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amarv12
Hard-core CEG'er

Reged: 05/12/02
Posts: 2007
Loc: Michigan
Re: Random summer mods (56k warn.)
#1312357 - 09/05/06 01:48 AM

Originally posted by CSVT#49:
Don't suppose you can post a How-To on the dome light??





Most of the physical details of the LED dome lights are basic. In order to mount the LEDs and heatsinks you need to pretty much gut the lamp areas....you can see from the pics how i opened them up. The way that the lamps work is by having constant 12V fed to the lamps at all times, then grounding out under certain conditions...like when the door switch grounds out or you flip the switches. So for the front lamp you can see if you look at all that metal stuff behind the lamp you have to ground out the driver for the LEDs on the center post of the center switch. The back dome light works the same way, you grond out on the curved little copper "V" thing.

The reason that you need drivers for the LEDs is that there can be a lot of spikes in the car's electrical system, so just using resistors can kill LEDs relatively quickly, or at least reduce their life greatly....and each of these leds are about $4 to $6, so it wouldn't be very fun to lose them. Some people use voltage regulators, as well, but most recommend constant current drivers. This is a good driver that i used for the two foot well LEDs, its very cheap, but the issue is that it produces quite a bit of heat...so you have to use a heatsink to dissipate the heat...which takes up more space. That's why i chose switch mode drivers for the dome light LEDs...much more efficient, like over 90% efficient at auto voltage. This is the datasheet for the driver i used on the dome lamps, one for each. But if you're seriously considering this mod, this driver is actually on sale this month, and about 66% the price i paid for the other ones .

Anyway, the other consideration for the LED project is thermal management...The reason that these LEDs are able to produce more light than typical 5mm LEDs is because they can handle much more heat. The LEDs i used produce between 40 to 50 lumens...whereas, many 5mm white LEDs will make about 1 lumen. The LEDs themselves dont produce a ton of heat, but since they can't handle much heat, you need to cool them and pull away the heat that they do produce...usually done with heatsinks. The way you spec out the surface area is with thermal resistance circuits, Luxeon is pretty generous this way, they outline the process on their website and give other data to help you make the decision, details based on the type of heatink, flat or finned, horizontal or vertical, forced or natural convection...like for the passenger footwell, i used a flat aluminum plate since space was so tight. The heatsink area will also depend on the ambient emp you define...for the dome lights in summer heat choose a high temp...if heatsink size isn't feasible, you can always derate the LEDs and rund them below 350mA.

Anyway, links...

You can use whatever type of LEDs you want, but i used 1 watt stars, with lambertian output pattern (probably the best for courtesy lamps without external optics). Page:
http://lumileds.com/products/family.cfm?familyId=2

Future Electronics is their official distributor...but when i tried to buy from them before they kept giving me BS availabiltiy times (a luxeon rep even told me it was BS!) plus i always have problems with their website, so i dont like them.

I bought R-bin LEDs from:

www.ledsupply.com

Specifically:

http://ledsupply.com/lxhl-mw1d-r.php

Due to the manuafacturing process, i guess there can be a lot of variation in the final LED product, so output of the LED (flux output of light), and color can vary...so to specify what the output is, lumileds bins the LEDs...they just break them up into groups based on properties, and define the properties with a code. Link:
http://lumileds.com/pdfs/AB21.pdf

I chose R bin for the flux since it's the highest output.

Link for thermal considerations:

http://lumileds.com/pdfs/AB05.pdf

Link for electrical info:

http://lumileds.com/pdfs/AB11.PDF

Datasheet for the star family of LEDs:

http://lumileds.com/pdfs/DS23.pdf

Overall, i'd say read through all the info before taking on the project, it makes it much easier and safer to set up the lamps.

PM me if you have any otherr questions after going through all that info.

--------------------
1998 Mystique LS:
-2.5 Duratec ATX
-Vibrant White
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Entire thread
Subject Posted by Posted on
* Random summer mods (56k warn.) amarv12 09/04/06 12:24 AM
. * Re: Random summer mods (56k warn.) Tony2005 09/05/06 01:56 AM
. * Re: Random summer mods (56k warn.) amarv12 09/05/06 02:01 AM
. * Re: Random summer mods (56k warn.) ChattavegasSE 09/04/06 01:19 AM
. * Re: Random summer mods (56k warn.) amarv12 09/04/06 01:55 AM
. * Re: Random summer mods (56k warn.) IRingTwyce 09/05/06 04:31 PM
. * Re: Random summer mods (56k warn.) amarv12 09/05/06 07:09 PM
. * Re: Random summer mods (56k warn.) posthuman63t 09/04/06 02:28 AM
. * Re: Random summer mods (56k warn.) CSVT#49 09/04/06 02:55 AM
. * Re: Random summer mods (56k warn.) amarv12 09/05/06 01:48 AM
. * Re: Random summer mods (56k warn.) m4gician 09/05/06 12:55 AM
. * Re: Random summer mods (56k warn.) amarv12 09/05/06 01:56 AM
. * Re: Random summer mods (56k warn.) BigBEN 09/04/06 02:53 AM

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