How to wire up 11 LEDs off 12v source?

[Spr0ket 10+ year member]

The blue LEDs are 3.3V max with an MCD of 4000 (some of the brightest blue I have found). To give you an idea of how bright they are, eight of them will give out the equivalent light of a standard 12W dome light. 16 LEDs should be freaking insane. If you have put the LEDs into a plexiglass housing, you should be fine and have little to no blotchy patterns. If any of them are exposed to a visible area of the plexiglass, I would shave the very top of the LED down using a simple plastic file. Don't shave it beyond the rounded part though, that can cause trouble. As for wiring them up, I would wire them up parallel with their own 480 ohm 1/4W resistor for the best even glow. That will limit the power draw down to roughly 3.28V on a 14.4V feed. Now if you have an upgraded electrical system or plan on upgrading to a high output alternator, you will need to use 560 ohm 1/4W resistors or higher. The difference in ohm change is not even noticable. Just for grins, here's a daytime pic of my domelight (8 blue, 8 UV LEDs)

 

[Spud2388 10+ year member]

Well, my Alpine logo is about 9 inches wide and 1.5 inches high, and i'm planning on running 27 blue LEDs behind it, should be PLENTY bright. I dont have that much room to work with, so i decided that i would run 6 sets of 4 LEDs wired in series and have 3 on resistors to get them down to 3 volts. Would that be right?

OR, is there a way i could come off of a switch with a resistor (drop it to 3 volts) and have them wired up in parallel?

 

[Spud2388 10+ year member]

Like this... http://www.solisearch.net/ims/pic.php?u=204942cMn0&i=129911

Would it work properly?

 

[Spr0ket 10+ year member]

The diagram you gave will not work. You will have most of the LEDs burn out before you can even blink. Here's how to properly wire LEDs:

Paralell:

Series

Paralell & Series

Follow those guidelines in series or parallel depending on what you want to do. It is better in parallel for uniformity. Keep in mind that if you wire in parallel, every LED requires its own resistor.

 

[req 5,000+ posts]

http://www.LSDIODES.com is the best supplier of super bright LEDs... period.

if you thing 4000mcd is bright, take a look at their "5mm Blue THC3 11000mcd"

 

[Spud2388 10+ year member]

Thanks guys, yall really cleared it up for me. I guess i'm going to run 6 sets of 4 in series and have 3 on resistors, so i dont have to worry about getting 27 resistors if i ran in parallel. Preciate it!

 

[Spud2388 10+ year member]

What resistors do i need?