LED Taillights, Custom Made for the 914 Options

[Spoke]

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
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[Spoke]

Got the lens samples in this week. 2 of the samples seem to work well.

The only issue I see at this point is the beam angle (12 and 18 degrees) may be a little too tight. These collect the light very well but produce more of a focused beam than a distributed light. I will need to put these behind the 914 lens to see the diffusion added by the 914 lens.

This first one is the Polymer Optics lens. This has a 12 degree beam angle.

I have only 3 samples shown here. This is with 200ma current through the red LEDs. At 200ma, the LEDs remain cool as ever. I've run these for 15 minutes at a time and they are just above ambient temp.

Here

This is the pattern on the ceiling about 6 feet above my desk. The light is quite bright but as is observed, very focused. This is 3 LEDs, I'm planning to have 20 LEDs for the brake/running lights.