Need help - led tail lights

[Dark-5.0]

Hi guys. I recently found these forums and I am in need of some help. I just bought 100 white leds off ebay and want to set up led tail lights for my 94 mustang. I wanna make a sheetmetal panel for the top two stripes of each tail light. The middle stripe will serve as the driving light and brakes while the top works as the turn signal. I know the best was to go about it is to wire it in series. But my questions are, how would I go about wiring it to the stock harness so when i use the turn signal, it flashes and when i hit the brakes, it will apply more current to light them brighter. I am very new to leds and I am just in need of education on making this work. Any help would be much appreciated. Thanks in advance. Here is a picture for reference.


Jeremy

[Rob]

Welcome to the boards, Jeremy.

Let me get a few thoughts together on this topic, and I'll post some detailed info soon. Thanks for being patient while I took a brief holiday break.

[Dark-5.0]

Thanks Rob, I also sent you a pm before I started the thread. I was wondering where in Kansas you were located. I'm in the Souther Kansas City area. I think what I want to do is just use the middle strip. Use a pwm and have the inner half of lights be the brakes and the outter half be the turn signal. And the whole strip be a running light. I just know how to make it work as a brake light and turn signal. I'm assuming I need to use a pwm to increase the current to light them up brighter but how do I make them flash for a turn signal. And make it all work with the factory harness. Sorry for all the questions, I'm just new to this.

Jeremy

[Rob]

I live near DeSoto, not far from you.

Here's the things I think need to be considered on your project:

1) Is this street legal? Answer will depend on colors and a couple other things.  Can you clarify for me: is this intended to replace the existing lighting, or supplement it?

2) Are white LEDs the best choice? I'll answer that for you: no. Inexpensive white LEDs are blue LEDs with a phosphor that converts some light to yellow, and the resultant mix is white. When you filter that down to just red or yellow (as with a taillight or turn signal lens) ou throw away a lot of the luminous intensity (brightness, more or less) in the process. Red LEDs would be the first choice for your brakes, and yellow for turn signals.

3) How to make this a reversible mod. I think you are on the right track with building something that connects to the stock sockets.

Brake and running lights are pretty straightforward. Turn signals aren't because the stock flasher needs a larger load to operate. You'll want to look into getting an electronic flasher (auto parts stores have these) to replace the flasher unit for the turn signals.

You could start off by looking up the lamp part numbers (such as 1157 or 3157) for each lamp you want to replace. If you have some failed/burned out lamps, hang on to them, because you can smash away the glass part and connect your board into the base.

You should probably check into superflux (aka piranha) LEDs. Look at the projects in the gallery, there's lots of good pics. What you have a lot of is power, and what you're short on is space, so these are a good upgrade for a taillight because they put more light out than the 5mm and occupy just a tad more space. They're also better from a thermal perspective--you don't want to spend hours putting this together and have it look dim (or dark) after two weeks becuase the LEDs overheat. 5mm LEDs aren't really made with thermal management in mind, and are mediocre choices for larger arrays, especially in a safety-critical application.

Let me know what you have planned with the exosting lights and I'll sterr you a little more specifically down the path. If chopper sees this, I bet he could weigh in with some good advice too, or any of the other taillight builders.

[chopper]

  Jeremy, this sounds like an interesting project. Here are a some suggestions from my experience with like projects.

   The flasher that Grote makes and is suggested for leds has never worked for Me. It is a load dependent product better used for pick ups towing a trailer. You can buy a component to make Your existing flasher work or use incadescent bulbs to make Your flasher work.

   The white leds would make a nice reading light or under kitchen cabinet lights but as Rob said not so good for tail lights. Your budget is the only restriction for the results You desire.  If possible purchase red/orange power leds like the luxeon. Play with the led series calculator and try to have Your leds consume as close to 13.6 volts as possible to reduce the need for large resistors which can produce lots of heat. You should enter 13.6 as the source voltage and enter the typ fV and typ fI for the leds You want to buy.

   Lastly, do searches from the top of this page for like projects it will help You immensily.  Then ask any questions You are uncertain of. Rob or one of the other "bigguns" are always happy to help. Good Luck!!

