Changes in Lighting Products

"Future Shock", by Alvin Toffler.

So, on my LED questionnaire I can put a checkmark in the "I like 'em" column for you?

Isn't the longevity of the ballast related to how often it's turned on? What is the expected longevity of the LED?

Thanks, but I don't smoke pipes, I smoke ICs.

I smoke railguns - and ICs.

Hi,

Come again....LED tubes that work with instant start ballasts?? I hvn been around LED fixtures long enough but this seems pretty odd to me. Electronic ballasts + LED tubes!! Goodnss, I hv much more to learn.

Regards.

Just in general, I believe most lifetime predictions for LED's are grossly over-rated. Sure they are going to last a long time, but not THAT long.

It seems it wasn't more than a couple of years after installation, that I started to see "dead pixels" in the red and green lights on traffic signals. And these LED's are not driven particularly hard like LED's for general illumination purposes.

Don't get me wrong, there is a lot to like about LED's and I have been systematically replacing all the G4 halogen incandescent bulbs in my RV with LED replacements, but for my household lighting, CFL's are the best value for me in terms of purchase cost and cost of operation. Baltimore Gas & Electric (BGE) has been subsidizing the purchase cost of various CFL's at local stores in the area and an 8-pack of 13W CFL's (~60 W equiv.) are currently selling for $1.62 at Sam's Club. Yes, that is correct, $1.62 for eight.

Heat of course is the mortal enemy of LED's and I believe the best performance for LES's will be when fixtures are specifically designed for LED's and are we are not just creating Edison base screw-in LED lamps and so on. That way, the fixture can be designed to best dissipate the heat from the LED's and improve their life. It will take some time, but the Edison base light fixture's days are numbered.

Cheers !

Those dead pixels are due to solder-joint failures more often than not. You'll often notice that groups seem to fail all at once. The LEDs are series connected in multiple strings. One bad LED or solder joint and the whole string goes out or flickers.

LEDs grow dimmer over time rather burning out suddenly like incandescent bulbs do.

Dead pixels I see in these traffic signals are randomly scattered over the field. I find it hard to believe this would be solder joints. That is one thing the industry actually has pretty well in hand per IPC-A-610, IPC/WHMA-A-620, and J-STD-001. The dimming is the wear out mode of failure on the far end of the bathtub but heat related failures are sudden and complete.

I've never observed bad pixels "randomly scattered over the field". I usually see segment blocks or zig-zag lines out.

About 10 years ago I picked up the active board of a defective red LED streetlight, and the defect was indeed a bad solder joint. A bit of flux, solder, and heat in one single spot and everything worked again.

Actually LED lifetime predictions are... underrated. !00.000 hours is not the life that the led will fail, it is the time that it's light production will fall to 50% of new, and that if working at 100% power capacity. There are conditions of course, controlled temperature, no exposure to humidity, voltage spikes, corrosive environment and mechanical stress. Now to have something to compare, 50% less light is TOTTALY UNDETECTABLE by average human eye, given time to adapt. But have no fear, you will not live to see a design... stupid enough to exploit that potential, I'm sure they will find a way to design them to fail. Or have they already? They seem to. Using switching supplies, a well understood technology that WILL gracefully fail before 1/50 of that lifetime, at best. They also use that "ecological" solder, that takes away half the component's life while soldering. And component's are not cats. They have only one. This EXACTLY was the case of the traffic lights you mentioned. The new crappy solder IS the failure point, combined with un handled mechanical stressing from temperature expansion cycling, and bad environment isolation. Simply, noting is made nowadays TO LAST, and LEDs wouldn't be left to differ... S.M.

I clearly see the convenience factor of just replacing the fluorescent tube with an LED tube, but beyond that, it does not seem logical.

Fluorescent tubes are inherently higher voltage devices, especially at start-up. LEDs are inherently low-voltage devices, so the driver in a fluorescent-tube replacement LED system is going to have to handle that start-up pulse.

To me it seems much more logical to eliminate the ballast and directly connect the LED driver to the 120V AC directly. I am assuming you are referring to 120V systems...

One of our traffic light signals failed in such a way that it looked like the "hand" was giving you the middle finger.

Given the militant entitlement of some pedestrians in the more politically correct parts of metro Boston, we could use some of those around here.

They have traffic and pedestrian lights in Boston?

Funny, I never noticed.

Do you mean to tell me they don't come out of the box like that? NO wonder everyone in town seemed miffed 24/7....Everything in this town, is pretty much life throwing you the middle finger.