I've wanted to convert my 914 taillights to LED for a while but never got around to it.

Finally I started working on the design of the taillights. This will be a single custom PCB for each side and will have all the LEDs and control circuits on it. One PCB will be used for both sides.

The plan is to remove the existing plastic reflector and bulb assembly and mount a custom board in its place. With proper standoffs, I should be able to mount the board using the same 2 screw holes that secure the reflector.

I'm trying to decide now how many LEDs to use for each purpose. Right now, I have 8 LEDs for the backup lights, 20 LEDs for the running/Brake lights, 24 LEDs for the turnsignals, and 4 LEDs for the side marker.

I've been observing modern cars with LED taillights and some use a few LEDs (like 8) and some a lot (+20).

I would like your opinions on how many LEDs you think would be good to use. On the board below, the LEDs are spaced about 0.7 inches apart. These will be medium brightness white LEDs. (I'll let the lenses provide the color).

The first cut at the board is shown below for the driver's side. The side marker LEDs will be right angle LEDs pointing out the side of the board. They can be seen on the extreme left side of the board.

If these work out, I could manufacture them for World members. One thing though, they won't be cheap. The LEDs are about $0.50 through Digikey and there are more than 55 LEDs on each right now. Plus there's 2 dc-dc converters for providing constant current for the tail/brake and turnsignal LEDs.

Cheers

Nice. Are you going to follow up with front light assemblies?

I like this please keep the forum updated with progress. In my opinion the maximum LED's you can use for running/brake lights is preferred so we can make the back of our cars as visible as possible. Our cars are very low and with OEM lighting leave a lot to be desired for rear visibility, that's why so many are adding 3rd brake lights.

Good Idea. I like to see lots of leds. I don't like the look of a few bright lamps. I think lots of leds will give a more even display. Our reflectors are getting old and often have the chrome flaking off. Should be a good replacement

I would definitely be in on this buy. I like your configuration as is and would rather see more than less LED's as these cars are hard to see.

I would like to see a kit for the front that would replicate the european design turn-signal bucket configuration and the US version. I would be happy to convert my Six to these lights during the build.

I would still add the high-mount 3rd brake light too.

Do a search. Someone was putting quite a bit of effort into doing this a couple years ago. I don't recall if it ever got finished, but IIRC he was close

I'd do the math with the brightest LEDs available and see what the cost winds up at. I think you'll find these get pretty expensive, my guess is you'ld be into these at $75 a pop ($150 a set) once you got all your costs together. Maybe you can do a little better, but these things add up quick. The key is to sell enough units to spread the cost out over more. You may be able to make them at $35 a pop if you can do 100 sets, it's just seeing what the market for these are, and investing a big chunk of change to get the numbers to work.
I wish you luck.
PS you may want to check with the 1st guy to see why he didn't make them, there may be some issues that are not readilly apparent here.

Or,

You could just do this.....



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Little Ones Too......

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I work for an LED Manufacturer, so I ordered these up for the car, I haven't tried them yet.

Sorry for the crappy photos

John

I've been looking at these bulbs myself, and hope you can let us know how they work out. Seems like a nice, easy way to upgrade and hopefully make the car a bit easier to see (there's a reason that I like yellow for small cars - most visible color). You might want to put together a listing of the part numbers of the LED bulbs you used.

My car isn't ready yet, so,

Maybe I can get a local volunteer to try them.

Scotty-In-NH Where are you?

Found it

http://www.914world.com/bbs2/index.php?sho...e.d.+taillights

If you're upgrading to LED's (or not, they work with regular bulbs too), you might consider a "back off light" or "taillight flasher". I know many people are concerned with getting rear-ended and protecting their precious teeners. This is usually one of the first mods I do to any motorcycle I ride regularly. The manufacturers advertise something like a 40% reduction in rear end accidents on motorcycles. Also, many newer ambulances feature a similar technology for safety reasons. If anybody wants more info on these I have a large variety of models I can order from at a decent discount as well.

This video is one of the better examples I can find. Most videos look wrong because of frame rates on the cameras. Some modules allow you to fine tune the flash rate, number of flashes, and even integrate turn signals.


https://www.youtube.com/watch?v=e368R4ttjCE

Check out the sequential tailight vid that comes up at the end of this vid. IMHO the vertical LED's like that would look best, and making the turns sequntial would be VERY effective, as they really grab people attention

https://www.youtube.com/watch?v=WEREH0XDipo

Thanks for the replies. I'll try to address each question comment here.

"Nice. Are you going to follow up with front light assemblies?"

Haven't thought about it yet. Which function would the LEDs replace/add? Turnsignals? Running lights?

" I like to see lots of leds. I don't like the look of a few bright lamps. "
AND
"rather see more than less LED's as these cars are hard to see."