[Rob]

Good point--specific questions are always the best. If you have doubts on how to start, post up a description of how you intend to proceed and let us throw rocks at it make helpful suggestions. Doing this before going shopping is usually the best plan.

[Dark-5.0]

Thanks for your responces guys. I need all the feedback I can get. I don't plan on using the stock incadecent bulbs. I am building this to replace the stock lighting so it is all led. Rob, since we're not too far from each other and I'm going between here and lawrence all the time. Maybe I could get some personal help from you. I could bring the tail light over and we could plan something out. I seriously need all the help I can get and I'm determined to have led tail lights just because I've never seen anyone do them on a mustang. I've been looking at pictures of new cadillacs and acuras and such with leds and the cadillacs seem use just use roughly 30 5mm leds in their lense. But from what I can see in the acuras, like the TL. Is it uses a larger set up, maybe the piranha bulbs you speak of.

Jeremy

[Rob]

I don't mind helping, online or in person, but the great thing about a discussion board is you get input from a lot of folks, not just me. So I encourage you to not abandon the path of working out the design details on the discussion board.

The high-level process for this project should look about like this:
1) finalize your specs (sizes, colors, bulb socket types)
2) select appropriate LEDs (what package and color, source)
3) design the arrays electrically (the LED wizard helps there)
4) design the board layout (perfboard, or premade or DIY PCBs, establish final sizes)
5) validate your design with a prototype (for example, build one string of an array and connect it to the car for testing)
6) build and install the boards for the final project.

Helping out in person gets to be realistic at about step 5. I have test gear and stuff to make that easier (like measuring actual current and voltages in the array prototype, measuring light output).

[Dark-5.0]

Yea I know what I want to do to build it. So I suppose I could make my template and drill the holes for it and everything, but wiring it up so it works is what I might need in person help with.

Jeremy

[Rob]

Yea I know what I want to do to build it.

I just bought 100 white leds off ebay and want to set up led tail lights for my 94 mustang.

I don't think white LEDs will work out. In any case, I'm betting you'll need quite a bit more than 100 to do all the lights on your car.

[justDIY]

I agree white is out of the question

a white LED is a blue led with some paint on it, that glows (primarly yellow) when exposed to blue light ... so you end up with yellow + blue = gives the apperance of white light

however, if you view a white LED through a red filter (or yellow) it will look very dim - this is because the majority of the light output is blue, and is being absorbed by the filter.  to confirm this, look at the datasheets for your white LED - it will show a very strong emission in the blue region, and a weak broad-band curve in the green, yellow and red regions

red leds are not strictly 'street legal'  - you need to use DOT approved red-orange, otherwise called DOT Red.  Lumileds (and many others) offer both super flux (piranha) and high-output (luxeon) leds that are DOT approved red-orange in color.

as far as I know, the DOT has less stringent requirements on yellow, but still requires them to be Amber, which is a orangish yellow (think traffic light yellow), not yellow like a bananna (which is a greenish yellow)

those look like aftermarket lenses you have on your 'stang already ... would it be possible to purchase another set, and use them as a form for building your LED array into?   If you measure the visible area of the lens, you should be able to get a rough idea how many leds you'll need to fill that area.  Using red-orange for the red parts of the lens and white leds for the clear part of the lens (the backup light).  Luckily the math works out pretty nicely for red leds and automotive power.   If you figure 14v as your supply voltage (engine running), you can run a series string of 7 leds without any need for a resistor (7 leds * 2 volts ea = 14 volts).   Then you wire these strings in parallel as many times as you need to achieve good ilumination through your lens.

I strongly recommend using either power leds (luxeon, lumilux, ufo, etc) or a super-flux leds (piranha) ... using inexpensive 5mm leds might look good to start with, but they won't hold up to the abuse of the automotive world (heat and voltage surges).

the cadilliac tail lights look like 5mm leds because of the design of the lens... there are different versions, some use piranha some use surface mount power leds

[Dark-5.0]

Well damnit, haha. I never thought this project would become so complicated. I figured white would work because essentially the stock bulbs are white and its a red lense. Mine have a transparent black paint on them which tints the red without taking away light output. I would have gotten red ones if I knew they would have worked better but I just assumed since the stock bulb is white, a brighter white led would work. Like I mentioned above, I just want to use the middle stripe so I don't think I'll really need more than 50 on each side. But with all this complication to just light them up, I'm really losing motivation.

