[prx984]

iv been looking for some information on LED's, just how the different colors are produced. For instance a clear LED producing red light and green light.

the reason being, my dad got a clock that projects the time on the ceiling and so far we have gone through 5 of them, and everyone of them, the Green Light died. The red one however (for the temperature) kept working. the green one seems to go dim, and bright and go back and forth constantly.

im interested in certain things , like what produces the different colors, whether it be gases or special plastics or something. iv searched on wikipedia and howstuffworks.com to no avail.

thanks in advanced
-cygnus

[bonestonne]

http://electronics.h...rks.com/led.htm

hopefully that does it for you

[prx984]

thanks but:

Quote

iv searched on wikipedia and howstuffworks.com to no avail.

[tain]

Try this: http://www.theledlig...technical1.html

[prx984]

thanks tain

im still looking for one key element though, what makes the color of a red led thats clear and a green led thats clear? anyone know?

[bonestonne]

well, it explains how they work, and judging from that, i think you can piece together that the diode is becoming unresponsive...in my eyes, its the chemicals that create the different colors. can't really give any better thought than that.

[prx984]

i would like to know what the actual chemicals are...

[mark]

How about these two:

First

Second



DL

Found one that would be interesting if someone could translate here.

This post has been edited by DL: 09 October 2006 - 09:08 PM

[prx984]

thank you

my dad and i read through both of them and we now know whats going on

thanks again

[mark]

You're welcome. Now tell us what is going on?

DL

[prx984]

i needed the information to draw a conclusion as to why the green LED's in a projection clock my dad bought would keep dieing. he bought 4 or 5 of them, and all the green LED's just either died or went dim and bright.

hes gotten tired of returning the clocks, so this time we're just gonna get some new LED's at an electronic store today and replace the light himself.

we're thinking the reason the bulbs kept dieing was either, a bad batch of LED's was used to make them, or the green LED's are susceptible to some kind of certain death due to the kind of materials they are made of.

[tain]

Well that was...anticlimactic

[prx984]

sorry

[mark]

TAiN, on Oct 10 2006, 07:18 AM, said:

Well that was...anticlimactic

<chuckling>


DL

[LLXX]

Cygnus, on Oct 10 2006, 06:12 AM, said:

i needed the information to draw a conclusion as to why the green LED's in a projection clock my dad bought would keep dieing. he bought 4 or 5 of them, and all the green LED's just either died or went dim and bright.

hes gotten tired of returning the clocks, so this time we're just gonna get some new LED's at an electronic store today and replace the light himself.

we're thinking the reason the bulbs kept dieing was either, a bad batch of LED's was used to make them, or the green LED's are susceptible to some kind of certain death due to the kind of materials they are made of.

This is probably a bad manufacturing run, as according to the Wikipedia article:

Quote

The mechanism of degradation of the active region, where the radiative recombination occurs, involves nucleation and growth of dislocations; this requires a presence of an existing defect in the crystal and is accelerated by heat, high current density, and emitted light. Gallium arsenide and aluminum gallium arsenide are more susceptible to this mechanism than gallium arsenide phosphide, indium gallium arsenide phosphide, and indium phosphide. Due to different properties of the active regions, gallium nitride and indium gallium nitride are virtually insensitive to this kind of defects; however, high current density can cause electromigration of atoms out of the active regions, leading to emergence of dislocations and point defects, acting as nonradiative recombination centers and producing heat instead of light. Ionizing radiation can lead to creation of such defects as well, which leads to issues with radiation hardening of circuits containing LEDs (eg. in optoisolators). Early red LEDs were notable for their short lifetime.

...the red ones are supposed to have a higher failure rate.