Lightbulbs - the facts?

Do you find car LED tail lights distracting? I do - to me they appear to move slightly separately from the car itself. Not enough that it causes a danger, but very irritating.

I think they should be banned, requiring the use of a resistance rather than a pulse for a constant light, or required to use a far higher pulse frequency (several kilohertz at the very least). I hate to think what they do to epileptics, some of whom are *really* sensitive to such things.

Neil

Not nearly as much as bright headlights, especially if badly aimed.

--=20 Davey.

Eh? DC, isn't it?

I doubt it in my case.

Pulsed DC at about 100Hz. The mark/ space ratio is varied on tail/ brake lights.

Ah, righto. So not just extra LEDs coming on for the brake lite then.

And used in in good daylight.

Ugh, that's *far* too low for use on a moving object.

Definitely think 1kHz+ is required.

Neil

I have no motive - in fact as far as I know, you don't have to sign up to anything to see that image.

Couldn't care less if you sign up or not tbh :)

Darren (Chapman)

Yup, the same LEDS just driven harder. They're not rated to do it for long, though.

Yup, some of them...

I like the LED cats eyes you get in some places worse though - first they are pulsed so strobe, and secondly they light up on both sides - so you see them as a strobing trail in your rear view mirror as well.

I would not ban LEDs as such (especially as the faster rise time on brake lights actually amounts to a car length or more extra stopping distance at speed), but I agree that a higher PWM frequency for brightness modulation would be a good thing.

Extra lights used to be the way when LEDs were introduced for brake lights (in fact quite often alongside incandescent tail lights). Those were DC and posed no problem. Now there seems to be a trend for only one set of LEDs doing both, and PWM being used to control the brightness. These are not so nice!

Make that a foot or two of extra space. 21 watt bulbs get to full brightness in tens of milliseconds. Your theory would make it about a quarter of a second. Unless you're talking about Formula one on the straight, of course.

A car length? I haven't done any sums, but I suspect that the faster rise time of LED brightness of LEDs only gives you (at most) a few mm extra stopping distance.

But am I alone in finding the 'bang-bang' on-off of LED rear lights (and especially the indicators) extremely annoying? I would much prefer that the on-off action was tailored to mimic incandescent bulbs.

They are on some London buses - one LED stays on longer than the whole matrix and (in a stepped manner) fades out.

It's just the flicker that annoys me, though. Up it to 1kHz+ and I wouldn't care.

Neil

Yes.

Agree completely.

I was following a really silly one the other night - the tail lights flickered for maximum annoyance, yet the indicators were real bulbs for that slow ramp up.

Andy

I doubt it's as high as 100Hz. I'd go for 50.

Usually the brakes are full on.

Andy

My high-level light is LEDs, the others are bulbs.

It's a lots of 10s of milliseconds. I'd have gone for a quarter of a second. Anyone got a high-speed camera?

Andy

Its typically at least 100ms to get to useful brightness... you only need to watch the lights on cars with traditional incandescent brake lights, and a high level LED light - 100ms of difference is easily observable. Thick filament 12 lamps are quite "slow". Even at only 15m/s that's 1.5m