Re: White LEDs as tail/etc lights.

["David McAlister" <davidmcalister@mindspring.com>]

Use red LEDs and skip the filter in the lens.  No need to generate other
colors just to filter them out.

----- Original Message -----
From: <jcmassey@netspace.net.au>
To: <ev@listproc.sjsu.edu>
Sent: Thursday, May 31, 2001 8:41 PM
Subject: White LEDs as tail/etc lights.


> Hello list, me again.
>
> Has anyone else been playing around with the white 6000mCd LEDs.
>
> I have found the following:
>
> A matrix of 150 3500mCd amber LEDs (consuming 0.6A from 12V) has similar
> intensity (to my eyes and to those I have shown it to) as a matrix of only
> 18 white LEDs of 6000mCd (9 paralell of series pairs consuming 0.18A total
> from 12V). This is without any lenses in front of the matricies.
>
> Due to the forward voltage drop amber LEDs can have 5 in series with a
> current limiting resistor, but white require a little over 10 volts for
> three in series - too close to a nominal 12V battery voltage for use of a
> current limiting resistor - can use a resistor and a LDO 3-terminal
voltage
> regulator, but probably not a good idea (get a low battery and - no
> lights). Better to only use 2 in series and a resistor.
>
> That was to encourage anyone who has looked at using LEDs and dismissed
> them as a waste of time to take another look.
>
> However, there are some things that I have not tried with these LEDs. The
> most obvious one is: are they still as comparably bright once put in an
> orange or red lens assembly? I know that some light will be absorbed,
etc.,
> so no lectures on optics, please (I've done the optics module in the B.
> Tech I'm working on).
>
> Has anyone put white LEDs into a tail-light assembly and done a
comparative
> test to standard incandecents? If so, how did they go?
>
> If no-one has, then I'll do some tests in  the next few weeks and post the
> results.
>
> James Massey
>