In article >,
Dave Plowman (News) > wrote:
>In article >,
> Richard Sexton > wrote:
>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.

The cost, complexity and lack of "instant on" make these non-starters in
automotice use for anything other than specialized purposes. IMO to suggest
all cars shpuld rely on HID sole; is naive. Nothing personal...

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

I don't know anybody that prefers carbs to injection but I do know a few
folks that will not convert older cars to pointless systems. Maintenance
is minimal and they point out if/when they fail you can pretty much fix them
with a rock but if a pointless system fails, you're screwed. I'm neutral
on this and just keep my cars original.

>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.

I think it's the lack of an "instant on" abaility.

>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.

Understood. In halogen fixtured that have the bulb base and reflector than
can handle it you can ho pretty high. Not sure what's actually under debate
here.

>> >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.

LED"s shoot light out in one direction and lighting regulations require
signalling lamps be seen from more than one direction. It's an issue.

>> >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.

Perhaps, when LED's can do what incandescents too. But until then.

Hey I *hate* incandescents in the house and everythning is CFL here,
but having tried LEDS in the dask and dome lights - they just don't work
well at all.


--
Need Mercedes parts? http://parts.mbz.org
Richard Sexton | Mercedes stuff: http://mbz.org
1970 280SE, 72 280SE | Home pages: http://rs79.vrx.net
633CSi 250SE/C 300SD | http://aquaria.net http://killi.net