On Wed, 27 Feb 2013 14:01:21 +0000, John Williamson
wrote:

The principle lets them use cheaper dies for the same apparent output
and life. As the human eye is closer to being a peak level sensor than
an average level sensor when light is pulsed, everyone is happy, except
those who can see the flickering.

My headlamp strobes on low power, but not on high. Something to beware
of when viewing rotating machinery. I reckon it's around 40Hz.