DIYbanter - View Single Post - Do switch mode power supplies flicker in time with mains?

gregz

Bubba wrote:
On 12/19/18 9:22 AM, wrote:
In this case they will NOT be in sync. Switching power supplies are
usually free running and the frequency will be drifting around. Even
if they are the same model, component tolerances and temperature
variations will mean they are on slightly different frequencies and
there will be no defined phase relationship.
mark

Correct. My strings of cheapo imported LED Christmas lights appear to
the naked eye to be on 100%.

However, when viewed through my cheapo webcam, they appear on for 5
seconds, fade to off 2 seconds, off for 5 seconds, fade to on 2 seconds,
lather/rinse/repeat.

It's so simple to see 60 or 120 Hz flicker. Everyone knows how move your
eyes quickly around the light source and lines will be visible with blank
sections. Your eys turn into icilloscope. Everyone ? Anyone ?

Greg