From: John Beckett 

"Geo."  wrote in message
news::
> I don't see the problem, the LED lights that you stick in the ground are
> yellow because the clear plastic that houses the light is yellow. I would
> guess they can make that plastic shield any color they want.

I think that the light emitted by a LED is in a very narrow band of
frequency (at least it was, when I learnt about LEDs). So a red
LED emits light (almost) only at the red frequencies.

Therefore, you can't just filter it to whatever colour you want.

John

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