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LED Lights Interferes with DAB signal

Discussion in 'DAB Digital Radio & FM Radio' started by anthonylawrence, Sep 26, 2010.

  1. supraTTman

    supraTTman Member

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    It's all down to the switched-mode power supply you use. They all run at different frequencies (few hundred KHz) and they all generate many harmonics (multiples of few hundred KHz) right up to FM, DAB & TV frequencies (few hundred MHz).

    I'm convinced that, in most cases, the source of this interference is not usually the LED 'lamps' themselves for 12V MR16 or similar. For 240V AC GU10's, there is so much voltage conversion circuitry involved to power the 3V DC LED's that these are far more likely to radiate 'mush'.
  2. jackord

    jackord Member

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    We live in a suspect area for DTV reception, we have spent a lot of money on getting arial items up to the highest standards, including boosters, arial, cabling etc.

    Generally it is summer and early evening when the reception is likely to fail, winter poses no issues at all.

    We were running mr16 Halogen lights in our kitchen and living areas, the only noticable thing with them generally was that when we switched on the main kitchen lights (ceiling) often the TV would blink and make a loud noise, but as it was only momentary it was of no concern. If they were contributing to the summer lousy TV reception I do not know.

    Anyway after experiencing all the common problems with these dreadfull lights, including them dropping out of their holder due to them being so distored from the heat they generate and nearly hitting our 18mth grandchild on the head (which could have had disastrous consequences) and constantly having to replace them due to this and the worry of fire, I decided to look into the LED scene to see if the prices on the globes had come down to resonable levels to make them a viable purchase.

    It seemed that they were now worth a try so a few months back I bought 10 x 4w led mr16 globes (chinese) to replace the 50w halogens.

    Sadly they are simply not good enough in the kitchen, but no noticeable TV reception loss, so I went back to the internet and searched for higher capacity globes, found the 3x3 9w cree chip versions, thinking that these would solve the problem I bought some of each colour, 3000k and 6000k.

    I did not change the transformers at all, they are the Nelson iron types.

    While the lights are much better and in fact for the working areas like the kitchen the 6000k are perfect, and the softer 3000k are nice in areas where you do not want to read, we then by accident I noticed that the DTV would not work (I was complaining that we had no reception at all, could not figure it out, did not make any sense, began to think that there had been some sort of catastopic disaster which stopped the TV stations from broadcasting....lol) then someone turned off the ceiling lights in the kitchen and hey presto on came the TV.

    We have 5 in the kitchen, two are wired off the "POWER circuit" which supplies to the range hood and a power point on the wall.
    The others are wired off the "LIGHT" circuit in the ceiling.

    It is the ceiling ones that stop the TV from working, the others make no difference at all.

    We can have two 4w in the TV area on (ceiling, light circuit) and the two (power circuit) ones on with no noticeable TV interference.

    So I am wondering why this is the case?

    I did experiment with the ceiling lights, as I thought that the transformers may have been at fault.

    I disconnected them one at a time and no combination would allow the TV to work. Not even one light on. I then found that I had a couple of Nelson 60VA Cougar Electronic transfomers, so I fitted up two lights with these, tried the TV and it all seemed to work ok, this was during the day. But that evening low and behold, they had the same effect as the other transformers.

    I am wondering if TV reception is a bit weaker at night and the slightest interferrence causes it not to work.

    Anyway I am at a loss with this and I find it amazing that stuff like this happens. I did not find anything that warned me that LED lights would cause these sorts of problems, just like there was no warning that the Halogen lights were health hazards in so many ways.

    With all of the consumer protection we have around these days one wonders how these sorts of products can be marketed.

    Anyway if anybody has a solution it would be appreciated as I know nothing about electronics.

    Cheers
  3. jackord

    jackord Member

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    You will have to excuse my ignorance, but am I to assume that you are simply running your 12v LED lights straight off the power supply (no transformer) also am I to assume that this is the same sort of thing that is used in PC's?

    It makes sense that they would work like that after all they only need 12v to operate.

