Author Topic: electrically gifted people please read this ~ (Read 8367 times)

78whiteorbs · « **on:** November 15, 2009, 05:33:21 PM »

http://dotheton.com/index.php?topic=10210.0

this is what I am trying to do with my tail light . Any electrically gifted people know what kinda resistor I should get and where exactly you install it in the ciruit?

You might try looking at led trailor lights. I have one on my bike and it works good. You will need to modify it to work as a tail/brake light but this is easily done by taking a resister at the right ohms connecting the running light to the resister and jumping the resister with the wire coming from the brake switch so that when the light is on you get 6-8v and when you hit the brake you get the full 12v. this will cost about $10-15 and about 5min- 1hr depending on how you have to mount it.

this could save mucho dollars for people!

Industrial Cafe · « **Reply #1 on:** November 15, 2009, 05:45:56 PM »

something is strange about this thread, is that a quote in there?

you'll need a 12v ballast resistor I think.

78whiteorbs · « **Reply #2 on:** November 15, 2009, 05:48:36 PM »

Jep, from the http://dotheton.com/index.php?topic=10210.0

"You might try looking at led trailor lights. I have one on my bike and it works good. You will need to modify it to work as a tail/brake light but this is easily done by taking a resister at the right ohms connecting the running light to the resister and jumping the resister with the wire coming from the brake switch so that when the light is on you get 6-8v and when you hit the brake you get the full 12v. this will cost about $10-15 and about 5min- 1hr depending on how you have to mount it."

that was the quote .

Industrial Cafe · « **Reply #3 on:** November 15, 2009, 05:55:14 PM »

oh i see now

78whiteorbs · « **Reply #4 on:** November 15, 2009, 05:58:42 PM »

Found another example but no specifics:

"You should do a quick addition for dual intensity.

Taillights are on "dim" (parkers?) then go bright for brakes.

Its really easy to do by wiring some resistors inline;
the brake signal bypasses the extra resistors for extra brightness. "

from http://www.drccentral.com/forums/index.php?showtopic=13466

bmarshall · « **Reply #5 on:** November 15, 2009, 06:00:23 PM »

I second the trailer light (I did regular bulb, about $12 bucks), I did that on my RD400, go to autozone or any auto parts store (can't think of the name). I got some aluminum L channel and 90 degree brackets and all is good! Some have a black rubber gasket around the edge, some don't.

78whiteorbs · « **Reply #6 on:** November 15, 2009, 06:09:17 PM »

bmarshall , how did you make it work as a running light and tail light specifically?
I am basically mildly retarded with electricity so use laymen s terms please. You got your tail light working as a running light and a brake light right? If it just a cheap regular light then it has to be modified. I am interested in the details of this mod,eg what resistors and wear to wire them blah blah blah

Industrial Cafe · « **Reply #7 on:** November 15, 2009, 06:28:40 PM »

yeesh-

Industrial Cafe · « **Reply #8 on:** November 15, 2009, 07:15:01 PM »

what's wrong with something like this, but in red?

http://cgi.ebay.com/ebaymotors/2x-1157-AMBER-36-LED-TURN-SIGNAL-BRAKE-CAR-LIGHTS-BULBS_W0QQcmdZViewItemQQhashZitem27ad034c34QQitemZ170406399028QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

Gorms · « **Reply #9 on:** November 15, 2009, 07:19:35 PM »

I could be wrong, but I dont think LEDs have variable brightness based on the voltage you give them like incadescent bulbs can (to a degree). They require a specific (lower) voltage where anything less wont turn them on and any more and you will ruin them. To make them work in a 12v system, you must use V=IR and P=IV to find the required resustance you must add and at what power rating. Incandescent bulbs come in dual filament bulbs to give you a running and a brighter brake light. For LEDs I would imagine only a fraction of them light for running lights and they all light for the brake light.

