Custom LED tail light help

[Loki]

I made a led tail light with integrated turn signals. I put two 20ohm resistors on the running light and brake. Went to test it and with the resistors on it i got nothing. Bypassed the resistors and then i blew my fuse. My multimeter doesnt read ohms very well and so i dont know what resistance i need to put on my LEDS so i dont blow my fuse all the time. Here are some pics before i put the resistors on. The LEDS are wired in parallel and are able to handle 12v, just my current thats all. Help please.

 

[americanthunder]

you have alot more patience than i could ever wish for[up][up]

 

[CowboyKS]

You will be able to see it from space!

[up]

 

[jasoncummings64]

20 watt 10 ohm.. i have a set if you wantem... pay for the shipping and you can have them for free. they came with my led integrated tail light and i didnt use them

 

[Butters]

I think you might need to consider adding some more LED's...

 

[Loki]

MOAR LEDS!
And yes jason i would love them. Can i see a picture?

All the LEDs i have here are white and i have running light, brake, and signals. the running and brake are 5v LEDs and are wired in parallel to get the same voltage all around and the turn signals are wired the same but are 3v.

 

[dave_xb12r]

That looks like series to me. All it takes is one backwards LED and the whole thing won't work. Plus you need them in legs of 6.

Also, you shouldn't be wiring LEDs in parallel with just one resistor, if you have to have it in parallel, you should have a resistor for each one.

Maybe this will help you.

 

[rah7777777]

Within reason, Voltage doesn't mean too much to LEDs, Current is what you need to keep your eye on.
You need a solid constant current flow that is rated BELOW your LEDs current max.
Seeing how there is no current regulator installed, you need to check the current with the bike running and off idle.

Those LEDs probably have a low current rating too.
( 2-pin LEDs such as those are not high power, so they are weak. They also have a more direct light output which is bad for a tail light )

I'd highly suggest wiring in series. This keeps voltage down and keeps current same in all the LEDs in that leg of the circuit.


By running in parallel you are dividing current but keeping the voltage the same ( and in your case high ) by running in series, you can keep current the same through that "leg" and voltage drops at each LED.

But either way you should figure out your max current values and redesign the board to fit that.

I've been there, my first light didn't look much better.
But once I realized the importance of current regulation, I went back and spent a LONG time redesigning the whole circuit ( current regulation and other safety circuitry ).

Oh and if your popping a fuse, it's either
#1 a direct short or #2 your fuse is too small.

Good luck!

 

[Sirius815]

Current regulators can be gotten cheap from here - http://s.dealextreme.com/search/current+regulator

What rah said is 100% correct. Let us know if you need some more insights.

 

[anrkizm95]

everything you need

 

[jasoncummings64]

****! looks like you got some more research todo././ ill try and get a pic up today, looking st all that math **** they might not work for you, either way, once you get your values figured out, if the ones i have are suitable, they are still yours.

 

[Loki]

Dave... its wired in parallel trust me and i wasnt using one resistor and ive tested the parallel lines before i tried it on the bike and it works so nothing is backwards.
With wiring it in series wont i have a few lights brighter then the seeing how the first lights will get more voltage. and if i put huge resistors on it so the first lights blow wont my last lights be suuuuppppeeer dim?
What if i wire it in series-parallel with 6 rows in series?
Im just confused on why i didnt blow the LEDs instead of the fuse.
I think ill just buy a few cree lights that are 12v or 6v and use thos. Those are bright as all hell if i get some 205lm ones.

Lol anrkizm, theres no way in hell im paying 205$ for something i can build just as bright for 50$.

 

[oh9bolt]

theres no way in hell im paying 205$ for something i can build just as bright for 50$

Agree 100% I bought phillips super flux leds I used 60 leds (running light,brake light, and turn signals) and made my own it looks awesome without the lens it doesn't hit the correct parts of the refractors so I'm ordering the ecliptech lens to help the situation will post pictures when my bike is running. Google led array calculator that's what I used to figure out what resistors to use and how many to wire in each row.

 

[oh9bolt]

LINK

Here is the link I used. I also put a 12v regulator on each circuit for extra protection just in case.

 

[Sirius815]

Be careful about the 6 and 12volt LEDs (or any LED over 1W) as they REQUIRE a heatsink.

Also - most LEDs are 1.5v or 3.3v (ish) so you can do 8 1.5v LEDs in series (12V total drop) with a regulator or 3 or 4 3.3V LEDs in series (9.9-13.2V drop). Then build parallel paths. This is the most efficient way to power lots of LEDs with the 12V system.

 

[oh9bolt]

A pic of my tail light

 

[Loki]

Ya i think ill end up doing the series-parallel route. Am i limited on how many strings i can have? For example. my 3v leds, ill run 4 in series and have 6 series lines hooked up in parallel? Would that work?

 

[dave_xb12r]

I don't see why not. That's how I'd probably do it. But you'll want a voltage regulator on each of your power inputs.

 

[Sirius815]

Dave is correct - for the normal light you'll need a regulator and also for the brake light portion.

There is a limit, which is based on what current the LEDs are rated for. For instance, if the LEDs are 150mA, then 6 strings would give you 900mA. Your regulator needs to be able to put out that amount of current.

 

[Loki]

Im going to use 3.2v 5mm LED at 20ma. Plan on having 30LEDs for each light (brake, running, turn signals) and 3 x 10 array uses 30 LEDs each 3 leds will get a 120 ohms resistor.

Now for the regulator. I knew how to make one earlier in the year but have thus forgotten. Do any of you guys know how i can make the proper regulator?

(I love electronics, its what im going to college for )

Dear lord this is going to be so much desoldering. The middle LEDs are 5v leds and the turnsignals are 3.2v. So ill just take the 5v ones out and toss those most likely. I ordered more 3.2v ones. They are 25000mcd so they are bright.