LED Taillights, Custom Made for the 914 Options

[CptTripps]

I ordered a shit-ton of LEDs off of eBay a few weeks ago. I'm planning on building custom tail lights that are patterned a lot like the new Audi tail lights. It'll be worth an experiment anyway.

[Cairo94507]

Spoke/Jerry- I am looking forward to this project hitting the classifieds so I can update the rear lighting of my Six without changing the look of the car.

Considering how much light new cars with LED's have in the rear these days, I believe that should be the goal. I want people to see the car and see it is stopping so they don't pile into it.

Aside from the LED taillight project I still plan to have a hi-mount 3rd brake light fitted into the roll bar chrome trim that is about 12-18" long.

[Spoke]

I ordered a shit-ton of LEDs off of eBay a few weeks ago. I'm planning on building custom tail lights that are patterned a lot like the new Audi tail lights. It'll be worth an experiment anyway.

What LEDs did you order? Do you have a part number? I tried many different LEDs and found a great deal of difference in the output.

[Spoke]

Spoke/Jerry- I am looking forward to this project hitting the classifieds so I can update the rear lighting of my Six without changing the look of the car.

Considering how much light new cars with LED's have in the rear these days, I believe that should be the goal. I want people to see the car and see it is stopping so they don't pile into it.

Aside from the LED taillight project I still plan to have a hi-mount 3rd brake light fitted into the roll bar chrome trim that is about 12-18" long.

I've been swamped at work and haven't had time to finish this up.

The last I worked on this I was looking for an efficient high output amber LED.

I got a couple from Digikey but they turned out to be more red than amber.

I'm not sure my design will be very marketable. They will be very expensive to build.

The high output LEDs that I've found cost $1.5 to $2 each. Plus each LED needs a lense to focus the light rearward. The lenses are about $1 each.

So with 20 LED for the brake, 30 LED for the turnsignal, 8 LED for the backup light, there are about 60 LED per side or 120 for both sides. Considering only the LED and lense costs, I would up to $360 not including circuitry, PCB, and assembly.

[McMark]

Aren't all white LEDs cheaper? Colors might be nice, but we have white bulbs in there now... (IMG:style_emoticons/default/idea.gif)

[Spoke]

Aren't all white LEDs cheaper? Colors might be nice, but we have white bulbs in there now... (IMG:style_emoticons/default/idea.gif)

White LEDs are not always less expensive. Also they tend to have higher ON voltages (3.4V vs 2.4V for red).

I started with white LEDs and someone pointed out that red LEDs pass through red lenses more efficiently than white.

High power LEDs are generally more expensive and one issue I have is that I don't want to make this fixture and find out that the LEDs are not bright enough. I'd rather tend to have too bright than not bright enough.

[Cairo94507]

As strongly as I feel about our cars needing more light in the rear, I am willing to pay for the LED's and work as I believe these will make a big difference in accident prevention. (IMG:style_emoticons/default/driving.gif)

[CptTripps]

LEDs are CHEAP no matter what. I just bought 1,000 Red, 500 White, and 500 Amber on eBay for $60 shipped.

Red: http://r.ebay.com/NEVFr3

Amber: http://r.ebay.com/bRYrcs

White: http://r.ebay.com/6XMI1E

[CptTripps]

This is the layout I was thinking of doing.

It's a rough idea, and I'll have to play with it, but this is what I'm thinking right now.

I was also going to make my own lenses out of 1/4" 50% smoked plexiglass.

::: sorry for the hijack :::

[Chris H.]

Another thing for me to copy you on Douglas....NOT making my own lenses though...

[CptTripps]

Oh I'm quite sure it'll end up quite different than what I'm planning right now, and it won't be anywhere NEAR as nice as what Spoke is working on.

I'm going to have a lot of hot-glue, resistors, wire, solder, and drill holes in mine! As long as it's presentable from the outside, and I can hide it in the tail-light housings, I'll be in good shape.

