Page 1 of 2 12 LastLast
Results 1 to 10 of 14

Thread: Automobile Bulb Technology - Anorak Point of View

  1. #1
    Lighting Specialist jaudette3's Avatar
    Join Date
    Jun 2003
    Location
    Bend, Oregon
    Posts
    4,255

    Bulbs are designed & engineered for a specific purpose

    It’s interesting how easy it is to take for granted some everyday common things that are in reality highly thought out and precisely engineered. Automobile headlights for example. Headlights are highly engineered precision instruments.

    I’m always doing research on identifying the best bulbs to use in my headlight restorations. I admit that at one time I took it for granted that H1’s, H4’s, signal bulbs and the rest were just commodities, like potatoes. Then one of my customers (I learn a lot from my exceptional customers - that’s a whole other story that I’m going to post sometime - different demographics really create different customers - but I digress) asked me what bulbs I was going to install in his newly restored Cibié Bi-Iode headlamps. And I said the typical install was 55w in the low beams and 100w in the high beams, for which we would need a relay kit. And he said, no I mean what brand of bulb. Duh, I dunno, Hella or Bosch. So thus began the descent into the netherworld of automobile bulbs. As it turns out, there’s a lot going on...

    Take a look at this illustration of an H4 bulb high beam in action for example:

    Name:  high beam.png
Views: 617
Size:  260.5 KB

    The filaments in the bulb are precisely placed to project and therefore reflect the beams off precise spots on the reflectors on both the top and the bottom (and probably the sides). Now take a look at this low beam illustration:

    Name:  low beam.png
Views: 571
Size:  186.3 KB

    Same precision but in this case the light beam is only reflected of the upper half of the reflector.

    One of the things that caused me to dig in this area is the practice by some to install an LED bulb in a reflector headlight, a move that appears to be a clever way to get more light while saving money. Au contraire. The results are rubbish - and dangerous. A bright glaring unfocused blob of light is produced that does a poor job of illumination for the driver - and blinds oncoming drivers in the process. When I posted this at Pelican Parts and at Rennlist I was roundly criticized and ridiculed which was amusing, especially when I called it a hillbilly solution.

    Headlights are precision instruments. Halogen bulbs, such as H1's and H4's, are designed precisely to work in reflector headlights. The filaments are positioned precisely on the center line of the reflector and beam out to precise locations. Sticking a glob of small LED bulbs in there makes a giant mess.

    There's much, much more. I know you might be bored staying at home, but I doubt that you are bored enough to go full anorak.

    Cheers,
    John
    Last edited by jaudette3; 04-20-2020 at 01:19 PM.
    Lighting Resources for Hardcore Air-Cooled Porsche Enthusiasts”
    ——-
    John Audette - Porsche Lighting Anorak
    AC Shop: BEST-IN-CLASS Air Cooled 911 Lighting Parts => 911BestInClass.com
    AC Site: The Air Cooled 911 Light Resource => AudetteCollection.com
    Instagram: Please Follow => AC Shop Instagram

  2. #2
    Senior Member
    Join Date
    Aug 2011
    Location
    New York
    Posts
    425
    Lets not forget the Fresnel Lens from lighthouses.
    Name:  Fresnel_lighthouse.png
Views: 540
Size:  88.1 KB
    E Sully
    1973.5 911T

  3. #3
    Senior Member
    Join Date
    Oct 2008
    Location
    Burford, ON, Canada
    Posts
    4,237
    Just because it looks simple does not mean it isn't precision engineering. Optics in particular require a lot of design. It helps to be a physicist.
    Porsche Historian, contact for Kardex & CoA-type Reports
    Addicted since 1975, ESR mbr# 2200 to 2024 03
    Researching Paint codes and Engine Build numbers

  4. #4
    Senior Member NorthernThrux's Avatar
    Join Date
    Jun 2012
    Location
    London, Ontario, Canada
    Posts
    2,258
    Dave is right. Although it has been 37 years since I took advanced optics in my Honours Physics undergrad program, the general principals for headlamp design remain. It's all ray tracing. You figure out where you want the rays to come (the beam pattern on the road) from and then reflect or refract them using mirrors or prisms to the light source (i.e. the bulb). The Fresnel lens uses reflection at the edges and prisms (refraction) and lenses (refraction) in the middle 1/3 and inner 1/3 respectively. Not much too it really.

