Topic: My Rear Taillight LED Conversion - a Show'n'Tell

[TomatoSoup]

As mentioned elsewhere, I've just finished my LED taillight conversion. (Yay!)

This comprises a ring of 20 so-called 1/2 watt (actually nearer 1/4 watt) 8mm RED strawhat LEDs mounted in holes drilled in the reflector, a center 3 watt MR16 (12V) LED bulb, plus a constant-voltage driver circuit. The outer ring of 8mm LEDs are lit in 'low' mode for the standard lights, then are lit in 'high' mode, along with the center MR16 bulb for brakes and turn signals.

I got the 8mm LEDs off eBay in a pack of 50 for around $20. 

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The driver components were from Digikey ~$15, and the MR16's off eBay for ~$10.  Plus some bits and pieces I had in my spares boxes

The final result looks like this (hazards on in daylight):

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Plus here's a quick video comparison taken at night with the new LED cluster on the left and old OEM bulb on the right.  Note the thermal delay of the incandescent bulb... http://s949.photobucket.com/albums/ad339/TomatoSoup_GXP/?action=view&current=LEDTailComparison.mp4

The following posts will show photos of the various stages of this.  A lot of work, but I'm very happy with the result... although the photos don't really do them justice, they are brighter than the OEMs, a nicer red color, and of course they have that much sharper and more noticeable on-off transition that LEDs have over regular bulbs.

One final note: no load resistors were required to avoid hyper-flashing.  Even when I was testing with just the 3 watt MR16 bulbs alone there was enough current flow for the car not to do the hyper-flash "bulb out" warning.

[TomatoSoup]

Mounting the 8mm LEDs in the reflectors required marking the position of the holes and then drilling a 1/16" pilot hole with a mini-dremel to confirm exact placement plus re-drilling as necessary to correct the position.  Followed by a 1/8" pilot for the step drill and finally opening the hole up with the step drill to 5/16" (equiv. to 8mm).  These are the tools I used (note the multiple hex extensions to get in to the tight spacing around much of the reflector):

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Drilling one of the 1/8" pilots:

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All the crud left over from drilling the holes... this had to be blown, vacuumed, blown, wiped and vacuumed out - a real pain:

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The rear with all the holes drilled out, and the center openend up for the MR16 bulb - I used a regular dremel for this with a rotary cutting bit, and then a drum sanding bit for final cleanup:

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All holes drilled and in process of crud cleanup:

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LEDs in process of being glued in the holes.  I used 5-minute epoxy and did a few LEDs at a time (due to the short working time).  Note the LEDs are all oriented radially to match the reflector lines, and are alternated +/- to ease wiring:

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This shows the LEDs after the daisy-chain wiring was done (MR16 test-fitted).  They are wired in 5 groups of 4xLEDs plus resistor, all in parallel.  See the circuit diagram shown later.

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[TomatoSoup]

To make it a plug and play operation - and to allow the easy retrofit of the original lights just in case - I "modified" (with a BFH) the bulb holders to reuse them as connectors.

The following mosaic shows the stages of deconstruction.  The lighter gray bulb base cylindrical part is heat-welded into the dark gray connector base, so need to be destroyed to remove it:

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Here's the deconstructed connector, with the wires soldered-in.  The pins have been epoxied in place to stop them sliding backward:

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Finally filled with (Brazen'ish-colored) silicone caulk to both protect and help anchor the pins:

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Note, I used the "Oogoo" method with the silicone (thanks Sly Bob!) for coloring and fast-setting: http://www.instructables.com/id/How-To-Make-Your-Own-Sugru-Substitute/

[TomatoSoup]

I used a constant voltage driver circuit to protect the LEDs from over-voltage and provide constant light output.  There are two 7812 voltage requlators for each lamp cluster.  One to regulate the side/running light voltage and one for the brake/turn light voltage.  This is the circuit diagram:

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... and here is the circuit layout for using common parallel-track bread-board PCB:

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Here is the wired board from the top:

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... and from the bottom:

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The regulators are attached to an aluminium bracket made from 3/4" L-cross-section extrusion (Home Depot).  This acts as both a mount and a heat sink (doesn't need much).  You can see that I had to file a gentle curve along one side to fit snug onto the plastic reflector support bracket:

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... and here's the bracket, now curved, and the position of 'captured' mounting nuts, epoxied onto the plastic piece:

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[TomatoSoup]

Just a quick note around the MR16 bulbs.  Again these are 3-watt, 3 LED red bulbs and only light for the turn signals and brakes.  You can get them from eBay or Dealextreme.com or similar.  

