led array and layout on a small head light bezel

[rpmp3]

I have 84 leds specs are:
SOURCE MATERIAL:InGaN
EMITTING COLOUR:White
LENS TYPE:WATER CLEAR
LUMINOUS INTENSITY-MCD:18000 TYPICAL20000MAX
REVERSE VOLTAGE:5.0 V
DC FORWARD VOLTAGE:3.3V TYPICAL/3.5V MAX
DC FORWARD CURRENT:20mA
VIEWING ANGLE:+/-20 degrees
3 leds in parallel with a 120ohm 1/4 watt res.
12volt system
I put them in a headlight bezel on my tractor now the bezel is not a flat surface it is concave/half rounded like the shape of a banana, it seems to light a large area but not really bright straight in front of the tractor, just wondering if I put all 84 on a flat piece of material if that will give me a much brighter view. It is really alot of work but before I tackle it just wondering if its worth the effort. A friend gave me some old leds off a fire truck blue and red and the manufacture used 40 leds and they are mounted on a flat board and the blue lights are brighter and makes a shape of a circle beam of light. any thoughts or suggestions.

 

[KJ6EAD]

It sounds like you're considering repopulating a board that had blue and/or red LEDs with white ones. You can do that but the circuit paths on the existing PCB may not support it without significant modification, especially if you're putting white where red used to be. I'll assume you'll make series strings of 3 LEDs. If the only current control is a resistor for each string of LEDs, you will have to change it to a value that keeps the current through the string of LEDs at or slightly below 20 mA at whatever measured supply voltage you get from your tractor's charging system when running. There are much more sophisticated devices and methods for controlling the current with a varying supply voltage but that may exceed your intended effort level.

To the matter of the light dispersing in a pattern that is useful. Your white LEDs mounted flat have a lambertian dispersion of 40 degrees. Point them all straight ahead on a PCB mounted as close to the front of the housing as possible and enjoy the result. No external optics such as the parabolic reflector in the old lamp housing are needed for a tractor light.