OT: Motorway lights one cones... in sync?

[Chris J Dixon]

It's not just me then?

There is clearly an engineering mind set, which leads one to be perpetually wondering how things work. I gather some folk have a similar interest in people ;-)

I remember when very young, I thought I had gained my younger sister's permission to take one of her dolls and "see where the 'ma ma' came from". I certainly found out, but, unfortunately, reassembly proved beyond my skills. (BTW It was a simple but cunning combination of waveform generation and envelope shaping, involving a rubber sheet and shaped peg.)

Chris

[Skipweasel]

Known in our family as "The kiss of death". My brother and I both had it

- insatiable curiosity about how things work.

Another thing I've noticed since having kids is that they have litle idea of the strength of materials these days since there's so little thy can break without getting into trouble. They don't know how strong a tree-branch is when it's green or dead, they're flummoxed by ceramics etc.

I let both ours break things that are being slung out simply so they get an idea of how strong things (and kids) are.

A friend used to be a nursery teacher and one of the most popular activities she used to have was a box of old appliances - toasters, irons, radios, typewriters, that sort of thing. She'd put them all on the floor with a selection of tools and let the kids take them all apart. Of course, these days some busybody would come along and tell them it wasn't safe.

[Dave Liquorice]

I can't say I have noticed any LED vehicle lights with a flicker, they are rather bright/harsh though and switch on/off too quickly but once on the light is steady. I really don't like the fast on/off or off/on transition though, same applies to LED traffic lights. It can't beyond the wit of man to build a quick fade up/fade down into the LED "bulb" can it?

The vast majority of the warning lights in my car are LEDs, the one that I know isn't is the blue main bean one as the car pre-dates cheap commercial blue LEDs.

[Andrew Gabriel]

One of the more amusing examples was on Dessert Island Discs (radio 4) some weeks back. I can't recall who was being interviewed unfortunately (possibly a surgeon), but he recounted an incident from his childhood. At somewhere around age 5, he found his guinea pig had died. Ever curious, he decided to take it apart to see how it worked, very much to the horror of his mother who turned up when he was well in to the disassembly process.

[Chris J Dixon]

AFAIK, the only LED on my Mondeo is the aircon indicator, which is completely invisible in daylight. As the switch is push-on, push-off, this is very much less than helpful.

Chris

[Mike Clarke]

Simple enough to do but I did come across an argument that LEDs were better for brake lights because they came on instantly instead of the fraction of a second filaments needed to heat up, giving the car behind fractionally more braking time.

[Clive George]

Try scanning your eyes across fairly quickly. I find the LED car lights appear as a series of dots, showing it's flashing.

cheers, clive

[Dave Liquorice]

Hum. In my view the momentary dazzle and shock of the instant bright red light more than out weighs any thing gained from them coming on that much quicker.

[Skipweasel]

Our five year old daughter found a dead toad on holiday and happily buried it in an ant nest, coming back every day to disinterr it to see how it was getting along. She was really excited when bones started showing.

[geoff]

In message , Skipweasel writes

... or how to react in unknown circumstances or emergencies, since they are never allowed to get themselves into suck positions

... or in fact testing the limits of anything

[geoff]

In message , Mike Clarke writes

So fractionally that it sounds like bollocks to me

[Andy Champ]

I have a high-level LED strip, and bulbs for the others. I've noticed when reversing in the dark that the high-level one does come on a tad sooner. Maybe 0.2 of a second.

70MPH is about 30m/second, so that's stopping 6m sooner. A good car length.

Andy

[<me9]

Oh but they do... Teachers, the law, they have tested the limits.

[John Rumm]

Its a couple of hundred ms, which at 70mph is a car length. So it can make the difference between stopping in time and not...

I tend to find LED indicators more unsettling than break lights because of the sharp attack and delay times.

[Andy Hall]

Except that one should not be so close that that makes a difference.

[Dave Liquorice]

Quite, and the above posters are not taking into account the momentary dazzle that the instant on of LED brake lights produce. Particulary at night, in the wet, on non-illuminated roads.

At least with a filament lamp your iris has a chance to react and reduce the dazzle. I wonder if the sudden on also cause overshoot on the iris as well, so you are effectively blinded for a short period until the iris sorts itself out. Wonderful, blind when you really need to see what is going on, and I'm not thinking of flowing high speed traffic but busy slow and/or stop go traffic...

Where is the research that shows LEDs are "safer".

[Mike Harrison]

Probably, but the suddenness of the switch-on probably makes it more noticeable in peripheral vision, which is very desirable for a brake light.

[Mike Clarke]

It certainly looks like there's good reasons why LED brake lights might be less safe but I wonder how soon some nannying knee jerk lawmakers decide that it must be A Good Thing because of that extra 0.2 seconds warning and require all new cars to have them, especially since it will be another case where filament bulbs can be replaced by low energy devices to "help us reach the CO2 targets".

[<me9]

they also seem to be considerably brighter than filament brake lights, and more capable of dazzling.

They are a pain in the A*** when stopped (the correct distance) behind them at traffic lights and junctions. Is one no longer required to use the handbrake in such circumstances.

[geoff]

So creates even more of a concertina effect on the M25 then ...