In article >,
Richard Sexton > wrote:
> >> That's pretty naive in my opinion.
> >
> >Really?

> Really. That's my opinion. It's not a fact and reasonable people disagree
> all the time. I'm listening.

I'm not objecting to you disagreeing - merely objecting to you calling my
opinion naive. Which suggests I haven't given it any thought or know
nothing about lighting.

> >> Nothing could be easier than incandescents. You apply voltage to two
> >> pins and they make light. They're cheap.
> >
> >Well just about everything on a car has moved on with improving
> >technology. Or perhaps you want to go back to points ignition? That's
> >cheap too. As is a nice single downdraught carb.

> No. We're talking about lights here.

But the 'simple and cheap' arguments are often put forward in favour of
points and carbs. And those who do simply ignore efficiency.

> >> HIDs ARE great, but, they have a lot of problems with automotive
> >> applications: they don't come on instanly and a lot has to be done to
> >> get around this.
> >
> >Err, how often does it get dark suddenly? I've never found the time they
> >take to get to full output a problem.

> Well, YOU haven't had a problem but the fact remains, with incandescents
> when you turn on the switch you get full brightness immediately. There's
> a non-zero chance this will be a problem somewhere sometime.

Again why? Many cars still have incandescent main beams. For signalling
purposes if nothing else. No reason why they couldn't be incorporated into
a main beam HID setup for just this reason.

> >> They require weird voltages and an extra large striking
> >> voltage. They're expensive and complicated.
> >
> >They *sell* for much more. But then so does everything when it's new.

> I know why, I'm just pointing out it falls in the "con" not "pro" column.

> >> They are however more efficient so you get the same light from less
> >> voltage and that's important.
> >
> >Actually, less current.

> True. Less energy what what I meat to say and module some teenager
> pranging in my ear I actually might have.

> >> They're not THAT much brighter, they just look brighter
> >> because of the color of the light.
> >
> >They produce approximately three times the light for the same current -
> >not difficult since incandescent lamps are incredibly inefficient.

> Understood, but incandcents, using more energy yield very close to
> the same light, and advanced ones lke CSR's put out more light than
> HIDs.

The light output of any lamp can be increased or decreased. Saying you can
already buy an 150 watt H7 incandescent but only a 35 watt HID is pretty
meaningless in the scale of things. However, upping the wattage of an
incandescent can often result in reflector or lens damage due to heat. And
voltage drop in the wiring etc can also cause problems.

> >For things like tail lights etc you don't need omni directional
> >radiation - indeed this just means you have to add some form of
> >reflector.

> No and no. You need to check lighting regulations and yo're guessing
> (wrongly) about the reflector.

The reflector behind a incandescent lamp in say an indicator or tail light
- not a passive reflector needed for safety. Because ordinary incandescent
bulbs have a near omnidirectional beam pattern, some form of crude
reflector is needed to increase the efficiency. Not so with an LED type
where the lens is built in.

> >For many applications around the car, filament or point source lamps
> >are anything but ideal. Interior lighting for example would be better
> >with large soft sources. As would most other lights apart from
> >headlamps. We're simply used to filament lamps - that's all.

> Well, I've tried LED's inside. Worthless. You go try it ane lemme know
> what you think. Luxeons are nice ones to play with.

LED technology has a long way to go - as with much else in lighting. But
the sure thing is the tungsten filament bulb's days are numbered.

--
*If love is blind, why is lingerie so popular? *

Dave Plowman London SW
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