Good to hear. I like the "panel" look to modern LED tail/brake lights.

"Do a search. Someone was putting quite a bit of effort into doing this a couple years ago."


LED Tail Lights

You found the same one. Not sure how it worked out. I don't want to modify the housing so mine will screw into the existing mounting holes and use the existing wiring. That's the plan at least. I will have to deal with the lower current draw to keep the flasher happy. I may have to add a power resistor to get enough current. The goal is to do LED lights, not save power.

"I'd do the math with the brightest LEDs available and see what the cost winds up at."

Agreed. This won't be cheap. Individual LEDs are expensive (> $0.50 each). Plus I'm using dc-dc step-up converters to get very stable LED currents regardless of the supply voltage. They will add $15 to the BOM cost.


"Or, You could just do this....."

The goal is a cool LED panel like modern cars. LEDs allow the modern automotive designer to design all kinds of light panels like pyramids, slanted boxes (parallelograms), perimeter tails with brakes in the middle, eye brows, etc.

"you might consider a "back off light" or "taillight flasher"

Neat idea. It might not be that hard to put this in.

Very nice. BTW, if you are keeping the original plastic cover, make sure your LEDs are the appropriate color - otherwise you are wasting the light. So brake LEDs should be red, turn LEDs should be yellow and backup should be white. Please use warm white (not that ugly "bluish" white).

I'm currently using the plugin LED replacements, and they work ok. According to another electric 914 owner, he used the colored ones to much better effect. I was going to replace mine with red and yellow ones, but if this is ready soon, I'd rather use this.

Oh, since I live in San Diego, you should make sure the components you use can handle the heat. And I'm sure that there are some who actually drive in snow (snow???), so that's another concern.

I also vote for the more-is-better camp.

Cheers! Peter

I thought about using colored LEDs for turn and brake but thought white would still work with the colored lenses.


Finished up most of the placement of the components and the wiring on the board.


I will add the capability to do the "back-off" brake lights and sequential turn signals. The turn signals are arranged in 6 vertical strings of which I can control each of 2 strings separately.

The BOM cost for components alone is reaching $60 of which 1/2 of this is for the LEDs.

Here's a close up of the outside end of the board. The side marker LEDs are mounted on the edge of the board.

The circuitry is a constant current dc-dc boost converter to drive the turnsignals. This will provide constant current regardless of battery voltage which we all know varies all over the place in the 914. This converter and associated components represents about $10 cost but will give superb operation.

The outside edge of the board is cut at an angle on the top and bottom to allow the same board to be used on both sides.

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This little T cut-out is for the webbing in the lens cover. The one mounting hole is very close to the cut-out. I'm hoping to not have to trim the webbing but that wouldn't be that bad to trim the webbing a bit.

The 5 holes at the top are to solder the wires from the enclosure. I'm trying to think of a better way to connect the wiring to the board.

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Very nice.

What kind of software are you working with?

I definitely want these

I am in for LEDs, will they replace the entire assemblies or plug into the existing bulb sockets?

I have tried those plug in LED bulbs from FLAPS and the brake light is barely noticeable.

So I am thinking these custom versions would be better, right ?

Thanks. I'm using Altium. It's pretty powerful as you can do schematic capture and go right to PCB layout. Change in the schematic? No problem, just reload the schematic and parts removed disappear and new parts appear on the PCB.

These will fit in the existing enclosure with the original lens. It will replace the reflectors/bulb sockets. The goal is to not have to cut any plastic or change flashers to install.

Cool stuff, there is a company that does something similar for 356s...but that's the only model they build them for.
It never hurts to have brighter lights these days

interested

Very interested..

interested

Your welcome.

I'm always impressed by creative solutions to an existing problem. The software sounds like a very good setup and I'm glad it works well for you. I know how expensive CAD software can get.

I can definitely help with installation instructions and/or the hardware to install the buckets if you need me to.

Lots of those drop in LED "bulbs" are very directional. They end up being less visible on a car as low as ours.

I like this idea. Using good LED's with a wide pattern would work great.

I would be in for a set for sure.

I think it is a bit more difficult as it shows......

There are lot of different LED's so you havs the choice and the
challenge to find the one which matches the requrirements.

For the back driving light and fllasherlight I use the bulbs like Mark
shows.
For brake light and rear light I use a Spider LED like this
Spider LED
These are mutch brighter and makes a huge different between back and brake light

Interested!

I have installed LED bulbs in my car. I have also added cheesy chrome tape to replace my fading backing. I have a LED third brake light that is only noticeable when I step on the brakes. I agree the more LED's you have on each bulb the better I went with a company that sells them and I don't regret it. Those that went to Hershey last year have seen my brake lights.

Paul (smrz914) made them. I don't know how many. I funded the project and received the prototype. TonyAKAVW (electro wizard) has it now. I don't think they will be any cheaper to make but IIRC, Tony did say they are nice.

