It seems that everyone is wanting to make an LED Matrix for one reason or another. LED cubes are getting a lot of attention, but those are built from an array of LED Matrices. Most of the pre-made matrices are extremely small. The tutorial makes one that is 8 inches by 8 inches. It was built to hang in the back of my car window to display messages to the people behind me. So, without further to do, here is how I quickly build my matrices.

Parts needed

22 gauge Insulated wire
20 – 22 gauge solid copper wire, not insulated
10x10 Plexiglass sheet
Soldering Gun and Solder
Prototype board
64 LEDs
16 Wire screw-downs for the prototype board
Resistors (if you want to protect your LEDs)
Plasti Dip Spray (Lowes has it with their spray paints)
Masking Tape
Female Pins for the prototype board (or male if you prefer, or you can use a mix)
Jig:
- Wood
- Screws
- Drill
- Measuring Tape

Step 1: Building the Jig

If you are planning to make a lot of LED Matrices, then the best thing to do is to make a jig to help make the actual soldering of the LEDs extremely easy and fast. Plus, it will insure that each LED in a row is equidistant.

So, in the picture of my jig, you can see all of the scorch marks made from soldering. Those marks are actually down the center of the jig. The holes that hold the LEDs are off center so that the leads can lay across the wire. I made an extremely fancy drawing in MS Paint that shows the dimensions of the Jig. This will take a few moments for you to make, but if you are planning on doing a lot of matrices or cubes, this will save you hours!

Now, I bet you are saying to yourself, “Self, let’s start using that jig!” NO! Now you have a very, very, very boring part to accomplish…the testing of all 64 LEDs to make sure they work properly all have the similar brightness. It would be horrible to go through all the work just to find out that you had a bad LED in the middle!

Basically, all I did was hook up the breadboard with 3V and then just plugged LEDs in 8 at a time and compared to make sure they match. Of course, you probably will want to test others.

Step 2: Building a Row of LEDs

Now it is time to load up a jig and start building!

Building the LED Array In the picture, you can see that the first thing I did was run a 20 gauge bare copper wire through the outside holes where it lays nice and flat across the tops of the jig. This also give you extra wire on each side to work with, say if you were building a cube. Next, take all of the positive anodes and bend them at a 90 degree angle and inserted the LED into the jig’s holes, and have the anode lay across the bare wire. Now, you have a nice solid surface to be able to solder all of the LEDs to the copper wire. The next two pictures show the item in the jig soldered, and then removed from the jig. There you have it, the first “row” of your matrix is done! By using the jig, you know that each of your LEDs are exactly 1 inch apart. The 20 gauge bare wire is perfect to work with in this application, as it has the stiffness to allow you to bend and shape it however you wish without breaking. So, now do another 7 sets of these to finish up your 8 rows. I’ll wait.

Step 3: Assembling the LED Rows

Awesome! You now have 8 rows of LEDs that are not connected together! Now, for some bad news….I did not take a picture of the next step…so, we will need to have to use a little imagination...

Take your plexiglass sheet and measure out your 64 holes in your 8x8 pattern, one inch from each other from the center of each hole…again, make the hole only 5mm to fit the LED in, but not large enough for the LED to slide all the way through it. DO NOT REMOVE THE PLEXIGLASS COVERING! Again, I’ll wait…

Now, with all 64 of the holes drilled, take each of your rows of LEDs and place them into the plexiglass. This will now hold all of your rows in place, so now you need to solder all of the cathodes together in columns so you have all of the LEDs in a row soldered by anode and all of the LEDs in a column soldered by cathode.

This is the reason you did not remove the cover from your plexiglass, as that covering would protect the plexiglass from any splattering or popping of solder that may happen. Now, once you have all 64 together, you can remove the matrix, then remove the plexiglass cover, and replace the matrix.

Ok, so I am really, really hoping you have something that looks similar to what I have above. Now, the fun part is, more testing! Yep, that is the REAL reason I have those alligator clips! So, once again, fire up your favorite 3V power source, add the alligator clips and start testing. The rows, as you remember (I hope so) are the anodes, so clip the positive onto the row, and then on by one, touch the negative to the cathodes that are running across the bottom. You should see the corresponding LED turn on for each place you touch the negative on the row that the positive is connected. In the picture above, the positive is connected to the fourth row from the bottom, and the negative is on the fourth column from the left. The two connected = light! We are on the way now. Repeat 63 more times.

Step 4: Insulating Your Wires and Adding Leads

So, your thought now is….but all of these wires are bare, pointy, and will short. Ok, that was mine too! To fix this issue, go through and clip all of the extra LED leads that are past all of the soldering points. Don’t get too close to the solder point, because it could weaken it, but get fairly close. Once clipped, you need to prepare it for the fun of Plasti-Dip! So, using your favorite masking tape, cover the outside edges of the anodes and cathodes with the tape, so that we will still have some clean wire to apply solder.

If you are not familiar with Plasti-Dip, it is my new favorite friend in the world. They make two versions of it (you can google if you wish), in a can or in a spray can… What it is designed for is to coat tools or other objects in an insulated rubber to protect you from electrocution. Perfect! That is what we need! Well, not that 3v-5v is going to kill us, but we certainly do not want a short. Plasti-Dip dries into an rubber film that, if you need to remove it, peels off. It sticks to nearly everything, and it is now my go to stuff for painting things. I use the spray can version…shake well, then start spraying the entire thing…plexiglass and all. Make sure all of the wires are covered. This stuff is so amazing, that if you put it on thick in one area, or not evenly coat it, it will settle itself down and dry perfectly flat!

So, after you do one coat, wait a couple hours, and examine your work…move the rows and columns back and forth and inspect for any missed areas and bare wire. Make sure you get those spots with the second coat. If you need, apply a third, fourth, however many coats you feel you need.

Hopefully, something like what is in the picture will appear… Well, not really because you haven’t soldered your lead wires in yet, but you can at least see that your plexiglass is now no longer clear, all of the wires are insulated, and you can bend them flat to make it look nice.

So the next part, as you can tell by the picture, is to solder the leads onto the bottom and sides. So remove the tape, showing that bare wire you left! Remember, the rows were positive, so solder the red to the rows and the black to the columns…Trim the extra copper wire off, and then, you guessed it…give this thing another nice blast with Plasti-Dip!

Step 5: Building the Prototype Board to Allow Connections

Now, the matrix is fully formed, we just need to make it usable for connecting to something. So for that we are going to break out the prototype board and build the following.

First the two rows of screw-down connectors (Green things on both sides) are used to connect the wires from the matrix to the board. I then connect each of those connectors to a set of female connectors. These female connectors is what you will use to connect to your Arduino, Raspberry, or any other circuit.

Notice that I added some resistors to mine…that’s because I really didn’t want to try to replace any LEDs if they got fried. It may be a good thing for you to add as well, unless you are a brave person and like to live dangerously!

After the board is created, I just simply used some cable ties to attach it to the LED matrix, and voila, you are ready to go!

I hope you found this tutorial useful. Please feel free to contact me with any opinions or improvements.

Edward.Norris@BlackBatSoftware.com