"strobe" brake lights?
Pro
Joined: Apr 2005
Posts: 507
Likes: 4
From: Keene NH
It is caused by the video camera's shutter speed running in & out of sequence with the LED's frequency. You see similar illusions when video camera's make wheels look like they are spinning backwards by the shutter speed. 
Video camera's do the same thing when they record a TV in action. 
Video camera's do the same thing when they record a TV in action.
Thread Starter
Advanced
Joined: Apr 2005
Posts: 70
Likes: 2
I understand why the strobe effect is there on non-tungsten lighting utilizing AC voltages but a car is DC and the LED uses DC voltage, not AC at 60hz. Still don't understand the strobe effect on a stationary object such as the Corvette is in this clip.
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Moderator
Joined: Feb 2006
Posts: 39,066
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From: DFW Area TX
Perhaps the LED drivers use Pulse Width Modulation (PWM). PWM turns the LEDs on and off and can be used for dimming, or to control the amount of power delivered without using resitive means. PWM is more efficient than using resistors.
Racer
Joined: Aug 2001
Posts: 352
Likes: 0
From: San Diego CA
The frequency of the pulsing should be fast enough (say 100 Hz) so that it's not noticeable when you look at it in person (although I do notice the flicker in some tail lights when I move my eyes quickly).
Some video cameras, especially cheap ones, only hold their shutter open for an instant when they capture a frame. Even though they're capturing at 30 Hz (for example), they may only hold the shutter open for 1/100th of a second every 1/30th of a second. Sometimes then this fast shutter catches the LEDs in their "off" state and magnifies the apparent time that they are off from 1/100th to 1/30th of a second which is slow enough for you to see it.
Scraping the splitter.
Joined: Jun 2005
Posts: 8,111
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St. Jude Donor '13-'14-'15
I can't believe people are still asking this question and actually believe that the tail lights will really strobe like they do in this single video.
With the strobing tail light option, you get a mini-disco ball to hang off the rearview mirror.
S.
With the strobing tail light option, you get a mini-disco ball to hang off the rearview mirror.
S.
Racer
Joined: Jun 2006
Posts: 285
Likes: 8
There are actually two reasons why the LEDs would be strobed. The first was already mentioned, to make the LEDs appear to run at something less than full bright. This allows the same actual LEDs to be the running and braking lights. With conventional bulbs you either use two (or more) bulbs or have a dual filament bulb.
The other reason to pulse LEDs is because you can actually drive them brighter that way. For what ever reason you can get more average light out of a red LED if you over drive it then turn it off for a moment. I don't remember the details of this as it was over a decade ago I looked into it. Anyway, I know the earliest automotive LEDs were driven this way since otherwise the red LEDs weren't bright enough. I assume they still do it since it would allow you to use lower cost LEDs that aren't as bright.
The other reason to pulse LEDs is because you can actually drive them brighter that way. For what ever reason you can get more average light out of a red LED if you over drive it then turn it off for a moment. I don't remember the details of this as it was over a decade ago I looked into it. Anyway, I know the earliest automotive LEDs were driven this way since otherwise the red LEDs weren't bright enough. I assume they still do it since it would allow you to use lower cost LEDs that aren't as bright.
Drifting
Joined: Sep 2012
Posts: 1,665
Likes: 789
From: Hernando MS
I can't believe so many people are somehow just seeing this video effect for the first time. I remember wondering (and google'ing) what caused it when the first videos of the then new 458 began to circulate.. and that was about 4 years ago.
Burning Brakes
Joined: Aug 2010
Posts: 1,040
Likes: 1
From: Motorsports Capital of the World..Indianapolis Indiana
Great, now i watched the video and have DIO Holy Diver stuck in my head
OMFG over and over, really, I wouldn't even be able to speak, just trying to breathe and not tear up when I see the first one
Corvette is my PASSION
Oh yeah, not to be off topic......strobe light=rice and doubtful
OMFG over and over, really, I wouldn't even be able to speak, just trying to breathe and not tear up when I see the first one
Corvette is my PASSION
Oh yeah, not to be off topic......strobe light=rice and doubtful
Le Mans Master
Joined: Nov 2004
Posts: 5,885
Likes: 371
From: Cape Coral FL
Some of the newer Porsche's and MBs are coming with this from the factory. I see a Porsche in my area that has them?
http://api.viglink.com/api/click?for...13616344427685
http://api.viglink.com/api/click?for...13616344427685
Le Mans Master
Joined: Jul 2010
Posts: 6,582
Likes: 2,643
From: Lancaster, PA
Flashing LED and strobe light are NOT the same thing. I venture to say we'll see real strobe brake lights (activated by hard braking) in the future.
Imagine a KIA trying to slow down behind a car with CC brakes.
Imagine a KIA trying to slow down behind a car with CC brakes.