XPost: alt.home.repair, uk.d-i-y   
   From: Gothberg"@internet.co.is   
      
   Yes I know they have very bright pulsed LEDs in car lights so they can get   
   pretend to look brighter than they really are.  The average light output is   
   the same, but the peak output is higher, which fools our eyes.  Damn annoying   
   if you have decent    
   eyesight and can see the flicker.  And also if you try to film it - I see TV   
   programs about cars where the headlights are flashing as they aren't in time   
   with the camera frames.   
      
      
   On Wed, 19 Dec 2018 17:11:20 -0000, Brian Gaff    
   wrote:   
      
   > Well the answer as in many things these days is it depends.   
   >  Some are very simple and do have a kind of pulsing taken from ripple on the   
   > mains. Others seem to not do this, indeed poking a phototransistor connected   
   > to an amplifier shows many different results. the same seems to go for CFLs   
   > as well.   
   >  You would need to know what circuit they were using etc to figure out why.   
   > One particular led in a stood across the road has a 1khz whine when point   
   > the device at it but modulated onto a 100 hz buzz.   
   >   
   >  I often wonder if there is some jiggery pokery going on to drive leds hard   
   > for split seconds to make them brighter.   
   >  Brian   
      
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