[hpsdr] Starting BOM already

[Christopher T. Day]

Ok, I'm lost. Here is the Kingbright LED datasheet, which is typical of
most of the SMT LEDs I found on Mouser.

 

http://www.hamsdr.com/personaldirectory.aspx?id=156 

 

Here is the Vishay LED datasheet at an order of magnitude less current.

 

<http://www.hamsdr.com/personaldirectory.aspx?id=155 >

 

The way I would read these intensity values, they are about 1/1000 the
values you are talking about.

 

Clearly, I have no idea what I'm doing here and await enlightenment.

 

 

            Chris - AE6VK

 

 

  _____  

From: KD5NWA [mailto:kd5nwa at cox.net] 
Sent: Monday, March 13, 2006 4:00 PM
To: Christopher T. Day
Subject: RE: [hpsdr] Starting BOM already

 

They must be horribly inefficient LEDs. It should be more like 1ma to
2ma for a modern diode.

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.


At 05:43 PM 3/13/2006, you wrote:



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?
 
 
            Chris - AE6VK



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