XPost: alt.home.repair, uk.d-i-y   
   From: rod.speed.aaa@gmail.com   
      
   "William Gothberg" <"William Gothberg"@internet.co.is> wrote in message   
   news:op.zubminnfo5piw3@desktop-ga2mpl8.lan...   
   > On Thu, 20 Dec 2018 08:19:58 -0000, gregz  wrote:   
   >   
   >> Clare Snyder  wrote:   
   >>> On Wed, 19 Dec 2018 19:34:57 -0000, "William Gothberg" <"William   
   >>> Gothberg"@internet.co.is> wrote:   
   >>>   
   >>>> On Wed, 19 Dec 2018 18:03:19 -0000, Clark W. Griswold   
   >>>>  wrote:   
   >>>>   
   >>>>> On 12/19/2018 11:36 AM, William Gothberg wrote:   
   >>>>>> On Wed, 19 Dec 2018 16:18:29 -0000, Mark Lloyd    
   >>>>>> wrote:   
   >>>>>>   
   >>>>>>> On 12/19/18 5:23 AM, William Gothberg wrote:   
   >>>>>>>> Do switch mode power supplies flicker in time with mains?   
   >>>>>>>> Specifically   
   >>>>>>>> LED power supplies in commercially available domestic lamps. By in   
   >>>>>>>> time, I don't mean at the same 50/60Hz, but anchored to it. I.e. if   
   >>>>>>>> you   
   >>>>>>>> have several such lamps each with their own built in supply, will   
   >>>>>>>> they   
   >>>>>>>> all flicker in time, using the mains frequency to keep them in   
   >>>>>>>> time, or   
   >>>>>>>> will they be random, making the room overall not flicker due to   
   >>>>>>>> them all   
   >>>>>>>> being random?  And is there any way I can test this?  I tried   
   >>>>>>>> taking   
   >>>>>>>> photos of them, but my camera only goes as fast as 1/2000th of a   
   >>>>>>>> second,   
   >>>>>>>> which shows all the lights at the same brightness each time, I   
   >>>>>>>> suspect   
   >>>>>>>> the flicker is above 2000Hz.   
   >>>>>>>   
   >>>>>>> I once had an audio amplifier with a solar cell rather than a   
   >>>>>>> microphone   
   >>>>>>> for the input transducer. This made it possible to listen to light.   
   >>>>>>> The   
   >>>>>>> sun is steady, incandescent lights (AC powered) hum.   
   >>>>>>>   
   >>>>>>> That was 40 years ago. Maybe something like that would work today.   
   >>>>>>   
   >>>>>> The trouble is I want to compare 2kHz+ from one light with 2kHz+ from   
   >>>>>> a neighbouring light and see if they're in sync.   
   >>>>>   
   >>>>> Maybe use a dual trace oscilloscope?   
   >>>>   
   >>>> Haven't got one unfortunately.   
   >>>>   
   >>>>> Since this landed in alt.home.repair, I gotta ask.  Do you have   
   >>>>> single-phase or two-phase?   
   >>>>   
   >>>> Single.  I'm in the UK.   
   >>>  so 50 Htz - you can almost see an incandescent flicker at that   
   >>> frequency (at 25 you could)   
   >>>   
   >>>  (also rules out the previously mentioned "engineer friend")   
   >>   
   >> Lights flicker at twice the frequency, once for positive cycle, and once   
   >> for negative cycle. LEDs only once unles using a bridge rectifier, or   
   >> steady on using DC. Even though blinking they look normal straight on, my   
   >> brain says something is wrong   
   >   
   > Some brains (or eyes) seem to be faster than others.  I can easily (and   
   > annoyingly) see flicker on CRT monitors below 90Hz, others don't even see   
   > the 50 or 60Hz ones.  I can see flicker on 80% of car LED lights, others   
   > don't see any.  Designers really ought to account for those of us with   
   > better eyesight.   
      
   No point in doing that.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)