LED Front Turn Signals How-To

[niles]

Tools:
Phillips screwdriver
Soldering Iron with a good precise tip
Voltmeter is highly recommended so you can test your connections and stuff

Supplies:
500 Amber 3mm LEDs
100 1/4 watt Resistors 100ohm
Spool of small-gauge connecting wire or ribbon cable (like what’s used on computers)
1 large Phenolic Proto-board (I used part # EXPBRDLGPHEN)

Optional:
Turn signal housings: so you can build the LED ones without messing with your originals.

Additional Info:

If you have the original Honda flasher it will flash really fast. You have two options:
1) Buy an electronic flasher sold at any auto parts store
2) Mod the existing flasher like POS_carb: https://www.3geez.com/forum/showpost....3&postcount=10

I did option 2 and I love the adjustability, plus it applies to future plans for me. Thanks POS_carb! BTW I used a 100Kohm pot and it works perfectly (says 104 on it).

LEDs:
The ones I bought were marketed as Amber/Orange but they are more orange than anything. Always check the specs before deciding to buy. If there are no specs DO NOT BUY. You will need this information to make sure you use them properly. The most important part of all is that the LONGER lead is POSITIVE, or the LED will not work.



Resistors:
Will be different depending on how you decide to make your circuit. Be careful to not give your LEDs more current than they can handle or they will burn out. I will only provide the SAFE values, which is 100ohm in this application.

Layout:
The LEDs I bought handle 20mA and drop ~2V across each LED. So I am running 6 LEDs in series with a 100ohm resistor at the end. So each turn signal has 36 sets of these running in parallel. I found this fits perfectly inside the housing, right between the two screw holes. Each signal has 216 LEDs in it so you have some room for mistakes, but trust me, you do not want to fix any mistakes.


-Do this 36 times

Because of the limited space I chose to put the resistors on a separate board. The board I bought was 180 x 128mm, part # EXPBRDLGPHEN and it was perfect size for all my needs. The LED array is 8 x 27. Here is how I laid it out:



The thing I like most about this layout is that all the LEDs face the same direction so it's easier to assemble.

There are 4 columns of 8 rows, and then the end has 4 groups of six LEDs.
I connected all the Positive leads using connector wire so that only one positive wire was going to the light socket in the housing.
Each negative lead MUST go to its own individual resistor, and then all resistors will go to the ground on the signal housing.

[niles]

Here is how the board fits in the light:


Assembling the Resistor Array:


I painted the board white, after assembly I wished I went with gray or black...


And here you can see how it looks expanded out:

[niles]

A good look at how I connected the LEDs:



And the finished product without the lens. I am building new lenses out of clear privacy-textured acrylic. I am hoping it looks somewhat like the new Cadillac tail lights when finished. Additionally this does fit inside the original lenses as well.

[2ndGenGuy]

Awesome work! Been wanting to do something like this for a while! Fantastic write-up! Went ahead and made this a sticky. I'm going to re-host the images locally in case they get taken down off of Facebook one day.

[niles]

Thank you 2ndGenGuy!

[2ndGenGuy]

Coming to the Portland meet?

[niles]

I am going to try to make the photoshoot, but the rest of my day will be spent at the tattoo shop. I forgot which saturday the meet was...

[Vanilla Sky]

These look really good. I've had all but the board laying around my shop for years.

[89HatchbackLxi]

Wow, Nice write up! Super detailed too!

I'll have to try doing this after I finish up with all the bodywork I'm doing on my car. I might actually try doing a sequential version of this.

[Vanilla Sky]

I hosted the pictures on our server and made an entry in our How To section. You can see the finished How To here.

[2ndGenGuy]

Oh ok sweet. Thanks for doing that.

[niles]

These look really good. I've had all but the board laying around my shop for years.

I got the board from http://www.futurlec.com/protoboards.shtml
the part number is in the post.
Their prices are unbeatable on a lot of things...

