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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Ok, I’m lost. Here is the Kingbright
LED datasheet, which is typical of most of the SMT LEDs I found on Mouser.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><b><font size=1 color="#0000cc" face=Verdana><span
style='font-size:7.5pt;font-family:Verdana;color:#0000CC;font-weight:bold'><a
href="http://www.hamsdr.com/personaldirectory.aspx?id=156">http://www.hamsdr.com/personaldirectory.aspx?id=156<span
style='font-weight:normal'> </span></a></span></font></b><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Here is the Vishay LED datasheet at an
order of magnitude less current.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><</span></font><b><font size=1
color="#0000cc" face=Verdana><span style='font-size:7.5pt;font-family:Verdana;
color:#0000CC;font-weight:bold'>http://www.hamsdr.com/personaldirectory.aspx?id=155</span></font></b><font
size=1 face=Verdana><span style='font-size:7.5pt;font-family:Verdana'> </span></font><font
size=2 color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The way I would read these intensity
values, they are about 1/1000 the values you are talking about.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Clearly, I have no idea what I’m
doing here and await enlightenment.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> Chris
– AE6VK<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> KD5NWA [mailto:kd5nwa@cox.net]
<br>
<b><span style='font-weight:bold'>Sent:</span></b> Monday, March 13, 2006 4:00
PM<br>
<b><span style='font-weight:bold'>To:</span></b> Christopher T. Day<br>
<b><span style='font-weight:bold'>Subject:</span></b> RE: [hpsdr] Starting BOM
already</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>They must be horribly inefficient LEDs. It should be more like 1ma to
2ma for a modern diode.<br>
<br>
You also might want to consider the light output of the LED, for a status light
inside a piece of equipment you can run it at less current that the specified
for full output. 3,000 to 12,000 millicandelas will be annoying as heck if you
look at it straight on.<br>
<br>
<br>
At 05:43 PM 3/13/2006, you wrote:<br>
<br>
<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Ok, guys, we – or at least I – have a problem here. All the
0805 SMT LEDs I see in Mouser have an operating point of 20mA. At 12V, I make
that out to be 0.24W into the dropping resistor. All the 0805 resistors I can
find are limited to 1/8 or 1/10W => they won’t last very long. The
Vishay TLMC3100 that I’d picked originally has an operating point of only
2mA, but is packaged in PLCC-2 form, which is about twice the size of 0805
(unless I mix up my metric and English and miss Mars) – go figure. Any
chance of making the LED pads PLCC-2 and going with the original choice, or is
it too late for that?<br>
<br>
<br>
Chris
– AE6VK<br>
<br>
<o:p></o:p></span></font></p>
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