New Possibilities From Fading Lighting Technology

Like the incandescent bulb before it, the compact fluorescent (CFL) bulb is rapidly fading into obscurity as there are fewer and fewer reasons to use them over their LED successors. But there are plenty of things to do with some of the more interesting circuitry that made these relatively efficient light bulbs work, and [mircemk] is here to show us some of them.

Fluorescent bulbs require a high voltage to work properly, and while this was easy enough for large ceiling installations, it was a while until this hardware could be placed inside a bulb-sized package. When removed, the high voltage driver from the CFL is used in this case to drive a small inductive heating coil circuit, which can then be used to rapidly heat metals and other objects. After some testing, [mircemk] found that the electronics on the CFL circuit board were able to easily handle the electrical load of its new task.

When old technology fades away, there are often a lot of interesting use cases just waiting to be found. [mircemk] reports that he was able to find these light bulbs at an extremely low price due to low demand caused by LEDs, so anyone needing a high voltage driver board for something like a small Tesla coil might want to look at a CFL first.

54 thoughts on “New Possibilities From Fading Lighting Technology

  1. I like it . It’s how we know ChatGPT isn’t writing the articles.

    Now back on topic, an induction heater…This definitely wouldn’t have been something that I would have thought to try.

    1. But ChatGPT will trawl these websites and decide that it can English.

      Actually, what happens when ChatGPT is retrained on newer material that has been generated by earlier versions of itself? It won’t be possible to weed out all the poor examples, so it will either poison itself, or it will have to limit itself to material published before it was invented and start regurgitating Chaucer or Shakespeare.

      Verily and forsooth!

      1. What happens? Same thing that happens when people are cyclically regurgitating rubbish… conspiracy theories!

        Anyway, let the induction heaters do their jobs. These might be great for those solder loaded butt splices.

    1. I suppose no, because of phase and frequency differences. They should be somehow synchronized to work correctly. I saw such circuit, it first converts AC to DC, then to high frequency high voltage AC, so output isn’t synchronized with mains.

    1. The irony is that T8 tubes are just as efficient as LEDs – unless you compare to very low CRI LEDs – but baby with the bath water it goes.

      The long lifespan claims of LED replacements never materialized because they’re more susceptible to heat and electrical stresses (brownouts/overvoltages). It’s completely down to luck and location whether they last a year or a decade. The color quality is a tradeoff with efficiency and price, so most LED products out there are no better or even worse than tubes/CFLs at many times the price, and the built-in smart features are planned obsolescence or vendor-lock-in.

        1. Metallic mercury isn’t that dangerous, and the amount is tiny. About four milligrams per tube. It’s kinda like lead in car batteries: terrible stuff in principle but practically a non-issue since nearly all car batteries get recycled.

          1. Fluorescent bulbs are notably more fragile than car batteries, and while a single broken bulb only releases a tiny amount of mercury, you have to consider the potential quantities involved.

          2. The largest emitters of mercury are mining (notably: gold mining), metal refining, cement production, and combustion of coal. These completely eclipse the mercury emissions from broken fluorescent tubes by a factor of a million or more.

          1. @Dude – Laws vary from place to place. I don’t know where you are but if rewiring your own lamp isn’t legal I am willing to bet it’s a long way from where I live!

            I’ve bypassed the ballasts, added noise filters and replaced the bulbs with no-ballast LED replacements in all the florescent bulb fixtures in my house. It’s perfectly legal here and I am very happy with the result!

          2. I spent many hours on the clock disconnecting the ballasts of old fluorescent light fixtures so they would be compatible with LED replacements. It is incredibly easy.

          3. > It’s perfectly legal here

            Any fixed luminaire is the domain of electricians. You shall not touch it beyond replacing the tube and igniter. Even if it was a detachable unit with a wall plug, modifying the internals would be illegal for non-qualified people.

            The reason being, the CE marking on the device means the manufacturer ensures the device is compliant with the Low Voltage Directive (LVD) 2006/95/EC or 2014/35/EU, and if you open it up and modify it yourself, this is no longer the case. Therefore it is not a CE compliant device, and having such devices installed in your home means your insurance company would like to have a word with you.

        2. I don’t think most people realize that there are different forms of Mercury and that metallic Mercury isn’t nearly as dangerous as they say. I mean I’m not going to go licking the stuff or anything but organic Mercury is the real terrifying one and what it does to you with just a minute amount of exposure is terrifying and irreversibly terminal.

          1. Is the mercury in CFLs metallic, or is it some kind of mercury salt? And even metallic mercury has the issue that it doesn’t just sit there, it’s quietly evaporating all the time, or forming compounds with whatever surface it’s sitting on. It’s also a cumulative toxin, so small doses add up over time. I agree that we should clean up mining and burn less coal, but we should ALSO use less CFLs.

