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Discussion board help and admin topics => Half Baked Ideas => Topic started by: jadaro2600 on January 07, 2009, 11:19:27 PM

Title: LED questions
Post by: jadaro2600 on January 07, 2009, 11:19:27 PM
I just got a green 4 pin LED,

What do the following mean:
"High flux output"
960 mlm
...I understand the rest, i'm assuming that the forward current of 20ma means that it uses 20ma of power per hour.

Also, what use is a 4 pin LED good for or is this just a structural implementation?  The LED is insanely bright when hooked to a cellphone battery - like retina damaging bright.  There is no mcd attribute for this LED on the packaging.

The item: http://www.radioshack.com/product/index.jsp?productId=3125356 (http://www.radioshack.com/product/index.jsp?productId=3125356)

*please note the forum status 'newbie' :P
Title: Re: LED questions
Post by: MrMag on January 07, 2009, 11:47:22 PM
Jad,

From looking at the picture, It would appear that the 4 pins are actually 2 cathode and 2 anode connections used for structural mounting as you implied. Here is a website that might help you out with any questions regarding LED's.

http://www.theledlight.com/technical.html

P.S. I haven't seen the mlm rating used before ??
Title: Re: LED questions
Post by: Michelinho on January 08, 2009, 03:06:57 AM

Hi,

960 mlm means milli Lumen

QuoteThe lumen (symbol: lm) is the SI unit of luminous flux, a measure of the perceived power of light.
http://en.wikipedia.org/wiki/Lumen_(unit) (http://en.wikipedia.org/wiki/Lumen_(unit))

Take care,

Michel

Title: Re: LED questions
Post by: jadaro2600 on January 08, 2009, 08:38:49 AM
Thank you Both!
Title: Re: LED questions
Post by: jadaro2600 on January 10, 2009, 06:32:48 PM
Yet another: Is there a such thing as a low voltage LED? ..something say, around the vicinity of .5 volts?
Title: Re: LED questions
Post by: gyulasun on January 11, 2009, 07:21:35 AM
No,  there is not, unfortunately.

Here is a colored figure attached for the different LEDs forward voltages in the function of their forward current, from the link: http://www.maxim-ic.com/appnotes.cfm/appnote_number/1883

White LED is not shown, it has an average 3.1 -- 3.2V drop for a 15-20mA forward current, just a bit less than for the blue LED.

So the red LED has the smallest drop of around 1.5V.

rgds,  Gyula

PS Just found this useful 'arsenal' : http://www.densitron.com/displays/led_color_chart.aspx