PCBWay 3rd PCB Design Contest

4x4x4 Led Cube

Why build this LED cube?

* When you finish you can display beautiful and intricate pattern.

* It makes you think and problem solve.

* It is fun and satisfying to see how well it all comes together.

* It is a small and manageable project for anyone new to soldering and electronics to learn, and is still large enough to display dazzling and impressive patterns.

* The arduino code is fairly easy to manage.

* A relatively low cost for a high entertainment and the huge amount that you will learn if you are new to electronics.

First I will show you how to make this quick 4x4x4 led cube that requires only a few hours of work to get set up (once you make the jigs) but also is a sturdy design. I will try my best to explain so that everyone understands my design choices. Finally I will explain how to program new patterns in 2 different ways.

Supplies:

Parts:

  1. 10cm * 15cm prototyping board - 1x $2 ea
  2. sn74hc595n - 2x $0.57 ea
  3. 120 ohm resistors - 16x $0.04 ea(The value is dependent on your LED see step 7)
  4. 10k ohm resistors - 4x $ 0.10 ea
  5. Fqp20n06l N channel MOSFETS - 4x $0.95 ea
  6. Arduino nano v3 - 1x $22 ea
  7. 5.5 mm dc jack - 1x optional $0.35 ea
  8. Tinned copper wire 20 AWG - 15ft $0.12/ft
  9. Ribbon cable 40 conductor or other small gauge (AWG) wire - less than 1ft $2.3/ft
  10. 5mm plywood 6",12" - 1 x $2 ea
  11. solder .8mm - 1x $10.89 ea
  12. 1" x 6" x 4' board - 6" $8.39 ea
  13. 5mm diffused LEDs - 64 $15 kit
  14. 100nf ceramic cap - 2x $0.25 ea

Estimated cost per cube: $40 (if parts are bought in bulk the cost per will drop significantly)

Tools:

  1. Needle nose pliers x2
  2. Flush cutters or Side cutters
  3. Soldering iron
  4. Wire strippers
  5. Table saw
  6. Drill (Drill press recommended)
  7. Hacksaw or band saw
  8. Computer for programing


Step 1: The First Jig**

The First Jig**The First Jig**

The first jig consists of 2) 0.8mm drill bits, prototyping board, and a 5mm hole for the LED. Start out by taking your prototyping board (at least 2cm wide and 2.54mm(0.1") spacing center to center of the holes) mark the first dot on one of the edges of the board. Then in a straight line make another mark after moving up 3 more holes. Then mark the dot that is 2 holes further up(see image #1). Next in the center marked hole drill a 5mm hole I used a 13/64 inch bit and it worked fine. It is best if you use smaller bits and work your way up to the 13/64 inch just to make sure it is perfectly centered in the hole if it is not the entire cube will be off. Then on the outer marking use the 0.8mm bits to slightly widen the holes. Make sure that all holes are perpendicular to the prototyping board if available use a drill press but a hand drill will work. Cut 3) 1" squares It is easiest to use a band saw but a hand saw will work also. With elmer's glue make a small wood stack with all of the edges lining up with one another. Finally glue it to the prototyping board clamp it all together and wait. Once everything is dry re-drill everything so that the holes in the prototyping board go all the way through the wood backing. Place the 0.8mm bits into the hole that were made on the edge. If everything was done correctly it should look like picture #2.

**The jigs pictured are designed to make an 8*8*8 LED cube so they are slightly oversized. Your jig will be smaller. These jigs are based off of Steve Manley's designs for his 8*8*8 RGB LED cube. It looks and works great. I would recommend checking out his videos.

his you-tube channel



Step 2: The Second Jig**

The Second Jig**

The second jig is made of 5mm plywood. Start by marking and cutting 3

pieces that are 4" by 2" for this I used a band saw but a hand saw would also work. On one of the pieces mark in 1" on the 2" side on both ends and draw a line in between the two. On the 4" side go in 1/2" on the previously made line the next mark should be 1" from the current one continue until you reach the end of the board. The other two pieces should be aligned and glued together with elmer's glue. Once the glue is dry take both the marked section and the glued section align them clamp them together. Drill out 5mm(13/64) holes at were the lines cross on the board. The final step is to make the glued together piece's holes bigger I went with 1/4".


Step 3: The Third Jig**

The Third Jig**

The third jig is made from a piece of a 1" x 6". First cut the board

down into a more manageable section about 5" long. once this is done you can take it to a table saw to cut the groves about a 1/4 in in depth any orientation will work. They should have a spacing of 1 inch center to center of the groves. The kerf (the slot made by the saw blade) should be 0.1" wide. Start by cutting the first slot inch from the edge of the board. Then shut off the saw and move the fence over 1" repeat this process until you have 4 slots cut into your board.The jig should look like the above picture.



Step 4: Using the First Jig

Using the First JigUsing the First JigUsing the First Jig

This is the most monotonous part of the build bending all of the leads of the LED's. The reason you want to use this jig is to get a sturdy construction that looks great. Take your first jig bend the cathode (short lead see picture 2) up to the closer (0.2") drill bit, then wrap it around the bit and loosen. Take the anode and bend it around the second bit and loosen. Cut the extra lead with flush cutters / side cutters and remove the LED. Flatten the both the anode and cathode. Twist the cathode 90 degrees so that it is facing down (see picture 3) continue the process 63 more times.

