The whole idea of running LED lights with sophisticated switching power supplies so they are screw-in compatible with standard bulbs is poorly conceived. This just causes excessive consumption of raw materials by an overly complicated design that invariably leads to premature failure not related to the LED's themselves.
When tube fluorescence's were introduced, no one complained about having to switch to new light fixtures. So why not also with LED lights?
Light fixtures for LED's could have a small step-down transformer built in, like a doorbell transformer, that would last a lifetime. Then the LED bulbs would only need to run on low voltage, eliminating the costly power supply that needs to work on 120 AC and be able to resist lightning surges.
This is so obvious I's surprised no major company is pursuing it. Changing the light fixture is a do-it-yourself project for most homeowners, so I don't think it would be opposed by the public looking to upgrade lighting in the family home.
The result would be a better, safer, and lower cost design with much better reliability. How do we tell our non-technical lawmakers they are going down the wrong path?
So while KRagh says there may not be an RFI problem from the LED itself, it is the entire LED lighting assembly from the LEDS to the power supply that needs to be evaluated and this is where the flaw in the design is.
From my measurements on CREE and Panasonic household LED fixtures which were used in an RF emissions testing screen room and in an aircraft hanger along with similar findings recently observed in public safety Strobe lamps as used in Police and fire vehicles and in Avionics wing Tip Green and Red LED strobe lights of airplanes.
It is the inverters which are of such poor unfiltered designs that they in fact create more RF problems in the HF thru lower UHF region as opposed to the older incandescent cousins previously used which had no such problems.
Unfortunately the range of RFI emissions that these new LED assemblies emit falls within the frequency ranges used in avionics and other mission critical radio systems.
They may be good to some who want to save the earth however I equate this new LED technology to governments starting a war without an army.
Things have not been thought out on operating a 1.2 volt LED off of high voltage inverters and unfortunately industry jumped on the bandwagon without any guidance at all from the FCC as to requirements on real world reduction of RFI emissions from the inverters.
In fact from what I am measuring it appears that the FCC will allow any incidental RFI radiator as long as it is of the so called Green technology or a new start up technology.
Don't get me wrong I have no problem with conserving but when a poor thought out technology creates an after effect that no one wants to address then that's where my concerns are.
Presently being an RF engineer I am faced with numerous Radio Frequency Interference, RFI, issues to avionics transceivers in aircraft and Public safety radios in ground based vehicles and it appears to only be the tip of the iceberg on what is to come by poor inverter/power supply designs.
I'm not so sure about that. I installed a no-name in my garage door opener and while the light is on it blocks the remote signal. I've also tried three of the major manuf. and 2 had some interference, one had little to no affect with the remote.
I hope it will be a good device, thanks to your post.
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There are some interesting points in time in this article but I don’t know if I see all of them center to heart. There is some validity but I will take hold opinion until I look into it further. Good article , thanks and we want more!
My experience with CCFLs has been that they have a life span either dramatically less than an incandescent or, about the same. I read that the CCFLs were designed to operated in an open fixture with the base down and that the rated life-span was dependent upon adhering to those operating conditions.
How ridiculous is it to sell a product that only operates on a specific set of conditions that are not in place more often than they are. I don't have a single light fixture in my house were the bulb isn't either enclosed or mounted base up. I could get 500,000 miles out of my car with little or no wear and tear if I'd only put it on a trailer and tow it everywhere.
When I look at the workmanship on the circuit boards shown in this article, I can't help but expect that we'll be seeing the same thing with LED bulbs due to poorly made power supplies.
I too am concerned about the lifetime.
I am afraid that we are going to get the same failure to meet reliability claims that we had with CCFLs: Six years ago I replaced most of the lamps in my home with CCFLs that came with a 6-year warranty (or was it 9?). In about a year half had died. Unfortunately I had lost my receipt and could not claim replacements.
Now these LED lights are claiming 25000 hour lifetimes. I wonder? I am most concerned about the 330uf capacitor I see on the photo. Most electrolytic caps have a lifetime spec of only a few thousand hours at 85 degrees C. I did a quick search and found only one with a lifetime spec of 18000 hours, and it was large and expensive - not the one in the photo.
I would like to see the teardown include the make and spec of the cap in question, as well as other components likely to be problematic. Also I would like to see some actual temperature measurements - wire up the device with thermocouples in strategic locations, and run it in a hot environment for a while. Just like we test every new product we build.
A Book For All Reasons Bernard Cole1 Comment Robert Oshana's recent book "Software Engineering for Embedded Systems (Newnes/Elsevier)," written and edited with Mark Kraeling, is a 'book for all reasons.' At almost 1,200 pages, it ...