Oh those troublesome holes. Takes forever to fill 'em. Insatiable.

LED's are much faster than incandescents. Look at most any vehicle that has LED's in the side mirrors and incandescents in the rear turns. The timing is visibly different and painfully obvious. At least one vehicle maker has recognized this and compensated for it in the driver timing, even PWMing the LEDs during turn on to emulate the familiar incandescent "warm up".

The inherent flicker in LED tail lights (and other LED lighting) bothers the crap out of me. I know not everyone sees it, but apparently my eyesight is a bit more responsive than some. I see the flicker in neon signs and various LED backlights as well.

The PWM rate is designed to be faster than normal visual threshold of detection, but below the audio threshold of annoyance... that is, over a hundred HZ or so, but out of the sweet spot of human hearing, a few hundred HZ to a few KHz. It seems counter-intuitive that the visual threshold is lower than audio, but in this case, it is.

The PWM rate could easily be set above the hearing range, but that has potential implications for causing EMI certification problems.

We installed LED lights in our bathroom fixtures -- and one of the wifes' hair appliances modulates the LED bulbs badly. I'm not sure if I should blame the bulbs or the curling iron in this case.

Terry

All LEDs have some start delay. Even the original ones used for
indicators had a short delay. It's while the electrons fill the
electron holes where they should be.

Steve

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