 | Home > Technical > Suppression of radio interference from LED lights |
 
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| Mountain_man Member Since: 09 Dec 2011 Location: Right side of Offas Dyke Posts: 756  
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Finally got around to fitting some (Bearmach) LED stop/tail lights on the 110 as the original Wipacs fell apart once too often! Boy they are bright! Happy enough with the lights themselves, but whenever I put a foot on the brakes or turn the lights on for night driving I am getting considerable interference to the FM radio signal.
Does anyone have any suggestions of the best way to suppress this? TIA |
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3rd Jun 2020 11:06pm |
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| Swine&Small Member Since: 20 Mar 2017 Location: Norfolk Posts: 1223 
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put the old lights back on again ?
 1983 Series 3 Pick up in Marine Blue
1967 Morris Traveller 1966 Morris Convertible 2012 VW T5 Camper Quod Abundat Non Obstat. |
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3rd Jun 2020 11:37pm |
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| kmac Member Since: 07 Oct 2009 Location: Middlesex Posts: 1308 
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A common mode choke in the feed to the light bar will help cut some of the interference
See here https://www.defender2.net/forum/topic26844...mode+choke |
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4th Jun 2020 6:14am |
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| discomog Member Since: 09 May 2015 Location: Notts/Lincs Border Posts: 2526 
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As Custom90Steve says, I would try ferrite clips first of all as they are relatively cheap to buy and easy to install. Lots on Ebay and Amazon. Defender 90XS SW
Mini Countryman Cooper S Morgan Plus 8 |
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4th Jun 2020 7:34am |
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| Mountain_man Member Since: 09 Dec 2011 Location: Right side of Offas Dyke Posts: 756
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Yep. Straightforward 3 wire stop tail sealed LED units. I couldn't work out why my radio had suddenly got so bad driving round mostly after dark. The one day as I was driving I noted that every time I pressed the brakes the interference was there. So I flicked the lights on and it was there all the time. No brakes or lights on, and perfect reception. Eureka moment. Thanks for all the advice guys. I will have a go at fixing it and report back. |
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4th Jun 2020 7:38am |
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| Mountain_man Member Since: 09 Dec 2011 Location: Right side of Offas Dyke Posts: 756
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Just done some reading about these ferrite clips.
Would it be better to get smaller ones that fit tight to the wire (I think 3.5mm is as small as they go), or go for a slightly larger bore and make a few wraps of the wire through the thing before clipping it together. There was plenty of spare wire on install if I recall correctly (maybe this is half the problem!) EDIT: And should all 3 wires per lamp be wrapped, i.e., the earth wire as well as both feeds? |
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4th Jun 2020 7:53am |
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| MadTom Member Since: 10 Sep 2013 Location: Olomouc Posts: 616  
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Try one or more wraps of wires, there is no one and only right way for it. Just test. But place all wires inside the core - ferite core should be effective only for AC (high frequency) current, and no DC current from powering the light. With boths (all three) wires inside, the DC current in the ferrite core just cancel it self. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo
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4th Jun 2020 9:04am |
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| Mountain_man Member Since: 09 Dec 2011 Location: Right side of Offas Dyke Posts: 756
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To conclude this thread. I bought a couple of these from the Bay of E
https://www.ebay.co.uk/itm/TDK-CLIP-ON-FER...%7Ciid%3A1 Made sure to buy the one with a bit more diameter in the middle. I passed all 3 wires through the thing and then made a wrap so they went through again. Clipped together and stuffed em back in the hole. Result is a drastic reduction in noise when lights or brakes are in use. I would go as far as to say it has completely fixed the issue other than in really poor reception areas when you can still just discern a difference when the lights come on. Happy camper now. So thanks for all the advice given above. Hopefully it can help someone else. |
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19th Jun 2020 8:22pm |
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| MadTom Member Since: 10 Sep 2013 Location: Olomouc Posts: 616
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With this improvement try to add another one next to the first. It should help more.
Because the source of interference is in the LED lamp, try to place the clip on ferite as close to the LED lamp as possible. Wires between LED lamp and clip on ferite works like an antenna. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo |
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19th Jun 2020 8:57pm |
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| Mountain_man Member Since: 09 Dec 2011 Location: Right side of Offas Dyke Posts: 756
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Cheers Tom. At that price I may just try it
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19th Jun 2020 8:58pm |
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| PCM Member Since: 25 Jan 2019 Location: North East Posts: 874
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I had a massive amount of iFM and DAB nterference when adding LED DRLs to a bumper.
Found that I could reduce a lot of it by using 3 ferrite rings in succession. Larger ones with wire loop wrapped was better than just with the cable through. However in the end I couldn't reduce it to a very low level. I therefore changed the LEDs. Tried 4 different brands. 3 cheap ones and one fancy set. In conclusion using the expensive CE marked brand and the interference just vanished. Also the radio (Kenwood JVC) had a rubbish DAB reception module. Changes to a pioneer in the end and the DAB reception is rock solid. Good luck |
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19th Jun 2020 9:25pm |
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