Re: [MBZ] Strobing?

2012-07-07 Thread Rolf
I certainly see it. Leds have to be pulsed or they burn out.

Sent via string from my tin can.

OK Don okd...@gmail.com wrote:

I'll try that, as I haven' noticed the strobing either.

On Fri, Jul 6, 2012 at 6:38 PM, Craig diese...@pisquared.net wrote:

 With subject car about 100 - 150 yards ahead, glance to the left side and
 then slew your eyes to the right side. When I do that, I see the strobing
 very clearly. And, yes, I wear glasses, too, but I cannot see how it
 matters.


 Craig

 --

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2001 ML320
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Re: [MBZ] Strobing?

2012-07-07 Thread Max Dillon
 Almost every single appliance I own uses LED lights, so they are all pulsing 
and strobing?  Guess I'm lucky I don't notice it.  Do you notice it everywhere?


Rolf r...@winmutt.com wrote:

I certainly see it. Leds have to be pulsed or they burn out.

Sent via string from my tin can.


-- 
Max Dillon
Charleston SC
'95 E300, '87 300TD

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Re: [MBZ] Strobing?

2012-07-07 Thread Craig
On Sat, 07 Jul 2012 09:31:17 -0400 Rolf  r...@winmutt.com wrote:

 Leds have to be pulsed or they burn out.

No, LEDs do not have to be pulsed. Some of the newer high-brightness
ones, for example, have a shorter life if they are pulsed.


Craig

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Re: [MBZ] Strobing?

2012-07-07 Thread Rich Thomas
I don't find an issue with LEDs but if I am in a flourescent-lighted 
room for any length of time I start to get eye twitches and headaches.


--R

On 7/7/12 10:29 AM, Max Dillon wrote:

  Almost every single appliance I own uses LED lights, so they are all pulsing 
and strobing?  Guess I'm lucky I don't notice it.  Do you notice it everywhere?


Rolf r...@winmutt.com wrote:


I certainly see it. Leds have to be pulsed or they burn out.

Sent via string from my tin can.






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Re: [MBZ] Strobing?

2012-07-07 Thread Jim Cathey

Leds have to be pulsed or they burn out.


I disagree.  They CAN be brighter WITHOUT burning out IF pulsed.

-- Jim



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Re: [MBZ] Strobing?

2012-07-07 Thread Allan Streib
Max Dillon meadedil...@bellsouth.net writes:

  Almost every single appliance I own uses LED lights, so they are all
  pulsing and strobing?  Guess I'm lucky I don't notice it.  Do you
  notice it everywhere?

It used to be pretty obvious on old LED digital displays (calculators,
watches) but I always assumed that was because each segment was being
driven sequentially by the hardware.

 Rolf r...@winmutt.com wrote:

I certainly see it. Leds have to be pulsed or they burn out.

I've never heard that an LED must be pulsed, just need a resisitor in
series to control the current.  Is this incorrect?

-- 
1983 300D
1979 300SD

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Re: [MBZ] Strobing?

2012-07-07 Thread Dan Penoff
Manufacturers use PWM (pulse-width modulation) to send a square wave to the 
LEDs with a peak voltage and current above the continuous rating.  This allows 
the LED to be driven at a much greater brightness that it would have with a 
continuous (lower) voltage applied to it.

Depending on the frequency used to pulse the LEDs, the on/off cycles or peak 
versus continuous voltages, the variation in brightness between the two might 
be visible.

I haven't noticed it myself, but then again, I haven't looked that closely, 
either.

Dan


On Jul 7, 2012, at 10:29 AM, Max Dillon wrote:

 Almost every single appliance I own uses LED lights, so they are all pulsing 
 and strobing?  Guess I'm lucky I don't notice it.  Do you notice it 
 everywhere?
 
 
 Rolf r...@winmutt.com wrote:
 
 I certainly see it. Leds have to be pulsed or they burn out.
 
 Sent via string from my tin can.
 
 
 -- 
 Max Dillon
 Charleston SC
 '95 E300, '87 300TD
 
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Re: [MBZ] Strobing?

2012-07-07 Thread Rolf
A resistor is all that is needed but that is inefficient and then you 
lose the ability to control intensity (brake lights).


I've found cadillac's brake lights to be the worst.

-Rolf

On 7/7/2012 10:40 AM, Allan Streib wrote:

Max Dillonmeadedil...@bellsouth.net  writes:


  Almost every single appliance I own uses LED lights, so they are all
  pulsing and strobing?  Guess I'm lucky I don't notice it.  Do you
  notice it everywhere?

It used to be pretty obvious on old LED digital displays (calculators,
watches) but I always assumed that was because each segment was being
driven sequentially by the hardware.


Rolfr...@winmutt.com  wrote:


I certainly see it. Leds have to be pulsed or they burn out.

I've never heard that an LED must be pulsed, just need a resisitor in
series to control the current.  Is this incorrect?




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Re: [MBZ] Strobing?