Jeremy

[chopper]

   Jeremy, it isn't as complicated as it seems, lets just assume Your budget will allow You to purchase the Luxeon stars that are currently on a screaming deal as I'm certain You have read about. Think about ordering six of part #LXHL-LH3C three for each side @ $4.63 ea. and a driver for $21.00 for a total of $27.78 for the leds and $21.00 for the driver =$48.78. This may seem like a lot but it will be brighter than any array I have ever built and will accomplish far beyond Your expectations of what You may have originally thought of when first thinking of this. If this is not in Your budget, say so and I will help You find what is. If it is within the budget...wow what a jammin tail light assy You will have. From there it will be a matter of soldering and following directions. Iam 52 years old and knew absolutely nothing about how to do this just a few months ago, I learned all right here on this forum. Whaddya say?? Lets keep trying! Carl. oh if I rambled it is cuz I been  tonite...

[justDIY]

great post Carl!

just to clarify something:

future is already sold out of the red-orange luxeon star iii with a lambert lens, however their site claims these parts are still available:

part #LXHL-PH09 - luxeon iii red-orange emitter with lambertan lens (a four watt led!!) - $4.03
part #LXHL-FH3C - luxeon iii red-orange star with side emitting lens (a four watt led!!) - $4.63
part #LXHL-MH1D - luxeon i red-orange star with lambertan lens 1 watt - $2.55
part #LXHL-MHAC - luxeon i red-orange star with batwing lens 1 watt - $2.55
part #LXHL-FH1C - luxeon i red-orange star with side emitting lens 1 watt - $2.55

the difference between star and emitter is... the star provides a 'base' to facilitate installing the LED in things, the emitter is a bare LED, which needs to be glued to something

Personally, I think you're better off without a driver and use several leds... here is my math

Luxeon I star is 2.95v (for red orange)

V_F = n * V_LED = 4 x 2.95v = 11.80v ... lets say while your engine is running, you'll have 14volts at the battery, so we need to drop 2.2v

R = E / I = 2.2v / 0.350A = 6.28 ohms ... so round that sucker up to 7 ohms

P = R * I² = 7 ohms * 0.350²A = 0.86 watts ... round that up to 1 watt

you need one 6.5 to 7 ohm 1 watt resistor, you could get away with two 3 ohm 1/2 watt resistors, or four 1.5 ohm 1/4 watt resistors

luxeon 3 emitter - things get a bit harder here

the red luxeon 3's take 2.95v at 1.4 amps! *choke*

copying the same first few steps from above:


so, you'll need a minimum of 8 leds, four for each taillight, or you could be really fancy and go with 8 per taillight, 4 for running and 4 for brake/turn

4 x 2.95 = 11.80 ... 14 - 11.8 = 2.2

next:

2.2 / 1.4a = 1.57

and the part that makes me cry:

1.57 * 1.4²a = 3.1 (rounded up) ... 3.1 watts gets wasted in the resistor

so you need three 0.5 ohm 1 watt resistors, or some other combination that gets you 1.5 ohms and 3 watts capacity

but ... that will give you a sixteen watt tail-light - It will be brighter than your stock bulb!

-----

alternately, you could go the superflux route:

BHK doesn't have DOT red for some reason (email them, maybe they can order it) ... but you could mix red and amber to get close to the red-orange color

http://www.besthongkong.com/index.php?cPath=18

figure on at least 100 leds for each taillight, ideally you'd want many more than that

[Dark-5.0]

Well aslong as I have your guys help. I still want to do it. I recently aquired a new job so I'll have some money once I start that in about a week. To tell you the truth, I'm not concerned with DOT approval. There are a lot of non DOT approved things on this car. Its not much of a daily driver, just a nice weather cruiser. So the leds don't need to be dot approved or anything. I just want a clean looking set up. Heres another picture. Like I said, I just want the middle strip to light up when lights are on, the inside half to light up brighter for the brakes and the outer half to flash for the turn signals. But I want it to appear like the stock. I don't want big circles of leds with spacing between them.





Jeremy