Fascinating. I would be in for a set if this comes to fruition.

Agreed, I can vouch for the effectiveness of the "Back-Off XP" which I installed on my 914 shortly after I obtained the car a few years ago. Vehicles give me a measurable increase in following distance under braking, which started as soon as I wired in the weather proof module inside the car behind the center of the backpad. If I understand correctly the "Back-Off XP" is the original/best unit that most motorcyclists use? My LED 3rd brake light will utilize the 5-flashes before steady illumination function too once I have it installed. The flashing is certainly more effective with LED taillights so I look forward to see what sort of 914-specific LED taillights develop in the coming year?

Buy it here: http://www.amazon.com/Signal-Dynamics-Brak...4/dp/B001F85OUM

If you build them we will buy!!

Every time I find myself behind a newer car with LED's I find myself staring at them. I feel they are one of the best new safety features on any new vehicle

Do you have any information on which LEDs were used or how they were powered?

I have no pride WRT copying something that works or improving on a previous idea.

PM sent.

Spoke let me know if you need any help on this. I deal with these everyday and I have very good connections with all of my Board suppliers. If the order is small enough, I can probably have these boards ran for free or nearly free. I buy close to 5 million in bare boards each year and have good reputations with PCB houses. I would love to help you get the cost down as I am interested in these as well.

I can probably get the LEDs at cost as well. I can run them through a personal PO to Avnet, Digikey or TTI. Whichever has a better deal...

Thomas

Thanks Thomas, I'll keep that in mind.

The main issue right now is to find an LED which is efficient enough to give the brightness I'm looking for and somewhat affordable.

Any suggestions of an LED would be appreciated.

The first one I tried didn't give the output I was looking for. Here's the info at Digikey:

Cree LED

I found an OSRAM LED with twice as much output. I'll get some samples of this one and give it a try.

OSRAM LED

I am also interested in these lights. I have a radiance tail light on my harley and it had the sequential turn leds with the flashing brake and it was bright.

Very interested. Count me in

David

Here's the test fixture that I've used to evaluate the LEDs.

These LEDs are bright as hell but still not bright enough for this application.

Here's the comparison with the existing brake light @ 13.6V vs the LED. Keep in mind that these are only 1/2 of the LEDs that would be used for the brake lights.

The standard backup light is 25W which is slightly more power than the brake light at 21W.

Here the difference is not so obvious. The next LEDs that I am looking at are about 1.5x brighter.

Cool! Thanks for the reponse. Looking at the pictures above, it appears these are gonna turn out very nice. Also in my opinion, the brighter the brake lights the better

Another great thing about this upgrade, is the lower current draw of the LEDs should allow more current for ignition and stereo components ....

You might consider doing your testing with red LED's. The white LED's produce light in many wavelenghts. The red lens filters out all of the light except for the red wavelengths. If you start with an LED of a given wattage a specific color LED you should get more light in the wavelengths you need.

From the Superbriteleds page:

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Harvey

Always wondered about this. Does this mean the same when using regular bulbs?

If I use red incandescent bulbs; are they better than clear?

Does that mean two different specs, one for US lenses and one for Euro lenses?

7TPorsh:


I would think that most standard incandescent bulbs produce a wide range of wavelenghts and the red envelope does the filtering to remove unwanted colors producing the red light. While the red lens will pass most of the red light, there will still be some additional filtering losses so you would probably be better using a clear bulb and do all of the filtering with the lens. I don't believe most LED's are truly monochromatic (like a laser), but rather they produce a variety of wavelengths within a fairly narrow band. {red(ish) or blue(ish) or.....} Anybody know about this???

Zymurgist:


From what I think you're asking: optimally you would use white LED's for the backup light portion of the taillights and red LED's for the red portion. For the Euro lenses you would also need amber LED's for that specific portion of the lens. Also, amber LED's for the US spec front lenses and marker lights.

Harvey

Oddly enough I was just researching LEDs a bit ago. Wiki has a decent summary on the technology behind how LEDs work, and to summarize it all up, it would seem you're exactly correct in saying that LEDs emit light in a relatively narrow range of wavelengths (colors). It seems they may or may not be totally monochromatic depending on the semiconductor material and doping materials used (there is such a thing as a diode laser, apparently). I'm certain you're also correct about incandescent bulbs emitting a wide range (more or less white light) of wavelengths.

In contrast, LEDs typically emit light in a certain color (i.e. not white) due to how the light comes about from the electrons' behavior in the diode's doped semiconducting material. Hence, LEDs do not typically use filters at all unless for some special application or circumstance. It's tricky to get white light from an LED and while it is of course possible, there are several ways of doing it (including using more than one actual LED in each "light" assembly).