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'[OT] Re: Car LED lighting system; PIC filament mon'
1999\07\26@155704 by Matt Bennett

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face
At 02:25 PM 7/26/99 , you wrote:
>In a discussion with someone else, I was asked if all a car's
>"auxiliary" lighting could be replaced with LEDs, and/or how to monitor
>existing bulbs with a PIC (so you can tell when a turn signal bulb burns
>out, etc.)

One feature of incandescent bulbs that you can exploit is that when off, an
incandescent filament is very low resistance- much lower than when it is
glowing.  You can trickle a small (fractions of a milliamp) current through
the bulb- if there is current flow, the bulb is good, none, the bulb is
burnt out.  This method can only tell you the health of the bulb when the
bulb is off.  Make the current small enough not to light the bulb.  I can't
remember the issue, but this was detailed in one of the "design ideas"
columns in EDN or Electronic Design a few years back.

Matt Bennett

1999\07\26@183732 by David E. Olson

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face
FWIW, I use HP LED's for custom motorcycle lighting. Their web site has lots
of information on where folks are using them. Haven't worked on filament
monitoring yet - a bit of overkill on a bike (especially since the local
constabulary will usually tell you if there's a bulb out ;))

http://www.hp.com/HP-COMP/tran/Lite.html

The "square" ones are really cool. Super bright and used in many brake
lights.

-DO

1999\07\26@185843 by Wagner Lipnharski

picon face
There is a simple way to check if a filament is open or not.  Apply a
low current square wave at the switch side of the lamp. It doesn't
matter if the other side of the lamp  goes to +12Vdc or Ground, since
one polarity of the square wave signal will try to lit the lamp, and the
current is an indication of good filament.    It is not so common to
check lamp filament when the lamp is not lited, but it can be done.

Just a curiosity about lamp filaments:
Airplane crash investigation take a special attention to panel lamp
filaments.  They can almost identify if a lamp was on or off at the
crash moment.  Alarm and "red lamps" are important to understand why an
airplane crashed.  A lited lamp has a hot filament that breaks it easily
at a crash impact. A cold filament is more difficult to break... well...
it helps.

--------------------------------------------------------
Wagner Lipnharski - UST Research Inc. - Orlando, Florida
Forum and microcontroller web site:  http://www.ustr.net
Microcontrollers Survey:  http://www.ustr.net/tellme.htm

1999\07\26@192540 by Dennis Plunkett

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At 18:36 26/07/99 -0400, you wrote:
>FWIW, I use HP LED's for custom motorcycle lighting. Their web site has lots
>of information on where folks are using them. Haven't worked on filament
>monitoring yet - a bit of overkill on a bike (especially since the local
>constabulary will usually tell you if there's a bulb out ;))
>
>http://www.hp.com/HP-COMP/tran/Lite.html
>
>The "square" ones are really cool. Super bright and used in many brake
>lights.
>
>-DO
>
>


Yup,
There is nothing stopping a manufacturer from using L.E.Ds in tail lights
etc. EXCEPT->

                                   ********   COST    ********

Can't do it cheeper than a globe!


Dennis

1999\07\26@195321 by David E. Olson

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[Dennis said...]

> Yup,
> There is nothing stopping a manufacturer from using L.E.Ds in tail lights
> etc. EXCEPT->
>
>                                     ********   COST    ********
>
> Can't do it cheeper than a globe!
>
>
> Dennis

Oooo. Big time! I did a job recently that had 100 of those buggers for each
light - total of two. Lit up like a Christmas tree though. Figured since I
was doing that many, I'd toss in a PIC to make them dance in all sorts of
weird ways. Fortunately, this was a $50k show bike.

We also use them in high-vibration situations - like for turn signals on a
swingarm.

Got them in my own bikes. I call it R&D. My wife calls it insanity.

