Category: Projects

Parabolic Reflector

To achieve best light output we are working on a parabolic reflector which will be placed on top the the LED arrays. It will be molded out of plastic and then painted in chrome.

Front Top View

Front Top View


Front Bottom View

Front Bottom View

Here are some pictures of the Corner PCB. Each side of the car will use one of these. Each PCB will have 24 LEDs mounted on it.

Corner PCB Lit

Corner PCB Lit


Corner PCB lit together with 2 STOP/TAIL PCBs.

Corner PCB lit together with 2 STOP/TAIL PCBs.

Here are some pictures of the STOP/TAIL PCB. Each side of the car will use two of these. Each PCB will have 40 LEDs mounted on it.

Top layer of STOP/TAIL PCB.

Top layer of STOP/TAIL PCB.


Solder layer of STOP/TAIL PCB. The PCB has 5 sections each of which can be lit individually.

Solder layer of STOP/TAIL PCB. The PCB has 5 sections each of which can be lit individually.


STOP/TAIL PCB with LEDs and connections soldered.

STOP/TAIL PCB with LEDs and connections soldered.


STOP/TAIL PCB with LEDs Lit (dimmed for photograph)

STOP/TAIL PCB with LEDs Lit (dimmed for photograph)


STOP/TAIL PCB mounted in housing inside the car.

STOP/TAIL PCB mounted in housing inside the car.


Top section of PCB lit.

Top section of PCB lit.


Fully lit PCB

Fully lit PCB


Comparison between incandescent and LED taillight.

Comparison between incandescent and LED taillight.

Design Testing

Here are some pictures of the prototype. The LEDs in the picture are much brighter than they appear. Slow flash was used in this picture which causes the LEDs to appear a lot dimmer then they really are.

PWM board with 2 4 LEDs in series.

PWM board with 2 4 LEDs in series.


The LEDs are cross connected in a grid fashion.

The LEDs are cross connected in a grid fashion.


The test circuit inside the housing attached to the car. The finished version will be two 5 x 8 array of LEDs and a smaller array for the blinker. The LEDs in the picture are actually a deep red and not white yellow.

The test circuit inside the housing attached to the car. The finished version will be two 5 x 8 array of LEDs and a smaller array for the blinker. The LEDs in the picture are actually a deep red and not white yellow.


The final design will yield a brighter and larger area but even with only 8 LEDs the array is very bright. The LED data sheets suggest the use of 12-24 LEDs min of this type for taillight applications. We will be using 80.

The final design will yield a brighter and larger area but even with only 8 LEDs the array is very bright. The LED data sheets suggest the use of 12-24 LEDs min of this type for taillight applications. We will be using 80.

Since the LED PCB will just house LEDs it does not solve the problem of stop and tail functionality. Each bulb on the 3000gt is dual filament which means they have two positive leads allowing two levels of brightness for each bulb.

To recreate this effect the LED PCB needs a circuit that will light them at different levels. Usually a simple two resistor setup could be used for this but because SnapLED are high flux and require a lot of current to work a PWM circuit works much better. There are also three diodes in this circuit to prevent damage to the LEDs from electrical transients that can occur in cars.

pwm3pwm

STOP/TAIL

This is the STOP/TAIL section for LED taillight. It consist of 5 sections that can be individually lit. Each sections has 8 LEDs giving the PCB a total of 40 LEDs when all sections are filled. If less then 8 LEDs are used in a section a resistor has to be added to compensate for the missing LEDs. Large connecting traces were used to better dissipate heat that is created by the LEDs.

st_pcb

Not to Scale

CORNER

The corner PCB can be used in either the front corner lenses or in the corner part of the taillight. There are 3 separate sections which can be lit individually each holding 8 LEDs, 24 LEDs total.

Not to Scale

Not to Scale

PWM

A PWM circuit is used to control the STOP/TAIL function. Since the LEDs we use are very high flux and require higher currents than regular LEDs we need to use a PWM. Instead of current limiting using resistors to change the light level we pulse the LEDs to achieve the same effect. This PWM has 28 positive and 7 ground connections allowing you to connect two STOP/TAIL PCBs. The board also allows you to set certain sections of the STOP/TAIL PCB to run independently.

Not to Scale (Pixilated until complete)

Not to Scale (Pixilated until complete)


This image shows some of the possible configurations using the PWM.

This image shows some of the possible configurations using the PWM.

Each taillight of the 3000GT houses 3 incandescent bulbs two of which are brake/tail and one blinker. Opening the housing of the taillight you can see the three sections and the holes where the bulbs go.

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The housing also contains two diffusers that diffuse the light given out by the bulbs. The whole thing is held together with a type of hot glue which can be softened by placing the entire housing in an oven for a few minutes. You can also use a heat gun to separate the Lexan from the housing.