XPost: alt.home.repair, uk.d-i-y   
   From: Gothberg"@internet.co.is   
      
   On Thu, 20 Dec 2018 04:22:39 -0000, Clare Snyder  wrote:   
      
   > On Wed, 19 Dec 2018 19:36:51 -0000, "William Gothberg" <"William   
   > Gothberg"@internet.co.is> wrote:   
   >   
   >> On Wed, 19 Dec 2018 17:47:17 -0000, trader_4  wrote:   
   >>   
   >>> On Wednesday, December 19, 2018 at 11:35:06 AM UTC-5, William Gothberg   
   wrote:   
   >>>> On Wed, 19 Dec 2018 16:21:41 -0000, Mark Lloyd  wrote:   
   >>>>   
   >>>> > On 12/19/18 6:01 AM, William Gothberg wrote:   
   >>>> >   
   >>>> > [snip]   
   >>>> >   
   >>>> >> They probably are fairly crude.  I know they flicker, for example if I   
   >>>> >> use my cordless drill, the chuck appears to spin the wrong way under   
   the   
   >>>> >> LED lighting.   
   >>>> > I remember seeing that with a washing machine (under fluorescent   
   >>>> > lights). As the tub was slowing down, the row of holes around the tub   
   >>>> > would appear to reverse direction. Same thing with (spoked) wagon wheels   
   >>>> > in movies.   
   >>>>   
   >>>> It looks absolutely ridiculous with modern cars with LED headlights in   
   films.  How hard can it be to put a smoothing capacitor on the output of the   
   power supply?   
   >>>   
   >>> I've never noticed that.  Any films come to mind?   
   >>   
   >> A lot of Top Gear programs showing the DRLs of cars fitted with LEDs.  With   
   a feature film, they might take the time/trouble/money to do something to stop   
   it.   
   >>   
   >>> It seems especially   
   >>> weird, since cars have a 12V supply with a big battery to smooth   
   >>> anything out.  I guess the power supply that reduces that to whatever   
   >>> the LED headlights use though might have a switching power supply these   
   >>> days too.   
   >>   
   >> AFAIK it's deliberate, making the LEDs operate brighter than they are   
   capable of, but only 1/4 of the time.  Our eyes just see the brightest part of   
   the cycle, so we think they're four times brighter than the LED is really   
   capable of, without    
   overheating itself.   
   >   
   >  That is PWM Overdrive. Peak junction current is over the nominal   
   > rating, but the average power consumption is below nominalmaximum   
   > current - and the peak lumen output is significantly enhanced without   
   > reducing the junction life appreciably.   
   >  THIS would definitely cause flicker as there is a "significant" dead   
   > period between the "strobe flashes"   
      
   Agreed, although Rod thinks only freaks can see it.   
      
   I wonder why none of my houselights use this?  Do car lights have to make more   
   brightness from a smaller area?  Or would flickery houselights annoy people   
   more?   
      
   If it's the extra brightness, I don't understand - because I have a torch with   
   a single LED and parabolic reflector that gives out 20W equivalent without   
   overdrive.  Simply have three such lamps with their own little (only 1.5   
   inches across) reflector    
   next to each other to make the headlamp.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)