Note: It is often helpful to have a small needle nose pliers to bend the leads around the drill bits.


Step 5: Using the Second Jig

Using the Second JigUsing the Second JigUsing the Second Jig

Before we use this jig we need to straighten and cut our 20 gauge(awg) tinned copper wire. First cut off at least 36 4" sections of wire it is best if you make 4 more section because it makes the cube symmetric (note: it is helpful to straighten larger sections of the wire before you cut it to length but either way would work). For straightening the wire just take two pliers and pull from each end stretching the wire a little bit. This method is difficult so if you have a vice you can clamp the wire into the vice and pull from there and you will get much better results easier. Once you have all of the wire prepared place 4 LEDs into jig #2 (see image #2) the cathode should be facing away from you. Place one of the 4" sections of wire through the cathode loops solder all 4 joints (it is recommended that you test all LEDs before you solder). Once you have soldered all of the LEDs lift up the top section and press on the jig so that the rounded ends of the LEDs on the flat surface. The row of LEDs should pop out. Now do this process 16 more times.


Step 6: Using the Third Jig

Using the Third Jig

Now that you have all 16 of your rows of LEDs done it is time to use the final jig. Take 4 strips of LEDs and place the metal link wires down in one of the slots making sure that the all of the holes from the different sections line up. Insert one of your sections of wire from bottom up into the remaining holes of that column. Make sure that it is square then solder all 16 connections and move on to doing 3 more.


Step 7: The Electronics

The first thing you need to do is calculate the 16 resistors that are needed for the cube to operate. This can be done through this calculator or this formula Resistance = (voltage source - LED voltage) / led current. The only problem is that often times the seller does not give the needed values. If you are using the the link provided for the LED kit that I got, the yellow LEDs need 120 ohm because they are 2v and for blue 75 ohm 3v. If you don't want to worry about this you can just use the 220 ohm provided in the kit they should work fine but your cube will be a bit dim at times the yellow can be a bit to dim (the brightest color I have found from this kit is blue, excluding white which are not diffused).

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Step 8: The Electronics

The ElectronicsThe ElectronicsThe ElectronicsThe Electronics

So now you have 2 options you can go off the schematic below/create your own layout using the pictures to aid in a good layout, order a custom PCB using the Gerber file found below (great if you are making several).

PCB and schematic-- https://easyeda.com/editor#id=63a136d6b20f4aebaede857853e31526|e43c643b328347348d007d8a95e4a44a


Step 9: Soldering the Cube to the PrototypingBoard

Soldering the Cube to the PrototypingBoardSoldering the Cube to the PrototypingBoard

Now that you have the electronics connected together you need to take the 4 vertical sections that you made earlier. Place one of the sections in as shown in the first picture solder it in making sure that it is square with the prototyping board. Add another with 9 holes in between finish by adding the last 2 in the same manner.

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Step 10: ​Connecting the Layers

​Connecting the Layers​Connecting the Layers

Next you need to connect the common cathode layers take a piece of wire that has been straightened and lay it on the piece of common cathode wire that is sticking out make a solder joint at each intersection. You need to do at least 4 but you might notice that I did this on both sides to make the cube look symmetric. After you have done all of the layer connections you need to add wire from the prototyping board to the layers of the cube. This can be done by taking a straightened section of wire that has a 90 degree bend on the that sticks out about a 1/2". Stick the long end of the wire near were you want to connect to the first layer solder it to the layer. repeat while moving out a hole and going to the next layer. When you get all 4 layer connections done move to the next step.


Step 11: Last Bits of Wiring

Last Bits of WiringLast Bits of Wiring

The next part is to connect the drain of the MOSFETs to the layers see the first picture. Once that has been done connect the outputs of the shift registers to the columns of the cube. See schematic for more details.


Step 12: Programing Your Cube

You have 3 options for coding the cube use the provided codes, use arduino, or use arduino with python to achieve a easier coding experience. The only one I am going to explain is arduino with python due to it being the easiest to use but you will need just a little experience with arduino/the language structure. Start by downloading all of the links in order starting with arduino software and ending with the tkinter library for python. The way the python editor works is mostly self explanatory just run the python code down below. When you press the save button the python shell will spit out binary bytes that you will need to paste into the arduino array that says slides. You will then need to add delays into the arduino array that says delay_array the number of slides that you have is the number of delays you need. The max number of slides that you can use is 150 due to the arduino nano's memory it sounds like a lot but when you start to do graphical translations it quickly eats away at that number.

The codes are in groups of 3 because I couldn't get them to download as one file except for the python file.

file groupings (all files in the group must be put in the same folder for it to work properly)

hard coded arduino (clear_all, led_cube_4x4x4, show_pattern)

arduino byte coded files(clear, easy_programing_v2, show_pattern)

python gui(4x4x4 code generator V2)

https://www.arduino.cc/en/main/software

https://www.python.org/downloads/

https://docs.python.org/3/library/tkinter.html#mod...


Step 13: It's Done

At this point you should be able to display at least few patterns on your cube and hopefully everything went smoothly.

If you have any questions ask down below in the comments.

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Feb 12,2020
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