[R-390] OT: LED tail lights, white LED physics

[Dave Maples]

All: Not to mention that the replacement cycle for the LED lamps is measured
in years and years as opposed to standard incandescent bulbs.

In the commercial radio business (Nextel) we are seeing more and more tower
lights move harder and harder toward LED technology.  It's way more reliable
than xenon strobes.

I don't think I'd want to be in the incandescent business much longer.
Methinks that before I die in 20-30 years it's going to be well on its way
out.

Dave Maples

-----Original Message-----
From: r-390-bounces at mailman.qth.net
[mailto:r-390-bounces at mailman.qth.net]On Behalf Of Tom Norris
Sent: Wednesday, July 07, 2004 3:23 PM
To: R-390 at mailman.qth.net
Subject: [R-390] OT: LED tail lights, white LED physics


According to USDOT and such, they are supposed
to be annoying. Apparently the instant on feature
cuts as much as a quarter second off the response
time that would otherwise be spent getting an
incandescent filament lit to full brightness. A
quarter second is a long time as accident response
goes, and can mean the difference in avoiding an
rear-end or sliding under the vehicle in front of you.

That being said, as far as LEDs for running lights,
the red is too "spectrally pure" and is way hard on my
eyes too.

I tend to agree on the white LEDs being somewhat
"harsh" since they tend to have a blue shift to then.
Indeed all should, the white leD is manufactured
from a blue or uv led die, which is then doped with a
mixed spectrum phosphor-like material. The effect is
not unlike that of a florescent lamp. The harshness
comes from the blue or uv/blue that is emitted as
the phosphor doesn't do much to block it.

Tom


>James Miller wrote:
>
>>  I prefer the "soft" on and off times of filament lamps over the
>>  instantaneous on-off of LEDs.
>>  Ever drive behind a car with those obnoxious LED brake lights,
>>  especially the Cadillacs?, They flash on instantly... no soft warm up
time.
>>  It's grating on the nerves.
>
>Or new "large cars" (18 wheelers). EXTREMELY annoying....!!! We
>just returned from a 3967 mile trip out east to visit relatives. Traffic
>around Minneapolis was chaotic.
>
>Ken W7EKB
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