2012-07-07 Thread clay monroe
Blinker maybe has no impact on energy saving, but you will drop amperage draw 
using LED for always on applications.   BiL changed out all lamps to LED in his 
rig and amperage went from 70 to 7.

clay
 
On Jul 6, 2012, at 8:37 PM, David Bruckmann wrote:

 I see the same thing. There's a definite strobing effect with LED taillights 
 and brake lights. Definitely on GM products; not sure about MB.
 
 To me, the LED blinkers are purely idiotic. The afterglow from an 
 incandescent bulb increases the chances that you will notice a blinker vs. 
 light that is instantly absent as the flasher cycles. And I don't buy the 
 argument that there are any significant energy savings to be had in such an 
 application.
 
 D.
 
 On Fri, 6 Jul 2012 17:38:28 -0600, Craig wrote:
 
 With subject car about 100 - 150 yards ahead, glance to the left side and
 then slew your eyes to the right side. When I do that, I see the strobing
 very clearly. And, yes, I wear glasses, too, but I cannot see how it
 matters.
 
 
 Craig
 
 
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Re: [MBZ] strobing

2012-07-07 Thread clay monroe
I was thinking about swapping in LED to the headlamps.  Pretty cost ineffective 
if that application would not work.  The glare shield in the euro lamps reduces 
light bleed head on and a bit to the side.  Not silvered so it does not reflect 
photons back toward the reflectors.



clay 


1974 450sl -  Frosch - Two tone green
1972 220D - Gump - She is green, simple and ran
1995 E300D - Cleo - Used by the Queen of Denial
POS 1987 SDL - Beware Nigerian Scammers







On Jul 6, 2012, at 9:41 PM, Jim Cathey wrote:

 Flicker perception is highly variable.  My main objection
 is the instant-on/off nature more than any modulation
 artifacts.  Very jarring.  And yes, overly bright on-axis,
 overly dim off-axis, and hideously expensive when something
 does go wrong.  I think LED's might have a place in marker
 lights, but not for the big lumen jobs.
 
 -- Jim
 
 
 
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Re: [MBZ] Strobing?

2012-07-07 Thread Fmiser
 Rolf wrote:

 I certainly see it. Leds have to be pulsed or they burn out.

No.  

Heat dissipation is a major limiting factor in the light output
of LEDs.  The simple way to avoid overheating the LED is to set
the current limit to low enough that with constant current the
substrate can dissipate the heat fast enough to keep the
junction below failure temperature.  No pulsing - steady,
continuous light output.

A trick that works because of how human eyes see is to pulse the
drive current.  So long as the average is low enough to not
damage the junction, the intensity of the light while it's on
can be much higher.  This is NOT how all LEDs are driven!

--   Philip


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Re: [MBZ] Strobing?

2012-07-06 Thread RELNGSON
 The LEDs themselves are not the problem; the way the engineers 
 designed
 the drive circuits for the LEDs is. On some LEDs, you can get more light
 out of them by pulsing the current driving them, with a higher peak
 current but the same average current than just driving them with a
 constant current. If the engineers just drove them with a constant
 current, the illumination would be constant.
 
 I _really_ dislike the strobing in cars, too...
 
How many of you that see this strobing effect wear glasses?

I see lots of cars with LED lights and none of them do what you describe. 
Just yesterday I was behind a new Cadillac SUV-thing with bright rear LED 
lighting and aside from being overly bright there was no strobing effect.

RLE

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Re: [MBZ] Strobing?

2012-07-06 Thread Dan Penoff
I was trying to understand these comments as well.  I haven't noticed any sort 
of strobing when observing LED taillights.

And yes, I wear glasses if it matters.

Dan


On Jul 6, 2012, at 7:12 PM, relng...@aol.com wrote:

 The LEDs themselves are not the problem; the way the engineers 
 designed
 the drive circuits for the LEDs is. On some LEDs, you can get more light
 out of them by pulsing the current driving them, with a higher peak
 current but the same average current than just driving them with a
 constant current. If the engineers just drove them with a constant
 current, the illumination would be constant.
 
 I _really_ dislike the strobing in cars, too...
 
 How many of you that see this strobing effect wear glasses?
 
 I see lots of cars with LED lights and none of them do what you describe. 
 Just yesterday I was behind a new Cadillac SUV-thing with bright rear LED 
 lighting and aside from being overly bright there was no strobing effect.
 
 RLE
 
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Re: [MBZ] Strobing?

2012-07-06 Thread Craig
On Fri, 6 Jul 2012 19:24:27 -0400 Dan Penoff lwb...@yahoo.com wrote:

 I was trying to understand these comments as well.  I haven't noticed
 any sort of strobing when observing LED taillights.
 
 And yes, I wear glasses if it matters.

With subject car about 100 - 150 yards ahead, glance to the left side and
then slew your eyes to the right side. When I do that, I see the strobing
very clearly. And, yes, I wear glasses, too, but I cannot see how it
matters.


Craig

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Re: [MBZ] Strobing?

2012-07-06 Thread OK Don
I'll try that, as I haven' noticed the strobing either.

On Fri, Jul 6, 2012 at 6:38 PM, Craig diese...@pisquared.net wrote:

 With subject car about 100 - 150 yards ahead, glance to the left side and
 then slew your eyes to the right side. When I do that, I see the strobing
 very clearly. And, yes, I wear glasses, too, but I cannot see how it
 matters.