-DO

1999\07\26@195948 by Sean H. Breheny

face picon face
Hi Wagner,

At 06:57 PM 7/26/99 -0400, you wrote:
>Just a curiosity about lamp filaments:
>Airplane crash investigation take a special attention to panel lamp
>filaments.  They can almost identify if a lamp was on or off at the
>crash moment.  Alarm and "red lamps" are important to understand why an
>airplane crashed.  A lited lamp has a hot filament that breaks it easily
>at a crash impact. A cold filament is more difficult to break... well...
>it helps.

I don't really know the right answer to this myself,but I seem to recall
from a crash investigation TV program I saw,that it was exactly the other
way around: Lit filaments tend to stretch rather than break. Cold filaments
tend to break. It kinda made sense to me, but I can also see arguments in
favor of what you said.

Sean


>
>--------------------------------------------------------
>Wagner Lipnharski - UST Research Inc. - Orlando, Florida
>Forum and microcontroller web site:  http://www.ustr.net
>Microcontrollers Survey:  http://www.ustr.net/tellme.htm
>
|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
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1999\07\26@200606 by Andy Kunz

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>I don't really know the right answer to this myself,but I seem to recall
>from a crash investigation TV program I saw,that it was exactly the other
>way around: Lit filaments tend to stretch rather than break. Cold filaments
>tend to break. It kinda made sense to me, but I can also see arguments in
>favor of what you said.

Try it with your own droplight (no pun intended).

With the bulb off, drop it a foot.  Turn it on.  It probably works.

No drop it 6" with the bulb on.

POOF!

(I'm sure you can figure out why I recommended a droplight).

Andy

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------------------------------------------------------------------
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1999\07\26@203317 by Des Bromilow

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Just a curiosity about lamp filaments:
Airplane crash investigation take a special attention to panel lamp
filaments.  They can almost identify if a lamp was on or off at the
crash moment.  Alarm and "red lamps" are important to understand why an
airplane crashed.  A lited lamp has a hot filament that breaks it easily
at a crash impact. A cold filament is more difficult to break... well...
it helps.

ACTUALLY, the analysis of light bulb filaments is a little more scientific... basically the heat from the lit bulb will allow the metal to move in the direction of the crash, so a lit bulb will break, but the broken filament will display a "conical" shape since the near molten metal has moved to one end of the filament.
This is how they can differentiate between a bulb that broke due to being stepped on, and a bulb that was lit.

This technique can be used to tell if a smashed car light was actually on before the car crash totalled the lights. (Used to determine if the drunk was driving with his lights on or off..etc)

Des Bromilow

1999\07\26@205400 by Wagner Lipnharski

picon face
Isn't nice when we share information?  We learn things everyday.
Thanks Des Bromilow.
Wagner.

Des Bromilow wrote:

> ACTUALLY, the analysis of light bulb filaments is a little more scientific...
basically the heat from the lit bulb will allow the metal to move in the directi
on of the crash, so a lit bulb will break, but the broken filament will display
a "conical" shape since the near molten metal has moved to one end of the filame
nt.
> This is how they can differentiate between a bulb that broke due to being step
ped on, and a bulb that was lit.

1999\07\26@222922 by Russell McMahon

picon face
Another method is to measure the voltage drop across a short section
of the wiring caused by current flow to the bulb. A common voltage
comparator will have enough gain to allow this. Unlike the other
method mentioned, this one only works when  the bulb is ON.


