XPost: uk.rec.driving   
   From: no@spam.com   
      
   On Tue, 23 Apr 2013 11:10:27 +0100, Dave Plowman  wrote:   
      
   > In article ,   
   >     wrote:   
   >> On Mon, 22 Apr 2013 19:44:38 +0100   
   >> "Major Scott"  wrote:   
   >> >Surely they can design LED lights on cars to have a higher frequency   
   >> >PWM= ?  Even =A3100K cars flicker dramatically, especially when filmed.   
   >> > It m= akes them look really cheap.  All it would take is a higher   
   >> >frequency PW= M, or a smoothing capacitor?   
   >   
   >> They flicker for a reason. If they smoothed the current they might just   
   >> as well use DC direct from the battery. I don't know the technical   
   >> reasons why but apparently using the equivalent DC voltage required to   
   >> get the same brightness as you can get by strobing them would burn them   
   >> out. I'm sure some electronics guru on here can explain more. But it   
   >> does lead to interesting effects on video as you say :o)   
   >   
   > Pulsing an LED is a way of getting a higher light output from it without   
   > overheating. Overheating an LED kills it in short order. Seeing a flicker   
   > from them on a video is the same effect as wagon wheels appearing to turn   
   > backwards on old cowboy and indian films - stroboscopic effect.   
      
   The front LED running lights don't even flicker on camera.  And I don't think   
   brakes do either.  So why make the tails any different?  They're made up of   
   many LEDs, so just power up less of them (which I've seen buses doing) for   
   tail and all of them for    
   brake.   
      
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