X-Virus-Scanned: clean according to Sophos on Logan.com
Return-Path: <marv@lancaironline.net>
Sender: <marv@lancaironline.net>
To: lml@lancaironline.net
Date: Thu, 01 Dec 2005 00:12:46 -0500
Message-ID: <redirect-852581@logan.com>
X-Original-Return-Path: <jeffreyb.peterson@gmail.com>
Received: from xproxy.gmail.com ([66.249.82.193] verified)
  by logan.com (CommuniGate Pro SMTP 5.0.2)
  with ESMTP id 852443 for lml@lancaironline.net; Wed, 30 Nov 2005 21:09:35 -0500
Received-SPF: pass
 receiver=logan.com; client-ip=66.249.82.193; envelope-from=jeffreyb.peterson@gmail.com
Received: by xproxy.gmail.com with SMTP id h30so162485wxd
        for <lml@lancaironline.net>; Wed, 30 Nov 2005 18:08:49 -0800 (PST)
DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
        s=beta; d=gmail.com;
        h=received:message-id:date:from:reply-to:to:subject:mime-version:content-type;
        b=YeOTiowthcRFtVe0o27kx1PUeYPCv8sYMRAEf3GFGr08QDtalipf77osywfhEUrlq0I2Y7U1J4oxLZK9hCQAExapOHqTCmpEimvxWAVNhFC6vmFxbhi09kheYLwkWxfzRmmtSzgopvG+utHe3qRYF8DDgjqvsG0WnFJN/J3rKkM=
Received: by 10.70.74.13 with SMTP id w13mr1105324wxa;
        Wed, 30 Nov 2005 18:08:49 -0800 (PST)
Received: by 10.70.115.11 with HTTP; Wed, 30 Nov 2005 18:08:49 -0800 (PST)
X-Original-Message-ID: <7b85bf8e0511301808k5b3ece82l5fcbb584512bb2f0@mail.gmail.com>
X-Original-Date: Wed, 30 Nov 2005 21:08:49 -0500
From: Jeff Peterson <jeffreyb.peterson@gmail.com>
Reply-To: jbp@cmu.edu
X-Original-To: Lancair mail list <lml@lancaironline.net>
Subject: Re: LED Position Lights
MIME-Version: 1.0
Content-Type: multipart/alternative; 
	boundary="----=_Part_47930_25199804.1133402929756"

------=_Part_47930_25199804.1133402929756
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline

>Jeff, Wouldn't locating the resistor somewhere else lower the heat load on
>the heat-sink?

TYes, but the heat from the resistor has to go somewhere, and the heatsink
is a
good place for this.



>The other option often used to power LEDs is a modulated waveform.

The red LED has a current rating of 15.6 A so you can get quite a lot
of extra effective brightness by strobing the current.

The green LED is rated ar 2.3 amps so again rapidly strobing would
allow pulses more than twice the DC level.

Very likely, for short pulses, you can exceed the max current rating, but
these are so bright I prefer enhanced reliability to a bit more light.

Even if you pulse the current you will not get the Voltage across the
LEDs up to 13V. I believe that WOULD kill them rather quickly. You need a
"swinging choke"
if you want to duty cycle modulate and eliminate the resistor dissipation.

I wanted simplicity, so I just used a resistor.
--
Jeff Peterson

------=_Part_47930_25199804.1133402929756
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline

<br clear=3D"all"><tt>&gt;Jeff, Wouldn't locating the resistor somewhere el=
se lower the heat load on<br>&gt;the heat-sink?<br>
<br>
TYes, but the heat from the resistor has to go somewhere, and the heatsink =
is a<br>
good place for this.<br>
<br>
<br>
<br>
</tt><font face=3D"Tahoma" size=3D"2">&gt;The other option often used to po=
wer LEDs is a modulated waveform.<br>
<br>
The red LED has a current rating of 15.6 A so you can get quite a lot<br>
of extra effective brightness by strobing the current.<br>
<br>
The green LED is rated ar 2.3 amps so again rapidly strobing would<br>
allow pulses more than twice the DC level.<br>
<br>
Very likely, for short pulses, you can exceed the max current rating, but<b=
r>
these are so bright I prefer enhanced reliability to a bit more light.<br>
<br>
Even if you pulse the current you will not get the Voltage across the<br>
LEDs up to 13V. I believe that WOULD kill them rather quickly. You need a &=
quot;swinging choke&quot;<br>
if you want to duty cycle modulate and eliminate the resistor dissipation.<=
br>
<br>
I wanted simplicity, so I just used a resistor.<br>
</font>-- <br>Jeff Peterson<br>

------=_Part_47930_25199804.1133402929756--