Source For LED Panels (See Design)
 

On Sat, 12 Nov 2005, JosephKK wrote:

How about coming up with some off the shelf or homemade diffuser of
some kind to snap or attach to the end of the 1157 LED bulbs?

The "1157 LED bulbs" don't put out nearly enough total light, period.
No diffuser is going to help that.

And you came up with this how?

Photometric testing.

legal requirements state otherwise. --

Actually, the legal requirements in force in North America agree with me,
and not with you. If you believe otherwise, your understanding of the
applicable regulations is faulty.

DS (the legal requirements in force everywhere else in the world also
agree with me, but that's beside the point).

Source For LED Panels (See Design)
 

On Sat, 12 Nov 2005, JosephKK wrote:

Seems to me I see a lot of trucks with new LED signal/stop lights, and
I can get close enough to see no SAE imprimatur on them. Then I see
celebrities breaking the law. and president's since Nixon, and
presidents circumventing the Consitution since I was born and I have to
wonder what good is the "rule of law?" It is a matter of what I can
get away with - not what is legal. So how bad can LED lights be?

This sub-thread got me curious, so i looked it up found 49cfr564.
Roughly it says if it gives equivalent light (including color
characteristics) and is otherwise interchangeable with original it is
legal. Thus halogen lamps, LED's, induction lamps or whatever are OK.

That is not correct. 49CFR564 contains the specifications for replaceable
headlamp "light sources" (bulbs). The actual Federal requirements for car
lights, contained in 49CFR571.108, actually state the opposite of your
faulty understanding: The design and performance characteristics of every
light source are mandatory, and cannot be selectively modified to suit the
whim of whoever's doing the modification. Any modification -- different
power rating, different filament configuration, replacement of filaments
with arcs or arcs with filaments (or arcs or filaments with LEDs, etc.) --
means it is a different light source, not legally interchangeable.

Furthermore, 49CFR564 contains the specifications only for forward
illumination light sources ("bulbs"). Signalling light sources are not
contained in 49CFR564. The exact legal reason behind the illegality of
"LED bulbs" is a little tricky to follow: When such bulbs are installed,
they spoil the compliance of lighting devices designed to use a filament
bulb of one sort or another, and manufacturer-certified as compliant with
FMVSS108 when using that filament bulb. So it's not the bulb itself that's
illegal to sell, buy or install, it's what happens to the performance of
the vehicle lighting device as a result of installing the "LED bulb".

In actual fact, "LED bulbs" do not produce anywhere near the same amount
of light as a filament-type signalling bulb, nor do they produce anywhere
near the same (Lambertian) distribution of light...even those clever ones
with sideward-facing LED emitters in addition to the rearward-facing
items. Installing "LED bulbs" in bulb-type car lamps doesn't just spoil
their compliance with the applicable safety standards, it spoils their
performance. The light is too dim, the illuminated area is too small, the
intensity ratio between bright (brake or turn) and dim (tail or park) is
improper, and the vertical and horizontal angles of visibility are much
too small. All of this adds up to grossly reduced vehicle conspicuity and
safety.

DS

Source For LED Panels (See Design)
 

"Daniel J. Stern" wrote in message
.umich.edu...
On Sat, 12 Nov 2005, JosephKK wrote:

Seems to me I see a lot of trucks with new LED signal/stop lights, and
I can get close enough to see no SAE imprimatur on them. Then I see
celebrities breaking the law. and president's since Nixon, and
presidents circumventing the Consitution since I was born and I have to
wonder what good is the "rule of law?" It is a matter of what I can
get away with - not what is legal. So how bad can LED lights be?

This sub-thread got me curious, so i looked it up found 49cfr564.
Roughly it says if it gives equivalent light (including color
characteristics) and is otherwise interchangeable with original it is
legal. Thus halogen lamps, LED's, induction lamps or whatever are OK.

That is not correct. 49CFR564 contains the specifications for replaceable
headlamp "light sources" (bulbs). The actual Federal requirements for car
lights, contained in 49CFR571.108, actually state the opposite of your
faulty understanding: The design and performance characteristics of every
light source are mandatory, and cannot be selectively modified to suit the
whim of whoever's doing the modification. Any modification -- different
power rating, different filament configuration, replacement of filaments
with arcs or arcs with filaments (or arcs or filaments with LEDs, etc.) --
means it is a different light source, not legally interchangeable.

