All engineers are different, some are clean-kept while others are unorganized and messy (I get bonus points there), some prefer picaxe microcontrollers over BASIC Stamps, and so on and so forth. However, we all have one thing in common: We all use LEDs, or Light Emitting Diodes. You see them everywhere: in your phone, your Xbox, computer, watch, and just about everywhere else.

Today I will show you a fun, simple, and cheap project that will teach you about working with LEDs.

A little while ago I went down to Radioshack and got a bag of 20 LEDs for $3.00. If this sounds amazing to you, wait. The 20 bag bundle is extremely poor quality, and only comes with green, red, orange, and yellow LEDs. I highly recommend you invest a couple extra dollars and get 5 higher quality LEDs rather than 20 cheap ones, or better yet, buy your LEDs online if you can. Remember to test them before you use them, I learned to do that the hard way.

Here are the parts for this fun and simple project:

-3 3volt LEDs of any color

-1 project box (optional but highly recommended)

-1 9v battery

-1 9v battery clip

-1 switch of any kind

-1 330 ohm resistor

-1 zip tie (optional)

-a soldering gun

-some solder

-and lots of hot glue!

Now that I look at at, this list looks long for a simple project, but its really a lot less daunting than it sounds, I promise.

These are the LEDs that came in the grab bag:

Unfortunately the bag did not say what voltage they used (typical Radioshack), and the guy there looked at me like I was asking him to name every neutrino in existence when I asked him about the voltage. I guessed about 2 or 3 volts, and went with 3 to be safe.

LEDs have what are called cathodes and anodes, or positive (+) and negative (-) sides. The anode is the long wire, while the cathode is the short one. I chose to color the negative red and the positive green so I would not confuse myself.

Drill three holes in the lid of the project container. I did this my my all-time favorite tool, the Dremel.

Sorry if the image is a bit difficult to view, I’m an engineer, not a photographer so you will have to bear with me as far as images go.

Glue in the LEDs and solder their anodes to their cathodes. This is really simpler than it sounds, hook together the greens with the reds and apply solder. Now solder your 330 ohm resistor to one of the two open leds (the little wires jutting out of the LEDs). Then solder the other end of the resistor to the correct battery side (guess and check to see which side works). Now wire the other open wire from the battery to one side of the switch (for easy access you should cut a hole in your box for the switch, depending on what kind you used), and finally the open LED’s led to the switch. I used a zip tie to hold the wire to the battery to make it easier for me to close the box.

Attach the lid to the container with the parts resting inside and flip it on. If all is well, your three LEDs should illuminate the room (unless you used Radioshack LEDs, in which case you will illuminate much less).