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Are all LEDs the same quality?

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Silver:
Is sandpaper the best way to diffuse the light given off?

I've got a pile of bright LED's (free off a friend!) but they are all 20 degrees (ie quite focussed). I was wondering if there is any (cheap) substance I could put over the top of the LED when its in the button to diffuse the light?

PS LED-Whiz just arrived. Very happy about that!

ShinAce:
Flattening the tip would be the best. With a fine grinding wheel, flatten the concave part, but not entirely. Buffing the flattened part may help afterwards.

Sandpaper to scuff the surface is not the most effective.

JoyMonkey:
I'm by no means an expert, but from reading over a few threads here's my general understanding of it for anyone still wondering...

A high MCD is great, but if the viewing angle is too small and you have the LED positioned so it's pointing straight up you'll end up with a big hotspot in the center of the button and not much light will show through the button's bezel. This is especially bad for buttons that are very transparent (whoever's playing will be blinded if they look directly at the buttons!)
With a higher viewing angle the light is more evenly distributed through the whole button and you end up with less of a hotspot and more light in the bezel.
Here's a drawing to show what I mean...

I'm using SuperBright RL5-R3545 (3500mcd, 45degree) red LEDs and have them mounted like this in translucent red buttons and I think they light the whole button up great. I also have a few translucent leaf-switch buttons that I'm going to try out and see how lighting them with two LEDs on each side (like how MikeQ shows it here) compares to lighting a Happ style button with one LED in the center.

juggle50:
Hey Joy Monkey,

I just ordered mine and they are 30 degrees.  Do you think thats not wide enough.  They have pretty bright mcd around 4000.

JoyMonkey:

--- Quote from: juggle50 on January 30, 2006, 02:24:35 am ---Hey Joy Monkey,
I just ordered mine and they are 30 degrees.  Do you think thats not wide enough.  They have pretty bright mcd around 4000.

--- End quote ---

Like I said, I'm not an expert, but I'd say you might be better off mounting two of those LEDs per button and have them pointing into the button's edges like in MikeQ's setup.

As Randy has pointed out before, when you're mounting the LEDs so they're pointing straight up through the button (like in the above drawing) the most important factor in choosing an LED is it's luminous flux, which is determined by it's MCD and beam angle.

Here's a nice calculator to help you easily figure out an LEDs luminous flux:
http://led.linear1.org/lumen.wiz

While I'm at it, here's another useful calculator for determining what size resistor each LED needs:
http://led.linear1.org/1led.wiz

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