Subject: Re: Best way to power array of LEDs?
Summary: What do you think of these ping times eh?
References: <0001HW.B9C26E7400A7161B165FEAC0@news.covad.net> <3D9D32DE.email@example.com>
X-Newsreader: Forte Agent 1.91/32.564
Date: Sun, 06 Oct 2002 05:03:04 GMT
NNTP-Posting-Date: Sun, 06 Oct 2002 01:03:04 EDT
On 4 Oct 2002 10:07:12 -0700, firstname.lastname@example.org (Tim Shoppa)
>> Have assembled an array of LEDs for use as a 3rd brake light in my car,
>> What is the best method to power these from an intermittent (whenever I press
>> the brake pedal) power source?
>HP has a pretty good application note, AN 1149-1, _Using Super Flux
>Automotive Signal Lamp_, that discusses these issues in detail. Some
>of the details are technical (e.g. not exceeding LED power
>others are economic (e.g. linear or switching current regulators), and
>are legal (e.g. does the light put out the required brightness to be
In cars that a third light is being added to, there is no obligation
to even have the light, so brightness would be operator choice. In a
circumstance where a newer vehicle was being serviced, or the third
(required) lamp was being swapped for another, that third lamp was
required to be included by the DOT in cars, but state laws only
require two rear brake lamps.
>You also will probably want to look at AN 1149-5, _Secondary Optics
>Design Considerations for Super Flux LEDs_, which discusses how to use
>and light pipes/lenses to meet the legal requirements for beam
There you go again. Were they replacing the two required brake
lamps, yes. As for number three, that lamp is not a legal requirement
on a car.
>This, IMHO, is vastly more complex (know a good plastic caster?) than
Buy a standard, off the shelf lensmatic array. But two or three.
Cut them up, and put them in front of your array.
BTW, jumbo, high brightness LEDs are some bright mofos.