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Query on pulsing LEDs: power vs. apparent brightness

On a sunny day (Sat, 17 Mar 2012 07:56:36 -0700 (PDT)) it happened snipped-for-privacy@yahoo.com wrote in :

I use >15 kHz PWM in my LED controllers, Perceived brightness is proportional to the duty cycle. I am not saying it is 100 linear, as I have not measured it, but it gives a linear feel. http://panteltje,com/panteltje/pic/ethernet_color_pic/ Color mixing of R,G, B works fine. I added an adjustable gamma correction in the software, but that is normally off, and when on makes very little difference for the eye for reasonable values of gamma. I use large multi RGB LED strips.

I have tried PWMing a white LED at a much lower frequency, and I think indeed there is some point where you could save power, but then some people would perhaps complain about flicker.

At even lower frequencies you can use the LEDs to make messages:

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that is completely on of, if you hold it steady you see the LEDs switch on and off at a few Hz.

Reply to
Jan Panteltje
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Your retina has pigments, that absorb light and bleach. It takes some time to notice that the light has CHANGED, but the retinal detection is as fast as the bleaching process (lots faster than any electric signals you're likely to send to an LED). Mainly, all that you worry about at the perception-of-light in the eye, is that flicker doesn't show up (48 Hz is high enough,

24 Hz, like oldtime movie projectors, isn't), and that especially the (alpha rhythm?) sensitive frequencies for causing epileptic seizures not be present.
Reply to
whit3rd

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