High effeciency LED's and Radio Interference

[sudsmaster]

Lately some very nice high efficiency LED light bulbs have come on the market. For example, FEIT (from Costco) has a 100 watt equivalent (1500 lumen) daylight LED bulb for $5 and it uses only 14 watts. It's not "true color" and the CRI isn't listed, but my impression is that it's probably round 80. Their warm white bulb is even brighter, at 1600 lumens and 17 watts. However the warm white bulb has a lot of RF interference, so in various spots I've had to replace it with two 60 watt equivalent bulbs on a splitter instead, which don't cause RF problems. An advantage to the 60 watt warm white version is that it's also "True Color", with a CRI over 90. That is nice. The draw back is that each 60 watt bulb uses 9.5 watts, so two together use 19 watts. But what the hell, it's still a lot less than 100 watts.

 

I figure the RF interference must have something to do with the higher efficiency designs using high frequency voltage modulation to get more output and less heat from the diodes. It might be a good tradeoff for a workplace or other areas where one may not be wanting to listen to FM radio, but it's a problem in most areas of my home.

 

Anybody else have similar problems with the new higher lumen output LED bulbs?

 

 

[kb0nes]

The RFI was a problem on the FM radio? Typically the interference I have seen/measured is much lower in frequency, more in the AM broadcast band range. Are you in an FM fringe area?

Most all the LED lamps have some form of a switching power supply in them that will convert the AC power to DC then chop this DC at a high frequency (usually in the 100's of kilohertz range) so that a tiny transformer can convert the voltage down to the LED drive levels. Since the switching creates a string of pulses with abrupt transitions there are lots of harmonics ranging on up into the RF spectrum.

The key is how well a manufacturer filters or suppresses the emissions. But adding filtering into the lamp adds cost so it is often scrimped upon in favor of profits. I'd suggest reporting any RFI issues to the manufacturer, while it won't likely change anything, without complaints they surely won't make improvements.

There are different emission standards for lamps designed for commercial and residential use, not sure that makes any difference in this case. It is similar to the FCC Part 15 commercial vs residential standards.

Overall I have been less then impressed with the Feit lamps, but they seem to have gotten better over the years. There has been a lot of work done to really bring the cost of the A19 style replacement lamps down in cost. I have torn a few of the late model Cree and Philips lamps apart and I am seeing the electronics package getting simplified, perhaps this isn't a good thing if they are pulling out filtering. In theory they still have to meet compliance levels for conducted and radiated emissions.

So far the worst RF problem I have seen with an LED replacement lamp was from a 100w Philips unit. Our city decided to replace the lamp in one of the FAA clearance marker lights on top a local water tank. I maintain a radio repeater on this tank, our transmit antenna is ~3 feet from this light. When the light was hit with the near field of our 100w transmitter at 147Mhz it created RF noise everywhere and LOTS of it. Finding the problem was interesting, seemed it only happened at night. Once we thought that the light was photoelectrically switched we solved the puzzle. Clearly Philips didn't intend their lamp work in such an environment.

Being a ham I do hear some of the lights in my house, this is at lower frequencies then the FM band of course. Most of the noise I hear is conducted into the power lines and radiated from the wiring. I have a couple of boxes in the house where I have installed EMI filters to isolate the lamps to quiet things down.

The other thing that grundges up our local noise floor are all the little plug in wall warts and phone chargers. I have had more noise issues with these then with LED lamps.

 

[DADoES]

 
I've not noticed any radio interference, but I don't listen to radio except occasionally in the car.

RJ reported radio interference from LED bulbs recently installed at the latest rental refurb house (project in-progress).  I don't know the brand.  I can check but he probably didn't notice.

Referencing Cree:  Of the three PAR38 floods I discussed a while ago ... I ended up with four due a cross-up on their part with one of the warranty claims.  Of the four, two have again failed.  Two remain operable but one of those occasionally flickers.

 

[vacerator]

I have also experienced

noise generated from one of my model train locomotives which I retrofitted a digital decoder in. It has low voltage LED lights.
The noise gets louder as I increase the speed of it. The lights also dimly blink very fast. Not the best effect, because it's a steamer. I may have bought the wrong decoder.
FCC rules require all other than non military rf equipment to accept interfierance, and not cause any.

 

[kb0nes]

The FCC doesn't mandate that all non-military equipment must accept interference. All licensed services are protected to a degree by FCC rules.

My hunch is that you are thinking of the Part 15 rules which apply to small low power unlicensed devices. (like LED lighting). Part 15 rules state that any Part 15 device must accept any interference it receives and must not cause any interference to licensed services.

As for the Cree failures I have now seen 3 although they have all been A19 lamps, all my PAR38's I have running at work still work. It is a pity you had so many problems with yours Glenn!

 

[gusherb]

I have not had any Cree lamps fail on me yet and between us and all the ones my sister bought, more than a few dozen, none have failed completely. Some did start flickering more frequently so I got Homo Depot to exchange them. I have not had any LED lamps cause any noticeable interference.

Slightly OT, Cree just came out with a new line of LED's. Bought a box of the A19 60 watt equiv. 2700k bulbs and was disappointed that they had a poor light pattern and had a turn on delay. I like their older generations better.

 

[DADoES]

 
All my Cree A19 60-watt-equivalents are OK.

 

[dustin92]

We've bought a bunch of 60w equivalent LED's at Walmart (Great Value brand) because our utility company is running a special promotion with Walmart, only $1.97 for a 4 pack. Working on changing over from CFL's and have been very pleased so far. We bough a couple packs of GE daylight LED's mainly for outside, and they are crazy bright but noticed they do hum.

 

[sudsmaster]

Yes, it's definitely FM interference. I keep a small FM radio above the kitchen sink. The 60 watt equivalent bulb don't cause the static, but the 100 watters definitely do. So much that I've had to replace the 100 watt bulb above the sink with two 60's on a splitter.

 

I saw a similar interference, except much stronger, with a FEIT high output down light I tried putting in over the kitchen sink last year. I wound up returning it because of the strong interference.

 

It is distance dependent. More than six feet away, not so much interference. Closer, it's annoying to prohibitive.

 

Model trains have long created RF interference. I remember back in the 60's that I couldn't run the model trains in the attic above the living room, because they caused too much static on the TV screen below.