RM


From: Matt Bennett <.....mjbKILLspamspam.....ARLUT.UTEXAS.EDU>


>At 02:25 PM 7/26/99 , you wrote:
>>In a discussion with someone else, I was asked if all a car's
>>"auxiliary" lighting could be replaced with LEDs, and/or how to
monitor
>>existing bulbs with a PIC (so you can tell when a turn signal bulb
burns
>>out, etc.)
>
>One feature of incandescent bulbs that you can exploit is that when
off, an
>incandescent filament is very low resistance- much lower than when
it is
>glowing.  You can trickle a small (fractions of a milliamp) current
through
>the bulb- if there is current flow, the bulb is good, none, the bulb
is
>burnt out.  This method can only tell you the health of the bulb
when the
>bulb is off.  Make the current small enough not to light the bulb.
I can't
>remember the issue, but this was detailed in one of the "design
ideas"
>columns in EDN or Electronic Design a few years back.
>
>Matt Bennett

1999\07\26@225249 by A Rudzki

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> A lited lamp has a hot filament that breaks it easily
>at a crash impact. A cold filament is more difficult to break... well...
>it helps.


I think they also look at the filaments being elongated.  This would
indicate the lamp was on, and went off during rapid descent.  While the
filament cooled, the acceleration elongated it.


Tony

1999\07\26@225648 by Gary Crowell

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face
Dennis Plunkett wrote:
>

>
> Yup,
> There is nothing stopping a manufacturer from using L.E.Ds in tail lights
> etc. EXCEPT->
>
>                                     ********   COST    ********
>
> Can't do it cheeper than a globe!
>


I don't doubt that for manufacturing costs, but how do lifetime costs
compare?  Won't an LED last longer than a bulb, improving replacement
cost and don't forget the time & trouble to dig out the old bulb.  Isn't
an equivalent brightness LED more efficient, translating into fuel
savings?

But there is another interesting issue that I read about a few years
ago; I'm assuming its true... An LED comes up to full brightness faster
than an incandescent bulb, something like a couple of hundred
milliseconds faster.  Doesn't sound like much, but at 60 MPH, that's an
additional 18 feet of reaction time and stopping distance for the bozo
that's barreling down on you from behind.


Gary Crowell

1999\07\26@234810 by Anne Ogborn

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face
Last job we had some BIG LED info signs for a transit system station.
These things were so bright you couldn't look at them comfortably in the
lab. They also put out HEAT.

--
Anniepoo
Need loco motors?
http://www.idiom.com/~anniepoo/depot/motors.html

1999\07\27@023120 by Mark Willis

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Matt Bennett wrote:
>
> At 02:25 PM 7/26/99 , you wrote:
> >In a discussion with someone else, I was asked if all a car's
> >"auxiliary" lighting could be replaced with LEDs, and/or how to monitor
> >existing bulbs with a PIC (so you can tell when a turn signal bulb burns
> >out, etc.)
>
> One feature of incandescent bulbs that you can exploit is that when off, an
> incandescent filament is very low resistance- much lower than when it is
> glowing.  You can trickle a small (fractions of a milliamp) current through
> the bulb- if there is current flow, the bulb is good, none, the bulb is
> burnt out.  This method can only tell you the health of the bulb when the
> bulb is off.  Make the current small enough not to light the bulb.  I can't
> remember the issue, but this was detailed in one of the "design ideas"
> columns in EDN or Electronic Design a few years back.
>
> Matt Bennett

 (I don't understand why you made this OT, BTW, Matt.)

 I don't *have* EDN from a couple years back, Matt;  I don't think my
local library has it, either.  What I'm after is more like a quick
sketch of a schematic or the general idea <G>  From reading other posts,
sounds like, if I am using LED's with a PIC to monitor for broken LED
chains, it'd work pretty well to just put LED's to +12V (In sets of 4 in
series, with a 2V drop series resistor/equalizer), then in my module put
another (about 2V drop) series resistor that I can watch with a voltage
comparator, then a nice HexFET or the like to ground, paralleled with a
100k resistor, say;  If the LED chain's dead, when I make the FET
conduct I'd expect the top of that resistor to be under 1.5V, if intact,
I'd expect 2V or more.  That's sort of what I'm thinking, maybe add a
nice 12V TVS or Zener for safety...

 Mark

1999\07\27@025305 by Michael Rigby-Jones

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This appears to have split into two subject's i.e. whether or not LED's can
be used for turn/brake signals and monitoring lamps.

