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post #6 of (permalink) Old 02-15-2001, 09:00 AM
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Re: Custom Bronco With Stock Looking LED\'s...

I'm interested in these too. The expected life of an l.e.d. is 150,000 hours. they can be totally sealed with epoxy and silicone from the led's lens to the wire to keep out moisture. Also there are sealants sold that have a "leveling" quality, they will flow to fill small gaps then set up. The shuttle busses at the Philly airport have them and they are bright and come on and go off alot faster than an incandesent bulb. Volvo actually measured reaction time with the led light and it came out to something like 10 feet shorter stopping distance. This sure can mean a big deal especially to the A hole tailgateing you. They are also brighter. Now I think there is something in the DOT code that tail light lenses have to be red, the Euro-road rocket roller skates are at the legal edge with their clear lenses and red bulbs, and a certain percentage has to be reflective. All tail light lenses seem to have those parts where there are little pyramids on the inside. So, I guess I'll use the original equipment lens or DOT aftermarket light. I was thinking about a clear plexiglas one since the leds are red. I e-mailed Grote and asked, pointing out that the standard tail light on a Jeep is an industry standard fixture used on other trucks, if they where going to make an led version and the answer was no. About the brightness, with leds the more you have the brighter it gets. The trick is that you need to have enough of them to match or surpass the light output of the 1157 or whatever the bulb is. So stuff as many as you can inside the stock housing. As far as I can tell, the light output is rated differently between leds and bulbs. Bulbs being more capable of projecting light than leds. Leds seem to be a reflective or illuminous light. What helps us is the fact that tail lights aren't a projective type light. They are meant to be seen not to help us see. What hurts us is there are two levels of brightness in a tail light, nornal running and stop functions. This is acheived with two filaments in a bulb. So you have two power leads that can be used but they both use 12 volts. You need two different dropping resistors for the different brightnesses and probably a diode to prevent any back powering of anything, say if the running lights are off and you hit the brakes. This engineering of a legal, i.e. safe, replacement is what we pay for in after market ones. Look for the Hewlet Packard website, they sell and have info. on leds. The incandesent replacement leds with a bulb socket attached won't work in the original housing because the bulb mounts on an angle, not straight up vertical or horizontal. Leds have a very narrow light dispersion pattern that is 90 degrees from their mount, the mounting has to be straight up and down. Leds are usually made for "board mounting", the spaceing of their leads corresponds to the holes in the "wafer board". I have a '79 -7 and the tail lights do not have the side marker lights incorporated into them. The '85 that I used for parts did. This is another concern. Also the license plate must be illuminated. There are white leds coming out, but again they still do not have the projective power. Also there are round amber(yellow?) units that will fit nicely for front turn signals. Sit down with your favorite search engines, yes use more than one, and have at it. There is some useful info. out there. This has turned into a back burner project but it won't be forgotten. I think led lights are going to get more popular. The price will come down some. For now my work buddies have to listen to me goo gooing over the bus' "digital taillights".

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