Hi all.

Over the time I've had a few questions from people asking about purple lighting conversions. I've never done one, I've never been particularly keen to do one - reasons below....

Firstly - purple / violet LEDs are a reality now. It has taken a while, but since the intruduction of the once impossible colours like blue, white, and pink, they have now perfected the techonogy to give us UV LEDs. But this is the problem - Ultra Violet. Yes there is a fairly good percentage of visible violet, but mush moreso invisible UV - now for those that don't know, bombarding your retina with UV is not a terribly healthy thing to do. (and that's exactly what you're doing - it's dark inside the cab, so your pupils open right up - so all that UV is cooking your sight receptors)

Secondly - and this exacerbates the first problem - the UV LEDs don't have a hell of a lot of visible component as compared to the invisible, so you must get high intensity devices so that the precieved light is bright enough. This couples with the fact that the human eye is not as sensitive at the extreme ends of the spectrum - red down low, and violet up high. This means higher intensity devices STILL!!

Lastly - and the final nail in the coffin - I bit the bullet and tried one of these things just to stisfy my curiosity.... These LEDs will most commonly be shining against the inside of a switch or something - a piece of white diffused plastic. Now - as a result of the white plastic passing UV light through, the actual colour you see on the button cap is blue anyway!! LOL!!! Seriously, it is just as blue as if I'd fitted a blue LED! I first thought I'd made a mistake and fitted a blue LED, but when I checked it was defeintely a UV device.

So the bottom line is, it wouldn't work anyway!! Even after spending the extra money on the UV LEDs (and they are more expensive), the colour would be blue anyway.

Oh, as a side note - I actually tried at one stage to use high intensity white LEDs and a purple filter - the problem of the human eye sensitivity and the spectrum extremes came into play - by the time the purple light was filtered off from the white LED, it had knocked the brightness right down to almost nothing. (that's the case any time you pass white light through a filter - all other components of the spectrum are blocked - so if the colour is at the "low sensitivity end", then there's bugger-all gets through to us)

There you go guys - that clears it up. Purple conversions aren't really possible. Not in the mainstream anyway. I suppose something could be done, but I would have to consider that a fully custom job, and would therefore attract a much higher labour charge...

Cheerz!