Here in the UK, construction and use regulations (at least the most recent
I'm aware of) demand that all car lighting is incandescent.  The only
exceptions seem to be the high level brake lights which are invariably LED
based, and the new type projector headlamps which use some kind of high
voltage discharge lamp I believe.  It does seem like a very short sighted
view given the robustness and efficiency of LEDs, but I guess the DOT has a
reason for it.

As for monitoring, an after-market system I saw years back used fiber optics
which were stuck onto the lens of the lamp cluster.  The fibbers all ran
back to a control box. This way you could be sure that the lamp was actually
producing light, rather than current being drawn through a short somewhere,
like a connection with enough corrosion to ground it.

Regards

Mike Rigby-Jones


{Quote hidden}

1999\07\27@025520 by Dennis Plunkett

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At 20:56 26/07/99 -0600, you wrote:
>Dennis Plunkett wrote:
>>
>
>>
>> Yup,
>> There is nothing stopping a manufacturer from using L.E.Ds in tail lights
>> etc. EXCEPT->
>>
>>                                     ********   COST    ********
>>
>> Can't do it cheeper than a globe!
>>
>
>
>I don't doubt that for manufacturing costs, but how do lifetime costs
>compare?  Won't an LED last longer than a bulb, improving replacement
>cost and don't forget the time & trouble to dig out the old bulb.  Isn't
>an equivalent brightness LED more efficient, translating into fuel
>savings?

The manufaturer does not care as this is not a cost that they bare!

>
>But there is another interesting issue that I read about a few years
>ago; I'm assuming its true... An LED comes up to full brightness faster
>than an incandescent bulb, something like a couple of hundred
>milliseconds faster.  Doesn't sound like much, but at 60 MPH, that's an
>additional 18 feet of reaction time and stopping distance for the bozo
>that's barreling down on you from behind.
>
>

Add to this the 200mS that it takes for you to react! Better to change
driving habbits! Take a look at what happened in NY taxis when ABS was
first introduced.

Dennis

1999\07\27@084816 by Reginald Neale

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face
If you need separate hardware to drive the lamp anyway,I believe NSC and
Siemens both make "intelligent driver" devices that monitor the load and
provide a logic-level signal that indicate when the circuit is open. They
were designed for automotive signal light applications.

Reg Neale

1999\07\27@091727 by Wagner Lipnharski

picon face
> I don't doubt that for manufacturing costs, but how do lifetime costs
> compare?  Won't an LED last longer than a bulb, improving replacement
> cost and don't forget the time & trouble to dig out the old bulb.  Isn't
> an equivalent brightness LED more efficient, translating into fuel
> savings?
>
> But there is another interesting issue that I read about a few years
> ago; I'm assuming its true... An LED comes up to full brightness faster
> than an incandescent bulb, something like a couple of hundred
> milliseconds faster.  Doesn't sound like much, but at 60 MPH, that's an
> additional 18 feet of reaction time and stopping distance for the bozo
> that's barreling down on you from behind.

Here in Orlando we have a public transportation system that use LED read
lights, for flashing turn signal, break, and so on.  It is much brighter
than regular bulbs, and the flashing is solid and call much more
attention, since the speed of the light transaction is much faster than
regular bulbs.  I belive that as most of the animals, our visual sensors
are also based on movement and light changes.  It really works much
better than the old, hot, lazy, power hungry filament bulbs.

A regular break bulb consumes how much? 6 Watts? or it is  10W?   A
regular bright LED consumes 30mA x 2V = 60mW, so you can use 100 bright
LEDs to keep the same power rating, what I think would not be necessary
to reach the same irradiation level.  Cost? well, if you only think
about cost, a horse cost much less than a 2000 Convertible Mercedes
350se, and probably a pair of candles at the horse's rear would cost
much less than a pair of 6W 12V bulbs.

