One Way To Get Rid Of That Fluorescent Buzzing Sound

Tired of the persistent hum his fluorescent desk lamp made, [Andres Lorvi] decided he had to fix it. And by fix, we mean get rid of altogether. He liked the lamp though so he decided to convert it to LED — that way he’d save some money on electricity too!

Besides wanting to get rid of the hum, [Andres] had also been reading up on the effect of light temperature at night — bluish light is typically bad for your eyes when you’re trying to go to sleep. So he also took this opportunity to change the color temperature of the light in his room. Unfortunately it wasn’t as simple as just replacing the fluorescent with the LEDs — no, that would be far too easy…

Table Lamp

Because of the giant heat sink required for the LEDs, [Andres] decided it would be easier to rebuild the entire lamp head using his 3D printer, rather than trying to modify what he already had.  In order to make it a bit prettier, he used the acetone vapor bath method to smooth out the printed part. He also designed in a small diffuser using a sheet of acrylic sheet to help spread out the light better.

38 thoughts on “One Way To Get Rid Of That Fluorescent Buzzing Sound

  1. That’s interesting, I was just looking at the fluorescent light flickering in my garage in a near impossible to get to location and was calculating what it would take to convert the fixture to use LED’s.

      1. Around here the 4′ led retrofit lamps are about $19 at the local Platt. They do come in two flavors, one you can just stick in place and it runs off the internal fluorescent ballast, these are more expensive than the ones that require you to yank the ballast and wire 120v directly to the lamp sockets.

        1. I am learning all kinda stuff today-thanks guys :) Gonna have to hip my dad to the retrofits for his shop.
          Also kudos to Andres! Chief, I love that heat sink-it looks hungry to dissipate!

    1. Except modern fluorescent tubes are still more efficient than LEDs, so if you replace the ballast with an modern one, it beats the snot out of most diodes in every aspect.

      Better spread of light, higher CRI, lower energy use…

      The only LEDs that beat fluorescent tubes in light quality and efficiency at the same time are ironically hybrid designs. They have fluorescent domes that glow in the yellow-green spectrum and the LED itself only contains blue and red.

          1. But the exposed surface of a fluorescent tube is a lot larger than the die of a led, so the diode concentrates all heat generation in a single point. Not to deny your statement but probably there isn’t much difference between the two technologies. I’m very curious to see some test with commonly available lamps, tubes, leds etc. as I’m in the process of migrating to leds part of my house lighting.

          2. And, to follow qwerty’s comment, silicon junctions in LEDs like high temperature much much less than fluorescent lamps. In fact, the lower ambient temperature the better LEDs operate, fluorescent lamps quite on the contrary. Try putting fluorescent lamp outside in winter, its light will be dim until/unless it warms up.

        1. There isn’t one, because it isn’t true.

          The only old lamp tech that beats LEDs (older ones, at least) is low pressure sodium. Which no one uses much anymore because it is so yellow.

      1. Depends on if it’s a good design. If they’ve used quality components, the electronics have about twice the life of the tube.

        The issue with CFLs is that the electrodes don’t run hot enough to sustain hot-cathode action, so they ironically employ a small incandescent filament at both ends of the tube, which is constantly glowing slightly to provide the free electrons. All fluorescent tubes do, but the larger tubes only use them at start-up and the little starter canister switches the heaters off once the tube current strikes through.

        In CFLs, there’s a PTC resistor to regulate a small continuous current through the filaments.This is also the reason they are less efficient than the regular straight fluorescent tubes. The filaments then eventually erode and evaporate, blackening the tube ends. Once the filaments fail, the tube begins to start really slowly because it’s operating in cold-cathode mode until it warms up, and it loses most of its brightness because it’s just teetering on being hot enough for thermionic emission from the electrodes.

      2. If it is one that gets switches on/off a lot like a bathroom fixture, chances are the filaments break first. You can tell by looking at the base of the tube to see if it is black.

        Unlike a cold cathode tube in old LCD monitor, they have filaments that are heated up to allow them to start at a lower voltage just like the low tech florescent tubes. On a very cold day here, old CF don’t get to full brightness until they heats up enough. Filaments have a very low resistance when cold and hence causes a large inrush current until they heats up. The filament has a positive temperature coefficient.