[veekry9]

Oh I'm quite sure it'll end up quite different than what I'm planning right now, and it won't be anywhere NEAR as nice as what Spoke is working on.

I'm going to have a lot of hot-glue, resistors, wire, solder, and drill holes in mine! As long as it's presentable from the outside, and I can hide it in the tail-light housings, I'll be in good shape.

Cap'n
a newfangled compound for custom lens making.



http://www.masterbond.com/sites/default/files/mb-slogan.png

[zymurgist]

As strongly as I feel about our cars needing more light in the rear, I am willing to pay for the LED's and work as I believe these will make a big difference in accident prevention. (IMG:style_emoticons/default/driving.gif)

(IMG:style_emoticons/default/agree.gif)

If this project comes to fruition, I will definitely want a set.

Yep, LEDs are still spendy. Visibility on the road is priceless.

[Harpo]

(IMG:style_emoticons/default/agree.gif) Same here

DAvid

[McMark]

(IMG:style_emoticons/default/agree.gif) Pricing sounds about right for a quality component. I was just looking at adding a STACK remote fuel pressure gauge to my car and it's $220 for the setup. So $350 for awesome tail lights isn't a stretch.

[zymurgist]

Not an apples to apples comparison, but Harley-Davidson sells LED conversion headlight kits. The kit for the headlight only is $400, and the kit for a pair of passing lights (the 2 lights that flank the headlight) is an additional $400. I am guessing even at these prices, they have some takers.

[mikesmith]

Aren't all white LEDs cheaper? Colors might be nice, but we have white bulbs in there now... (IMG:style_emoticons/default/idea.gif)

"White" is a bit misleading when it comes to LEDs; they are actually blue LEDs with a secondary phosphorescent emitter.

There's more than you care to read about here:

http://www.olympusmicro.com/primer/lightan...urcesintro.html

This nifty little graphic is only approximate, but it might help:



The important part is that there's not very much red in the the output of a "white" LED.

There are some pretty nice, cheap COB (chip-on-board) LED modules available in the right colours these days, if you want to make something more complicated than the direct bulb replacements that are everywhere.

= Mike

[cpavlenko]

check this out. >>>>>>.

http://www.superbrightleds.com/cat/led-veh...rsche---/49---/

they even have the relay for the led lights. I'm thinking...

[Spoke]

The important part is that there's not very much red in the the output of a "white" LED.

I did a test with the white LEDs through the red 914 lens and the light output was not impressive. I did not have individual lenses on the LEDs which make a significant contribution to directing the LED light.

The red LEDs also have a much lower on voltage; like 2.4V vs 3.3V for white LEDs. This makes a difference when 10 LEDs are stacked together.

I've finally settled on a switching converter for the brake and turnsignals. Been looking at many different converters to find the best one for this application.

I will do a test board with just the brake/running lights, converter, and CPLD to make sure everything works together before laying out the entire assembly.

I've got the red and white LEDs chosen; just have to find some good amber LEDs for the turnsignals. I got some high power amber LEDs from Digikey but they were quite red. I've also bailed on the sequential turnsignal idea mainly for simplicity and since the turnsignal light size was not large enough to adequately discern the sequencing.

[Spoke]

Here's the brake taillight board top and bottom views.

This board will fit inside the existing taillight frame and will get brake and taillight power from the bulb socket. Not sure how I will get power but should not be too hard.

Also need to work on securing the board. This could be as simple as silicon caulk.

I removed all leading edge flashing from the brake light for simplicity.

The big gray looking structures on the top are the LED lenses, not the LEDs. The lenses are 9x9mm.

I'll use this board as a test fixture for now but it could remain in the car for the long term.

The LED current will be 300mA for brakes and 50mA for taillights. I want to make sure these are bright. I can turn them down if needed. By using a switching converter to provide the power, the efficiency of this circuit should be in the high 80s low 90s percent.