Wagner

1999\07\27@095318 by Andy Kunz

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face
>> There is nothing stopping a manufacturer from using L.E.Ds in tail lights
>> etc. EXCEPT->
>>                                     ********   COST    ********
>I don't doubt that for manufacturing costs, but how do lifetime costs
>compare?  Won't an LED last longer than a bulb, improving replacement
>cost and don't forget the time & trouble to dig out the old bulb.  Isn't
>an equivalent brightness LED more efficient, translating into fuel
>savings?

FWIW, I was passed by a trucker last night with apparent LED tail lights on
his trailer.  It had multiple LEDs it appeared.

Andy

==================================================================
Andy Kunz               Life is what we do to prepare for Eternity
------------------------------------------------------------------
EraseMEandyspam_OUTspamTakeThisOuTrc-hydros.com      http://www.rc-hydros.com     - Race Boats
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==================================================================

1999\07\27@095320 by Dan Larson

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What will they do when all of the incandescent lamps
on the plane have been replaced with LEDs???

On Mon, 26 Jul 1999 22:51:02 -0400, A Rudzki wrote:

{Quote hidden}

1999\07\27@102307 by Wagner Lipnharski

picon face
> What will they do when all of the incandescent lamps
> on the plane have been replaced with LEDs???

Zillions of lamps are actual screen displays right now.

Today's board computers can log lots of things before a crash, but,
unfortunately the old and decreptic "black box" (that is orange) serves
only to keep it all in a total and dark secrecy (this is why they call
it "black box").
Isn't interesting the fact that with all the navigation and
communication computers on board could data link more than 1MB of very
important telemetry data to any "WorldWide Emergency Station" dedicated
to receive this information via satelite, by airflight company, or even
a service provided by the aircraft manufacturer.
Isn't strange that today we only know that a plane has a problem if
somebody ear in the RF the pilot reporting it?

The lamp filament's analysis system is based in lack of any other
technique to do the same job.  Man, I can build a strong data logger
with 2000 input sensors, one recording per second, to keep recorded the
last 20 minutes in a single 2MB flash memory, inside a strong "orange"
steel box, 3 inches tick, IrDa interface, so the box is sealed. They
don't use that yet? Here comes the question... What is the use of the
technology for?

Wagner

1999\07\27@104554 by Andy Kunz

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face
>steel box, 3 inches tick, IrDa interface, so the box is sealed. They
>don't use that yet? Here comes the question... What is the use of the
>technology for?

Keeping the boys in work.

Actually, they earn their pay.  Voice is the big reason they use audio
tapes.  Salt water doesn't kill the tapes.  Voice is often more important
than sensor data.

Andy

==================================================================
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1999\07\27@111704 by Wagner Lipnharski

picon face
> Actually, they earn their pay.  Voice is the big reason they use audio
> tapes.  Salt water doesn't kill the tapes.  Voice is often more important
> than sensor data.

you mean...as a recording like that:

copilot:    "Can you see that captain?"
pilot:      "Yes, isn't that weird?"
copilot:    "Very... what should we do about it?"
pilot:      "I really don't know, we are flying at 30 thousand ft"
copilot:    "Do you have experience to deal with this situation?"
pilot:      "I saw something like that once, during simulation practice"
copilot:    "Do you believe the passengers will notice if we don't tell
them?"
pilot:      "Very difficult to say, you know, people notice something
like that"
copilot:    "Perhaps we should inform them"
pilot:      "Good idea, mostly because they could suffer too"
copilot:    "Attention passengers, we regret to inform that we are out
of peanuts today"

Wagner

1999\07\27@124123 by Sean H. Breheny

face picon face
Ok, I know that I don't seem to get things straight when I watch those TV
programs about crashes <G>, but here goes another recollection:

If they haven't implemented it already on some aircraft, the idea is
definately at least in the proto stage to do exactly what you say,Wagner.
They are planning on a two-way data link that transmits weather info, air
traffic control info, aircraft flight/engine instrument readings,etc. IMHO,
I don't think it would be a bad idea to have an "external control"
switch,which you could turn on and it would allow people on the ground to
set the autopilot,etc. Just in case of the "Pilot and Copilot are dead"
situation,which the movies love ;-)

Also, I don't know about the IrDa,but they DO use digital recording
methods,and have MANY sensors, recording at a lot faster than once per second.