 Craig

 --

OK Don
2001 ML320
2012 Passat TDI DSG
1997 Plymouth Grand Voyager
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Re: [MBZ] Strobing?

2012-07-06 Thread Allan Streib
Dan Penoff lwb...@yahoo.com writes:

 I was trying to understand these comments as well.  I haven't noticed
 any sort of strobing when observing LED taillights.

I think it's more the instantaneous on/off of LEDs
vs. not-quite-as-abrupt brightening/darkening of an incandescent bulb.

Also if you are directly in line with the LEDs they are almost
blindingly bright.  

Allan
-- 
1983 300D
1979 300SD

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Re: [MBZ] strobing nicht

2012-07-06 Thread RELNGSON
 I was trying to understand these comments as well.  I haven't noticed 
 any sort of strobing when observing LED taillights.
 
 And yes, I wear glasses if it matters...
 
My question was for those who see strobing, do you wear glasses? Since 
you don't see strobing..

RLE

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Re: [MBZ] Strobing?

2012-07-06 Thread David Bruckmann
I see the same thing. There's a definite strobing effect with LED taillights 
and brake lights. Definitely on GM products; not sure about MB.

To me, the LED blinkers are purely idiotic. The afterglow from an 
incandescent bulb increases the chances that you will notice a blinker vs. 
light that is instantly absent as the flasher cycles. And I don't buy the 
argument that there are any significant energy savings to be had in such an 
application.

D.

On Fri, 6 Jul 2012 17:38:28 -0600, Craig wrote:

With subject car about 100 - 150 yards ahead, glance to the left side and
then slew your eyes to the right side. When I do that, I see the strobing
very clearly. And, yes, I wear glasses, too, but I cannot see how it
matters.


Craig


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Re: [MBZ] strobing

2012-07-06 Thread RELNGSON
 ...With subject car about 100 - 150 yards ahead, glance to the left side 
 and
 then slew your eyes to the right side. When I do that, I see the strobing
 very clearly. And, yes, I wear glasses, too, but I cannot see how it
 matters...
 
I can. It's your correction. 

BTDT with another visual phenomenon (halos around lights at night) which 
was eliminated with a small change in my prescription.

RLE

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Re: [MBZ] strobing

2012-07-06 Thread OK Don
Peception of halos is due to the image not being in focus on your retina.
Yes, cured by a new prescription.

Strobing perception is more likely due to neurology - same as those who
can't look at a 60Hz CRT monitor without getting headaches.You can
see strobe effects some times when watching the wheels of cars going past
you while sitting at a stop light if you swing your eyes one way or the
other. I don't thinkglasses will have anything to do with perceiving the
strobe effect.

On Fri, Jul 6, 2012 at 10:39 PM, relng...@aol.com wrote:

  ...With subject car about 100 - 150 yards ahead, glance to the left side
  and
  then slew your eyes to the right side. When I do that, I see the strobing
  very clearly. And, yes, I wear glasses, too, but I cannot see how it
  matters...
 
 I can. It's your correction.

 BTDT with another visual phenomenon (halos around lights at night) which
 was eliminated with a small change in my prescription.

 RLE

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-- 
OK Don
2001 ML320
2012 Passat TDI DSG
1997 Plymouth Grand Voyager
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Re: [MBZ] strobing

2012-07-06 Thread RELNGSON
 ...Strobing perception is more likely due to neurology - same as those 
 who
 can't look at a 60Hz CRT monitor without getting headaches.You can
 see strobe effects some times when watching the wheels of cars going past
 you while sitting at a stop light if you swing your eyes one way or the
 other. I don't think glasses will have anything to do with perceiving the
 strobe effect...
 
This is a question for an Opthalmologist, not a lay person here.

RLE

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Re: [MBZ] strobing

2012-07-06 Thread Jim Cathey

Flicker perception is highly variable.  My main objection
is the instant-on/off nature more than any modulation
artifacts.  Very jarring.  And yes, overly bright on-axis,
overly dim off-axis, and hideously expensive when something
does go wrong.  I think LED's might have a place in marker
lights, but not for the big lumen jobs.

-- Jim



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Re: [MBZ] Strobing?

2012-07-06 Thread Rick Knoble
On Jul 6, 2012, at 6:12 PM, relng...@aol.com wrote:

 I see lots of cars with LED lights and none of them do what you describe. 
 Just yesterday I was behind a new Cadillac SUV-thing with bright rear LED 
 lighting and aside from being overly bright there was no strobing effect.


I *think* they (LEDs) are controlled by pulse width modulation. Which 
means_they_strobe. Imperceptible to most maybe, but my eyes constantly move 
when driving. The movement of my eyes makes the effect noticeable. And no, I do 
not wear glasses when driving. Only for reading. The maturation process sucks. 

Rick
Sent from my iPhone

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Re: [MBZ] Strobing?

2012-07-06 Thread Jim Cathey

The maturation process sucks.


That's why I don't do it.  Getting _older_, however, seems
to be a bit harder to avoid, except the hard way.

-- Jim






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