XPost: alt.home.repair, uk.d-i-y   
   From: Gothberg"@internet.co.is   
      
   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.   
      
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