The Siren Board

up in in Nova scoia they had some dump trucks not only with amber strobes but a blue rotaor light usaly on the drivers side. i wounder what that is all about...

Dear Loudmouth,

Love to learn what you have to say, and you pose interesting questions,
but please improve your spelling.
Otherwise it is more difficult to read what you say - requires
more brain effort and I don't want to hurt myself.

Colorado uses yellow and blue for snow plows.
Supposedly, blue light cuts through snow better and yellow is much brighter. Also, one can tell what direction truck is heading: blue on left
you are following, blue on right you are head-on.

On our ambulance, blue was the most striking and stood out.
But also the dimmest because filaments don't emit much
light in blue spectrum. In bright light we.re unsure
whether some of our blue PAR-36 (rotating beacon) bulbs
were even lit. The blink was so brief and bulb not bright enough.
Sometimes they seemed more greenish.

Love the new rich pure LED blues. Butoo expensive.

Hate to say this but I think the purple might be really good emergency light.
Unique and stands out and conveys both red and blue.

We find it is best to use clear to catch eye attention, and
keep colors steadily lit or flashing, but not strobing or used
in rotating lights which very briefly blink.

Hey, anyone ever notice the strange purple light of some brake lights in the distance?
Recently saw one on a motorcycle.
When we got close, discovered it was a nickle-sized blue lens inserted in the middle of the red brake light cover.
Close up you see red with the small blue lens.
From a distance you see a striking strange purple color from the whole light!
Neat effect. Not sure how legal it is.

I believe the price premium on blue LEDs is going way down now. I just looked at some LED items on Code 3's website and there wasn't any price premium. It was bound to happen as the companies got experience and demand for blue lights increased., Maybe it's time to revisit it.

I notice that white is being used less and less with LEDs. I guess it's because the LEDs are so much better as a warning in color.

Let's see: LEDs last much longer, they draw less current, and the colors are very intense

couple other things- 1) is that you can overdrive them somewhat with proper heatsinking and a short duty cycle. I've been able to hammer the crap out of "white" LEDs with drive voltages above their rating, as long as it was burst/flash and with an aluminum backing. 2) is that they have a very short rise/fall time, almost if not as good as strobes and far better than incandescents.

I notice that white is being used less and less with LEDs. I guess it's because the LEDs are so much better as a warning in color.

a big part of it is that there are no true white LEDs on the market. What you find now is a blue or UV LED with a phosphorescent coating; the UV emission from the LED makes the phosphors glow white. thus, they're more expensive.

a big part of it is that there are no true white LEDs on the market. What you find now is a blue or UV LED with a phosphorescent coating; the UV emission from the LED makes the phosphors glow white. thus, they're more expensive

.

Actually, there are true white LEDs on the market now, they use a ZnSe chemistry (don't know what kind of dopant, though).

I have Blue LED's on my Jeep Liberty and I'm not a cop. I volenteer EMS. I have 2 in the front and one on the trunk hood. It's compact bright, with like 21 avalible sequences. People ask me what the lights are for all of the time. And your right. Boku bux. YOu will pony up for some good lights though. The Halogen are big, massive and arent unmarked. They are intence lights though. I wish I could find my strobe dash mount. Roatars are only good of you have a fast flash.It depends upon what you can do and afford.

How come when I look up the word "dopant", my picture is shown?!

Interesting to make a UV LED to fluoresce phosphor! Clever! Same principle as ordinary fluorescent lights.

There are white LEDs but they are too expensive.

Best to use clear bulbs or Xenon tubes witheir greater intensity to catch the eye and attract gaze.
Then steady colors to convey the message.

Hey Squad, in case you are interested, we bought some oval Stop/Turn/Tail LEDs for only $23 ea. at AutoZone.
They have clear covers, not red as usual, and black background.
Fit nicely and are very bright.

I'd like to get blue LEDs but would probably needefibrillation after seeing the price. Are yours also clear case?

Like I said, I saw blue LED lights on Code 3's sight for no extra money. The point of some of the things we all have been saying in this thread is the state of the art is changing fast and that something tht was true just a few months ago (no true white LEDs) may not be true now.

squad2498 wrote:I have Blue LED's on my Jeep Liberty and I'm not a cop. I volenteer EMS.

As I said, SOME areas have them set only for police vehicles such as Maryland

I think your right. The fire police in Frederick County have to use red lights and even with that, there is a strick guidline on how and when they can be used. I'm not sure how volunteer personel fall into the mix but I'm sure it's along the same lines.

As far as here in Pennsylvania, all of the fire police only use blue. I'm not sure on the by-lines for my state but they probably can't use red, as that is probably considered for use only with emergency vehicles.