PWM in cell-phone torch

[Sceadwian]

No, perception of brighter vs darker over actual increased optical clarity in a situation which requires perception of more than simple lighter or darker.
The placebo affect is real, doesn't mean sugar pills make you not sick =) Just makes you feel like you're not sick. Actual quantification of perception vs reality is painstakingly difficult.

 

[PCBWING]

Read up similar stuff on a couple of websites, and from what I gathered, driving the LED via pulses actually gives u the freedom to send current as high as 500mA(depends on the diode) in short-duty-cycle pulses. Thus, the average current would be much less, and within safety limits, while higher brightness is ensured. Also, seems some research has found out that the human eye *perceives* pulsed light to be brighter than continuous light of the same luminous intensity.

I think it is for this reason

 

[audioguru]

I use PWM as an efficient dimmer for LEDs. They look dimmer, not brighter.

 

[Sceadwian]

The average current can't be less =) do the math.

 

[audioguru]

The average current of LEDs driven by PWM determines their brightness.

 

[Sceadwian]

Their absolute brightness yes, but not their apparent brightness. Human perception is a bit tricky. A pulsed LED delivering a peak light output 1.5 times the average light output of a steady state LED will be visible to the human eye from a greater distance, even if the average brightness of the pulsed LED is equivalent. I don't think this effect is useful in close quarters though it's just at the lower limits of perception where it's noticeable.