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New LED bar causing RFI

Moderator: -Scott-

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Canyonero 4x4

Posts: 375

Joined: Mon Mar 03, 2008 4:29 pm

Location: Camden NSW

Post Sat May 25, 2013 1:05 pm

New LED bar causing RFI

Hi.

I have just installed my new 20x5W LED light bar (100W) and it's wired up through a relay, using 4mm wire, as the old driving lights were. It's a fair run from behind the drivers seat, through front fender (where the factory stereo antenna is located), and out to the bullbar.
Now when I turn it on, I get bad interference across all FM stations. AM is fine.

Has anyone else experienced this and how did you get around it?
Can I get a shielding wire capable of running around 10A?
Dave
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-Scott-

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Joined: Sun Jan 11, 2004 11:36 am

Location: Adelaide

Post Sat May 25, 2013 1:48 pm

Re: New LED bar causing RFI

Canyonero 4x4 wrote:Hi.

I have just installed my new 20x5W LED light bar (100W) and it's wired up through a relay, using 4mm wire, as the old driving lights were. It's a fair run from behind the drivers seat, through front fender (where the factory stereo antenna is located), and out to the bullbar.
Now when I turn it on, I get bad interference across all FM stations. AM is fine.

Has anyone else experienced this and how did you get around it?
Can I get a shielding wire capable of running around 10A?


I've never heard of this happening with LEDs, but if you don't have a short arcing to the chassis (I doubt it) then I guess it's the driver circuit that is driving the LEDs. A shielded cable might help, but an easier fix (no guarantees) may be to earth the lights as close to the lights as you can (that's presuming you haven't already done it.) How are they mounted? Anything metal that goes straight to the body?
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joshy

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Location: Wellington

Post Sat May 25, 2013 6:01 pm

Re: New LED bar causing RFI

My light bar does this aswell, so I just put the iPod on.
D22 Navara....hydro coilovers, hydro steer, 42's...
76 Landcruiser tow rig
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Canyonero 4x4

Posts: 375

Joined: Mon Mar 03, 2008 4:29 pm

Location: Camden NSW

Post Sat May 25, 2013 7:57 pm

Re: New LED bar causing RFI

Cheers for the replies.

We have the same issue with our solar panels on the house and the AM band. We just bought a digital radio.
Can you get them for cars yet?
Anyway, I've been playing around with it this afternoon.
I ran a new (temporary) earth to the bonnet catch with the same result.
I connected it directlyto the battery terminals with the same result.
It seems to interfear with the radio in the garage aswell.
I also put the earth through a capacitor with the same result.
The light bar seems to be radiating alot, and I no longer feel a shielded wire will help being that the case is metal.

The light is mounted to clips on the top of the bullbar, so not directly to metal/body (being that the powdercoat is insulating).
I fellow I bought it off who I know very well has the same light and has had no issues, so I plan to swap with his and see what happens.
It seems as though the LED bar is generating a noise and the case needs to be earthed to form a shield and this may be a manufacturing fault.

Does this make sense Scott?

Otherwise, yes. It's Ipod time.
Dave
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-Scott-

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Posts: 14209

Joined: Sun Jan 11, 2004 11:36 am

Location: Adelaide

Post Sat May 25, 2013 10:01 pm

Re: New LED bar causing RFI

Canyonero 4x4 wrote:It seems as though the LED bar is generating a noise and the case needs to be earthed to form a shield and this may be a manufacturing fault.

Does this make sense Scott?


Entirely plausible to me, but I can't guarantee this is the cause / will fix your problem.

If I were a betting man I would say the drivers are creating noise that is conducted along your power wires, which in turn is radiating the noise like an antenna. In an ideal world this noise would be conducted straight to "earth" by the shortest route possible, such as metal casing in direct contact with the chassis.

A potential solution (other than Ipod) is a suppression ferrite of some description. They are put over the wire that is radiating the noise, as close to the noise source (i.e. the lights) as possible. Also called a "choke" as they "choke" the high frequency components.

http://search.jaycar.com.au/search?w=ferrite&view=list

Something like this is useful because it's easy to clip on and off, and you can possibly put multiple passes of the wire through the ferrite - more passes means more attenuation. However, this one may not be effective at the problem frequency, as the larger ones tend to work only at higher frequencies (like 300 - 500 MHz, not 90 - 110 MHz).

Something like this will probably work very well for FM interference, but it's listed as 5.6mm ID - it may not fit over your wires. If you do some more googling (try "suppression ferrites") you may find an ideal ferrite, but you'll probably have to order it from somewhere.

Good luck.
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Mick.

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Joined: Fri Feb 10, 2006 6:38 pm

Location: Newcastle

Post Sat Jun 01, 2013 5:45 pm

Re: New LED bar causing RFI

A lot of the light bars can cause some static on radio frequencies. This is caused by Pulse Width Modulation. This means the leds are driven by small strikes many times a second. If you could record a LED light bar and slow it up they look like a strobe light. This is supposed to give the led time to cool down between strikes so they can get the most lumens out of them without burning them out to quick. The higher end light bars are electrically protected against RFI/EMC interference but this wont stop it entirely.

I've used those suppression ferrites like mentioned above and they have helped a little bit and another thing that can help is this stuff. I use this when making my own HID wiring looms. This can also help to protect against interference.

http://www.ebay.com.au/itm/10mm-x-50cm- ... 2329f658c3

Cheers Mick
Micks HID Projector Retrofits
Phone 0403596123 or PM me here
All custom and DIY kits available
http://stores.ebay.com.au/Projectors-retrofits?_trksid=p4340.l2563&clk_rvr_id=398088641161
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bazzle

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Joined: Sun Nov 24, 2002 8:57 pm

Location: Melbourne

Post Wed Nov 13, 2013 10:19 am

Re: New LED bar causing RFI

You need quad shielded aerial wire.
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MARKx4

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Posts: 1321

Joined: Tue Aug 03, 2004 7:56 pm

Location: Jamisiontown NSW

Post Tue Nov 19, 2013 5:36 am

Re: New LED bar causing RFI

As mentioned you need quad shield aerial wire, another tip is to have the power wires from the light as far away from stereo wires as possible.
"It's a fair run from behind the drivers seat, through front fender (where the factory stereo antenna is located)" This is your main problem right here, even when i used to install high powered stereos to cars we couldnt run anything near the aerial due to interference.

My suggestion is relocate your wiring before you try anything else (after moving wiring and that doesnt help), then you can try one of these -
http://www.ebay.com.au/itm/NOISE-FILTER ... d65&_uhb=1

If that doesn't help add a quad core aerial cable as well.

Quick link to introduction of suppression capacitors for you to read if interested
http://www.vishay.com/docs/26529/gentecin.pdf

Mark.
Its not cool, unless it's got boost :)

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