    Bulbs also have their peculiarities. Wound filaments used in automotive applications have homogeneous radial light distribution (perpedicular to the spiral winding) so you can insert a reflective shield in them to direct the light. LED replacement for such bulbs should do the same, but very often send the light forward, thus completely invalidating the original design parameters. Lenses designed for forward facing light sources like LEDs are quite different than those that have a bulb that generates light that bounces off a reflector.

    I have a good friend who designed some of the most advance optics in the world. Things like the multi mirror telescope where instead of one big mirror, you have a lot os smaller mirrors that can each be adjusted to bring the incoming light to a single focal point in real time (to reduce blur and atmospheric effects). Used in reverse, this approach can adaptively shape the beam of a headlight to adjust the width and throw and cutoff. Which is exactly what some of the new LED arrays in Audis etc actually do.

    It IS all physics! Thanks for letting me nerd out again.

    Ravi
    Early 911S Registry # 2395
    1973 Porsche 911S in ivory white 5sp MT
    2015 Porsche Macan S in agate grey 7sp PDK

  5. #5
    I wish this forum had a "like" button - I like this thread
    73 911S Targa

  6. #6
    Lighting Specialist jaudette3's Avatar
    Join Date
    Jun 2003
    Location
    Bend, Oregon
    Posts
    4,255
    Great paper from Daniel Stern on why LED bulbs should NOT be installed in reflector headlights:

    https://www.danielsternlighting.com/...nversions.html

    I find I generate a lot of antagonism when I carry this flag, but I’ll keep slogging along, honey badger style.

    Cheers,
    John
    Lighting Resources for Hardcore Air-Cooled Porsche Enthusiasts”
    ——-
    John Audette - Porsche Lighting Anorak
    AC Shop: BEST-IN-CLASS Air Cooled 911 Lighting Parts => 911BestInClass.com
    AC Site: The Air Cooled 911 Light Resource => AudetteCollection.com
    Instagram: Please Follow => AC Shop Instagram

  7. #7
    Senior Member raspritz's Avatar
    Join Date
    Sep 2012
    Location
    Colorado
    Posts
    562
    Great thread. I love the diagrams. Very evocative. In the early 1950s my father taught TV repair, and we had an RCA widescreen TV; actually, we had two—one to watch and one for parts. Years later, I dissected it. As I recall, a tiny CRT aimed downwards into a cannister, and the image was bounced back upwards by a parabolic mirror with a hole in the middle (to avoid optical interference beaming past the CRT?) The whole shebang was surrounded by some Rube Goldberg chain/pulley arrangement that I guess somehow had to do with focusing the beam. The image was bounced up past and around the tiny CRT to a plane mirror tilted at 45 degrees and then to the back of the plastic rear projection screen and voila! Widescreen TV! Talk about precision mechanics-electro-optical engineering!

    Edit: I know it isn't Porsche-related, but I found this 1945 RCA blueprint diagram online and couldn't resist.
    Name:  TV.jpg
Views: 300
Size:  178.9 KB
    Last edited by raspritz; 07-16-2020 at 08:53 AM.
    Rich Spritz

    1959 BMC Huffaker Mk1 Formula Junior racecar
    1967 Porsche 911 racecar
    1969 Porsche 911T
    1970 Winkelmann WDF2 Formula Ford racecar
    1973 Merlyn Mk24 Formula Ford racecar
    2007 Porsche 997C4 cab (totaled by an idiot running a stop sign)
    2014 Porsche 991 TurboS cab
    2019 Cayman GTS (wife's)

  8. #8
    Lighting Specialist jaudette3's Avatar
    Join Date
    Jun 2003
    Location
    Bend, Oregon
    Posts
    4,255

    Fresnel Lenses

    Quote Originally Posted by ESully View Post
    Lets not forget the Fresnel Lens from lighthouses.
    Fresnel lenses can be very beautiful. They are commonly used in lighthouses and have been since the 1800's. Henri-Lepaute Fresnel, an evidently brilliant French physicist, devised them in the early 1800's. I volunteered as a docent at Cape Blanco Lighthouse here in Oregon a few years ago. Constructed in 1869, it's the oldest continually operating lighthouse on the Oregon Coast. It's equipped with a revolving second order Fresnel lens which replaced the non-revolving first order lens some years ago (the original lens was "lost" in Astoria). A 250w halogen bulb (!) sends a beam 21 miles out to sea.

