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LED Lighting RF Noise

 
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Old 09-16-2019, 05:43 PM   #1
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LED Lighting RF Noise


Hello all,

I have experienced what seems to be RF Noise
that is generated from LED lighting.

I don't have the exact spec's but just wondering
if anyone here knows of what to look for as to
packaging labels or spec's on LED lighting, if any.

The issue just came up today when talking to a customer
that has just recently had LED lights in there bar.
He says now there is noise that is being heard on the
background music speakers it the area for the customers.

I can speculate a lot of thoughts on why and how this
happens but, would like to know the opinion from
the masses here.

I did not install the lights or the audio system.
Just trying to understand and possibly come up
with a solution.

Thanks for any input.

Les
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Old 09-16-2019, 06:53 PM   #2
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Re: LED Lighting RF Noise


Pulse width modulation vs traditional filtered DC supply.

I haven't had occasion to research LED lighting specs in that regard, but googling your thread title ought to lead you down a few rabbit holes.

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Old 09-16-2019, 07:00 PM   #3
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Re: LED Lighting RF Noise


It's a big issue.

I have cheap LED worklights on my truck, and when I turn them on, they pretty much wipe out the two-way radios.

This is why on firetrucks and other emergency vehicles, they use $400 a piece Whelen or Federal Signal lights, and not $30 a pair stuff from Amazon.

The difference is good shielding, and grounding.

You should look for an FCC Part 15 Certification. Unfortunately, a lot of Chinese companies are faking FCC, and I'm sure a lot of other, certifications and standards.

You're better off finding a brand that guarantees no interference, and has a history to back it up.
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Old 09-17-2019, 07:32 AM   #4
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Re: LED Lighting RF Noise


Thanks for the input Tin & Seven,

Yes, did some research on Google. Lots of stuff there.
It seems that the one fix might be Ferrite Cores.

I am guessing that the noise is created more by the
power supply to the LED's rather than the LED's themselves??
But then I don't really know for sure.

On the particular issue it really isn't my problem or
job (yet) to fix. Just curiosity on my part.

Thanks,

Les
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Old 09-17-2019, 02:23 PM   #5
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Re: LED Lighting RF Noise


Put a ground cheater on the amp an prepare for a hum free experience.

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Old 09-17-2019, 05:58 PM   #6
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Re: LED Lighting RF Noise


Quote:
Originally Posted by ABLE1 View Post
I am guessing that the noise is created more by the power supply to the LED's rather than the LED's themselves??
Yep. LEDs work just like a regular diode (but with different voltage drop and reverse breakdown characteristics). They do nothing at all to generate RF noise.

But feeding smooth, filtered DC to a LED doesn't produce a great amount of light generally. So many manufacturers overdrive the LED with more current than it can actually handle non-stop with a series of pulses--essentially a square wave. The periods of zero voltage [current] let the junction cool down between the periods of high current.

And those square waves generate harmonics all over the spectrum.
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Old 09-17-2019, 06:39 PM   #7
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Re: LED Lighting RF Noise


Thanks for the confirmation.

I am also guessing that the manufactures have little concern
about the noise produced and focus on getting better light
from the LED's. Which is a bit sad to think............

Les
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Old 09-17-2019, 08:14 PM   #8
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Re: LED Lighting RF Noise


Ferrite cores supposedly work, although I have not had any luck with them. I installed them on my truck, but it didn't fix the issue.

But I guess there are different types of ferrite cores for different applications, and someone suggested that I might not have the proper type of ferrite cores, and/or the right number of wire turns.

Bit beyond my pay grade.

A radio shop might be able to give you some help as to which ferrite cores to use.
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Old 09-17-2019, 08:17 PM   #9
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Re: LED Lighting RF Noise


Quote:
Originally Posted by ABLE1 View Post
Thanks for the confirmation.

I am also guessing that the manufactures have little concern
about the noise produced and focus on getting better light
from the LED's. Which is a bit sad to think............

Les
Depends on the manufacturer.

The ones that make lighting for the Emergency Response trade, they absolutely have to work. You can't be at an incident, with scene and emergency lights active, and not be able to use your radio.

So I know that some companies make LEDs that do not cause interference.
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Old 09-17-2019, 08:51 PM   #10
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Re: LED Lighting RF Noise


Ferrite cores alone can work depending on the frequencies involved and the severity of the noise. In your case, you would probably also need a capacitive shunt. The exact combo can involve some pretty mind-numbing measurements and calculations.

Back in my uphill in the snow both ways days, we usually just ballparked it and managed to tune it in after a couple-three tries.
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Old 09-17-2019, 09:31 PM   #11
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Re: LED Lighting RF Noise


Quote:
Originally Posted by Tinstaafl View Post

Back in my uphill in the snow both ways days, we usually just ballparked it and managed to tune it in after a couple-three tries.

LOL
There are different words for exactly that, but I shy away for posting
here for fear of getting blasted of the site.
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Old 09-19-2019, 08:38 PM   #12
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Re: LED Lighting RF Noise


Follow Up Report

Well it seems the speaker buzz was not due to the newly installed LED
lights. Owner got to playing around with various other equipment and
determined that when the Comcast Modem was unplugged the buzz
stopped. Somehow they came up with a Ground Loop Isolator device and
installed it on the cable and another Ground Loop Isolator device at
some other point near the amp and the buzz is gone.

Case closed!!!

Thanks for all the input. I got an education.

Les
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Old 09-19-2019, 08:58 PM   #13
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Re: LED Lighting RF Noise


And thank you for the followup. Would be nice if you got paid for your research... but so the cookie crumbles.
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Old 09-19-2019, 09:08 PM   #14
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Re: LED Lighting RF Noise


Tin,

Yea but it is OK!! Very Good Customer!!!

There have been many times I have gotten
a free meal for my efforts!!

Maybe I will stop in tomorrow at noon just to say Hi!!

Have a good Friday!!

Les

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