[s-cars] Replacement HID bulbs

[Kirby Smith]

OK, here's the scoop on arc lights.  When powered at low power,
especially if low pressure, they emit in lines characteristic of the
gasses being arced.  Addition of mercury vapor adds more lines. 
Generally, lights for viewing use zenon, with or without metal halides. 
The color temperature is a misnomer for conditions of mainly lines from
such lamps, as they do not behave as a black body radiator.  However, to
our tri-color vision, they can appear to have a color temperature.

High pressure short arc lamps fill in the spectrum.  When the arc is
saturated, the lamp is purely black body radiative, and a color
temperature is clearly defined by the peak wavelength of the radiation
curve.  Fully saturated arcs may have short life (hundreds of hours, so
I expect automotive lamps operate well below saturation.  If xenon, most
lines are in the near IR, so the black body radiation that accompanies
the lines determines the color temperature.  

Now, for a given xenon lamp, the color temperature is determined by the
current allowed by the ballast.  The lamps exhibit negative resistance,
so the ballast essentially provides a positive resistance in series. 
This can be a transistor circuit, however, and not necessarily a
resistor.

But since the lamp is not going to last long if the color temperature is
raised a lot, then one can also say it is determined by the lamp.  So
both sides are right.  One could keep the average power constant by
modulating the lamp at higher peak current and keep the average current
constant.  This might degrade life only a bit while establishing a
higher color temperature.  Such a circuit would be a bit expensive to
develop.

So be happy with 4k degrees kelvin, or 6k degrees kelvin, or whatever
you get stock.  Note that running the lamp to a higher color temperature
than about 5500 degrees kelvin reduces efficiency as that is the
approximate color temperature of the sun to which we are adapted.

For more, try rummaging around....

http://optoelectronics.perkinelmer.com/Catalog/Category.aspx?CategoryName=Cermax+Xenon+Lighting

kirby


Fred Munro wrote:
> 
> Hi Pram;
> 
> Thanks for the info. When I had to replace my ballast, I specifically asked
> the supplier whether the capsule or the ballast controlled colour
> temperature and he said it was the ballast. My lights are in the 4100K
> range - they produce a bright white light which I prefer to the bluish light
> of the higher colour temperatures and I wanted to make sure I didn't end up
> with one at a higher colour temperature.
> 
> Fred
> 
> -----Original Message-----
> From: Pram [mailto:pramtt at sbcglobal.net]
> Sent: April 9, 2004 11:26 AM
> To: Fred Munro
> Cc: lee at wheelman.com; S-Cars; Qlist
> Subject: Re: [s-cars] Replacement HID bulbs
> 
> Fred:
> 
> Actually, it is not the ballast that determine determine the color
> temperature.  Some aftermarket HID supplier has tried to change the
> color temperature by altering (increasing) the output voltage of the
> ballast but this is not the "proper" way of doing thing.  I have been
> told by a reliable supplier that altering (increasing) the output
> voltage of the ballast will shorten the life of the HID components.
> 
> The proper way is by altering the "salt" composition in the HID bulb
> like it is being done in the 6000K Phillips Ultinon HID bulb.  Some
> vendor also goes by changing the color of the glass of the HID bulb.
> 
> BTW, most of the CATZ HID kit were made by McCollough headquartered
> here in Santa Fe Springs, CA.
> 
> HTH,
> Pram
> 
> On Friday, April 9, 2004, at 07:08 AM, Fred Munro wrote:
> 
> > Hi Lee;
> >
> > I've had a ballast blow, but not a capsule. Are you sure it's the
> > capsule?
> >
> > Any replacement capsule that fits your socket and can be wired to your
> > connector will do ( I'm assuming the igniter is in your ballast not on
> > the
> > capsule, as there is very little room in the headlight housing for
> > igniter-integral capsules). The ballast determines the colour
> > temperature of
> > the capsule, so if you have to replace the ballast, you have to
> > specify the
> > colour temperature or you may have one purple light and one white :o)
> >
> > HTH
> >
> > Fred Munro
> > '94 S4
> >
> >
> >
> >
> > -----Original Message-----
> > From: s-car-list-bounces at audifans.com
> > [mailto:s-car-list-bounces at audifans.com]On Behalf Of Lee Levitt
> > Sent: April 9, 2004 12:29 AM
> > To: S-Cars; Qlist
> > Subject: [s-cars] Replacement HID bulbs
> >
> >
> > I think I've got an HID bulb blown in my HID setup. Anyone else ever
> > bought
> > a replacement HID bulb? Suggestions regarding vendors appreciated.
> >
> > This is for the H1 Catz kit I installed last year, purchased as part
> > of the
> > Rennlist GP.
> >
> > Thanks,
> >
> > Lee
> > '95.5 S6 avant
> > '96 A6 quattro avant
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