tail lights

So I want to build some custom tail lights for my 91 MR2. BUt I dont realy know much about LEDs, just that I want to use them. And I want to not get pulled over by the cops they dont havve to be DOT but just look like it.

I want the tail light to be all red. I plan on taking clear lexan and paint it red with some kind of paint. I dont know what kinds of LEDs to get. If I get the super bright ones can I dim them down at all?

thanks
Chris

I was looking at LEDs. what would be the best angle of LED? And what would make an LED work in my car. I have read that any LED will work as long as I use the right resistor?

chris

Hows about this for a quick Plun n play option Clicky


Tim.

Those seem nice. but i wonder why they do not have the amber ones for turn signals. it would be nice to have them with built in timer circuits too

I would but I plan on changing the hole look of the tail light changing the hole housing. I was thinking of some thing like this.



but make it my self. I want a round edge for the running lights. Then have the inside light up for the brake light. Or have the hole housing light up as the brake light.
does anybody know where I can buy small LEDs like this and make a light like the one in the pic?

what size do you think these LEDs are?

chris

bucket_chris said:

I would but I plan on changing the hole look of the tail light changing the hole housing. I was thinking of some thing like this.

but make it my self. I want a round edge for the running lights. Then have the inside light up for the brake light. Or have the hole housing light up as the brake light.
does anybody know where I can buy small LEDs like this and make a light like the one in the pic?

what size do you think these LEDs are?

chris

Click to expand...

They look like either 3 or 5mm LEDs.......Readily available for not much money all over the place - eg - E-Bay .
The hardest part will be making the PCB from scratch.

Good luck,


Tim.

whats the PCB is that the board its on. Is there any good write ups on how to make the LEDs work with a 12v system? making the stuff is not hard its just getting the right stuff and how to make it work.

If Im going to use alot of LEDs should I go with the cheaper dimer ones or still go with the brighter ones? and what angle should I get.

I was looking at some on ebay.
Material : InGaN

Size(mm) : 5mm

Lens Color : Water Clear

Emitted Color : Red

Intensity Typ : 8,000mcd

Viewing Angle : 20°

Forward Voltage : 1.9v-2.2v

Forward Current : 20mA

can I get these to work I see the 1.9v-2.2v. I dont think that will work but cant I use a resistor to make it work?

if any bodys got a good write up that would be grate.
chris

Yes...PCB stands for Printed Circuit Board.

You could use a high value resistor with each LED to get the right drive level.
Or you can do as in the example that you have provided and connect a number of LED's in series (5 in your example) in parallel connected sets (7 in your example).

This means that only 1, much smaller value resistor is needed for each string of 5 series connected LED's

In your example the power can be routed through 2 separate lines to your LED's....One with high resistance for a dimmer 'running light' and one with lower resistance for bright 'braking' light.

As far as LED viewing angle goes.....
Wider angle will be more visible from the sides but will appear much less bright from behind than the tighter viewing angle variants.

I recon the 20 degree LED should be OK as it's more important that the vehicle directly behind you (who is most likely to run into you) sees that you're braking.

I'm no expert....There are many highly skilled experts on this forum who could advise your best course of action and could probably design you a circuit board as easy as falling off a log.

First you need to decide on :

1) Your format - ie 2 brightness levels - or - outer ring - 'running' light and centre portion 'braking' light.

2) How many LED's you want to use and their specific power requirements of your chosen LED's.

3) Size of your rear light cluster.

4) Voltage output at your rear lights with engine running


Tim.

1) Your format - ie 2 brightness levels - or - outer ring - 'running' light and centre portion 'braking' light.

This is how I want to lay out the lights. The x's will be the running lights the squares will be the brake lights. I would like the breaks briter then the turns. I plan on having another circle for the turns.
I plan on haveing a red lens so I am not sure what color of LED to get. white or red.

2) How many LED's you want to use and their specific power requirements of your chosen LED's.
I guess a lot my count on the brakes is 90 and 26 for the running lights. I might put just a LED bulb brake light at the center or just less LEDs



3) Size of your rear light cluster.

the cluster to 4x12 in.



4) Voltage output at your rear lights with engine running

I will check this out.

I also plan on running an MR16 12v LED as revs. lights.

chris

OK....In the absence of any other suggestions...Here are my thoughts on a possible PCB layout.




It doesn't look very elegant and I'm sure there's a far more efficient layout....But basically what I 'think' I've done here is connect your inner 'Braking' LED's in 9 parallel connected strings of 5 LED's (connected together in series)
Each string of 5 LED's has a 14 Ohm resistor for approx 20ma drive level.

The outer 'Running light' LED's are connected as 2 parallel strings of 6 LED's and 7 Ohm resistors for around 20 ma drive.

The resistors are calculated on the basis that the LED's have a Vf of 2.2V and the voltage at the tail lights is 13.5v
(Adjust resistor values depending on specifics of LED spec and voltage output)

I'm sure someone will point out any glaring errors


Tim

Thanks

So I can use 2.2v LEDs if I use this way?

If there is a series circut and one LED goes out will all the LEDs in that circut got out?

and can I adjust the light levels with a resistor?

Chirs

Yes....Red LED's are nominally 2.2v or thereabouts (Use red LEDs behind a red lense)

If a LED blows in a series connected string - then the whole string (in our case, 5 LEDs) will go out as the circuit path is broken.

The output can be varied with resistor value.....Less resistance = brighter and vice-versa
As long as we know the actual voltage supply at your tail lights - then we can fine tune the resistor values and minimise the possibility of blowing out any emitters.

Of course..The best way to power LEDs is via a constant current regulaor circuit which will compensate for any fluctuations in supply voltage.
Should be available from LED specialists...Check 'The Net'.


Tim.

Im going to go ahead and build a mock up of a light, and see where it gets me. So now I get to owder LEDs. There is alot of places to get them but I was looking at E-bay. I can get alot for cheap from asia area. has any body done this and if yes could u sugest a person off e-bay. If not then just a US supplier would be fine.

chris

http://led.linear1.org/led.wiz

also, I would say go with 10mm leds, and btw, a lot of the lots offered on eBay includes free resistors (for a 12v source). I think you can even find some LEDs already prepd, soldered to resistor + wire... so all you have to do is connect the resistor to the 12v source and arrange the leds as you feel like...

what i would do is use some superflux led's. you would only need about 10-15 of them, and they are a lil more efficent with their light output... space then back bout an inch or 2 to alow them to dispers b4 hitting the lense. i think you will be rather impressed with those instead.

Did some LED mod for running/brake light "1157" for a group of biker friends previously, superflux LEDs are quite bright & wider in beam angle.