Today we are building a 1 meter square LED display panel.
It is designed for use in giant building-size clocks, but you can use it for anything you want!
A full panel takes a total of about an hour to construct, and you should take a break in the middle of the process to let the silicone cure.
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Step 1: Get Set Up
Put the template on a big, flat surface. Tape it down so it doesn't slide around.
Put a panel down on top of the template and align it to the bottom and lines on the sides.
Remove the protective film from the panel.
Step 2: Make a Caulk Guide for Fast and Straight Caulk Lines
I used an old piece of Ikea flooring, but any long straight object should work.
I added little rubber feet to the bottom to keep it from sliding around.
Step 3: Get Your Caulk Ready
I use GE I clear caulk because it works best.
Cut the tip off. I like to make the opening almost as small as possible.
Poke something long and pokey into the hole to pierce the skin inside the caulk tube. Most caulk guns have a built in poker.
Load the caulk into your gun. I use a power gun because it makes it easier to get a consistent bead, but you can use a manual one if you are a careful person.
Step 4: Get Your First Strip Ready to Stick Down
Make sure the connectors on the ends of the strip match the arrows on the template. Once you stick the strip down it is no fun to have to flip it!
Step 5: Lay the Bead and Press the Strip In!
I like to start at the top and work my way down.
Line up the caulk guide so the bead will end up over the black guide line on the template.
Wipe off the tip with a paper towel.
Hold the tip of the gun against the caulk guide and pull the trigger.
As soon as you see the caulk start coming out, drag the tip across the guide. Try to keep a steady speed to get a straight and consistent bead about 1/4" wide. It takes some practice.
Press the strip down into the bead. Double check to make sure the connectors match the arrows on the template - this is your last chance! Try to place the strip straight down so the caulk doesn't smear and make a mess.
Use your fingers or a roller to press the strip down into the caulk. The goal is yo get the caulk to squish out of both the top and bottom edges.
Take a second look to make sure there are no bulges. The full back surface of the strip should be adhered to the caulk bead. A little extra squish at the ends will add some extra strength there.
Step 6: Repeat for Each Row
Each row should go right over the corresponding line on the template.
MAKE SURE YOU CHECK THE DIRECTION OF THE CONNECTORS. They must match the template. They follow the pattern (from top to bottom) two one way, then six the other way, then six, then six, then six.
Try to leave a little extra blob of caulk at the ends because this is where most of the stress is.
Check each strip after placing for bumps. Try to push the whole strip down hard enough to get caulk to ooze out of both the top and bottom edge.
Step 7: Wait for Caulk to To Cure
Give it a couple of hours.
I know you are excited to finish, but if you rush this step then you might pull the end of the strips off when working on them.
Step 8: Trim Extra Power Leads
The connected red and white wires coming out of each end of the strip are the power leads. We only need the power leads on 12 of the strips, the rest are extra. We will trim the unnecessary ones so they don't get in the way and also just to make sure they can't accidentally fail about and and short to anything.
The template shows which leads to cut with red marking and the text "cut these power leads". BE VERY CAREFUL NOT TO CUT THE WRONG ONES. I've done it, and you will do it - just try to not do it more than once!
The right side of the panel is easy because we are going to cut ALL of the power leads.
The left side is harder. We are going follow the red marking in this pattern:
8 rows cut
6 rows leave
6 rows cut
6 rows leave
I like to arrange all the rows I am going to cut so that they are standing up first. This gives me a chance to double check I got it right, and then makes it very easy to do the actual cutting.
If you do make a wrong cut, all hope is not lost. LMK and we'll see if there is a way to compensate.
Step 9: Cut Power Supply Lines to Length
Cut the power supply lines. There is a length guide on the bottom of the template.
You should end up with a short red, short white, long red, and long white line. Four altogether. Note that the length does not need to be exact, we can trim later.
Step 10: Wire Up the Power Supply Lines
Now that the power lead pigtails are cut, you should see that there are two groups of 6 strips each along the left side of the panel.
We are going to run both a black (ground) and red (5V) power supply lead to each group. We will use the short supply lines for the bottom group and the long ones for the top one. Make sense?
To make the connections between the supply lines and the leads, we are going to use Scotch Lok 22/18 Gauge Double Bladed connectors. These are fast and reliable and cheap. You can get them on Amazon here...
It is also nice to have the special pliers to crimp them on, but really any lineman's pliers will also work.
I try to lay the supply line across the leads to get an idea of spacing and then star with the bottom lead and work my way up. This makes it easier to slide on the next connector.
Make sure that the lead is all the way into the connector before crimping, and then give it a tug afterwards to make sure the blade bit into it.
Repeat for both red and black wires, and for both top and bottom groups.
Step 11: Mount Power Supply
Drill four 1/4" holes at the marked positions on the template. I like to mark the hole location with a sharpie and then remove the panel to drill it.
Put the power supply on the panel and sinch it down with 2 zipties.
Now is also a good time to attach the mains power lead.
White -> N
Black -> H
Step 12: Connect the Power Supply Leads to the Power Supply
Strip the ends, add a terminal spade connector and connect to the power supply.
Black -> V-
Red -> V+
Step 13: Optional - Apply Conformal Coating to Controller Board
Adding an optional conformal coating will help your controller board survive condensation or splash exposure.
Start with some easy spray-on silicone coating, available on Amazon here...
The coating doesn't smell great, so best to do spraying outside.
I made a holding stick by putting an Ethernet cable into a piece of 1/2" pipe and crimping the end down with a vice. This also helps prevent spray from getting up into the Enternet port.
Shake well. Lightly coat both sides. A little dripping is ok, but you really do not need much. If you do this outside on a sunny day, the coat will fluoresce blue so you can make sure you didn't miss any spots.
It takes about 10 minutes for the board to dry. Try to set it down at an angle to keep the coat from getting into the Ethernet port.
Quick video here...
Step 14: Mount Controller
Just like the power supply, except on the right side of the bottom of the panel.
Drill holes per template, zip-tie on.
Step 15: Plug in All Connectors
Follow the template.
There are six strings in total. They start at the controller and then wind their way left and right up to the top. The last course only has two rows.
When you are done, you should have 6 dangling connectors. You can cut these off if you want to be neat.
Step 16: Assemble the Controller
You'll need a Beagle Bone Green (or black) computer...
... and a controller board...
They just plug together. The ethernet port should fit nicely into the slot in the board so you know you didn't get anything backwards.
Note that I like the Green better than the Black because it doesn't have an HDMI port (less stuff better), but either will work fine. I'd also look at the (pricey) Industrial that comes with a conformal coating pre-applied....