XPost: alt.home.repair, uk.d-i-y   
   From: Gothberg"@internet.co.is   
      
   On Thu, 20 Dec 2018 21:04:01 -0000, Rod Speed  wrote:   
      
   >   
   >   
   > "William Gothberg" <"William Gothberg"@internet.co.is> wrote in message   
   > news:op.zub0oriqo5piw3@desktop-ga2mpl8.lan...   
   >> On Thu, 20 Dec 2018 17:13:52 -0000, trader_4    
   >> wrote:   
   >>   
   >>> On Thursday, December 20, 2018 at 12:07:40 PM UTC-5, William Gothberg   
   >>> wrote:   
   >>>> 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?   
   >>>   
   >>> Like I said, I haven't noticed it in the driving I've done.  Nor have I   
   >>> heard anyone else mention it.  Next time I come across a car that has   
   >>> LEDs I'll look more closely and see if I can see anything.  If just   
   >>> scanning reveals it, you;d think a lot of people would be noticing it.   
   >>> Scanning is a part of driving.   
   >>   
   >> I'd estimate about 1 in 5 people can see it,   
   >   
   > Its nothing like that high and we know that because nothing   
   > like that many saw any flickering with fluorescent lights.   
      
   Er.... most people I know can see fluorescent flicker.  It doesn't annoy most   
   of them, but they can detect it.  One in five people I know could see 60Hz   
   monitor flickering.  And about the same can see car lights flickering.   
      
   >> similar to how many can see flicker on a 60Hz CRT computer monitor.   
   >   
   > Nothing even remotely like 1 in 5 can see that.   
      
   You must know some people with really shitty eyesight.  I noticed that more   
   people who were younger and/or didn't wear specs could see the flicker.   
      
   >> Don't most cars have LEDs now?  Or does your area have a lot of older   
   >> cars?  People (stupidly) around here seem to like cars that are no more   
   >> than 10 years old.  I don't think many cars after 2008 had bulbs.   
   >   
   >> Searching for "LED tail light flicker" without the quotes in google   
   >> produces 4.5 million results!   
      
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