On Thu, 06 Jan 2005 12:49:36 -0600, Cecil Moore
wrote:
Zero probability that you simply misunderstood my original question?
More to the point, did you? Aside from its sucker spin, then why ask?
Did you know it is now being used on automobiles?
LEDs have been in general illumination for quite a few years - even
for headlights. If they are new to you, you can't afford them.

Richard Clark wrote:
LEDs have been in general illumination for quite a few years - even
for headlights.

I know that. The question was and is: WHEN DID THEY START
TIME MULTIPLEXING AUTOMOBILE TAILLIGHTS? I am asking for
information and it's perfectly OK if you don't know.

Constant current LEDs have been in use for years. But it's
just over the last couple of months that I have noticed
the pulse-width modulation on some automobile taillights.
I suspect it's only one or two manufacturers so far.
--
73, Cecil http://www.qsl.net/w5dxp


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On Thu, 06 Jan 2005 13:30:37 -0600, Cecil Moore
wrote:
WHEN DID THEY START TIME MULTIPLEXING AUTOMOBILE TAILLIGHTS?
Who is THEY? This still sounds like a sucker posting.
Anyway, 5 years ago. Why don't you try rec.philosophy.automotive for
this topic?

Richard Clark wrote:

Cecil Moore wrote:
WHEN DID THEY START TIME MULTIPLEXING AUTOMOBILE TAILLIGHTS?

Who is THEY?

Shirley, you jest.

Anyway, 5 years ago.

Doubt it. I would have noticed long before now.
--
73, Cecil http://www.qsl.net/w5dxp


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Bill Turner wrote:

How interesting. I wonder if they are pulse width modulated to
compensate for day/night? What other reason could there be?


That might be it. It would be a convenient and efficient way of
adjusting brightness. They also might be compensating for voltage and
temperature by changing the pulse width.

Roy Lewallen, W7EL

On Thu, 06 Jan 2005 14:30:24 -0600, Cecil Moore wrote:
Richard Clark wrote:
Cecil Moore wrote:
WHEN DID THEY START TIME MULTIPLEXING AUTOMOBILE TAILLIGHTS?

Who is THEY?

Shirley, you jest.

Anyway, 5 years ago.

Doubt it. I would have noticed long before now.

Do you mean that the subliminal CW messages have had no effect on you? :-)

Jonesy
--
| Marvin L Jones | jonz | W3DHJ | linux
| Gunnison, Colorado | @ | Jonesy | OS/2 __
| 7,703' -- 2,345m | config.com | DM68mn SK

On 6 Jan 2005 22:37:03 GMT, Allodoxaphobia
wrote:
Doubt it. I would have noticed long before now.
Do you mean that the subliminal CW messages have had no effect on you? :-)

Hi Jonesy,

Like I figured, another sucker posting. Cadillac was doing this for
its 2000 model:

" The 2000 Cadillac DeVille was the first vehicle to go into
production that utilizes HB LEDs for its rear combination lamps
(RCLs) as well as for its CHMSL. Many of the benefits here are
intangible-examples are the "jewel like" appearance of the RCL and
the ability to provide the tail light function with a particular
shape associated with the DeVille line. There are several tangible
benefits that can be measured, however, including reduced
electrical load, reduced mass, warranty savings, and mass
production quality improvements.

Although the Cadillac DeVille is the only production vehicle with
a complete LED rear combination lamp assembly, several other
recent car makes and models have incorporated LEDs into various
signal functions. These are primarily limited production luxury
cars, such as the Mercedes S-Class, BMW 5-Series, and Nissan
Gloria."

On the Lincoln Town Car:

"light-emitting diode array on the rear of this vehicle in a
research project at California Partners for Advanced Transit and
Highways takes data from the wheels and brakes and sends a signal
to following cars indicating the acceleration and velocity of the
vehicle."

which, of course, fulfills your anticipation of subliminal CW
messages. ;-)

As the old adage goes "if you have to ask, you can't afford it."
rec.philosophy.automotive may provide more details - this is clearly
beyond the pale of electromagnetic anything from anywhere.

73's
Richard Clark, KB7QHC

That might be it. It would be a convenient and efficient way of
adjusting brightness. They also might be compensating for voltage and
temperature by changing the pulse width.

Hi Roy, You can do all the above with a regular light bulb. I think the
reason they use multiple LED's is to reduce the mean time between failures. If
a regular bulb fails, you are dark. If half of the LED's fail you still have
light. They generally have 20 plus LED's. in the stuff I have seen. Also,
LED's tend to last than bulbs (I think)
73 Gary N4AST

Richard Clark wrote:
Like I figured, another sucker posting. Cadillac was doing this for
its 2000 model:

" The 2000 Cadillac DeVille was the first vehicle to go into
production that utilizes HB LEDs for its rear combination lamps
(RCLs) as well as for its CHMSL. Many of the benefits here are
intangible-examples are the "jewel like" appearance of the RCL and
the ability to provide the tail light function with a particular
shape associated with the DeVille line. There are several tangible
benefits that can be measured, however, including reduced
electrical load, reduced mass, warranty savings, and mass
production quality improvements.

Although the Cadillac DeVille is the only production vehicle with
a complete LED rear combination lamp assembly, several other
recent car makes and models have incorporated LEDs into various
signal functions. These are primarily limited production luxury
cars, such as the Mercedes S-Class, BMW 5-Series, and Nissan
Gloria."

Uhhhhhh Richard, like I figured, you have no clue. The subject is NOT
LEDs used in automobiles. The subject is ***TIME-MULTIPLEXING*** of LEDs
used in automobiles and there is absolutely no mention of
time-multiplexing of the LEDs in your above posting, i.e. it is
irrelevant to my question.

On the Lincoln Town Car:

"light-emitting diode array on the rear of this vehicle in a
research project at California Partners for Advanced Transit and
Highways takes data from the wheels and brakes and sends a signal
to following cars indicating the acceleration and velocity of the
vehicle."

Again, absolutely no mention of any time-multiplexing of the LED
currents so your posting is completely irrelevant to my original
question which continues to be: WHEN DID AUTO MANUFACTURERS START
MULTIPLEXING THEIR AUTOMOBILE TAILLIGHTS. I suspect it was on the
2005 models and certainly not five years ago as you mistakenly
assert.

I first saw a time-multiplexed LED taillight on my 2004 Thanksgiving
trip to Memphis. I simply do not believe your assertion that
time-multiplexed taillights have been around for five years. The
onus of proof is upon you and your above posting is certainly NOT
proof of time-multiplexed LED taillights.
--
73, Cecil http://www.qsl.net/w5dxp


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On 07 Jan 2005 01:00:31 GMT, (JGBOYLES) wrote:

LED's tend to last than bulbs (I think)
Only if the bulbs are in American cars.

Hi Gary,

The filament lightbulb lifetime increases at the inverse 12th power of
its reduction from the "suggested" operating voltage. This curve
actually holds only for about the first 5 to 10% of voltage depression
(otherwise they would last forever at half power). This is one reason
to buy industrial bulbs (rated at 130V).

The benefit of LEDs is lowered current consumption for the same
brightness (which I will warn is another one of those tricks of the
brain). This is also a deficit for turn signals because it has a
tendency to change the tempo of the flashing which can be mistaken as
multiplexing. :-) The suggested fix is placing a resistor in
parallel to return the circuit current demand to the original level.

73's
Richard Clark, KB7QHC