Yes I know they have very bright pulsed LEDs in car lights so they can get pretend to look brighter than they really are. The average light output is the same, but the peak output is higher, which fools our eyes. Damn annoying if you have decent eyesight and can see the flicker. And also if you try to film it - I see TV programs about cars where the headlights are flashing as they aren't in time with the camera frames.


On Wed, 19 Dec 2018 17:11:20 -0000, Brian Gaff wrote:

Well the answer as in many things these days is it depends.
Some are very simple and do have a kind of pulsing taken from ripple on the
mains. Others seem to not do this, indeed poking a phototransistor connected
to an amplifier shows many different results. the same seems to go for CFLs
as well.
You would need to know what circuit they were using etc to figure out why.
One particular led in a stood across the road has a 1khz whine when point
the device at it but modulated onto a 100 hz buzz.

I often wonder if there is some jiggery pokery going on to drive leds hard
for split seconds to make them brighter.
Brian