Newer LED filament light bulb vs AM radio help

[Frito Ray]

When I place an older generation LED bulb (similar to picture below) in a desk lamp, it causes an annoying amount of interference with the AM radio sitting beside it. I get zero interference from incandescent bulbs, so I’ll stick to those if I must. (BTW fluorescent bulbs are pretty bad interference-wise also)

If you happen to have one of the newer LED filament bulbs that look similar to the picture below, could you bring an AM radio up to it (within a foot) and see if there is any interference please.

Thank-you.

 

[blethenstrom]

Yes this can and do happen with some LED bulb. LEDs are DC current driven devices so an LED bulb has to incorporate an AC to DC power supply. All these power supplies are switching power supplies which means that they switch on and off really fast and depending on the frequency that they turn on and off at it will generate a noise that will radiate radio waves from the bulb. Unfortunately AM radios are very sensitive to radio wave noise to start with so they will pick up this noise and you will hear it through the radio. Broadcast AM frequency band is 535 kHz - 1700 kHz and many many switching power supplies are switching in that range or a harmonic, or several, falls in that range. LED bulbs are so cheaply made and mass produced and they do not have the best means of preventing this.

Incandescent bulb are nothing more than a glowing wire and will not generate any of the radio frequency noise. This would be your best choice.

I hope that helped.

 

[Frito Ray]

I’m curious about the newer filament led bulbs that don’t have the ”massive” electronic switches the older led bulbs had.

 

[blethenstrom]

I’m curious about the newer filament led bulbs that don’t have the ”massive” electronic switches the older led bulbs had.

Well they do have many LEDs in series, but you still have an AC to DC power supply in the base of the bulb. All LED light that is powered from AC has an AC to DC power supply. Now they may have made it quieter than they used to be. It is a hit or a miss with LED bulb regarding this. Even garage door opener LED bulb can be a problem sometimes causing the remote to not work right. You might just have to try it out and see.

Yes fluorescent light can cause issues as well. They generate high voltage spikes that will generate harmonics up in those ranges as well.

 

[psfred]

LED lamps, especially the direct replacement 4' ones, are known to cause severe issues with FM reception too. Higher quality bulbs (read more expensive from a major maker) will have less noise, and if shielded properly, none. Cheap imports will have lots of noise and not last very long, the solder fails.

The real solution is to do what the Europeans have started to do, which is wire the lighting for 12V DC and have one DC power supply for the house, properly shielded. A huge pain to retrofit, but it's the best solution I think.

 

[Old Hippie]

The real solution is to do what the Europeans have started to do, which is wire the lighting for 12V DC and have one DC power supply for the house, properly shielded.

This. Being a ham radio operator who likes satellite and weak-signal work, I really hate rf-noisy bulbs.

One thing to note, however, is that many modern 12VDC power supplies are also switching supplies, so you may just be putting the problem in one place instead of in every light socket. Best to use for such applications would be a nice heavy regulated supply, and if I was doing it I'd put the darn thing in a Faraday cage just because.

O.H.

 

[blethenstrom]

This. Being a ham radio operator who likes satellite and weak-signal work, I really hate rf-noisy bulbs.

One thing to note, however, is that many modern 12VDC power supplies are also switching supplies, so you may just be putting the problem in one place instead of in every light socket. Best to use for such applications would be a nice heavy regulated supply, and if I was doing it I'd put the darn thing in a Faraday cage just because.

O.H.

KO4QLT here

 

[StillShaving]

Related to the earlier comments, I would try a newer generation bulb of high quality and/or low power consumption. Based on the assumption that lower power consumption per lumen should mean more of the energy went into light generation than RF. The Philip Ultra Definition bulbs have some of the best light quality and I believe Philips makes what they label as an "Ultra Efficient" bulb. I don't know about the RF generated by either bulb, but the visual flicker should be absent. I would stay away from the Dollar Store LED bulbs, even though I have some in a few spots around the house. (the ones I have have really poor color quality).

 

[Frito Ray]

Thank you all for taking the time to respond to this post.

It would be interesting to compare low/high powered, store-brands/name-brands for their effect on radio-waves, but since incandescent bulbs avoids the problem all together, I’ll stick with them for now.

If any of you happen to stumble onto a review or testing various brands of LED lights and their effects on radio waves please PM me.

 

[Old Hippie]

KO4QLT here

WB7PJR and VE7PJR.

O.H.

 

[Saxonbowman]

The last time I tried to listen to AM here it was just a mess of noise. I'll have to try it again when the light bulbs are off. I hope to get out the HF rig soon so we'll see how that sounds.

de KD4KWB

 

[StillShaving]

I don't have a portable AM radio or I would check against a few different bulbs that I have to see which are better than the other. It would also be interesting to compare against the TV, computer, LCD monitor and other appliances. To see which are the worst offenders. I am not dependent on AM as the one AM station that I would listen to with any regularity simulcasts on FM. And they stream online.

As you may know many electric cars don't include an AM radio due to all the interference from the power train. The issue of "dirty electricity" comes up sometimes but I think its effect on health is overstated compared to all other environmental factors. "dirty" in the sense of some interference that can be picked up by an AM radio next to some wiring in the home.

 

[blethenstrom]

I don't have a portable AM radio or I would check against a few different bulbs that I have to see which are better than the other. It would also be interesting to compare against the TV, computer, LCD monitor and other appliances. To see which are the worst offenders. I am not dependent on AM as the one AM station that I would listen to with any regularity simulcasts on FM. And they stream online.

