XPost: uk.rec.driving   
   From: dave@davesound.co.uk   
      
   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.   
      
   --   
   *WHY IS THERE AN EXPIRATION DATE ON SOUR CREAM?   
      
       Dave Plowman     dave@davesound.co.uk     London SW 12   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)