RFI From New LED Bulbs

Discussion in 'Off-Topic' started by hwy101, Feb 29, 2012.

  1. hwy101

    Thread Starter Active Member

    May 23, 2009
    Found this article sent in by a reader of our newspaper regarding the new LED bulbs.
    I have not purchased one yet but I have seen them in Walmart.
    anyone have any insight into this problem?


    If you are concerned about the electromagnetic signals produced by the new smart meters, let me add to your list of devices to fear: those new LED lights.

    A few weeks ago, I installed one in my computer desk lamp, and soon found out that it produces radio frequency interference (RFI) that is heard as a high-pitched noise on my hand-held aircraft radio. A quick search on the Interned (for led rfi) showed me that the problem has been known for a while. http://www.ok1rr.com/e107_plugins/content/content.php?content.181

    To make those lights more energy efficient and keep them small, the manufacturers use what is called a “switched-mode power supply” that produce a high-frequency signal to drive the LED. That signal should be filtered, and the circuit properly shielded, but on some of the cheaper products it is not done. Apparently, some of the floodlight-type LED lights can emit a very powerful RFI. One customer says on the Net: “I emailed the supplier, and he advised me that he has paperwork which certifies the lights with a C tick compliance. The paperwork is obviously fraudulent or he is just telling lies. Most of the goods from China have fake EMC compliance documents and certification.”

    While my desk lamp emits RFI, a bigger flood-light type in my garage does not. Someone with the proper equipment should check all those lamps.
    Last edited by a moderator: Feb 29, 2012
  2. magnet18

    Senior Member

    Dec 22, 2010
    use ESL bulbs :)
  3. Adjuster

    Late Member

    Dec 26, 2010
    This problem has been with us for a long time: whether the lamps be the more established compact fluorescent varieties or more recent LED types, a large proportion of energy-saving models produce noticeable RFI. It would be wonderful if everything could be made compliant with regulations, or better still dead quiet, but in these days of imports from less regulated lands this may be much easier said than done.

    Actually, there seem to be so many other noisy things about these days that I rather despair for the future of radio - for instance, the laptop I am using right now spoils AM reception within a few metres radius. In my house, getting French AM stations properly requires a lot of switching off, or else taking a radio into the garden.

    Perhaps this is all part of a plot to foist Digital Radio on us all, as (up to a point) it is more able to tolerate the buckets of electromagnetic cr@p which these modern gadgets chuck out!!!
  4. MrChips


    Oct 2, 2009
    We have electronics to amplify very low amplitude high frequency signals.

    It took me a very long time to track down the source of noise in the 50KHz range.

    It turned out to be coming from newly installed overhead high efficiency florescent lighting.

    Now we run our experiments with the lights turn off.
  5. magnet18

    Senior Member

    Dec 22, 2010
    That is one of the best things ive heard all day :)

    I hate those cfl's
    mainly because they have mercury
    if i want to use incandescent bulbs, let me dammit
  6. Wendy


    Mar 24, 2008
    Since congress seems to be mandating things I would suggest taking the time to point this out by writing them. Give the dunderheads something useful to do for a change.
  7. hwy101

    Thread Starter Active Member

    May 23, 2009
    You have those in your house?

    I have not seen them here in the stores.
  8. tom66

    Senior Member

    May 9, 2009
    The energy used by an incandescent, whilst high, is far less than say a tumble dryer, washing machine, microwave, TV, etc. Why not encourage these devices to be switched off, instead of forcing these CFLs?

    I do like CFLs because they save energy. But the ballasts run hot and burn out too quickly. #1 failure mode is not failure of the tube, it's failure of the
    ~2.7µF 400V primary cap due to heat or the 1.5n 1kV coupling capacitor, due to poor voltage margin.

    Another odd thing that gets me is there are lots of RFI requirements for consumer items but seemingly not for conventional voltage-doubler microwaves. They have an awful power factor around 0.3-0.4 due to the half wave doubler.
  9. magnet18

    Senior Member

    Dec 22, 2010
    they aren't fully released yet, but I'm hoping they will be soon :)
  10. Markd77

    Senior Member

    Sep 7, 2009
    I agree, it's very wasteful. I've opened a few different models of failed bulbs and all of them have a bulging 400V capacitor.
  11. magnet18

    Senior Member

    Dec 22, 2010
    And the companies making them probably wont change, because most people just assume they "burnt out" and go buy another, making the company more money.
    They could start using slightly more expensive components for longer bulb life, and watch sales fall.
  12. justtrying

    Senior Member

    Mar 9, 2011
    agree. It is always interesting how we rush into changing small things ignoring the big picture. I was doing a small search on different types of bulbs for a report and found an interesting study - apparently forcing incandescent bulbs out in areas such as BC will actually cause an increase in greenhouse gas emissions (when I have time I'll have to check this out some more). Why? We use hydro power for electricity and gas for heat. As you well know incandescent bulbs produce a lot of heat. Especially if your house is well insulated it does add up. CFLs do nothing to warm you up, that is why I don't like them.... "when I was a little girl in Russia and the heat didn't work at -30, a lightbulb was all we had" :) I guess I am emotionally attached to them.