sounds the same way, they built diodes for radios 50 years ago from germanium crystals, i think

Posted at 2:38 pm on May 7th, 2009 by Kiwisaft

@kiwisaft… Indeed. And the article makes reference to the “cat’s-whisker” diode.

Posted at 2:59 pm on May 7th, 2009 by Josh

Why does he insist on connecting the positive lead to the clamp?

Posted at 2:59 pm on May 7th, 2009 by Marco

Well, that’s how diodes work, without going too deep into the physics of the situation. To over-simplify, the spot where the cats whisker contacts the crystal is a PN junction. Electrons are pushed across the junction barrier by the application of electrical “pressure” leaving “holes”. When free electrons “fall” into those “holes” photons are liberated which we see as light. It only works in one direction, which defines a diode. I’m probably making some EE’s out there cringe, maybe they can do a better job at explaining.

Posted at 3:17 pm on May 7th, 2009 by bumblebee

I’m only trained as a servicer and that’s pretty much the basic overview I got on p/n junctions – ee’s delve into crazy shit that almost nobody else would want to know.

Posted at 4:00 pm on May 7th, 2009 by xrazorwirex

fun to watch, but i fail to see any practical application. meh.

Posted at 4:41 pm on May 7th, 2009 by vikki

@vicki…not everything here has to have a practical application. and not too many on this site lately are practical (ie, twittering gas emissions and toilet flushes). this article goes into the basics of how LED’s work, which is helpful for many who are just starting to learn how things work, and how it used to be done.

Posted at 5:11 pm on May 7th, 2009 by josh

Wow, thanks to feature my site! No there is no real application. But I am currently trying to use the silicon carbide from sand paper and some epoxy glue to make tiny replicas of the leds from soviet russia. To me the project was just about doing something that I thought was impossible at home in a few very easy steps :-)

Posted at 5:29 pm on May 7th, 2009 by Michael

Michael, how big is a ’sowing’ needle? I assume it is at least 1/2″ wide, otherwise how would you plant the seeds? (Joking of course. It’s spelled sewing)

I really like the idea here though.

Posted at 5:34 pm on May 7th, 2009 by jay

nice…not practical…but nice

Posted at 5:52 pm on May 7th, 2009 by ehrichweiss

cool.

Posted at 6:26 pm on May 7th, 2009 by nubie

to josh
even the twittering toilet has a more practical app than this, you could install them in public restrooms and see how often a particular toilet is used, if your the one responsible for cleaning them, this information becomes useful, a toilet that doesn’t get used, doesn’t need cleaned.

you want to learn about how led’s work, try http://electronics.howstuffworks.com/led.htm or http://www.thenakedscientists.com/HTML/content/questions/question/1135/ otherwise show me how to make a 5 watt led.

Posted at 7:44 pm on May 7th, 2009 by vikki

Ha, I find this awesome just because I love to do things the old hard way. Right now I’m working on building a minicomputer using RTL, and I have to say that, for whatever reason, I find that building things the way they were built when the technology was only first emerging is quite a thrill when you get it to work. I’m very interested to see how your soviet epoxy LEDs turn out!

Posted at 10:06 pm on May 7th, 2009 by stithyoshi

@bumblebee: that’s about right. You didn’t make me cringe. There are very specific rules for photons to be liberated (most of the times they don’t) but other than that your explanation is great.

Posted at 11:35 pm on May 7th, 2009 by Hackius

Nice Idea…
i have always tried this before and never had so good looking effects. But i took the sic from the socket of an old lightbulb like described on this http://www.b-kainka.de/bastel69.htm german website.

Posted at 9:50 am on May 8th, 2009 by hubert

This is pretty cool, its the kind of thing you would never expect to happen outside of a clean room where they are manufactured.

Posted at 10:44 am on May 8th, 2009 by mike

might also work with low melt alloy as the “clamp”… also its possible to spray paint or electroplate the SiC with ITO, allowing more of the crystal to glow.

-A

Posted at 3:03 pm on May 8th, 2009 by andre

They did this on MAKE a few months ago too. Check it out, it looks like it works fairly well.

http://blog.makezine.com/archive/2008/11/make_presents_the_led_a_m.html

Posted at 12:44 pm on May 9th, 2009 by Christa

@hackius…thanks…I guess that means I actually didn’t sleep through the lecture back in 1984 when I was getting my 2-year degree.

For those who think that this has no practical application…well not today, but it’s always a good thing to know the HOW and WHY of techie things because that’s what stimulates ideas on new developments. We’ve become far too dependent on “black-box” thinking. I’ve actually constructed a functioning vacuum tube out of a canning jar based on some plans I found through Lindsay Publications. Not for any practical reason, but because it was a challenge that our grandfathers took on. You simply never know when being able to “MacGuiver” something from absolute scratch might come in handy.

Posted at 12:51 pm on May 9th, 2009 by bumblebee