Re:flicker crashes (Score 3, Informative)

Cars and buses with LED tail lights are not running them at 60Hz. Nor are they being pulsed at any rate. The electrical system in a car is 12V DC. The LED assembly is either designed with enough LEDs in series such that the forward voltage drop over the set is 12V (roughly 10 LEDs) or they are in parallel with a buck-style switching power supply in front of it.

Now, before you go on about how the switching power supply causes flicker, you should research how they work. You will find that for cost and size reasons, it is better to run a buck topology as fast as possible. 250kHz, 500kHz, and 1MHz are common frequencies. Of course, the output from the switching portion is put through a LC filter such that the voltage ripple is reduced to a small percentage of the target output voltage. Besides, LED brightness is controlled by current. Even a 5% voltage ripple on a 2V output would trigger a few lumens of brightness difference.

So, if you are seeing flicker in car and bus tail lights, then you can see a 250kHz "flicker" with an average brightness delta of a few lumens. If you can, I'm sure there are plenty of researchers who would love to talk to you as you are the only person on the planet who can.

Of course, since cost is the driving factor in these types of devices, they probably aren't using the switcher at all and thus there is _no_ flicker due to electrical reasons. You are probably being more affected by the directionality of the LEDs and the lenses used being vibrated by the engine at idle speeds. You get the same effect watching a motorcycle headlamp on a rough road. The light isn't flickering, it is just vibrating enough that the beam is falling in and out of your eye.