      1. The long lifespan claims of LEDs never panned out for the same reason incandescent bulbs lasted longer forever ago: because no one’s dumb enough to actually make a bulb that’d last that long. Just cheap out on the filtering cap and number of LEDs and you’ve got yourself built-in failure.

        1. Number of LEDs is the big issue. Incandescents and LEDs are similar, in that underdriving them makes them last exponentially longer. If you drive them right on the line of failure, you get more light out of a cheaper product that doesn’t last as long. It’s pretty simple, really.

          1. The big difference is that incandescent efficiency goes up with power, like halogen bulbs: more power, hotter filament, more light per watt (double the power gives more than double the light), but… lifespan goes in the bin.

            With LEDs, underdriving actually gives you more efficiency, so if you have double the LEDs with the same total power, you actually get more light, in fact a lot more. AND the LEDs last far longer.

            It’s simply a “bad business choice”. I just recently changed a LED bulb just to see I still had a new one from the same buy. 3 years… less than the CFLs I used 10 years ago.

        2. There are manufacturers who make bad LED products that don’t last. There are manufacturers that make good LED products that do last. The consumer has no hope of knowing which is which until the product fails; the consumer has no practical means of testing the light output, power consumption, CRI and lifespan of an individual lamp, so anyone can sell you just about anything.

          The outcome is what’s called a “lemon market”. When consumers can’t trust high price to equal high quality, they choose low price to avoid getting ripped off, which drives the good products out of the market.

          The original reason for the “lightbulb conspiracy” was exactly this: everyone said their bulbs would last forever, but the tradeoff was poor efficiency and dim light, and many of the bulbs would still fail quickly anyways. The irony is that today, to solve this very same issue with LED bulbs, the government should have to mandate a similar standard.

          1. There’s a lemon in everything you buy no matter who makes it, my house is full of Great Value LED bulbs that have all worked great for 4 years. In the country I live in to get certain certifications and make certain claims your product has to pass certain government tests and you’re legally bound to the claims you make. As far as the “light bulb conspiracy” that is actually documented history. Originally incandescent light bulbs were capable of working indefinitely and there are a few cases of incandescent lights that have not been turned off in over 100 years. The major manufacturers realize that this would cut into their profits and agreed that anyone who made a light bulb that lasted over 1500 hours would face a severe penalty. Again this is not a conspiracy theory it is documented history.

          2. Yes, it is documented history, but it doesn’t beat physics: in order to make a bulb last forever, it has to barely glow.

            The point was, tungsten filament bulbs were new and competing with older proven technologies like carbon filament and tantalum filament bulbs. If the new bulbs weren’t consistently better in any sense, then people would choose the old proven technology instead. People were sold bad bulbs that would supposedly last, and they either would or wouldn’t, bright or dim. Manufacturing quality was highly variable; standardizing on the 1000 hours would eliminate both the bulbs that were manufactured badly and those which were deliberately under-driven to “fake” longevity. This effectively regained consumer trust in the market and eliminated the lemon effect.

            >my house is full of Great Value LED bulbs that have all worked great for 4 years.

            And yet those simple LEDs have nothing in terms of filtering or protection, so a lucky thunderstorm nearby can put out all your lights or severely degrade them in a single flash.

        3. What claims are you referring to? Most of the lights I see in sale at places like bic camera and yodobashi camera are from manufacturers like Panasonic and Hitachi. They typically claim 10 years, and I have never, ever had one stop working even though I started installing them around 2008.

          I have had some el cheapo ones from Amazon stop working (and they flickered horribly before that) – but I think quality fixtures have no issues.

      2. > The irony is that T8 tubes are just as efficient as LEDs

        That is a favorite statement, repeated all over the internets!
        (you can guess where this is going, can’t you? Your parade – it’s going to get rained on!)

        Wikipedia does have relative well-sourced table of luminous efficacies of different lighting methods:

        Now, a few of these links are dead. So, take this 2022 T8 replacement LED tube:

        Philips Master LEDtube UE 1200mm G13/T8 11.9W/840

        11.9W, 2500 lm, 4000 K, CRI of 80. That makes for a luminous efficacy of ca 200 lm/W. There’s no ballast to be driven. This is visible output per electrical in.

        For comparison, a T8 fluorescent tube typically has a CRI somewhere in the high 70s, but sure, there’s better ones, for photo studios and the like. You will notice that these already have been much more pricey. (there’s also better LED tubes. We’re comparing consumer / office use products, not scientific/photographic lighting.)

        So, the US government tells us what realistically, a 32 W T8 fluorescent achieves

        So, that’s 37W in, 5256 lm out, at a very similar, maybe slightly worse CRI. That’s 142 lm/W.