Industrial Cafe · « **Reply #10 on:** November 15, 2009, 07:22:17 PM »

my tail light uses a resistor on the LED bar for dual intensity.

in my personal experience LEDs will light up from 1 volt to the maximum recommended voltage just like a light bulb.

78whiteorbs · « **Reply #11 on:** November 15, 2009, 07:26:37 PM »

hmmm, that would coincide and sounds sensible about the only one brightness from an led. Well nope that can't be right . Look at IC's posted brake/running lights

on my thread here http://forums.sohc4.net/index.php?topic=60862.50

IC you got two different brightnesses from the same LED's right?

vanillagorilla · « **Reply #12 on:** November 15, 2009, 07:45:26 PM »

Quote from: TwoTired on November 15, 2009, 06:21:56 PM

I am reasonably trained and experience in electrical matters. But, I can't figure out what you want to do or with what.

Specify what bulbs/units you wish to use and for what function.

I do understand you want to change something regarding the tail light. Something about changing from an effective large lamp that signals other drivers where and what your bike is doing, to something other drivers will hardly notice making it even more likely they will run into you. Later, you'll probably complain of other drivers not seeing you despite how loud your bike is.
Did I get this right?

Still, if you want to increase the risk of riding, I'll help you with the electrical, provided you have something specific in mind.

Harsh...

vanillagorilla · « **Reply #13 on:** November 15, 2009, 07:50:24 PM »

Did you read what he had posted earlier? I am by no means a smart man, but I understood what he was trying to acheive. Dont know the answer, but I understand. Seems like you felt like lashing out at a young whipper snapper to me. While he is trying to save a buck and give the rest of us a good tip, too... Sorry if I offend anyone, but I thought that was a little unnecessary.

Spanner 1 · « **Reply #14 on:** November 15, 2009, 07:51:11 PM »

+1 with Ind.Cafe....LEDs are either on or off..can't be dimmed....what you want to achieve would ( for example ) have maybe 12 LEDs, 6 connected to the tail-light wire and 6 connected to the brake light wire..i.e., tail=6 LEDs, brake=12 LEDs......'cos brake comes on in addition to tail-light....easily done.
Whoops that is +1 with Gorms..... sorry.

Industrial Cafe · « **Reply #15 on:** November 15, 2009, 08:44:16 PM »

Quote from: 78whiteorbs on November 15, 2009, 07:26:37 PM

IC you got two different brightnesses from the same LED's right?

yeah, the kit comes with an inline resistor and bypass, wrapped in heat shrink.

Industrial Cafe · « **Reply #16 on:** November 15, 2009, 08:48:20 PM »

Quote from: Spanner 1 on November 15, 2009, 07:51:11 PM

+1 with Ind.Cafe....LEDs are either on or off..can't be dimmed....what you want to achieve would ( for example ) have maybe 12 LEDs, 6 connected to the tail-light wire and 6 connected to the brake light wire..i.e., tail=6 LEDs, brake=12 LEDs......'cos brake comes on in addition to tail-light....easily done.
Whoops that is +1 with Gorms..... sorry.

they can be dimmed by supplying less voltage. think about your 2 battery LED flashlight, it gets dimmer and dimmer as the batteries die. it doesn't just shut off when the power goes lower than 3 volts.

333 · « **Reply #17 on:** November 15, 2009, 09:05:54 PM »

Most trailer LEDs I've seen are already dual intensity, regardless of how it's done. Unless it's a marker light, in which case, it'll never be bright enough for a brake light.

Gorms · « **Reply #18 on:** November 15, 2009, 09:24:23 PM »

OK so an LED may have som dimming capabilities but its over the span of about .5 volts from off to 100% and its not linear. Its exponential and the useful brightness occurs over a very small upper voltage range which would be hard to regulate and its not really a useful characteristic of LED's as far as I can tell. You could have parallel sets of up to 6 red (2.2v) LEDs in series which would give you the best efficiency from your 12v source and would applify the .5v dimmer range of the LEDs into about 3v. But the variability between 50% brightness and 100% brightness of one LED may only be a few milivolts because of the non-linear function. This would be extremely hard to regulate so I dont understand how it can be done. Thats not to say it can't, just that I don't see how. If its done on one of the systems described above I am curious how.

