[hcker2000]

Hey there I'm new but a great source for leds is www.besthongkong.com

While some Chinese importers have really low low prices.
do watch out for inferior quality and por specs..

If you have all the right tools. You can make a tail light
in about 3-4 hours..

I order all my led's from besthongkong.com as they are realy great leds. I'v only ever goten one led that the color was a bit off of the others but it was just barley and behind a lens you would never know.

I'm planing to do some projects like a break light fader/blinker, 3 axis g force sensor, led light sequencer (this is already done just got to post the write up on my web site). I'm sure I will think of plenty more things to do too.

[Black_peter]

EDIT

Just to let you know during pre-flight inspection I noticed I have an LED burned out..
I suspect it may actually be the resistor.
However since I wired all my LEDs in parallel,
I only lost one (out of 20) rather than all of them..

[hcker2000]

Are you guys mesuring your max voltage at rpm? I would hope so because voltage is lowest at idle.

Best thing is to mesure your voltage at say some thing like 6k rpms and see what it is.

Leds also have different voltages depending usualy on color. Reds are 2.4 volt usualy green and blue are usualy 3.4v and white is just under 5v if I remember right.

Oh and a quick tip if you need to get the leds to have a wider viewing angle. Sand down the domed top of them so its flat.

[opelguy]

load sharing

So, let's say you have a post-98 with the built in signals up front and you do this LED conversion to the rear. Now your flasher isn't working right because it doesn't have enough load. You want to add some load (a resister) to make the flasher work or buy a new flasher unit, right?

There is an even better way to add some load, one that will actually use that extra power for something instead of just heating up a resistor. You could add a new bulb to the front with double the brightness, one that'll really make the front signals pop as well. Dennis Kirk sells a replacement bulb for the 1127 dual filiment bulb with a 50w bright filiment (standard is 28w) that'll make your front turn signal nearly twice as bright. (Part #22274 at Denniskirk.com) Twice the brightness on the front, load balanced back out, and everything working as it should with a pair of $9 bulbs.

In the pre-LED days these were the hot item for brake lights too, as they would really make your tail light up when you got on them. I'm not sure I would want them on all the time, drawing twice the current through stock wiring and switches and such, but I've never had an issue with them for brake and signal use.

[Black_peter]

Re: load sharing

So, let's say you have a post-98 with the built in signals up front and you do this LED conversion to the rear. Now your flasher isn't working right because it doesn't have enough load. You want to add some load (a resister) to make the flasher work or buy a new flasher unit, right?

Have you fixed fast flashing this way?
Current (like water) seeks the path of least resistance.
In this case it is through the LEDs to the flasher.
Adding "load" to the fronts will make them brighter but shouldn't effect the double flash. Adding a ballest resistor to the circuit is done either in the whole circuit (when LEDs are used all around) or in the LED circuit.
I havent seen MIBagentQ around but he has done a lot more LED work
than me.. I'm going to send him a PM because this have me scratching my head..

[Black_peter]

Are you guys mesuring your max voltage at rpm? I would hope so because voltage is lowest at idle.

My voltage calulations were made using the "standard" running voltage.
(13.5 volts)
I rounded in the resistor calculation (that should be in there)
15 volts would change the resistor from a 333 ohm (for a 3.5 Vd LED)
to 385 ohm. The next higher common resistor is 470 Ohm..
So you could use that if your worried. I have lost one element in
15 months of use.. I'm pretty happy.

[opelguy]

eh, well, that's sort of how it works

The whole idea with the LEDs is that they draw less current but are brighter, right? With the LEDs and their current limiting resistors passing on 20-60 mA each it would take a ton of them wired in parallel to pass the same amount of current as a bulb. They actually pass very little current in typical use, which is the problem.

The ballast resistor they add goes in parallel with the LEDs and is of a low enough resistance that it passes enough current meet the minimum current requirements for the flasher to work properly.

Basic round #'s:
-Typical turn signal bulb is 28W, which is roughly 2A. (easy math's sake)
-Turn signal circuit goes as follows: (+) terminal of battery, ignition switch, flasher, turn signal switch, left turn signals (or right) with front and rear wired in parallel, ground, (-) terminal of the battery. With 2 bulbs passing 2 amps each, that means the ignition switch, flasher, turn signal switch, and some of the wiring actually sees 4 amps, which is what the flasher needs to work properly. (Actually needs 5, on most of them anyway, so the round math is not perfect.)
-3V LED with a 330ohm resistor on 15 volts passes 45mA. Let's say you use 10 in parallel, then you get 0.45A total for the new LED light array. If that replaces one of the bulbs with this LED array then the rest of the circuit only sees the 2A bulb + the .45A LED for a total of 2.5A, which is not enough for the flasher. If you then also add a ballast resistor of 7.5 ohms or so, which will pass 2 amps by itself, in parallel with the lights you then get the 2A from the one origional bulb + the .45A from the LEDs + the 2A from the resistor that puts your flasher back at a happy 4.5A and everything works right.
-Putting a 50W bulb in the front means that now the front bulb is passing 3.3A all by itself. Add that to the .45 from the LEDs and your right back at the 4A we started out with (well close enough) going through the switch and flasher. Same effect, just different.