    Name:  cape-blanco-lighthouse.jpg
Views: 394
Size:  60.2 KB
    Cape Blanco Second Order Lens

    Name:  1st-Order-Fresnel-Lens.jpg
Views: 379
Size:  155.7 KB
    Inside first order lens

    Name:  fresnel-lens-split-rock-lighthouse-new.jpg
Views: 414
Size:  270.0 KB
    Focus with bullseye

    Remind you of automotive fluted lenses?

    Most folks don't appreciate the engineering behind projection lighting, it *is* all physics. Headlights are everyday things that are taken for granted but they are highly engineered precision instruments. Which is why you can't just willy-nilly do this or do that. A lot of folks over at Pelican are mad at me for talking about that.

    Cheers,
    John
    Last edited by jaudette3; 07-14-2020 at 02:59 PM.
    Lighting Resources for Hardcore Air-Cooled Porsche Enthusiasts”
    ——-
    John Audette - Porsche Lighting Anorak
    AC Shop: BEST-IN-CLASS Air Cooled 911 Lighting Parts => 911BestInClass.com
    AC Site: The Air Cooled 911 Light Resource => AudetteCollection.com
    Instagram: Please Follow => AC Shop Instagram

  9. #9
    Senior Member
    Join Date
    Jun 2010
    Location
    Garden State
    Posts
    312
    I believe the popular Quartz Halogen lamps are still the smart choice for headlights.

    Their slightly yellow color helps to eliminate a problem with the Blue component of RGB daylight colored light in that the Blue light focuses on a plane in front of where the Red and Green components do.

    This out-of-focus Blue component image in our eyes creates an ‘echo’ of sorts that degrades the sharpness of our vision.

    The Seregetti Drivers sunglasses lenses use a yellow filter just as photographers used a yellow filter to create sharper higher contrast images before Apo-Chromatic lenses that are corrected to focus all three colors closely on the same plane were affordable.

    This effect is also evident in the yellow goggles used by Alpine skiers where the high-altitude eliminates the atmospheric filtering of Blue and UV light that we enjoy at sea-level. The yellow goggles work well.

    The quartz halogen lamp is affordable, durable and its small filament and engineered reflector provides a long throw of crisp light for greater vision.

    The halogen gas inside the lamp bulb prevents the by-products of the hot filament from sticking to the quartz glass interior. Otherwise the black soot would buildup blocking the escape of the infra-red component of the light and the lamp would overheat and fail in short order. The Halogen gas helps the byproducts to re-attach to the filament as the lamp cools. This cycle goes on for the life of the lamp.

    Enjoy the great performance of everyday Halogen headlights. They are affordable, easy to service and available on the road at any auto parts store. Their 3200K color balance light emitted is perfect to render lifelike color and it also tames the vision distorting blue component.

    Their relatively high current requirement isn’t a problem for modern electrical systems and their high heat is controlled by the engineered reflector housing.

    You would need to go to great effort and expense to top a well engineered quartz halogen headlight.

  10. #10
    Senior Member
    Join Date
    Aug 2016
    Location
    NE Ohio
    Posts
    280
    Wow, love this thread. Optics, Physics..... supercool. When you think about it, is there any other part on a 911 that has benefited from more than 100+ years of research, testing and design? The lenses on the H1 and H4 are works of art in themselves.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Message Board Disclaimer and Terms of Use
This is a public forum. Messages posted here can be viewed by the public. The Early 911S Registry is not responsible for messages posted in its online forums, and any message will express the views of the author and not the Early 911S Registry. Use of online forums shall constitute the agreement of the user not to post anything of religious or political content, false and defamatory, inaccurate, abusive, vulgar, hateful, harassing, obscene, profane, sexually oriented, threatening, invasive of a person's privacy, or otherwise to violate the law and the further agreement of the user to be solely responsible for and hold the Early 911S Registry harmless in the event of any claim based on their message. Any viewer who finds a message objectionable should contact us immediately by email. The Early 911S Registry has the ability to remove objectionable messages and we will make every effort to do so, within a reasonable time frame, if we determine that removal is necessary.