        For the cheap made in China Wallyworld (Globe) CF I looked at a few years ago, the low wattage ones use a self oscillator while the high wattage uses a H bridge driver. In both cases, the filaments are wired to a secondary on a high frequency transformer without a PTC.

        http://www.cucumber.demon.co.uk/lights/diy/ Didn’t want to link this as the wiring doesn’t look safe.

  2. I was reasonably certain that LEDs weren’t significantly more efficient than CFLs … just cleaner-ish. Both have somewhat obnoxious power supply requirements relative to 120VAC.

      1. They’re more efficient than CFL, but less efficient than regular fluorescent tubes.

        A T8 tube with an electronic ballast reaches about 90-110 lm/W whereas ordinary white LEDs come out at 60-80 lm/W and CFLs are between 50-70 lm/W whereas incandescent lamps come at 15-35 lm/W for halogen and 5-15 lm/W for regular tungsten filaments.

        Generally speaking, the more powerful the lamp, the more efficient it is, except for LEDs where the more powerful the less efficient it becomes due to the difficulty of removing heat. The increased temperature causes the light output to reduce. The nominal luminous output of a LED is measured at 25 C junction temperature, i.e. within milliseconds of turning it on, which it never achieves under actual use conditions.

        The other difference of course is that the ordinary white LED has a color rendering index of about 50-70 whereas the CFL is about 80, the T8 tube goes up to 92 and the incandescent is a full 100. If you’re a photographer who likes prints, or a painter, artist etc. there’s no competition. It’s either halogens or tubes – the rest are simply crap.

        1. Raw lm/W figures are only part of the story.

          Consider also that a T8 emits light in all directions. To get the light going in the direction you want, the tube is put in a reflector – typically a cheap painted one with a non-optimal shape. By the time you subtract both reflector losses, and losses due to light restriking the tube, the usable lm/W of a typical T8 figure drops below that of a half-decent LED fixture.

          You’d have to go to T5’s in a properly shaped and mirrored reflector, for fluorescent to have a clear advantage over LEDs. Well, most LEDs anyway – remote phosphor LED setups surpass regular white LEDs and virtually any fluorescent setup. They look DIY-able, though I haven’t seen a DIY yet.

          You can produce high CRI with LEDs but it takes a carefully chosen blend of many different colored LEDs; with the associated initial cost and difficulty of doing so. I’ve seen some spectacular DIY LED aquarium lights with 98 CRI. Fluorescents are definitely easier and cheaper (at least up-front) if you want good CRI though.

          1. Well, depends on what your lighting intent is. LEDs are nice for spot lighting of course, but in a typical room you do want indirect lighting to avoid sharp shadows and glare.

            LEDs have the further problem that the different colors come from different spots in the optical path, so the color output across the beam isn’t uniform. The optics required to better spread the LED light output reduce its efficiency in similiar ways.

        1. There is not enough mercury in a fluorescent to hurt you, it is all elemental mercury which is not really bio-available and has a 15 day half life in your body. It is just reactionary crap, the same with metallic lead.

    1. I very roughly estimate light efficiency as: Incandescent ~= 5x CFL, incandescent ~= 10x LED. So LEDs are only 2x as efficient as CFLs, which isn’t a very big deal.

      Efficiency doesn’t tell the whole story, though. What is more important are the other factors:

      * LED bulb life is about 10x longer than CFL (meaning up-front cost per bulb spreads out over longer time) It also means that if the lamp is in a hard-to-reach place, I will only have to risk my neck on a ladder once every two decades or so.

      * LED bulbs do not degrade when powered on, whereas CFLs have only about 2000 switch-on/off cycles in them.

      * LED output does not fade nearly as much over time as CFL output; a CFL bulb with 3000 hours on it has less than half the output it had when new. An LED near the end of its life has over 85% of the original output.

      * LED bulbs are unaffected by ambient temperature, meaning they work in a Minnesota garage in the winter.

      * LED bulbs are instant-on, and never have a warm-up delay like some CFLs (LEDs are at maximum brightness immediately in my garage, but fluorescent bulbs used to take over a minute to get to full output.)

      * LEDs have similar (sometimes even more relaxed) environmental requirements to CFLs for installing in enclosed spaces.

