LED RF Noise Evaluation

A

ABLE1

Guest
Hello,

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
 
On Monday, September 16, 2019 at 6:40:04 PM UTC-4, ABLE1 wrote:
Hello,

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
Click to expand...

Some switcher in the LED power supply that has fast edges.
But first are you sure it's the LED's. Maybe someone next door
is making 'noise'.

George H.
 
On Mon, 16 Sep 2019 18:39:56 -0400, ABLE1 <somewhere@nowhere.net>
wrote:

Hello,

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
Click to expand...

Leds work on 2-3 volts and they use switching current regulators to
limit current to the leds. Anytime you switch power on and off
abruptly you create electrical noise.

To ameliorate the situation it could be as simple as grounding the
lamp housings, or running the wires away from the music system,
plugging one or both into different electrical sources. A ground to
the music system may help too. If it only has a two wire cord a
ground to the chassis may work.

Or adding some filtering. A common mode filter is what is usual. Some
are as simple as a clam-shell style ferrite core around the wire
feeding the lamps, or a wired in power line filter.

When it comes to filters they are way more effective at the source of
the noise than the device affected by the noise.

I had a situation where turning on compact fluorescent lamps (back in
those days) would trigger my passive IR sensor - small filters in
every switch box fixed it. Ditto my electric range would cause my
dial-up modem to crash, a humongous big filter fixed it.

Most designs today are better than that. A different current limiter
for the leds may work, but switching outlets is easy to try and those
clam-shell ferrite chokes take very little effort to apply. (close to
the source of the noise since the wires act as antennas and radiate
the noise out from them) Running the power cable through a ferrite
donut with a few turns around the core is another approach to
filtering.
 
On 9/17/2019 9:03 AM, George Herold wrote:
On Monday, September 16, 2019 at 6:40:04 PM UTC-4, ABLE1 wrote:
Hello,

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

Some switcher in the LED power supply that has fast edges.
But first are you sure it's the LED's. Maybe someone next door
is making 'noise'.

George H.
Click to expand...

Hi George,

Unlikely "next door". "Next Door" is easily a couple of
hundred yards away.

I have not done any investigating on this. Just going
by what my customer told me. "Just had LED lights installed
and now the speakers are buzzing."

First, I am trying to understand the problem for my own edification.
Second, maybe help with a solution. Again, not my problem to fix.

Thanks for the input.

Les
 
On 9/17/2019 10:22 AM, default wrote:
On Mon, 16 Sep 2019 18:39:56 -0400, ABLE1 <somewhere@nowhere.net
wrote:

Hello,

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

Leds work on 2-3 volts and they use switching current regulators to
limit current to the leds. Anytime you switch power on and off
abruptly you create electrical noise.

To ameliorate the situation it could be as simple as grounding the
lamp housings, or running the wires away from the music system,
plugging one or both into different electrical sources. A ground to
the music system may help too. If it only has a two wire cord a
ground to the chassis may work.

Or adding some filtering. A common mode filter is what is usual. Some
are as simple as a clam-shell style ferrite core around the wire
feeding the lamps, or a wired in power line filter.

When it comes to filters they are way more effective at the source of
the noise than the device affected by the noise.

I had a situation where turning on compact fluorescent lamps (back in
those days) would trigger my passive IR sensor - small filters in
every switch box fixed it. Ditto my electric range would cause my
dial-up modem to crash, a humongous big filter fixed it.

Most designs today are better than that. A different current limiter
for the leds may work, but switching outlets is easy to try and those
clam-shell ferrite chokes take very little effort to apply. (close to
the source of the noise since the wires act as antennas and radiate
the noise out from them) Running the power cable through a ferrite
donut with a few turns around the core is another approach to
filtering.
Click to expand...

default,

Thanks for the insight. Will pass on.

Have a good day.

Les
 
On Tue, 17 Sep 2019 17:03:27 -0400, ABLE1 <somewhere@nowhere.net>
wrote:

buzzing
Click to expand...
?

Buzzing implies a noise source with sharp rise/fall (as opposed to hum
(sinusoidal noise) or white noise (like a water fall) or low frequency
"pumping" sounds etc.

In the audio range, and if it also happens to be the same as the line
frequency...

Obviously in the audio range.. but some RF comes across as distortion
in music sources, not something you can quite describe but it shows on
a scope as parasitic oscillations in the rise and or fall in the music
transients.

Often the sound can give some clue to that is happening. A buzz at
60/50 cycles per second (line frequency) should be easy to quench, and
I'd lean more towards a lack of a ground somewhere or a ground-loop
and not something a filter can fix.
 
On Tuesday, September 17, 2019 at 5:03:34 PM UTC-4, ABLE1 wrote:
On 9/17/2019 9:03 AM, George Herold wrote:
On Monday, September 16, 2019 at 6:40:04 PM UTC-4, ABLE1 wrote:
Hello,

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

Some switcher in the LED power supply that has fast edges.
But first are you sure it's the LED's. Maybe someone next door
is making 'noise'.

George H.


Hi George,

Unlikely "next door". "Next Door" is easily a couple of
hundred yards away.

I have not done any investigating on this. Just going
by what my customer told me. "Just had LED lights installed
and now the speakers are buzzing."

First, I am trying to understand the problem for my own edification.
Second, maybe help with a solution. Again, not my problem to fix.

Thanks for the input.

Les
Click to expand...

Well if the buzzing starts and stops when the LED's are switched on and off,
then that would be a pretty good indication of the problem.

Then one has to ask how the interference gets into audio system.
Is it over radiated or conducted by the power lines.

George H.
 
ABLE1 prodded the keyboard with:

Hello,

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
Click to expand...

Some years ago I used red and yellow LED's as RF noise sources for
aligning VHF receivers.

--
Best Regards:
Baron.
 
On 9/16/2019 6:39 PM, ABLE1 wrote:
Hello,

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
Click to expand...

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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