custome sequential tail light.

I'm trying to design a custom sequential LED system for my 2000 Pontiac Firebird;Trans Am. It will function similar to this, https://www.youtube.com/watch?v=X9mgulVWSA0&feature=related

But the tail lights will look like this,

I have no idea where to begin building the system to operate the lights..?

If you want a simple "bar across" display with 9 bars, that is relatively easy by using a CD4017 "one of ten" output counter that switches in an extra resistor to increase the current through each group/band of LED strings.
IE, each group is switched on normally with a transistor that allows limited current thru the LEDs (for 1/2 or 1/4 brightness etc). Individual 4017 outputs (except output 0) ground an extra resistor to relevant transistor to allow full LED current thru.
More bands can be added by cascading more 4017s.

Anything more than that requires programmable stuff.
It looks like a PIC else CPU was used in the youtube.

Good luck!

Thanks for the reply, i want to basically fill each honey comb of the tail light with a LED

I would start a project like this by building the LED boards first and getting them working to your satisfaction. I would make each vertical strip it's own zone controllable by a (-) pulse. Once you get that part done then you can look in to automating them. The best solution would be to use PWM to control the brightness. You could then dim them for parking lights or full bright them for stop and turn and you would have control over each vertical segment. If it were me, I would most likely have one central processor and a data bus out to individual processors for each segment. The main processor would control all the logic for turns, parks, and brakes, and send the desired brightness to each segment. The local chip would be responsible for the PWM.

Another advantage PWM gives you is the ability to easily change the brightness without having to change resistors.

Your biggest hurdle, though, will be getting DOT approval to use these legally on the street!

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Kevin Pierson

Wow, this seems a little over my head.. What kind of LED strips can you recommend to use?

You don't use strips, you would use LEDs on a custom made circuit board so that all the spacing is perfect. You could find LEDs at a place like digikey.com or mouser.com. You can get free PCB layout software (like FreePCB) and have prototype boards made fairly inexpensively.

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Kevin Pierson

I like the idea of custom made board so that the spacing is perfect.. is that something i can find @ mouser.com?

No. Custom means custom. You would have to design it yourself and have it made by a PCB shop. PCB123.com or 4pcb.com or some place like that.

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Kevin Pierson

Great, thanks alot for the info. At least now i have a direction.

To be seen better through a red lens, would i go with red LED's or white ones?

I would start with red. When it comes to project like this sometimes some trial and error is required for best results.

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Kevin Pierson

Agreed. Red is cheaper. And the red lenses merely filter out all the non-red colors in the expensive white LEDs.


The problem is that changing the color later may change the number of LEDs you can have in a single series string - ie, 3 whites (~10V) or 5 reds, and hence your PCB layout if you want optimum efficiency (les series resistors). (Otherwise assume 3 LEDs & 1 resistor per string.)


But that's what the testing is for before the complexity of designing an the cost of a PCB.
Though a blank or "donut plated" holed matrix board may suit your LED & reflector spacing..)

To oldspark:
I will most likely go red, as that is the color of the lens.
And there will be something like 130 LED's per light and two lights

I wonder if somehow it would be possible to use the logic part of an old chaser light bar. Think KIT from knight rider. At least for the sequential part. Treat the entire assembly as one unit for the parking light and brake. That should be fairly easy. Lots of relays and diodes I am sure.

No relays. And none needed, nor desirable.

Many of those KITs used 4017s.