Furthermore, 49CFR564 contains the specifications only for forward
illumination light sources ("bulbs"). Signalling light sources are not
contained in 49CFR564. The exact legal reason behind the illegality of
"LED bulbs" is a little tricky to follow: When such bulbs are installed,
they spoil the compliance of lighting devices designed to use a filament
bulb of one sort or another, and manufacturer-certified as compliant with
FMVSS108 when using that filament bulb. So it's not the bulb itself that's
illegal to sell, buy or install, it's what happens to the performance of
the vehicle lighting device as a result of installing the "LED bulb".

In actual fact, "LED bulbs" do not produce anywhere near the same amount
of light as a filament-type signalling bulb, nor do they produce anywhere
near the same (Lambertian) distribution of light...even those clever ones
with sideward-facing LED emitters in addition to the rearward-facing
items. Installing "LED bulbs" in bulb-type car lamps doesn't just spoil
their compliance with the applicable safety standards, it spoils their
performance. The light is too dim, the illuminated area is too small, the
intensity ratio between bright (brake or turn) and dim (tail or park) is
improper, and the vertical and horizontal angles of visibility are much
too small. All of this adds up to grossly reduced vehicle conspicuity and
safety.

DS

Thanks Dan

I wondered why my city was replacing the traffic light lamps with led's.
Never knew that they had a smaller field of view. And ya during the summer
sun in the desert you can hardly see them unless there are hoods over the
lens. Ok they probably save a dime or two in maintenance and energy.

Source For LED Panels (See Design)
 

On Mon, 14 Nov 2005, SQLit wrote:

I wondered why my city was replacing the traffic light lamps with led's.

This is a departure from the topic that was being discussed (retrofitting
automotive lighting devices with "LED bulbs"). Were you wondering why they
were replacing the entire traffic light instead of just screwing in an
"LED bulb"?

Never knew that they had a smaller field of view.

Well, individual LED emitters give a highly directional beam (light
emitted in one direction), while a filament lamp produces light in an even
sphere (light emitted in all directions). But, LED traffic lights -- like
LED vehicle lighting devices -- are engineered to produce the required
amounts of light through the required angles of visibility.

And ya during the summer sun in the desert you can hardly see them
unless there are hoods over the lens. Ok they probably save a dime or
two in maintenance and energy.

H'm. That's an interesting complaint. Most all of the LED traffic signals
I've seen in North America and Europe are considerably more conspicuous
than their filament-lamp type counterparts. And, FYI, the LED traffic
signals save a fortune, not a dime or two, in maintenance and energy.

DS

Source For LED Panels (See Design)
 

"Daniel J. Stern" wrote in message
.umich.edu...
On Mon, 14 Nov 2005, SQLit wrote:

I wondered why my city was replacing the traffic light lamps with led's.

This is a departure from the topic that was being discussed (retrofitting
automotive lighting devices with "LED bulbs"). Were you wondering why they
were replacing the entire traffic light instead of just screwing in an
"LED bulb"?

Never knew that they had a smaller field of view.

Well, individual LED emitters give a highly directional beam (light
emitted in one direction), while a filament lamp produces light in an even
sphere (light emitted in all directions). But, LED traffic lights -- like
LED vehicle lighting devices -- are engineered to produce the required
amounts of light through the required angles of visibility.

And ya during the summer sun in the desert you can hardly see them
unless there are hoods over the lens. Ok they probably save a dime or
two in maintenance and energy.

H'm. That's an interesting complaint. Most all of the LED traffic signals
I've seen in North America and Europe are considerably more conspicuous
than their filament-lamp type counterparts. And, FYI, the LED traffic
signals save a fortune, not a dime or two, in maintenance and energy.

DS

Not a complaint, just an observation/realization. Until I read your post I
never thought about the field of view. Makes sense to keep lights "focused"
into the area needed. As long as you in the area being served the led's do
tend to stand out more. I will need to keep this in mind the next control
panel I build that has a "whole lot of little tiny lights"

I have installed LED's in exit signs when the company had the money. Over
all we have reduced the loading on the generators by ~25 kw. Also do not
have to visit the exit sign again, probably in my career. Most of the retro
fits are guaranteed for 10 years. Which means they will probably last a lot
longer.

Source For LED Panels (See Design)
 

This is a departure from the topic that was being discussed
(retrofitting automotive lighting devices with "LED bulbs"). Were you
wondering why they were replacing the entire traffic light instead of
just screwing in an "LED bulb"?



Around here they usually install LED retrofits in the traffic lights
unless the signals don't meet current spec in some other way. The
retrofits take the place of the reflector and lense, and mount in the
door with the existing lense mount.

I've also seen retrofits that were a disk shaped pcb full of LED's with
a screw base on a post on the back side but those are much less common.