Now the Ballast resistor works fine, and for most folks it's the easy answer because they just buy something and it makes their stuff work. Problem is that the ballast resistor has to do something with that current, basic conservation of energy. What do resistors do? They get hot. The aforementioned resistor would be turning 30W of energy into heat. Since your flashers aren't on all that often, and they flash, most people wouldn't notice as the resistor probably wouldn't get all that hot. If you tried using your hazzard lights, though, and left them on a while, that resistor might just melt plastic if it was near it.

More to the point, using a ballast resistor just seems kind of, well, wasteful to me. Same with the individual current limiting resistors for the LEDs, though there the trade off with reliability is probably worth it. With the same LEDs used in the round math above, wired 4 in series instead of in parallel, you could use a single 10 ohm resistor as your current limiter and still get the same light output from the same 4 LED's, but only use 1/4 the overall current for the array because you would be turning less to heat. But now your ten LED array only needs .13A, which of course makes the flasher even less likely to work.

Point is, the brighter bulb in the front trick will usually work. I have used it in the past and will do so on my own Kat as soon as I get that clear lens for the back. I like the idea of a single one of those bulbs in the rear taillight housing, with a red cover over just the bulb, surrounded by a slew of red LEDs for the tail and brake lights. Then, add a couple strips of yellow LEDs, one on each side of taillight as arrow shaped turn signals, all in the same housing. I think it would rock. But that'll have to be a seperate how-to, right?

[Black_peter]

I see what you are saying..
However:
Loads in series are added simply..
RTotal = R1 +R2 + R3....
So two 28 watt bulbs in series can be added.
Series would be 10.28 ohms (10.28 = 5.14 +5.14)
12(V)=2.3 amp*5.14 ohms (at 28 watt) Right?

Loads in parallel not so much.
RTotal = 1/{(1/R1)+(1/R2)+...(1/RN)}
That would be 2.57 ohms
2.57= 1/( (1/5.14) + (1/5.14))
2.57 = 1/((0.194)+(0.194))
2.57 = 1/0.389

[opelguy]

understand

I see we are going to disagree on this issue, and without drawing a Kirchov's Voltage loop for the circuit I don't think I'm going to be able to fully make my explaination. I have used the brighter light bulbs I recommended in the first post myself with excellent results, feel free to take or leave my recomendation as you will.

[notec]

Ok......enough formulas......your giving me a headache ........How about someone made up an led headlight.......now that sumabitch would be bright 8)

[hcker2000]

Ok......enough formulas......your giving me a headache ........How about someone made up an led headlight.......now that sumabitch would be bright 8)

High end auto manufactures are already doing led head lights using arrays of 5 watt luxeon star leds.

I agree that adding a ballast resistor is wasteful. The best thing to do is get an electronic turn signal flasher. This way you still get the energy savings.

Led's should be good for years of run time.

[Black_peter]

Re: understand

I see we are going to disagree on this issue, and without drawing a Kirchov's Voltage loop for the circuit I don't think I'm going to be able to fully make my explaination.

OK Buster!
First off it's Kirchoff (Gustav Kirchhoff 1824-1887)
And Kirchoff's Loop Rule doesn't explain anything here..
If you're going to pull out big guns like Kirchoff's Loop Rule,
you better follow through.

[Black_peter]

I agree that adding a ballast resistor is wasteful. The best thing to do is get an electronic turn signal flasher. This way you still get the energy savings.
Led's should be good for years of run time.

The real energy "savings" is only there if you use your "parking"
position (tail light on) Which I do.. The real reason I got into this was
because my new LP turn signals blew a bulb 3 days after install!!
Grrrrr!!!!!
The only replacements I could find were 3.99 EACH!
So I said to hell with it and built the LEDs..
In for a penny in for a pound so I did the tail light.
I like the tail light a lot more than the turn signals..

BTW I have a flasher all set to install on a pre 98 (maybe 98+ if
it has the same plug. ) No cutting and splicing needed.
However there is no lock mechanism for the plug so a wire tie
or tape is required.. See here:

http://www.katriders.com/forums/viewtopic.php?t=20806

[Black_peter]

hcker2000 is working on some LED accent lights.
His post is here:

http://www.katriders.com/forums/viewtopic.php?p=331791#331791

And the project is here.

http://ww1.hnetinc.com:82/Projects/ledpod/index.htm

[jakedkat]

i like it alot! i was wondering if anyone knew the laws on colors of LED's that i can use, i like to be different, how cool would it be to have green flashers to match your green bike, also, do they have LED's that imitate the color and look of blacklights? Just wondering, i dont know if it is good but i love the look of blur and thinking "if i stare long enough i might just go blind!"