On 04/05/2021 13:23, Brian Gaff (Sofa) wrote:
OK what do they use then, All I remember from my brief experience trying to
dim leds was that the most successful way of doing that was by duty cycle,
ie on to off times with them driven by some kind of oscillator with variable
mark space ratios. However it is obvious that even the briefest of ons and
the longest offs tends to still be visible in most cases, and not terribly
accurate if many leds are used as the load, there being a spread of
linearity in any given number.

PWM is the cheapest way as it needs no other component.

For a small improvement in efficiency then a constant current source
would be best but obviously costs more.