        Can we finally lay that claim to rest? Even these large, not space-constrained supply, fluorescent tubes are not 2/3 as efficient as a modern LED tube.

        1. >T8 fluorescent tube typically has a CRI somewhere in the high 70s,

          What I’ve seen sold for domestic use is >86, while the LED replacements are all 80 or below. It’s close enough though.

          What the LED suffers from is dimming soon as it turns on and heats up, whereas fluorescent tubes do the opposite. The lumens-per-watt figure is slightly misleading by the way it is measured. Also, many manufacturers quote the diode datasheet lumens-per-watt without any de-rating at all, which makes the figure a complete fantasy.

          1. Point in case:

            “Nennlichtausbeute (nom.) 210 lm/W”

            Nominal, meaning it is the datasheet number measured at a junction temperature of 25 C. This is valid for approximately 1 second after you turn it on. When the thing goes up to operating temperature – if it’s badly cooled as most LED products are – the brightness drop is usually 20-30% which puts it right in the ballpark of the fluorescent tube it replaces.

      3. Just look for the “Dubai bulbs”, there is a good YouTube video about them. The king decided he wanted bulbs twice as efficient and with a ridiculous lifespan, and offered country-wide exclusivity to the manufacturer with the contract for at least 7 years. You can’t get them anywhere else in the world.

        Good LED bulbs are possible, just bad business.

      4. Philips has 210lm/watt 80 CRI led bulbs (not just the leds themselves) in normal colors at reasonable prices. Has for a couple years now in EU. Not sure if they’ve done the same in a tube format but they’ll have something perfectly good. They last better than fluorescent even with poor power quality. You can also get much higher color quality out of LED arrays than you could ever get out of a fluorescent. Photography light panels are common and there’s probably some with a decent lumens per watt ratio even though they’re not optimized for that (instead approaching the same CRI as sunlight or a incandescent light at the cost of all else).

        1. The irony is, high CRI LED products are actually hybrids with internal/external phosphors that work exactly like fluorescent tubes. For example, the Philips L-prize bulb that won the competition for the first “incandescent equivalent” CRI 99 bulb.

          They subsequently pulled it off the market in favor of much worse products with better profit margins.

    2. Is it really great? If you don’t want, don’t buy them. Anyway, I can see no one is buying or selling these lamps, so banning them isn’t needed. We shouldn’t forget that EU previously forced us to use CFLs by banning incandescent bulbs while LED modules weren’t so developed (or rather tried – “heating bulbs”) .

      1. The light bulb ban came from the bulb manufacturers themselves, because the halogen bulb was becoming a race to the bottom – no profits since everyone can make them more or less “perfectly” at very low prices. The big corporations like Philips lobbied for the ban because they could put smaller competitors out of business with technology they had and the others didn’t.

        The consumer advocates at the time were saying that halogen bulbs would exit the market by themselves because LED was just around the corner, but nobody listened.

  2. I looked at the original article at Hack-a-day. It’s really hard to believe that a PCB from a 24 watt bulb can heat a nail (or whatever it was) to incandescence. A 24W soldering iron would barely be able to melt solder …

    1. Those indutive heaters use such a high frequency that the coil transmits power to the metal object, just like a transformer transmits power through the windings, and the metal object behaves like a short circuit, so it heats up.

      The catch is on the HF, that makes the current run arround on the surface of the object by skin effect. That mean the heater is directly heating way less materal than what is there, at first.
      The surface of the nail gets red hot, but the insides aren’t as hot, until some time passes and heat conducts to it

  3. >do a little rewiring

    That’s illegal. You have to call a qualified electrician.

    Oh come now . . . you’re telling me I can’t legally rewire a lamp in my own home? What’s next, call a “qualified electrician” to turn that light on and off?

    This is Hackaday, not We can do a LOT of things without needing to call a “qualified” whatever.

      1. Because the other person simply assumed it was.

        Generally in the EU, consumers are only really allowed to work on voltages up to 50 or 60 Volts in terms of the safety standards, and modifying mains powered devices would count as building your own, which makes them either illegal or your own responsibility in terms of any liability and insurance coverage. There are certain exemptions, such as allowing you to replace a frayed power cord, but beyond that you just aren’t supposed to touch anything with live mains voltage.

        1. So it is not illegal at all even in the EU, just a liability risk.

          If there is a fire or accident and you try to hide the fact you tinkered with something in order to commit insurance fraud then that opens you up to civil penalties at least, even in the US, and might be a criminal act but the original tinkering sounds perfectly legal.

          Sounds like the claim of blanket illegality due to CE certification was grossly overstated. Besides you tube is full of EU based tear down videos of cheap import products with CE markings that pose far worse hazards than a hacked CF bulb is likely to present.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.