LEDs are great for distant "signaling", you can see them from miles away, but the narrow bands of the emitted light frequencies (color) are such that they are poor for illumination.
"White" LEDs do not give off "White" light, but are combinations of Red, Green and Blue such as to appear White to the human eye. If what the lights is shining on is not close in color to one of the frequency bands of the LED then little or no light is reflected off if it and it will just appear dark to the human eye.
LED design is getting better at giving off wider bands of the 3 colors and so are better at general illumination than they used to be, but are still not like an incandescent light that gives off a much broader band of colors.
I have LED bulbs in some fixtures in my house and they are really bright to look "AT", but I cannot read a newspaper easily from the light they give off.
If you happen to have an LED display on your computer, (at night so there is no other source of light) set the screen to just a white display (like start a blank document and make it full screen). Looking at the screen it will appear very bright (maybe even hurt your eyes), but it will be difficult to read a newspaper from the light available from the screen (or even navigate around the room!).
I have noticed that some cars have LED headlights and they are near blinding when they come at you, but they do not illuminate the road in front of the car nearly as well as an old incandescent bulb would.
Semper Vaporo
Pkgs.
zugmannIt also doesn't help that many agencies use Disco patterns. And also put 15 auxillary LEDs on every spare inch of their cars and trucks. Used to be a simple rotator lightbar was sufficient. Now....I know they want to be seen, but being blinded isn't good either.
California Highway Patrol for many years just used the driver's side spotlight with a red lamp in it... It didn't even flash. The old "bubble gum machine" (or "Andy Griffith light") just doesn't do the job any more, though. Gotta have something to make people look up from their phones....
My light bar has, like, 16 potential patterns... I usually stick with one or two.
Another problem is the relative brightness of the colors. During the day, blue isn't very visible, one reason many police agencies use both red and blue.
LEDs are often "doped" to create the desired color (as opposed to mixing colors). That is, the amounts of the chemicals used are varied. This results in a very "pure" color. Almost too pure for those used to incandescent lights filtered by a lens.
This can be a plus for signals, as the all-wavelengths characteristic of an incandescent lamp can't overwhelm a fading lens.
One negative effect I've seen is that red lights placed at the top of the windshield (on the inside) are almost invisible if the top of the windshield is tinted (especially with a greenish tint). All the more reason for crews wearing neutral tinted sunglasses.
I am enjoying the reduction in my electric bill that's resulted from replacing almost all the bulbs in the house with LED's...
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
tree68California Highway Patrol for many years just used the driver's side spotlight with a red lamp in it... It didn't even flash. The old "bubble gum machine" (or "Andy Griffith light") just doesn't do the job any more, though. Gotta have something to make people look up from their phones....
Yeah, but having a fully loaded Liberty on the roof, dash light, TIRs on the pushbar, LED hideaways in the headlights and corners is just excessive. Then you start mixing red and blue together and you get this ugly purplish-white thing. And people STILL won't notice it.
At least kick them down when stopped alongside the road. CHP also did the studies years ago with using just amber flashers to the rear. You're not doing any favors blinding passerbys when stopped along the road.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
http://www.progressiverailroading.com/rail_product_news/details/GE-Lighting-LED-retrofit-for-wayside-incandescent-replacements--46475
Never too old to have a happy childhood!
This old dinosaur prefers the constant-on rotating yellow light vs the strobe in certain conditions. We keep both in our inventory.
(Have some really evil thoughts for some people that don't pay heed to signals and flagmen...at least I can throw my hardhat at the windshield of what's about to hit me.)
mudchickenThis old dinosaur prefers the constant-on rotating yellow light vs the strobe in certain conditions. We keep both in our inventory.
I've heard that pilots also prefer rotating lights on vehicles on an airfield - they are easier to track than strobes.
Many LED lights now feature flash patterns that provide a longer opportunity for recognition.
One of our firefighters pointed out a phenomenon that exists with rotating lights vs strobes or LEDs - the sealed beam of the rotating light bounces off other objects (like store windows "downtown"), something that neither strobes nor LEDs do.
This reminds me of the old mars lights. I always thought they were much more attention-getting than alternate flashing ditchlights.
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"A stranger's just a friend you ain't met yet." --- Dave Gardner
A complication to viewers of LEDs. Had first cataract removed from left eye and wow what a difference. LEDs and CFLs that were perceived as yellow are now white. ( compared to right eye.) LEDs that were replacements for incadescent now do not need as much lumens as before. So will downsize LEDs where possible as higher lumens no longer needed.
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