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 one 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 Makezine.com.