In fact, they use voice recorder ICs for the CVR. Even the tape which they
are no longer using on new models, was digital,unless you go way far back.
This last part I learned from the link which was recently posted here,

http://www.airdisaster.com

Sean


At 10:21 AM 7/27/99 -0400, you wrote:
{Quote hidden}

| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
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1999\07\27@162843 by Matt Bennett

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At 01:30 AM 7/27/99 , you wrote:
{Quote hidden}

'Cuz I edited out all the PIC stuff...

>  I don't *have* EDN from a couple years back, Matt;  I don't think my
>local library has it, either.  What I'm after is more like a quick
>sketch of a schematic or the general idea <G>

Well, I do have it, but it is one of about 1500 photocopied, yet to be
filed, pages on my shelf... so I'll give it a go with an ASCII schematic of
a similar circuit

                |---RRRR---|
                |          |
                |  switch  |
Light supply--------/ --------------
                 |            |   BULB
                 V LED        |    |
                 -            |   GND
                 |            |
                 R            |
                 R            |
                 R            |
                 R            |
                 |            |
                 --E          |
                    B---RRRR---
                   C
                   |
                  GND

the EBC- is a PNP transistor.  If the switch is off (open) and the bulb is
good, the bulb
shorts the base of the transistor to ground, turning the LED off.  If the
bulb is open (burnt out, the most likely failure in a incandescent) and the
switch is off, the LED lights.  If the switch is on, the LED is on too, no
matter the state of the bulb.  This is not the exact circuit that I saw
before, the other circuit was a bit more elegant, using a 555 to flash the
LED, and a little better logic in the circuit.  This was just to get the
point across.

You would have to adjust the resistors for the expected currents, etc.
This is not a circuit to monitor the state of a grain of wheat bulb.  You
would use this type of circuit for things like turn signal bulbs and the like.

Also, this circuit has the disadvantage that if there are multiple lights
hooked in paralell, you could only detect a 100% failure.

Matt Bennett

1999\07\27@183336 by Dennis Plunkett

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At 11:15 27/07/99 -0400, you wrote:
{Quote hidden}

Sounds much like your Star Trek bit, a frustraited script writer?

Dennis

1999\07\27@231208 by Anne Ogborn

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FWIW I notice the busses here have LED tail lights.

--
Anniepoo
Need loco motors?
http://www.idiom.com/~anniepoo/depot/motors.html

1999\07\28@035405 by Eric Smith

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> FWIW, I was passed by a trucker last night with apparent LED tail lights on
> his trailer.  It had multiple LEDs it appeared.

I should hope so!  They've made great strides in producing "super-bright"
red LEDs, but I don't think that a single of even the best ones now made
would be sufficient.

Someone mentioned that they'd only seen LEDs used in red traffic signals,
but not the other colors.  There's one intersection in Sunnyvale, CA at
which I've seen LEDs used in the green signal.  I suspect that they are
doing a trial, as I haven't yet seen them elsewhere.

1999\07\28@095812 by Dan Larson

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face
In the Minneapolis area lots of lights now have LEDs for the
red light and orange LEDs for the "Don't Walk" light.

I have seen only two intersections with all three colors in LEDs.

One town has white LEDs for the "walk" sign in addition to the
red "Stop" and orange "Don't Walk" signs.  I suspect that the REDs are
much cheaper than the other colors, and thus, are used more.  I also
suspect that the highway departments are currently evaluating the
maintenance costs saved by the LEDs and trying to determine if they are
worth what they cost.