The easier solution is to have half hooked up to the running light circuit, and the other half wired to the brake light switch. Scatter them evenly and with a lens over them blending their point light sources, you have a light that appears to be one light source with two brightnesses. This is the most common.

Industrial Cafe · « **Reply #19 on:** November 15, 2009, 09:52:08 PM »

Quote from: 333 on November 15, 2009, 09:05:54 PM

Most trailer LEDs I've seen are already dual intensity, regardless of how it's done. Unless it's a marker light, in which case, it'll never be bright enough for a brake light.

+1

Industrial Cafe · « **Reply #20 on:** November 15, 2009, 10:02:58 PM »

Quote from: Gorms on November 15, 2009, 09:24:23 PM

OK so an LED may have som dimming capabilities but its over the span of about .5 volts from off to 100% and its not linear. Its exponential and the useful brightness occurs over a very small upper voltage range which would be hard to regulate and its not really a useful characteristic of LED's as far as I can tell. You could have parallel sets of up to 6 red (2.2v) LEDs in series which would give you the best efficiency from your 12v source and would applify the .5v dimmer range of the LEDs into about 3v. But the variability between 50% brightness and 100% brightness of one LED may only be a few milivolts because of the non-linear function. This would be extremely hard to regulate so I dont understand how it can be done. Thats not to say it can't, just that I don't see how. If its done on one of the systems described above I am curious how.

The easier solution is to have half hooked up to the running light circuit, and the other half wired to the brake light switch. Scatter them evenly and with a lens over them blending their point light sources, you have a light that appears to be one light source with two brightnesses. This is the most common.

the led decreases in brightness when you decrease the amperage. that may be what the doodad in my tail light does.
my seat is being upholstered or I'd show you some pics or a video of the wiring and what it does when i do the thing toi owhf;oaeiuvh;aeworu ;gekfjsdvh ;aekrj gh;eoisdfh ;aewjrl nh;sdlkjvh q;eworu has;ddfffffffffff BARF!!! I'm going to bed.

bucky katt · « **Reply #21 on:** November 15, 2009, 11:52:02 PM »

i have an led marker/turn signal light from a tractor trailer shop. 16.95 and the red lens to fit it another 2.95 about 3x as bright as the original tail/brake light

Steve F · « **Reply #22 on:** November 16, 2009, 02:00:42 AM »

To achieve the "dual brightness", led lights use a kind of chopper circuit that makes the eye perceive the light as dim/bright. They give the led's a square wave input that is perhaps 50% duty cycle for a "dim" and full on for "bright". The duty cycle determines the "brightness" that the eye sees. That's why (I don't know if anyone else has noticed this) you see some of the newer cars that have led tail lights, and when you quickly glance away from the light, you see multiple images of the tail light. like a very fast flashing strobe.
In the pic below, I used an LED truck tail light that has such a circuit built in to give you the strobing effect, and goes full on when you hit the brake.

Queeg · « **Reply #23 on:** November 16, 2009, 02:11:17 AM »

heres what i did its off an old crapnow i forgot .... um 84 v four bike and not the sabre but ..... crap heres a link

http://www.23b.org/gallery/v/23b_members/lthe-life-and-times-of-a-fish/album322/honda/IMG_7505.JPG.html

78whiteorbs · « **Reply #24 on:** November 16, 2009, 06:04:39 AM »

Wow , lots of good info. After reading I am thinking the best route my to be as Gorms suggested and dremel in 4 new led locations and put them on the brake ciruit . Would there be any additional resistors needed I just would be wiring 4 new leds to the brake light from the brake light wire. This is good stuff .

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Author Topic: electrically gifted people please read this ~ (Read 8367 times)

bmarshall