Some advice for LED backlight spacing

[dcoker]

Hey everyone, so I'm working on an a320 flight deck and just getting started. I'm currently drafting up booklets for each panel with plans and a supply list with prices per panel and I needed some quick advice: I'm planning on using acrylic panels using the printed transparency/mask method and I just wanted to know how you guys spaced your LEDs (for backlighting) or if you have any rules of thumb or anything you've learned from playing around with backlighting that might be helpful. I'm planning on eventually grabbing some open cockpits cards and have heard of sanding the tips of LEDs to diffuse them, running pre-wired LED strips or just placing LEDs around an inch apart for the lines on the panels and perhaps one behind the lettering above the knobs. I will be running some tests but before I started I figured I'd see if anyone had any tips or things I might have overlooked. Thanks in advance!

Edit: I just wanted to add a few more things; would you guys recommend amber LEDs since I heard the actual a320 backlighting is amber not white? I figured if it was too orange I could make every other led a white one or possibly just use white all together and tint the bulbs. And would you guys recommend the cheapo LEDs from china? I could get a ton of them for pennies but I don't know if they're durable or worth the time.

[dcoker]

I knew I saw this at some point! If anyone is interested here is a link:

http://www.mycockpit.org/forums/showthread.php/20247-Best-colour-to-back-light-A320-main-instruments.

Also if anyone still has any other tips or would like to share what worked for them I'm all ears!

[KLM077]

Hi Dcoker,

There is no general rule or formula for this. The distance from the leds to the panel depends on several factors like the transparancy of your layers, the intensity of the leds and the angle of the led light bundle.
On this moment i'm also building the panels from scratch. First i just bought the leds bars and tested it with a pre-production panel to tune everything, really the best way is to test with a sample panel and fine tune this before making the rest.
In general : the leds too close= hot spots and too far away= low light conditions, to balance this, just test....
To adjust the leds: dim them and/or make the lens end flat to widen the bundle effect is a more diffuse light. This is a solution when you can't place the led farther away. I prefer place the leds farther away to have more spread and equal light.

Succes!

Regards,

Bas
KLM077

[dcoker]

Hi Bas,

Thanks so much. It looks like I'm going to go this route:
http://www.simu320.fr/8-eclairage.htm

Halfway down the page he has a shot of his back panel with LED strips. I saw a photo of an actual a320 panel on here and they must've used around 250 LEDs on their panel so I figured I'd need a lot more than I originally planned on and this should help.

Thanks again!
Deniz