LED Taillights, Diy

[kikkegek]

Matt

couple of thoughts here:

1. LEDS:
those leds you mention are the LEDs that are run on 20mA (DC foraward current) and thus NOT the brightest on the planet.

These leds http://www.philipslumileds.com/uploads/3/DS05-pdf

are Philips Superflux and have a forward current of 70mA. that makes a big difference.

2. COLOR:
your leds have a wavelength of 640nm...that is RED...behind your red lens of the taillight a lot of the output will be lost beause of that.

the leds I used (and that are used by allmost all on hidplanet.com) are of the orange-red kind that have a wavelength of 626nm.....difference seems little, but in output makes a hell of a difference:


I have bought 6 different LEDS to test these things and found out myself. And the guys from the hidplanet.com forum had told me in their first comment to go with the Lumileds.

resistor calculation:
keep in mind that you are not feeding the LEDS 12V, but 11.3V because there should be a diode inline after the voltage regulator.

as far as voltage regulator. why use an adjustable? to control brightness?
brightness isnt only partially controllable by voltage...under a certain voltage they just turn off...that is why some guys build the PWM circuits for dimming teh arrays. I just did some testing behind the lens with several resistors and found the correct size for my application.

keep in mind to allways check if the wattage of the resistor is big enough to dissipate the heat it will build up.

just some thoughts....but go for the Lumileds Orange-Red...you wont regret it...they are better quality, last longer and blind the **** out of the cars behind you when you hit the brakes...hahahaha

[Matt21lutz]

Originally Posted by kikkegek

Matt

couple of thoughts here:

1. LEDS:
those leds you mention are the LEDs that are run on 20mA (DC foraward current) and thus NOT the brightest on the planet.

These leds http://www.philipslumileds.com/uploads/3/DS05-pdf

are Philips Superflux and have a forward current of 70mA. that makes a big difference.

2. COLOR:
your leds have a wavelength of 640nm...that is RED...behind your red lens of the taillight a lot of the output will be lost beause of that.

the leds I used (and that are used by allmost all on hidplanet.com) are of the orange-red kind that have a wavelength of 626nm.....difference seems little, but in output makes a hell of a difference:


I have bought 6 different LEDS to test these things and found out myself. And the guys from the hidplanet.com forum had told me in their first comment to go with the Lumileds.

just some thoughts....but go for the Lumileds Orange-Red...you wont regret it...they are better quality, last longer and blind the **** out of the cars behind you when you hit the brakes...hahahaha

Just looked at the pdf in the link, the continuous forward current isn't listed, that 70ma rating is the peak forward current, i say this becuase yes it does say DC forward current but above that section it says "absiolute maximum ratings", so really that is the peak forward current. Which is actually a lower peak forward current then the ones that i have, mine run on a MINIMUM of 20, but you can run them at 20-75 or even greater, the peak for mine are actually 100ma. They run at 10 lumens at 20ma so if i beefed it up to 50 or 70ma they'll be closer to 15 or 20 lumens, the intensity for the led's that i have is about 5500mcd at 20ma. I don't want or need to blind people when i hit the brake i just want it to be clear that i am stopping, i don't need them rear ending me.

resistor calculation:
keep in mind that you are not feeding the LEDS 12V, but 11.3V because there should be a diode inline after the voltage regulator.

as far as voltage regulator. why use an adjustable? to control brightness?
brightness isn't only partially controllable by voltage...under a certain voltage they just turn off...that is why some guys build the PWM circuits for dimming the arrays. I just did some testing behind the lens with several resistors and found the correct size for my application.

keep in mind to allways check if the wattage of the resistor is big enough to dissipate the heat it will build up.

I have tried using resistors to regulate the brightness, 1/2 watt resistors, tried a few different ones, the problem with it is that get incredibly hot even when everything is wired correctly and you can not put a heat sink onto a resistor so I like the idea of a voltage regulator. More because if i don't want it as dim i can simple adjust the voltage a lot easier than i would be able to with a resistor, otherwise i have the desolder and put in a new resistor every time.