[POS carb]

http://www.futurlec.com/Protoboards.shtml
For some reason the link won't work on firefox if the P is lowercase

[Hazwan]

Hey do you happen to know anything about regulating the current/voltage to the LEDs properly? I've done many LED conversions in the past except they all went out after about 2 years. From what I understand LEDs don't like the current/voltage spikes from the car charging system. I've made some research and I've got myself confused So I was wondering if going with straight resistor setup like yours is a good idea or do I need some kind of regulation circuit so they would last?

Nice work BTW!

[Vanilla Sky]

That's what the resistor board is for. LEDs handle voltage fluctuations very well, as long as they don't overheat. If you overdrive them, they overheat.

[niles]

That's what the resistor board is for. LEDs handle voltage fluctuations very well, as long as they don't overheat. If you overdrive them, they overheat.

Hey do you happen to know anything about regulating the current/voltage to the LEDs properly? I've done many LED conversions in the past except they all went out after about 2 years. From what I understand LEDs don't like the current/voltage spikes from the car charging system. I've made some research and I've got myself confused So I was wondering if going with straight resistor setup like yours is a good idea or do I need some kind of regulation circuit so they would last?

Nice work BTW!

I designed the lights based on 14.5 volts from the alternator instead of 12 volt, this also means they will appear dim when they are turned on without the car running.

And yes, my LEDs will probably not last forever, especially since I got them for such a good price. They are probably very sensitive to too much power.

If you want your LED lights to last forever you absolutely have to have some kind of regulation. They sell LED drivers fo $5 to $10 each that would be a good investment if you are doing a real classy project. But I figured with the turn signal, it only has a 50% duty cycle and is only used when I am turning (or broken down, fingers crossed) so I should get relatively good life out of them.

I could also go way into the voltage drop across diodes and how that affects what resistors you use but I feel it is best to use a tool like this link if you don't want to make you brain bleed with electronics calculations: http://led.linear1.org/led.wiz

[niles]

And Vanilla Sky is right. They burn out when they get so hot internally that the silicon breaks down.

It's kinda fun to watch if you do it intentionally

[Hazwan]

I've been reading too much advanced posts on HID planet and its driving me insane >< I don't even know if I'm gonna be fine if I designed my resistors to go with 14v instead of 12v.

So are you saying if I keep the voltage to the LEDs within the spec (in this case, 1.9v for mine) with proper resistors designed for 14v, they gonna be fine?

[Vanilla Sky]

Ideally, you should have no problems. Deal Extreme is a good place for parts, as is eBay. Both carry DIY flashlight parts, and they make some VERY good drivers for high current LEDs that should suffice in this application. I would look into heatsinking any drivers, though, as they typically get pretty hot.

LEDs have a working range, and it's usually a range of at least half a volt. I know the Crees I work with will underdrive down to fractions of a volt, and will overdrive to 5 volts or more. The more you overdrive an LED, the shorter its life span. That's why passively regulated LED circuits can be hit or miss if they are designed improperly. A resistor based regulation circuit is 100% a passive circuit.

[niles]

Yeah, all is correct information. As long as you work within the specs you should be rather safe.

Sorry for the scatterbrain - I just got over a cold.

I would like to add the the voltage regulator on an alternator is one of the most robust regulators you will find anywhere without a doubt. Additionally the battery is an amazing filter because it will absorb excessive spikes and smooth out voltage drops if any. If you have good wiring, your LEDs will be relatively safe.

As far as the math goes: a small jump in voltage = a large jump in current with passive resistor-based regulation

[niles]

*Update:

I finally cut the plastic I had for the lenses. Will probably replace them with something less see-though or paint the inside part of the bumper white. Looks like privacy plastic is only private at a distance

[gfrg88]

Any pics from a little farther back?


Looks good! But I do agree that maybe an amber paint/film might look better. Keep it up!

[Civic Accord Honda]

i <3 leds!!! so doing for my crx except ill be keeping the amber lens cause i <3 amber!

[niles]

I will take better photos once the second edition is completed.

[niles]

Here is a sample of the new turn signal design. Improvements from the original design:
1) BRIGHTER!
2) Better Color
3) Less LED's to solder
4) Darkened the housing for a better look
5) Different lenses (pics soon...)