    So if one had a spare 300w computer power supply all one would need to do would be to fit a 3 pin plug to the light cable in the ceiling, then plug the PC power supply into there, then wire up the LED downlights to the 12v outputs, of which there are usually at least 6.

    Having said all of that, it seems that most switched mode power supplies can be a source of EMI, hence the issue with the transformers used for the LED lights. The ATX PC powersupplies, do have an EMI filter.

    Sounds like a nice weekend project coming up.
  4. Paul W

    Paul W Member

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    Sort of. These are not out of a computer or anything, they are a universal 12v 12.5A switchmode power supply made by" MeanWell ". i have now installed several of these on the troublesome groups of lights and all the problems have gone away.:clap: i could run the whole house on one of those things :laugh:
  5. jackord

    jackord Member

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    Thanks for your reply Paul W.

    I have been fiddling and now I am able to run 3 x 6000k off one transformer and 2 x 6000k of another without any ill effects on the TV.

    It is quite usual for one to simply buy the LED globes and fit them as replacements, thereby leaving all of the original transformers in place. It never occurs to people that they do NOT need all of those transformers. They are designed to run 50w globes so you can work out how many LED globes could be run off of one transformer, the only problem is how to connect them all up. Making up a suitable wiring harness and finding a suitable connection box is the next thing for me.

    Switching is an issue as we like to have different banks of lights independantly switched, which would mean using a transformer for each set of lights, which sounds like what you have done Paul?

    If one was building a new house all of this could be worked out quite easily. But retrofitting is a bit harder.

    I will press on as I have now spent the money on the 12v system. But I am sure that I can get some sort of satisfactory arrangement done.

    The Computer PSU works fine, if one wanted to make up a wiring harness to fit into the original wiring plugs on the PSU, then run them out to the light bulbs, then mount the PSU in the ceiling safely so that animals cannot tip it over or pee on it or whatever, only issue is that they run a fan so that will be on whenever the lights are on, this adds about 7w to the power usage. But once again you would need one of these for each set of lights that you want independantly switched.

    Oh well...........
  6. Paul W

    Paul W Member

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    when i was experimenting i found anything from 1 to a maximum of 4 LEDs were OK on 1 electronic transformer, if i added a 5th it would start to flicker and carry on after about an hour,pull it back to 4 and it was OK. i just recieved another 20 LED lamps today so i now can finish off the entire house retrofit and remove the uneccessary transformers, then see which other groups of lights start the TV carrying on and change them to the switchmode power supply.:smashin:
  7. daniel2002

    daniel2002 New Member

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    Sounds like a good plan.
  8. Chris Muriel

    Chris Muriel Active Member

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    Some LED bulbs create large amounts of RF interference- while others are properly designed with good suppression and filtering included.
    Interesting video on the subject here :
  9. Fudgemia

    Fudgemia Member

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    i had 8 halogen spotlights in my kitchen, one blew so i replaced with a Lumineux High Powered LED GU10 4.5w 230v. this had a life of 30,000 hours and would save a fortune in electricity. there was no need to change transformers they just plug straight into the existing bulb holder.

    turned the one bulb on my DAB radion stopped recieving signal, all lights still on the radio but no sound. Moved it around different sockets in different rooms still didn't work. Tried windup DAB so it didn't need plugging in i had to take it out of the house before it worked.

    Anyone able to help, what do i get rid of my DAB radio, can't too much choice of stations, or my LED bulbs.
  10. Rodders53

    Rodders53 Active Member

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    Get rid of the led bulb. It's faulty (or very poorly-designed).
  11. Fudgemia

    Fudgemia Member

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    I tried replacing the LED bulb that stopped the DAB radio working, following discussions with the supplier, with a different type (warm white as opposed to cool white). this had no effect it still stopped the DAB Radio working. thanks for the suggestion.
  12. Rodders53

    Rodders53 Active Member

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    That one, too if faulty or poorly designed (probably the latter)... although you may, perhaps, also be in a marginal reception location and more liable to interference.
  13. Chris Muriel

    Chris Muriel Active Member

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    Different type - but if the same make would likely be a similar design and create similar amounts of interference.
  14. rp2044

    rp2044 Member

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    Hi all,
    I'm a researcher in to light bulbs for a consumer magazine and I'm just looking in to this problem as we have also heard about it. Can anyone tell me specifically which brand/ make/ model of LED bulbs is causing this problem? we would like to purchase them and test them ourselves.
    Many thanks for any help!
  15. gr0mit

    gr0mit Member

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    Hi
    I'm just sending 5 of these back as faulty/non-compliant to EMC regulations:
    MASSIVE SAVINGS on MR16 LED Bulb 320 Lumens 50W Equiv

    Lights on, DAB off! Lights off, DAB on!

