LED lights and RF interference

Discussion in 'General Electronics Chat' started by studiot, Dec 5, 2011.

  1. studiot

    Thread Starter AAC Fanatic!

    Nov 9, 2007
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    I see there are some other threads here about the subject, but here is my experience for comment.

    I have just fitted two (very expensive) UK mains - 14 watt (120 watt tungsten equivalent, 28 watt CFL equivalent) LED luminaires in a building extension.

    I am now picking up intolerable interference on both AM and FM radios, throughout the house.

    Considering the cost, CE markings and other certifications and pedigree, this is very disappointing.

    I am plannning to try some delta suppressors and will report in due course. When I take the units down to fit the suppressors I will take some photos.

    Meanwhile any comments or experiences welcome.
     
  2. thatoneguy

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    Feb 19, 2009
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    Line driven Switching supply to limit LED current.

    The one I've seen is complicated than a currrent limiting capacitor and resistor, similar to what is in the base of a CFL, but simplified.

    Try putting a "line conditioning" power strip in front of the LEDs to see if it makes a difference. The kind of power strip that uses a couple of big toroid inductors for RF chokes.

    I assume the interference goes away when the LEDs are switched off? They shouldn't have much transmitting distance of the internal noise, maybe 20 feet max.

    Are your radios battery powered or line powered?
     
  3. studiot

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    I forgot to mention that there is no interference on DAB or on Internet radio.

    I have yet to try a battery powered radio.
     
  4. mcgyvr

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    Oct 15, 2009
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    People still listen to radios in their homes? Crazy. :)

    Does your bulb claim FCC compliance?
    CE markings are a joke and really don't prove/guarantee anything.

    Other standards may only apply to safety/construction/efficiency. Nothing about EMI/RF certification.
     
  5. studiot

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    I would have preferred a serious comment, but thanks anyway.
     
  6. steveb

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    Jul 3, 2008
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    I once had an interference problem from a faulty hysteresis setting in the thermostat of a small heater. The on/off toggling, at a high rate, caused the house power wires to make very nice antennas. My TV picked up the interference, and it was present even on a battery powered small TV that I used to track down the location of the problem. The distance of transmission was amazing. I live on 4 acres and could pick up small amounts of interference on my borders.

    What this tells me is that high-frequency high-current on/off toggling effects on AC power will generate interference very easily. Perhaps you are seeing the same type of effect? Not sure, but thought I'd mention it.
     
    Last edited: Dec 6, 2011
  7. mcgyvr

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    Most of it was serious..
    FCC/UL,etc.. all require true testing/qualification be performed.
    CE compliance is mostly self declared. No testing is actually required at all.

    My point was that you seem surprised because you thought you bought a "high quality" product because you payed a high price and saw a CE mark when in actuality you got a crappy product from a quality marketing department. Until the EU dictates mandatory testing/qualification for CE marking this will happen over and over again.
     
  8. studiot

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    First, thanks Steve.

    Since this type of lighting is the coming thing I thought I would purchase a couple to see how they went and share experiences with others.

    As a matter of interest the lighting itself is first class.

    However I am not sure why there is a need for an HF generator with LEDs.

    Sorry, but until you can show some pedigree as an expert in UK wiring and building regulations (as well as CE) I can't regard your input as serious.
     
  9. mcgyvr

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    Someones a little crabby because they got ripped off.

    UK/US wiring doesn't matter is all a giant antenna. Sorry you bought a poorly designed LED light.
     
  10. Adjuster

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    Dec 26, 2010
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    Some high efficiency lamps produce interference because they use switched-mode technology. Recent requirements for improved power factor may paradoxically have made this worse. Many systems now incorporate a switcher input instead of a simple rectifier, so that by having a suitably choreographed high speed PWM switch on the input, a near sinusoidal input current can be obtained.

    Unfortunately, all this lovely power factor improvement may lead to the input current containing more content at higher frequencies, unless the manufacturer provides efficient filtering, which may be difficult to do without adding significantly to the cost, as well as weight and bulk that may be significant for a lamp.

    FCC, UL, CE, or any other "quality" marking may have to be taken with a pinch of salt now that so many goods come from the East. It is not uncommon to hear of things marked with standards which they simply have no right to. Such things do not seem to be taken seriously in some cultures, and nowadays it can be difficult even to be sure where things have come from, so it may be difficult to enforce. Perhaps stricter import controls are called for.
     
  11. Wendy

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    Mar 24, 2008
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    You do realize the FCC is a purely American agency? They have nothing to do with British standards? The OP location is clearly shown?

    To Studiot,

    How serious are you about this? Would it be worth building a filter for it, for example, to see if it could be suppressed? I don't know the regulatory agency in Britain, but I think I would turn this company in, since LEDs are going to be the future. You're neighbors will eventually own something like this, and it would be nice if you could keep listening to the radio (something I do frequently). I like the BBC and music
     
  12. Adjuster

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    In principle, excessive interference is not allowed, but the degree of EM pollution in this country seems to have increased considerably in recent years. "Energy saving" lamps and systems for extending broadband over copper conductors may have played a part in this.

    I occasionally listen to foreign services on the long wave band (about 150kHz-280kHz, used for European broadcasting, not used in USA). Drive under some telephone poles with the ADSL going hammer and tongs, and there is nothing to hear on that band but hash. Anyone living in adjacent houses had better not expect much from AM radio. Radio amateurs can't be very happy with this situation: it may ruin their long-distance reception in some areas, at least on the lower bands. Possibly the use of optical fibre will eventually curb some of the interference, time will tell.

    I wonder if this is being allowed partly because of the plans to end analogue broadcasting in the fairly near future. Being digital, and transmitted at higher frequencies than most other radio, the DAB broadcasts are less susceptible to low-level interference. Internet "radio" is in a sense not really radio at all, unless you count the link from a "wireless" router, if applicable.

    The current economic situation and the inadequacy of digital coverage so far may delay the end of analogue beyond my lifetime, but it must be rather dismaying to vintage radio enthusiasts. I don't know how things stand on the Continent. Perhaps other members might comment
     
  13. Wendy

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    Mar 24, 2008
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    I doubt the FCC will end the AM/FM bands. They serve too many purposes, and are fairly constrained. The TV band was extremely wide, it was worth big bucks.

    Then there is the fact existing radio stations are already putting digital side bands into their existing signals. Add to the fact that the existing bands are used to teach beginners, I just got through looking for an easy AM radio transmitter for example.
     
  14. mcgyvr

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    So what. I'm sure the bulb isn't made by a company in the uk.
     
  15. Wendy

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    Yup, China is the usual norm. Think they have any regs?

    They are supposed to meet the requirements of the countries they ship too. Somehow I am a doubting Thomas.
     
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