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Forum: Analog Circuits LED from Silicon Carbide


Author: Leuchti (Guest)
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Hello,

I replicated the experiments of H.J. Round and Oleg Losev, the inventors 
of the LED and build an LED from a mineral substance myself. If you 
like, have a look on it, you might also want to try it ;-)

http://www.dlip.de/?p=99

Cheers!
Michael

Author: Andreas Schwarz (andreas) (Admin) Flattr this
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Nice idea! I have a big chunk of this stuff lying around (although I 
could never figure out what it was, now I know) and I'm definitely going 
to try the LED.

Author: Eddy Current (chrisi)
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Shouldn't the rear side of an old (maybe destroyed) processor work for 
such an experiment? I think about those CPUs, where the chip is mounted 
in flip chip technology without heat spreader. CPU goes LED :-)

Author: Jörg Wunsch (dl8dtl) (Moderator)
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I don't think plain Silicon emits visible light.

Author: Leuchti (Guest)
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No, doesnt work! It needs a semiconducting material with 
electroluminescent properties. Like SiC or SnO. What I really wonder is 
whether SiC grains from sand paper can be made working. That would allow 
a much greater audience to replicate the experiment. Is it plain SiC or 
coated somehow?

Author: Leuchti (Guest)
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Unbelievable! The article made it to hackaday.com!
http://hackaday.com/2009/05/07/make-your-own-leds/

Author: faustian (Guest)
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Author: Leuchti (Guest)
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oh, nice idea! It seems he smoked the setup pretty badly but it worked. 
A little more power and he would have had a incandescent lamp...

Author: Andreas Schwarz (andreas) (Admin) Flattr this
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I tried it, but I can't say I had a lot of success.

A picture of my material is attached. It is from a ceramics factory that 
works with SiC, and it looks like the SiC picture I found on Wikipedia, 
so it probably is SiC. Can anyone confirm?

The conductivity of the nice, big crystals on top is very low, I could 
only measure a finite resistance at the lower part of the material. When 
I connected my power supply and traced the material with the needle (a 
few mm from the connection) I had to crank the voltage to 30 V to get to 
10 mA. I do see a tiny light occasionally, but I also see some faint 
smoke, so what I'm seeing is probably the contact point overheating. I 
will give it another try tomorrow.

Author: Knut Ballhause (Company: TravelRec.) (travelrec)
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For me it looks like more or less "pure" silicon. Not SiC.

Author: Jens G. (jensig)
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pure silicon is grey, not black. Pure SiC normally is colorless, but 
normally black because of impurities (technical SiC). I think, these 
impurities (if not to much) causes the lighting like a LED.

Author: Leuchti (Guest)
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It depends on the material surface properties. As I wrote, I have a few 
boxes of the stuff and not all crystals work well. The LED effect can 
easily be distinguished from overheating by the green light. Overheating 
is orange and the LED orange or green. If it is green it's certainly not 
overheating. For your material I'd guess that it is not pure enough...

Author: Leuchti (Guest)
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Hi again, I just tried a bigger chunk just like yours. The molten 
surfaces seem to be ideal. They give much brighter light then the 
crystal surfaces. And what can make like almost every crytal work: use 
30 V, limit the current to 30 mA and attack the negative lead to a fine 
tip pencil (Feinminenbleistift). When tracing the crystal with that 
sucess rate is much greater, although there might be a lot of sparks 
having nothing to do with the LED effect. But typically for the LED 
effect a larger region lights up green or orange. Like a little crack or 
so in the crystal. These regions are reproducible and always give the 
same light in the same place and with the same shape.

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