    I got a 12v lead acid battery and connected the string of 5 lights directly to that instead of the mains torroidal transformer, and it still interfered with the DAB radio. Conclusion: These particular lights are causing a lot of RF noise in the 150-200MHz spectrum.
    Rgds
    gr0mit
  16. 4stringstu

    4stringstu Member

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    I have exactly the same thing with fluorecent tubes. I can get occasional reception but a small change in arial position stops it working
  17. Wildestcat

    Wildestcat Member

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    I have 4 x ALT 100V-240V 7W wide angle warm white GU10 LEDs on a seperately switched circuit in the kitchen/diner. The room also has 3 other seperately switched circuits carrying a total of 12 x 4W Kosnic warm white LEDs.

    Switch on the ALT circuit - DAB radio goes off, switch off the ALT circuit, DAB back on. Had to move radio to the far end of kitchen (directly below one of the Kosnic arrays) before reception returns with the ALTs energised 4 metres away.

    I have tried the radio on internal battery power - problem is unchanged, so nothing to do with connection to the mains. Tried a single ALT bulb with the other 3 removed - one ALT bulb is enough on its own to cause the problem.

    There are NO issues with the DAB radio anywhere within the room with all the Kosnics in use, plus Kosnics in place of the ALTs. (i.e. total of 16 x 4W 220V-240V Kosnic has no adverse effect on DAB radio).

    Note there are no transformers involved on any circuit - all bulbs plug straight into 240V light circuits.

    In my opinion the issue is with whatever electronics are fitted in the ALT bulbs (could this be linked to the wider 100V-240V input voltage range?). In future I will be buying Kosnic, although sadly they do not offer a bulb with the equivalent lumens or beam spread of the ALTs.

    Hope that may help anyone with similar issues!
    Last edited: Nov 29, 2012
  18. Jamessanders

    Jamessanders Member

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    I employed LED lights but no problem was faced
    Last edited: Dec 11, 2012
  19. Wildestcat

    Wildestcat Member

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    Have now found that Kosnic do offer a 6W wide angle GU10 replacement that is as good as the ALT.
    Part no KTC06PWR/GU-10-F30.
    Now installed & no DAB radio interference!
  20. supraTTman

    supraTTman Member

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    Intriguing - was there much difference in price between the ALT & the Kosnic lamps? Are they both made in China?
  21. Wildestcat

    Wildestcat Member

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    The ALT lamps were made in Taiwan. There is no information at all on the Kosnic packaging to indicate country of manufacture. I thought country of origin was a legal requirement, but seemingly not!
    The Kosnics were cheaper than the ALTs, but LED prices are falling all the time.
  22. niall campbell

    niall campbell Member

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    I have 12 LED lights which are Aurora and no interference from Amazon and 6 watts
  23. RutlandBoy

    RutlandBoy Member

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    I find the above all very interesting as today I came across the problem for the first time.
    I fitted LED lamps and drivers in April 2011. MR16 lamps with 60leds per lamp and LED drivers all from Lustrum Light in London. This week one of the lamps failed and as I had used up my spares stock and as Lustrum only warranted them for 12 months I had to look around for a replacement. I liked the look of a 4w 24SMD unit from 'LED Hut' so ordered 6 of them. As soon as I replaced the blown lamp with one of the new SMD units DAB reception was lost. I tested all 6 of the new SMD lamps and they all gave the same result...no DAB. Interestingly if I just hang the lamp outside of the housing to test I get interference but there is still a DAB signal. If I fully house and clip the lamp into place there is no DAB reception at all.
    From the above I conclude that it is the SMD lamps that are generating the interference and not the LED drivers.
    Not sure what to conclude re 'hanging' or 'seated' other than the housing seems to act as some sort of amplifier ??? Anyone got any ideas ?
  24. supraTTman

    supraTTman Member

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    Fascinating! The plot thickens. Perhaps the holders are acting as a dish and focussing the trash downwards towards your DAB.