Dan


On Wed, 28 Jul 1999 07:53:15 -0000, Eric Smith wrote:

{Quote hidden}

1999\07\28@202604 by Anne Ogborn

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> Someone mentioned that they'd only seen LEDs used in red traffic signals,
> but not the other colors.  There's one intersection in Sunnyvale, CA at
> which I've seen LEDs used in the green signal.  I suspect that they are
> doing a trial, as I haven't yet seen them elsewhere.

I've seen amber in several applications as tail lights.
I've just returned from a surplus electronics place, and the guy who runs it,
who'se friendly, showed me a really, really bright orange LED. It'll cast a
spot on the wall 8 ft away in normal room light. Alltronics if anybody's
interested.


--
Anniepoo
Need loco motors?
http://www.idiom.com/~anniepoo/depot/motors.html

1999\07\29@133058 by Zack Cilliers

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Hi There!

-----Original Message-----
From: Sean H. Breheny <spamBeGoneshb7spamBeGonespamCORNELL.EDU>
To: TakeThisOuTPICLISTEraseMEspamspam_OUTMITVMA.MIT.EDU <RemoveMEPICLISTspamTakeThisOuTMITVMA.MIT.EDU>
Date: 27 July 1999 06:41
Subject: Re: [OT] Re: Car LED lighting system; PIC filament monitoring


>Ok, I know that I don't seem to get things straight when I watch those TV
>programs about crashes <G>, but here goes another recollection:
>
>If they haven't implemented it already on some aircraft, the idea is
>definately at least in the proto stage to do exactly what you say,Wagner.
>They are planning on a two-way data link that transmits weather info, air
>traffic control info, aircraft flight/engine instrument readings,etc. IMHO,

The system is already implemented and uses the VHF communications rx/tx,
It is called ACARS. this is only one
data transfer system. The ATC system uses a new mode called the
Mode S, this is used for the TCAS (Transport Collision Avoidance System)
system, can also be used as a digital data transfer system.
Then there is the new SATCOM system wich replaces the old HF communication
system, which can also be used as a data transfer system. They are busy
building
centres all over the world to capture the data and send it from there to the
airlines,
and manufacturing places.

>I don't think it would be a bad idea to have an "external control"
>switch,which you could turn on and it would allow people on the ground to
>set the autopilot,etc. Just in case of the "Pilot and Copilot are dead"
>situation,which the movies love ;-)
>
>Also, I don't know about the IrDa,but they DO use digital recording
>methods,and have MANY sensors, recording at a lot faster than once per
second.
>
>In fact, they use voice recorder ICs for the CVR. Even the tape which they
>are no longer using on new models, was digital,unless you go way far back.
>This last part I learned from the link which was recently posted here,
>

This is true that the old tape models are being replaced by flash memory.
There is not only one "Black box" onboard an aircraft but two. One is called
the Cockpit Voice Recorder and the other the Data Recorder. Everybody knows
what the CVR does, the Data Recorder Records essential Data from various
sensors which is the most important. There is also a big difference between
the old aircraft which used the analog standard and the new aircraft which
uses
the ARINC 419 spec., more sensors can be recorded and at a quicker rate.

This is the only two units used for official enquiery int an accident but
there is another
data aquasitioning system which the airlines use for general performance
data, this system is capable to record more than just half an hours data and
much more sensors. To give an example, the tire presure of each tire is
recorded and the duration of each
Radio System is recorded plus much more, If memory serves correct over 2000
sensors lives on the aircraft but not all is recorded, this depends on the
ailines.

I can try and get more technical info if anybody is interested. I will
however not
be available for three weeks becuase i am going on vacation to CANADA

>http://www.airdisaster.com
>
>Sean


Zack

E-Mail: spazzmanEraseMEspam.....iname.com

One regrets more the things that you
did not do than the things you did do.

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