The front 'lips' around the bulbs had to be ground down to allow the bulbs to fit into the center holes in the reflector.  About 5 mins on a bench sander for each bulb did the job.  I also cut a couple of circles of acrylic diffuser and mounted them to the front of the bulbs - though I freely admit this may be pure overkill

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(The center bolt is the mount, the offset screw is just to stop it turning.)

[TomatoSoup]

Lastly, the final construction and some comparisons, old to new...

Test setup to make sure everything worked:

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Here's the final 'product', all wired up, the driver board mounted and everything  sealed from the elements with liberal applications of Liquid Tape.  The MR16 bulb is fiction fit into the hole and then sealed in place with Permatex Black Rubber Sealant:

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Final cluster in place, from the outside.  You can see now how the radial orientation of the LEDs matters:

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New cluster on the left, old on the right:

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Finally, two - both under and over-exposed - photo comparisons of the brake lights (at top) and running lights (at bottom) to give you an idea of the differences.  The digi-cam breaks down here a bit in both brightness and color representation.  The LEDs are really RED in real life and appear brighter, while the OEM lights are actually more orange:

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Hope this is of use to anyone who wants to attempt something similar!

[Arabas]

awesome!!!
very talented mr TS !

[Sly Bob]

Very well done and documented. I'm lookin' forward to seeing them at the mod meet.

[Critterman]

Well beyond my level of buchatry

[TomatoSoup]

What? You mean you're not butch enough?

[JimVonBaden]

Hmmmm, the Sky is way different, but I bet it could be done! Hmmm

Nice work!

Jim

[elff]

Love the lights!!!

[melissadunagan]

  Neat job, you must be a electoral expert. I need to borrow you to help me wire up my El Camino, Hee Hee.
  How would you change out a bulb if one goes out? And it looks like to me you could also use white bulbs since you have the red lens.

[TomatoSoup]

  Neat job, you must be a electoral expert. I need to borrow you to help me wire up my El Camino, Hee Hee.
  How would you change out a bulb if one goes out? And it looks like to me you could also use white bulbs since you have the red lens.

Electoral Expert?  I ain't no steenkin' politician!

All of the LEDs are replaceable, albeit with some difficulty, but the idea is that LEDs have extremely long life and so are not likely to need replacing... (as in, I hope!).

I could've used white LEDs but there were two reasons I didn't... one is that a lot of the light output of white LEDs (color frequencies other than red) gets blocked by the red lens, thus the transmitted light can be less than that from red LEDs of the same power, making them effectively less efficient.  The other is that the light that does get passed tends to make the result more orange'y and I wanted the pure red color.  In fact I already had two white MR16 bulbs for the centers, but had to wait for eBay shipment of red MR16's to 'stay true to my ideals'

[Sly Bob]

Yeah melissadunagan, you always want to choose LEDs that are the same color as the lens. Red lens, red LEDs. If you have an amber lens, you would use amber LEDs.

[TomatoSoup]

All of the LEDs are replaceable, albeit with some difficulty, but the idea is that LEDs have extremely long life and so are not likely to need replacing... (as in, I hope!).

So there I was at the MMM8 mod meet this weekend, so proud of my 'mad skillz', but my rear lights got a severe case of "demo-itis".  One segment of 4 LEDs was out.  It had been occasionally intermittent but went solid out at the meet.  How embarrassing!  Just a case of infant mortality really, but still embarrassing...


Today it took the cluster back out, traced out the bad LED and replaced it without too much effort.  Had to de-solder, pry out the bulb, glue in a new one and re-solder.  Result? SUCCESS!

Well, at least I proved it can be done

[scanner]

Very Very Nice!  Safer now too, when you step on the brake the folks behind you will know about 100ms sooner.

Clear Skies!

[ophidia31]

Whos jealous?
<-----This guy. 
Sweet job though. Seems much brighter than the stock incandescent bulbs.

[Kelu]

TO: no embarrassing moments at SMMM8 at all, we all knew what you have there, dunno about others but I was impressed about your mods