Tiger Countdown Project Struggles

Most of the time we only see the end result of a project, not the problems and solutions that you encounter along the way. I thought I'd share the daily struggles and fixes I've gone through in the making of a project.

My latest project is what I'm calling "Tiger Countdown". It will use an LED matrix to display the days/hours/minutes until the next Clemson football game. I thought this would be a fairly straightforward project, but it seems like the universe is against me.

Initial design - no problem. I modeled the project in Solidworks and then send it to my dad and asked him to make it. He made a few slight design changes/improvements, but nothing went wrong. He told me the dimensions of the place for the acrylic piece on the front and I went ahead and ordered the acrylic pieces.

When the acrylic pieces arrived, they were too big by about 1/8". I knew that I probably couldn't sand or cut that much off of the acrylic without it shattering, so I decided to remove 1/8" by 1.5 feet of wood from the project. I used my Dremel with various router bits to remove the wood, but it still took about an hour.

Problem: Acrylic pieces too big for wooden enclosure

Solution: Use a Dremel with router bits and sanding bits to remove a lot of wood.

Next I attached the LED strips to the metal plate, The LED strips already had adhesive on the back which was super helpful, I just had to use some measuring and geometry to make sure they were spaced evenly. Eventually I got all 10 of the strips of 25 LED's on the plate, and started soldering wires on. Soldering took about an hour but I didn't have too many problems. I did have to be a little bit creative on the right side with the data lines so that the strip matrix would hopefully still fit in the box.

After everything was wired up I folded the wires back a little so that they would fit in the wooden box, and in the process I broke a few of my solder points. I then had to resolder those points without burning any other wires.

Problem: Broke some solder points while bending wires

Solution: Solder them again and be more careful

After I had all of the wires soldered in place and bent as much as I could, it was time to put the matrix back in the enclosure. I started putting it in, and the matrix was a little bit too wide for comfort with all the wires on the side. I knew I could make each strip 24 LED's instead of 25 if I had to, but instead I just pushed the matrix in and hoped that all the solder points would hold.

Problem: Enclosure is a little bit too small for all of the lights with wiring

Solution: Just shove it in there and hope everything works

Using some alligator clips and a computer power supply, I wired up the project and tested the LED lights. All of them worked! However, there was a slight but noticeable flickering effect. The lights wouldn't be a perfect solid color, they would flicker a little bit randomly. I thought it might be the power supply, so I tried a different power supply (no effect). I thought it might need a capacitor to help with the varying power requirements so I added in a capacitor (no effect). I thought maybe I messed up a solder point and was shorting the data line to power or ground at some point, so I tested all of the solders with a multi-meter and didn't find anything out of place. I tried a different Arduino controller. I tried using a different LED controlling library. I tried turning interrupts off and on in the Arduino code. In the end I just gave up and accepted that the lights would flicker a little bit.

Problem: Flickering effect

Solution: Ignore it

As you can see in the pictures above, the "pixels" look a little bit blurry. I think this is because I printed the separating grid using white filament, and the white allows a little bit of light to bleed through. I tried printing the grid in blue, but that also let some light through, so I bought some black filament and printed the grids in black. I haven't tested them yet but I think it will look good.

Problem: White grid == blurry pixels

Solution: Print the grid in black

Next, I needed to get a power supply in the enclosure. The power supply would fit without a problem, but I realized that I forgot to include a hole/port for the AC power in. Luckily I was going home the weekend after I realized this, so I brought the power supply, enclosure, and AC receptacle home to my dad and he drilled a hole the correct size for it.

Problem: No input port for power supply

Solution: Take it home to dad and have him drill a hole

I realized that 120V AC wires would be exposed using the AC receptacle above, so I designed and 3D printed a cover for it. The cover is ~2mm thick, and is screwed to the wood. With everything wired up I am fairly confident that I won't be shocked while working on this project. The cover is the blue plastic piece in the picture above.

Problem: Don't want to be shocked by 120V AC

Solution: 3D print a cover for it

Once all of this is is wired up and I go to put it in place, I notice that the part of the matrix that I was calling the top is now on the bottom. Anything I write to the matrix will be upside down now. Due to the size/placement of the power supply and AC receptacle, there isn't any thing I can do to change it. I guess I'll have to flip everything in my Arduino code somehow.

Problem: The top of the matrix is now the bottom.

Solution: Suck it up and fix everything using code

Now that I have AC power safely wired up, it's time to plug in the power supply. I plug it in, flip the switch, and... nothing happens. Eventually I figure out that the AC receptacle doesn't have a fuse in it. I drive to home depot, and get a fuse.

Problem: AC receptacle doesn't have a fuse

Solution: Go to Home Depot and buy one

Time to try to turn it on for the second time. I flip the switch and it turns on, hooray! However, my multimeter says it is 7.1V instead of 5V, even with the potentiometer turned all the way down. My LED strips need 3.5V-5.5V to run, so 7V is not acceptable. I have a second 5V power supply that I was reserving for a different project, but I guess I can use it in this one for the sake of time. (As of writing this I haven't tried the other power supply yet, so I don't know if that is actually the solution)

Problem: 5V 20A power supply outputting 7.1V

Solution(?): Use a 5V 60A power supply I bought for a different project

You know that power supply mentioned above that was at 7.1V-7.9V? Well it was hooked up to my LED's during that. It burnt out all 250 LED's. So I have to remove the strips, desolder everything, cut new strips and put them on. Sigh. On the bright side, with resoldering I can make the top of the matrix be the top now instead of the bottom and writing complicated code.

Problem: Burnt out all 250 LED's

Solution: Desolder all of them, solder on new ones.

Took a nice month long break here to contemplate my life and build up motivation

Problem: Bottom 3 rows of LED's not working

Solution(?): Replace the top of the 3 rows?

...to be continued....

Jacob Thompson


Clemson, SC

© 2020 By Jacob Thompson

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