Date:         Tue, 18 Apr 2000 09:37:06 -0500
Reply-To:     Chris Smith <chris.smith@AQUILA.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Chris Smith <chris.smith@AQUILA.COM>
Subject:      Re: Third brake lights (tack-free)
In-Reply-To:  <4.3.1.2.20000417153511.040905d0@127.0.0.1>
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At 03:48 PM 4/17/00 -0400, David Beierl wrote:
>At 14:54 4/17/2000, Ron 'Coyote' Lussier wrote:
>>tacky, tacky, tacky!  :-(  So, what solution are people recommending for
>>adding a third brake light?  I want LEDs for durability.
>
>If there isn't an easy unit already built, I'd just build one with a bunch
>of LEDs.  The bright ones will no doubt be clear instead of red plastic --
>if you care could put red plastic or lithographic masking film (local print
>shop might give you a sheet) in front.  Look for discount rates by buying x
>many LEDs -- I think RS has a significant breakpoint at 10.  Remember you
>will have to use individual resistors for each LED, you can't combine them
>into one big resistor.  I'll help you with the formulas if you need
>it.  Don't forget to run them conservatively, allowing for high temperatures.
>
>Here's a site with sources of good bright LEDs -- look at the "taillight
>red" entries...
>http://www.misty.com/~don/led.html

Wiring your own is fairly easy.  Each LED should get around 1.5 to 2.2v
(check on package)  if you wire them in series (positive to negative) in a
daisy chain, all you need to do is to divide the voltage available by the
voltage of each LED to get the number of LEDs in each string.  For most
LEDs, 7 would be the correct number (2v times 7= 14v)

Chris Smith