MAKE presents: The LED

MAKE presents: The LED


LEDs are in technology all around us, familiar and helpful for sure but you may wonder – Who invented them? How do I use one? Is it possible to make my own LED?!? Learn the answers to these baffling questions and more in – MAKE presents: The LED

Suscribe to the MAKE podcast
| Download for iTunes

We also have a full transcript!

People are fascinated by light. I mean just glancing over at a display of flashing lights can grab my attention. Do you ever remember sitting around a campfire? Staring at the flames and just being totally transfixed, almost like if you’re watching TV. It’s comforting, and it can even by hypnotic. Recently, technology has made creating light a whole lot easier to do. For that, we have this little guy to thank. The light emitting diode, or LED for short.

LEDs have a lot of different uses, from a simple power on indicator to traffic signals. LEDs use about ten percent of the energy of a traditional light bulb, and they can last about thirty times longer. That makes them a pretty big hit with businesses looking to do large scale visual communication.

The first person to ever report the effects of a light emitting diode was researching another form of communication. In 1907, a man by the name of H. J. Round was researching radio waves for Marconi Labs. He was using a device called a cats whisker detector, which no, does not contain any cats or part of cats. Round was searching for a sweet spot on a crystal silicon carbide when he noticed something odd. Part of the crystal started to glow, it lit up a pale yellow, and that was an LED.

H. J. Round’s crystal experiment was so cool and simple that I had to try it myself. So I got a piece of silicon carbide, then I hooked that up to the positive lead on my power supply. That’s an alligator clip. I hooked a little sewing needle to the ground on my power supply. Then I began to search for light emitting zones.

I built my own sort of cats whisker detector in order to keep the needle in place on a particularly bright spot I found. Now I can sit back and enjoy the warm glow of a homemade LED anytime I choose, even though it’s pretty dim, but it’s still cool.

As far as we know, Round’s research into light emitting crystals ended here, which is a shame because he was definitely on to something. But of course that’s not the end of the story. Fifteen years later, in imperial Russia, a scientist and inventor named Oleg Vladmirovich Losev noticed that certain diodes in radios started to glow a bit when in use. Losev conducted a lot of heavy research and published his findings in several languages. But, sadly, they seem to have gone unnoticed. It wasn’t until 1962, that a visible light emitting diode was made practical by Nick Holonyak working at General Electric. He’s widely known as the father of the LED.

The technology that Holonyak brought to the public is remarkably similar to our crystal experiment. A thin metal wire connects one side of the circuit to a small piece of semi-conductive material on the other side. The LED’s two leads are cut to different lengths to show you how it should be connected. The longer is called the anode, and that connects to positive. The shorter is the cathode, and that goes to negative. To power an LED, you can just use a simple coin cell. This is a CR2032. And just make sure the longer lead is on the positive side, which is wider and smoother, and negative is on the other. If you plan to use a battery, let’s say a nine volt, you’ll also need a resistor to limit the current so we don’t burn out the LED. Connect negative to the cathode, the shorter lead, and we’ll put a 470 ohm resistor between the positive battery and the anode. For more useful info, check out the LED Center, and there’s a lot of great history at the LED Museum. For all types of project ideas, info, and inspiration head over to

28 thoughts on “MAKE presents: The LED

  1. Anonymous says:

    It’s silicon, not silicone.

  2. nzc says:

    Please tell me where I can get a chunk of silicon carbide like that pictured? I did some googling and found only suppliers of industrial quantities or industrial ceramics. United Nuclear doesn’t seem to carry it. Help!

  3. Gareth Branwyn says:

    But, BESIDES the mispronunciation of one word: Great job, Collin! Really clear, concise, very watchable.

  4. nzc says:

    Agree completely with Gareth — I was highly entertained, and informed — I had not known the bit about the early discovery of SiC light emission. Nice job!

  5. justDIY says:

    Excellent work Collin, high marks on both content and production quality.

  6. John says:

    Wonderful piece of information. Slick and interesting.

    I would love to see more.

  7. Paul says:

    Very good.
    Now that you’ve touched on the origins of the LED, maybe some of the latest developments? Like Professor Shuji Nakamura’s two-flow MOCVD reactor. (Basically had to hack an existing system to get to the point where a growing the crystals for a blue LED was even possible.)

    It’s an inspiring maker story.

  8. zof says:

    Your fellow information whores applaud with great gratitude, I learned something new and interesting today and it was as easy as clicking play. I could see small segments like this about all kinds of this very useful to science educators of middle and high schoolers!

    So whats the next segment on? :)

  9. Collin Cunningham says:

    @ nzc – I had a hard time tracking down SiC myself. I ended up getting some here in NYC @ Rock Star Crystal Gallery –

    not sure if they do mail order, but it is an awesome little shop to visit, cool people too.
    You can get smaller SiC (aka – carborundum) samples already mounted in ‘ceramalloy’ and even vintage detector stands here –

    @[blank] – I noticed the mispronunciation as well – oddly it was in every take I had. oh well =]

    @Paul – Nakamura’s story sounds very cool. I had some other details such as the IR LED’s story that unfortunately I was unable to cover – more to come!

  10. firehazrd says:

    I love LEDs.
    fistfuls of anodes!

  11. Anonymous says:

    I loved this segment! Please do more!

  12. John Oakland says:

    Could someone tell me the names of the songs?

  13. M. Smith says:

    Collin that was an excelent piece. I am nearing 50yr and you put on a great show considering all the cr@p we are force fed these days. Many thanx, M.

  14. Bubbles says:

    Check out the gift-shop of your local geologic museum.

    Otherwise check out mother nature – at least here in Norway “glassed rock” can be found pretty much everywhere, as long as you are aware of your surroundings.

    I’m not sure whether this glazed rock is the same thing as this, but it certainly is high on silicon, and most likely carbon as well.

Comments are closed.

Discuss this article with the rest of the community on our Discord server!


Maker Faire Bay Area 2023 - Mare Island, CA

Escape to an island of imagination + innovation as Maker Faire Bay Area returns for its 15th iteration!

Buy Tickets today! SAVE 15% and lock-in your preferred date(s).