lights in the summer because there’s plenty of light coming in through the windows at nothern latitudes where the lenght of the day changes with season. I typically have to turn my lights on at around 10 pm in the summer.

        –“How big does my AC need to be to deal with 3000W of heat from the lights?”

        Depends on the CoP of your unit. Air-air heatpumps have 1:5 ratios over moderate dT, so I would guess about 600 Watts.

        –“The ‘but they provide heating’ is a well-refuted furphy. Most of the energy goes into heating up the roof itself, and escapes there.”

        More than 90% of the heat from a lightbulb exits as infrared radiation, more than half of which ends up heating the floor and furniture of the room. In any case, many modern homes even come with ceiling heaters which work on the principle of down-radiated long wave infrared under the paneling.

      5. excuse me, but having 20-30 (40-100 watt = 3000kw max) incandescent lights at home which are not working simultaneously all day and night makes such a big difference in terms of heating?

    2. He doesn’t give enough information.

      At the 14:30 mark, he states the LED costs $32 to run, the CFL $76, and the incandescent $328.

      The sheet doesn’t say how they got those figures, nor the bulb wattage or quantity. He merely guesses at the 3 hours/day usage. I assume it’s years pricing for a ‘typical’ house usage.

      The upshot is CFL uses 1/3 the power an incandescent does, and LEDs 1/6th.

      Or he’s part of that big conspiracy. I say bring back whale oil and candles.

      1. “The upshot is CFL uses 1/3 the power an incandescent does, and LEDs 1/6th.”

        Not for the same light output though.

        Commercial LED bulbs are actually worse in efficiency than CFL when they use traditional LED dies with the phosphor embedded. The reason why they use less power is becuase they put out less light – it’s as simple as that.

        You can have better ones with external phosphors that beat most ordinary CFLs, like the Phillips L-prize bulb, but they cost $50 a pop after government subsidies.

      2. And before some dimwit goes “LEDs don’t have phosphor!” – yes they do.

        All white LEDs employ yellow phosphor to produce something that creates the illusion of white. They turn part of the blue spectrum into yellow-green, because using yellow LED chips would give such a narrow spectral output that the color rendering index of such a bulb would be potato.

  3. Hmm, they should add some extra resistance for the increased energy used in the building of the cfl and led lamps as well plus high purchase prices. Oh and figure that most of them never last as long as they are advertised to.

    1. I was active duty Navy for 13 years. I moved a LOT the last 5 years I was in due to random circumstances. Regardless, I bought my first CFL’s in 2005 and moved with them. I still have some of those same CFLs I moved with from back then. From that first move I have moved 4 more times all since 2007. Now that they are as old as they are, I don’t keep them in places that are constantly used but in my pantry area, and the bulbs I don’t always use in the basement and portable lamps. Regardless, I’d say even the older bulbs have MORE than paid for themselves considering the initial first 3-4 years they were my main bulbs and now are used as those one off location bulbs that get turned on maybe a couple times a week for a few minutes. Convenience factor also be considered of time not wasted changing them all the time as my time has a monetary value to it.

      1. I used to do commercial lighting for a living and there were only a couple CFLs that would last any length of time, and that was pretty much philips. These are like a $25 lamp. Most people dont want to pay that. The rest had a very high failure rate. Within one month of installation I would have a few blow at each location. And sometimes it is not very pretty how they go. Burning, smoking, etc.

        If you want long life try a 130v halogen. Those things last forever.

      2. A 75 Watt halogen incandecent bulb is worth about 2000-2500 hours, which means you can burn one at least 5½ hours a day for a year.

        If your time is that valuable that you can’t lose five minutes in a year, I suggest you hire a manservant to turn your light switches for you – it comes cheaper than doing it yourself.

    2. You’d have thought people would’ve gotten over trotting out the old “blah blah blah” by now.

      Out of 20-odd CFLs, I’ve lost 1 in 6 years, and that’s because I dropped it.

      Keep hoarding those incandescents, dude.

      1. Have you measured how much they’ve dimmed though? And how much longer they take to start now compared to when new?

        The “lifetime” of a CFL is typically measured to 70% brightness because they do lose light output all the time. They also change color temperature in use, so what you buy is not what you’ll get.

      2. I’ve got spares brought at the same time, if I find the lux meter I could compare brightness.

        The various consumer test groups have done those tests, it’s probably easier to track those down and read them.

    3. I think you need to redo your math if you get 5 minutes a year. As I never have incads last a year anyway in the main living areas where lights are on like you said on average of 5 hours a day. 6 -8 months seems to be about avg. I have 2 ceiling fans in my current living room and one in each bedroom and den which is 7 ceiling fans total which all accept 4 bulbs. I put 3 CFLs and 1 incad in each (I like the instant light of the incad). We are already at 28 bulbs, plus I have various lamps for reading light, bathroom lights and all..All of those are CFL and like I said, I have some dating to 2005 which those are now in little used places. I have tracked my power bill and have saved money at this point and have changed bulbs less…And at 5 minutes a bulb * 40 bulbs (being conservative) is 3.3 hours which at my current hourly rate saves me $200 minus how often I change CFLs (less than once biannually at current rate).

      1. I was talking about the new halogen incandecents.

        You know, the ones with a small quartz bulb inside the regular bulb? They’re about 40% brighter for the same wattage and last 2-3 times as long.

        I prefer them over CFLs because they have superior color spectrum, instant on, don’t mind heat or cold and they’re dimmable without paying extra.

  4. Some folks must have terrible luck with incandescent bulbs as I have not experienced this short lifespan everyone is going on about. I’ve lived in my current house coming up on seven years, and have only replaced two incandescent bulbs; one bulb in my oven and one bulb in my refrigerator. Perhaps I am not a typical user?

  5. Anyone ever build one of these that tests Real, reactive, and apparent powers? I mean with all the fancy “Smart” meters going into service, I’d wager that eventually the utilities will start charging for real, reactive, and apparent powers, along with TOU etc…

  6. Quartz halogen lights are not dimable to the full range. If you run them low most of the time, the halogen and hot bulb can not work to stop tungsten deposits on the glass. This will lead to a blackening of the glass and rapid heating and poof.

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