Newbie got a question, Please help.

seff · Dec 22, 2009

Hi, im peter. Im from Chicago, and im new!
I want to do one project on my motorcycle, but i need some help.
What i want to do is to put to 2 5mm leds in each of 2 headlights, and one right next to my speedo-meter <Just so i know if they are on or off> I made some diagrams but i dont know if these are any good.

seff · Dec 23, 2009

JohnR66 · Dec 23, 2009

Wire each pair of LEDs in series as such:
+---330Ohm------LED----LED-----G
+---330Ohm------LED----LED-----G
+---1kOhm------IndicatorLED-----G

G=ground (bike frame or negative)
+=positive at switch

Use low brightness indicator LED in the instrument cluster because you don't want a blinding bright one shining in your face.

Not sure of your lighting project if it is safe or legal, but that is your business.

Hope this helps.

seff · Dec 23, 2009

Thank a lot.

I didnt think about control led blinding me, but you right ill probably lose it then. I wont use the LEDs while riding.

Will these resistors work with Red 5mm LED (2V drop, 20mA)

When i tried to calculate the resistors here:
http://ledz.com/?p=zz.led.resistor.calculator

thats what i got:

400 Ohm
Nearest higher rated 10% resistor
470 Ohm
Calculated Resistor Wattage
0.16 WATTS
Safe pick is a resistor with
power rating of
.267 WATTS

JohnR66 · Dec 23, 2009

I would have guessed you are using white or blue LEDs...

Anyhow with red LEDs you have enough voltage head to put all 4 in series like this:
+---250Ohm----LED---LED---LED---LED---G

On battery power, lets assume 13 volts supply. The LEDs in series will be 8 volts, leaving 5 volts to drop. At 20ma (02amps): 5/.02=250, so a 250 Ohm resistor will work, but a 220 or 330 is probably easier to find.
5*.02=.1 watt, so a common quarter watt resistor will work.

TorchBoy · Dec 23, 2009

:welcome:

You should not put red lights in your headlights. You'll probably find there are laws against that sort of thing, even if they're only small LEDs. Red in your instrument cluster would be fine.

Web sites like http://ledcalc.com/ are handy for working out what resistors you need.

"If you post an image in your post, please downsize the image to no larger than 800 x 800 pixels." http://www.candlepowerforums.com/Rules.html#siglines

seff · Dec 23, 2009

TorchBoy said:
:welcome:

You should not put red lights in your headlights. You'll probably find there are laws against that sort of thing, even if they're only small LEDs. Red in your instrument cluster would be fine.

Web sites like http://ledcalc.com/ are handy for working out what resistors you need.

"If you post an image in your post, please downsize the image to no larger than 800 x 800 pixels." http://www.candlepowerforums.com/Rules.html#siglines

I know i can get in trouble for it, but im just gonna use them when the bike is parked.

Sorry about the image... Like I said Im a newbee

JohnR66 said:
I would have guessed you are using white or blue LEDs...

Anyhow with red LEDs you have enough voltage head to put all 4 in series like this:
+---250Ohm----LED---LED---LED---LED---G

On battery power, lets assume 13 volts supply. The LEDs in series will be 8 volts, leaving 5 volts to drop. At 20ma (02amps): 5/.02=250, so a 250 Ohm resistor will work, but a 220 or 330 is probably easier to find.
5*.02=.1 watt, so a common quarter watt resistor will work.

Thanks a lot for your help. Looks clear now.

But how would it work if i wanted to wire LEDs in parallel way.

JohnR66 · Dec 23, 2009

Parallel wiring is not desirable with LEDs. They would have to be carefully matched or one could possibly hog more current. This could lead to uneven brightness or failure of the LED getting the high current.

Secondly, it is wasteful of electrical power as you would have to drop 11 volts at .08ma and that would require a 1 watt resistor. Series only makes sense in this application. It seems easier to wire anyway.

seff · Dec 25, 2009

O and one more Question. Should I put a fuse in there ? If yes what kind?

LukeA · Dec 25, 2009

If you're using a wire guage that can carry dangerous current levels (like 18 ga or something), then a fuse is a good idea, but if you're using 30ga wire you won't really need one, because the wire itself will act as a fuse at about 1A.

Newbie got a question, Please help.

seff

Newly Enlightened

seff

Newly Enlightened

JohnR66

Flashlight Enthusiast

seff

Newly Enlightened

JohnR66

Flashlight Enthusiast

TorchBoy

Flashlight Enthusiast

seff

Newly Enlightened

JohnR66

Flashlight Enthusiast

seff

Newly Enlightened

LukeA

Flashlight Enthusiast

Similar threads

Latest posts