      * CFLs are fragile and release toxic mercury vapor if damaged, while LEDs are durable and non-toxic. When I accidentally broke an LED bulb’s envelope (the flimsy Home Depot bag split open over my garage floor), I realized the elements inside the bulb would still work fine. I removed the jagged glass, and installed the bare chip bulb out of reach into my garage door opener, where I will never have to touch it again for as long as I live. Compared to incandescent bulbs (which I replaced annually due to the vibration) and the CFLs (which glowed dimly in the cold winter nights), it was a perfect solution for not wasting a broken bulb.

      It used to be the breakeven point for CFLs and LEDs based on pure economy (initial price plus longevity plus efficiency, excluding convenience or other factors) was about the $15 price-point for LED bulbs. Now that LED bulbs can be had for around $6/bulb, it would be utterly foolish to buy a CFL.

        1. The PF depends on how the inverter is implemented. PFC would get you very close to 1, but cost more and not easily fit into the tight space inside base of the lamp. If your LED also runs off an constant current inverter instead of direct feed from AC, it would have similar limitations.

          A CF would run on DC too as it rectifies AC into DC then chops it up into high frequency AC.

      1. I’ve found LEDs tend to be affected negatively by temperature – the colder it is, the better. The ones I’ve got lighting up my driveway seem to be brighter on a cold winter night than even a warmer winter night.

  3. I am wary of the simple resistor (half ohm) as current limiting with the passive cooling.
    The best LED’s are twice as efficient as fluorescent. Shop Lite means the cheapest and least efficient fluorescent light.
    I have been wanting to try the 10watt LED units on old CPU heatsinks. The strings of 12volt LEDs are great to work with too. No fuss no heat just stick up and wire. Great for lighting places never well lit. Like under cabinets, inside base cabinets, in closets, under the toilet tank for late nite, etc.
    The tape and channel lights are great in interior design.

    1. The 12v strip LEDs work great, but don’t count on the adhesive to do its job. I’m currently using several strips for workbench lighting and several more to light up a 40 gallon aquarium. I use hot glue on the ends and in other strategic locations to keep the strips in place.

      1. I’ve been replacing fluorescent tubes with a 12V transformer and the LED strips for a while now. Yes, you cannot count on the adhesive strips to hold them up, wire them or use a rigid plastic strip or zip tie to augment the adhesive. This does require some wiring, as you’ll want to remove the ends where the tubes were, the ballast, and probably install an outlet instead (to directly plug in the transformer.) I then cut the strips to 4′ lengths and use 2 lengths to replace one tube. This means a 16 foot strip of 50/50 LED’s is brighter than the 40W equivalent T-8 and only pulls the power of a small transformer per two bulbs (typically I simply use one from an old unused cordless phone, 9V charger puts out 12V, perfect for the strips.) This is under a watt, for TWO bulbs. Since most of these fixtures have diffusers, you really can’t tell once you’re done, unless you’ve used a different (such as warm white) color strip. The fluorescent fixture is re-used, OR you could pull it and just put the strips on a wall surface. They also work great (as designed) as under-counter lights.

    2. Thing is, LEDs trade their higher efficiency by compromizing light quality. If you manage to find a monochromatic 550 nm LED you can get some mad lumen output per watt, but your CRI will be about nil. The light will be worse than one of those yellow sodium street lamps.

      The exact same radiation power spread evenly over the visible spectrum will give you about 1/3 the output in lumens, but a CRI of 100.

      1. It’s not nearly that bad. The phosphors they use to change the colors do reduce the output, but by only about 11%. When I purchased two 145W Aeon Lighting Technology flood lamps, the Cree chips came in my choice of colors. The “true white” came in at 10,800 lumens, the “natural white” came in at 9,600 lumens, and the “warm white” came in at 7,800 lumens. Because I’m using them to raise orchids, I wanted the spectrum to be slightly warmer than the harsh bluish color they called “true white” so I opted for the natural white, even though it reduced efficiency. (I make up the difference by running the lights about three hours longer per day.)

        Regardless, it’s certainly not losing 2/3 of the output to get to a pleasant color index.

        I used them to replace a High Pressure Sodium light (with the horrible yellow color). While the HPS produced about 55,000 lumens using only 400W of electricity, the unit ran crazy hot and I became worried about fire safety. That and the yellow light is mostly wasted by being reflected off the green leaves. Together the two LED lamps produce slightly more usable light for the plants than the HPS. Also, the color of the HPS was awful for enjoying the plants. But HPS is probably the most efficient light source available in terms of lumens produced per watt and price per fixture — assuming you need a lot of light.

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