XPost: alt.home.repair, uk.d-i-y   
   From: Gothberg"@internet.co.is   
      
   On Thu, 20 Dec 2018 16:25:22 -0000, trader_4  wrote:   
      
   > On Thursday, December 20, 2018 at 7:29:53 AM UTC-5, William Gothberg wrote:   
   >> On Thu, 20 Dec 2018 11:57:01 -0000, whisky-dave    
   wrote:   
   >>   
   >> > On Wednesday, 19 December 2018 16:35:05 UTC, 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?   
   >> >   
   >> > It's easy but that isn't the point. The most efficient way of driving to   
   make maximium power  into the LED means yuo have to pulse the LED's. Using a   
   capcitor to smooth out the DC is yet another mode of inefficincy as it would   
   get warm due to    
   current flow. Indictors in series might be better but then you run the risk of   
   'radio' interference.   
   >>   
   >> Being inefficient would presumably make it impossible to get enough   
   brightness out of LEDs that fit into the lamp holder.  The LEDs would get too   
   hot trying to give out enough brightness for a car headlight.   
   >>   
   >> However cars vary a lot, some are easy to detect flickering, some   
   difficult, and some impossible (with the naked eye).  Perhaps they just use a   
   higher frequency?   
   >>   
   >> Taillights are pretty bad on a lot of cars, as they dim the brakelights by   
   deliberately flickering them.   
   >   
   > Either you have eyes that are way more sensitive to this or you're in a   
   > country that uses different car lights than here in the USA.  There   
   > are a lot of cars with LED lighting, headlights and rear lights, and   
   > I've never noticed this flickering, nor have I ever heard it mentioned   
   > before this thread.  I haven't noticed flickering from any LED lights   
   > I've used either.   
      
   I can see flicker on a 60Hz CRT monitor, but not on a 90Hz one, so that'll   
   give you an idea on how good my eyes are.   
      
   Can you see flicker on tailliights if you scan your eyes across the scene?   
      
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