RFI/EMI Problem with Dimmable LED Lighting

Discussion in 'General Electronics Chat' started by ScottChi, May 20, 2015.

  1. ScottChi

    Thread Starter New Member

    Jun 12, 2012
    6
    0
    Hi Folks,

    I changed out the recessed CFL lighting in our kitchen with dimmable LED downlight retrofit kits last year. They look and work great. There's plenty of light, and no noticeable flicker.

    The downside is that every radio receiver in the house becomes noticeably noisier when the new LEDs are turned on, in inverse proportion to the dimmer control setting. The Kenwood stereo receiver we have on the same circuit is the worst affected, it became unlistenable whenever the new lights are turned on. Nothing but static roar out of both channels.

    Here's what I've tried so far. 1) I replaced the Kenwood's FM dipole antenna with a 75 ohm lead up to the TV antenna we have in our attic. The difference this made was undetectable.

    This suggested that it might be related to the power connection. So on to 2) Installing a multi-stage powerline filter. I ordered one of these rascals from Jameco,
    http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2197880_-1
    opened up the Kenwood, and spliced it into the power leads per the label instructions.
    It survived the smoke test, so I plugged the receiver back in downstairs and powered it up. Turned on the LED lighting, and...
    Roaring static noise, mocking my futile efforts. Still vanishes as soon as the lights go off.

    I'm out of ideas! Does anyone have a notion how to correct this? Is it time to invest in XM Radio, or wifi streaming? I'd rather go with an antenna on the roof next, but the neighborhood regulators won't allow that.

    Thanks much,

    Scott C.
     
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    bypass filters on the dimmeer, ferite filters on the wireing to the light. the noise is probably being conducted by the power line, which is acting like an antenna. if that fails, back to incandesant.
     
  3. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    Are the LED units rated to work directly from the mains?

    Leaving out the dimmer temporarily would indicate whether its the culprit.

    Antenna modifications are unlikely to do anything - if you have close neighbours, they may not be too happy as well!
     
  4. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Welcome to the wonderful world of cheap Chinese imported electronics and the fact that the money-starved FCC is asleep at the switch and is not enforcing the rules regarding certification and importation of incidental radiators, especially switching power supplies.
     
    Last edited: May 20, 2015
  5. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    Probably not a total loss if the grounding on any metal parts can be improved on, maybe threading the power leads a few times through some ferrite collars might do some good, maybe some X2 type filter capacitors in the usual places too.

    The interference needs to be stopped at source - there's very little can be done at the rasio/antenna side of things, but a ferrite collar on the Hi-Fi mains lead might slow down any thats getting in by that route.

    Another reason to stop the interference at source is neighbours!
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    yep....

    This is very common with LED drivers..
    Its also common that when your LED lights are on your garage door opener won't work.. (PWM frequency is similar to garage door opener freq)
     
  7. BR-549

    Well-Known Member

    Sep 22, 2013
    1,995
    388
    Did the dimmer come with the LEDs?
     
  8. ScottChi

    Thread Starter New Member

    Jun 12, 2012
    6
    0
    Thanks alfacliff. I'll see what I can do to quiet the dimmer and light circuits.
     
  9. ScottChi

    Thread Starter New Member

    Jun 12, 2012
    6
    0
    Thanks ian field,

    I am fairly certain that the dimmer is playing a role, because the lower the dimmer is set, the louder the radio interference becomes. The dimmer is very useful, however. We don't need 6 100W equivalents at full brightness most of the time. The LED downlight kits are advertised as being dimmable, but they do not specify any particular variety of dimmer control.

    This gives me the idea of searching to see if there are any specifically marketed for dimmable LEDs.

    Fortunately we do not have close neighbors.

    Thanks,

    Scott C.
     
  10. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    Not long ago; Everyday Practical Electronics published a power controller suitable for induction motors.

    It uses a high voltage power MOSFET surrounded by a bridge rectifier instead of a triac - so there is no switching noise as an added bonus.

    AFAIK: its a linear that dissipates power, but that may not be so serious if your LEDs use substantially less than filament lamps.
     
Loading...