As you may know many electric cars don't include an AM radio due to all the interference from the power train. The issue of "dirty electricity" comes up sometimes but I think its effect on health is overstated compared to all other environmental factors. "dirty" in the sense of some interference that can be picked up by an AM radio next to some wiring in the home.

I was not aware of that electric vehicles does not include an AM radio, but it makes perfect sense. Switching very high currents generate a lot of noise.

 

[Frito Ray]

I had to do some testing, couldn’t let it go



I purchased a 60w equivalent non-dimmable Philips new-style filament LED light bulb. On the packaging it states that it complies with part 15 of the FCC rules and the Canadian ICES-005 rules for a class B digital apparatus. Basically, it should not cause any interference.

Looked around the house and found a 15ish year old 60w equivalent dimmable Luminus old-style LED bulb, and a 10ish year old 100w non-dimmable Luminus old-style LED bulb. Both are UL listed.

A small handheld Sony AM/FM radio was used for the testing.

The good thing is that I could not detect any noticeable interference with the filament LED at any distance and on any band except when turning on and off the bulb. The worst interference was with the oldest Luminus dimmable bulb which started to get noticeable at four or five feet and got progressively worse closer to the bulb. The higher powered, non-dimmable old style LED did better than the other Luminus, but interference was detectable at about two feet and increased closer to the bulb.

So for consumer grade AM/FM radios, the new filament LED bulbs that comply with FCC and Canadian ICES-005 rules should all be interference-free…the Philips brand at least. UL listing alone does not equate interference-free operation.

I have no idea if these results would be the same for those with more sophisticated radios or ham radio operators.

 

[Old Hippie]

On the packaging it states that it complies with part 15 of the FCC rules and the Canadian ICES-005 rules for a class B digital apparatus. Basically, it should not cause any interference.

Been a few years since I looked at Part 15 in detail. Sheesh, whatta buncha bull...I mean, "bureaucratese."

I was amused to see that they still regulate super-regenerative receivers, which haven't been a thing since about 1930. Anyhow...

My understanding is that basically there are two big divisions, Class A and Class B. Class A is commercial/medical/research use, Class B is home use. The rules for home use are looser. While a device may not intentionally be made to create interference, unintentional interference is allowed up to a point. Receiving devices approved under Class B, for instance, are required to accept any interference that may come along even if that means the device is at least temporarily unusable.

There have been problems created by big-box stores selling lighting equipment approved for Class A installation to people who either don't know the requirements or simply intend to install them according to Class B requirements. Equipment for Class A is not necessarily required to be non-interfering, because other installation requirements such as Faraday shields and grounding will take care of that.

You are correct in (what I read as your assumption) that amateur operators and others who may have more sensitive or more broad-spectrum equipment may notice more interference than a person with an AM radio or shortwave receiver. One of the little tricks manufacturers do to reduce their overhead for interference-reducing design is to put their interference on frequencies that A) see little use by other services and/or B) are not received by commonly sold consumer electronics. One of those "outta sight; outta mind" things. A problem is that what is a quiet little backwater of the RF spectrum today might be a hot commodity for telecom industries tomorrow, and we've got a bunch of noisy little radiators all over sitting right in the middle of it.

Part 15 is, necessarily, complex. The short-short is that if you're using Class B devices properly you're probably not creating much interference but likely a little. If you are getting some, it's probably within the guidelines. Part 15 says the manufacturer only has to meet the guidelines and anything past that is up to you in Class B. Problem is that many manufacturers aren't directly under FCC jurisdiction and may have some financial incentive to game the system a bit.

O.H.

 

[Frito Ray]

Thank you O.H., that was a very informative post

When I went shopping, I noticed that some brands didn’t have the FCC blurb. I just figured I’d mention it to others who might be in the same boat.

 

[Bobbers]

Not sure if this helps, but they make a specialty led bulb for garage door openers. Some regular led bulbs interfered with the remote controls frequency for garage door openers.

 

[Old Hippie]

Not sure if this helps, but they make a specialty led bulb for garage door openers. Some regular led bulbs interfered with the remote controls frequency for garage door openers.

Hey, thanks for the rabbit hole! Had to do a little reading. Looks like a prime example of what I wrote above. Garage door openers operate on frequencies between 30 MHz and 360 MHz -- I suspect more on the higher frequencies, with the lower ones being used by older garage door systems. LED drivers (basically switching power supplies) operate in that rather broad range as well, so building a driver that operates outside that range would "solve" the problem by moving one of the variables over a bit.

So, did they go up or down? I'm guessing up. We have reliable electronics up into the microwaves now, and there's a lot more free bandwidth at the higher frequencies. Besides, it's low-power short range technology and doesn't need a long-distance-capable lower frequency to operate. The problem is that there really aren't any open frequencies, they're just moving the deck chairs around to accommodate use by whomever can pay for it. Kinda like the old joke about making a blanket longer by cutting some off the bottom and sewing it on the top.

Be interesting to frequency sweep one of those bulbs. Hmmm. I have an software-defined scanning receiver that goes up to 2 GHz and some spectrum analysis software, and maybe the hardware store has some of these bulbs...

I'll think about that for a while.

O.H.

 

[Frito Ray]

Be interesting to frequency sweep one of those bulbs. Hmmm. I have an software-defined scanning receiver that goes up to 2 GHz and some spectrum analysis software, and maybe the hardware store has some of these bulbs...

I'll think about that for a while.

Do it.

Do it.

Do it.