    I have had 3 Lustrumlight failures after 15 months - 2 were 12V MR16 60 LED and 1 was an SES (E14) 240V 60 LED spot for the kitchen.

    Yesterday, when I was cleaning I accidently knocked one of the (good) MR16's out of the holder in the bathroom and it broke into lots of pieces - still works mind!!

    Then Rutlandboy posted last night and this prompted me into delving deeper.

    The 3 photos show that these Lustrumlight 60 LED MR16's use a switching regulator (8 legged black IC at bottom) to boost the voltage from 12 to 18V DC. You can see from the oscilloscope shot that 40V peak-to-peak voltage is generated by the switcher at 27 KHz. It is the fast-rising edges that are responsible for RF interference. Surprisingly, these lamps don't interfere with my DAB or FM or my boat marine VHF (got 15 on the boat).

    Attached Files:

  25. RutlandBoy

    RutlandBoy Member

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    Hi SupraTTman, not sure what's going on with the housing/no housing interference but it definitely seems like the housing is making the issue worse. I am returning my latest batch of SMD lamps to supplier (LED Hut) as they admit that their lamps interfere with DAB. Next I'll try the Lustrum 60SMD 3.1w lamps as my 60led lamps from them cause no problem with DAB. Your photos/comment re the switching regulator used by Lustrum is worrying as it means it is likely to produce interference in the DAB spectrum, but as you say they don't. Really a bit clueless about what's going on here.
  26. supraTTman

    supraTTman Member

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    Something else that prompted me to investigate and reply to your post was the fact that we both had the Lustrumlight 60 LED MR16's for around 18 months and they started to pack in.

    Silly isn't it how we associate LED's with longevity and reliability. The truth is that the LED devices themselves will almost certainly last for many years, but the associated electronics won't - the Achilles' heel of modern lighting. And I saw yesterday why these devices pack in sooner than we would hope for.

    In the middle photo showing the lamp components, the 3 tall black components ran uncomfortably hot after being on for only 5 minutes. One of these components is the main switching coil that generates the high flyback voltages needed to increase the voltage from 12VDC to 18VDC, and the other 2 are electrolytic capacitors that smooth out all the ripple and for these to be running warm means that they are working stupidly hard and will eventually dry out and fail. And this was with the bulb broken and the heat able to escape, so heaven knows how warm these items get with the glass bulb intact and the bulb sat inside a housing!!

    Would be interested in measuring a noisy MR16 if anyone can donate one!!
    Last edited: Jan 9, 2013
  27. niall campbell

    niall campbell Member

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  28. supraTTman

    supraTTman Member

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    I think you are missing the point. All LED lamps run cool on the surface because the LED devices are very efficient. Inside the lamp is a very different story. Inside houses all the electronics that will fail before the LED devices - fact. Why would cheap Amazon GU10's be any different - they are all made in China.
  29. niall campbell

    niall campbell Member

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    The £40 previously advertised cheap bulbs ?? With 5 year warranty seem good to me.

    However I didnt know inside they were hot as you say.

    All I can report is no interference on my DAB equipment.
  30. SwingCat

    SwingCat Member

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    I am currently fitting out a new-build catamaran with LED lighting run off 12V batteries. The LED downlighters do not cause any interference. The problem occurred when I bought reading lights with halogen bulbs, which I replaced with MR16 12V bulbs - the result massive interference with Radio 4 (94.3MHz). The supplier has already said I can send them back, but I would be happy to donate one to further the excellent work being done in this forum.

    For the reading lights I would like 2.4W SMD LED bulbs (10W halogen equivalent). Can anyone recommend a source of RFI-free bulbs?

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