Hello everybody !

I made this box to "improve" my computer, with it you can switch the internet connection, audio output and microphone input. You can also turn on and off each fans of your computer case and control their speed even if they are not PWM-ready ! But that's not all !

(PS: I'm french, I hope my english is not too bad... :)

Let's go !

Step 1: Designing the Box

First, I used the PowerPoint software to get a good approximation of the position of the buttons and switches. Each button represents a function I want to add to my computer. Here, potentiometers are used to control 3-pins PWM fans (not PWM ready but I will now be able to control their speed thanks to a PWM generator).

The key switch will be use to power up / reset the computer. The red switch to kill the internet connection, the orange one to kill a USB connection, the blue one to mute speakers and the green one to mute my microphone. The 3 buttons at the bottom left corner are use to:

- Put my computer into sleep mode

- Control my computer case LEDs

- Power up a (future) watercooling

The emergency stop button stops the computer immediately.

Then I calculate the area needed to support all these buttons, the final dimensions of the front side are 100*300mm

After that, I used SolidWorks software to draw the shape of the box panels so I can print it to real scale. (usefull for later)

Step 2: Designing the PWM Generator

I inspired myself from these schematics to build my own PWM generator. I computed resistors and capacitors values in order to have a signal with a higher frequency than the original circuit. I needed to reach a frequency about 20kHz (if the frequency is less than 16kHz, the circuit and fans will be noisy)

I reach a mean value of 18kHz.

When I get values for the oscillator part, I computed values for the monostable part.

Once it have been done, I tried the circuit with an oscilloscope and a LED...No smoke... So I tried with a fan and it works !

Schematics.PDF
Download

Step 3: Making the PCB

I made a detailed instructable on how to make a professional PCB. Just follow it to make the PCB. Or ask https://jlcpcb.com/ if you don't want to make the PCB yourself.

For soldering, start with ICs sockets in the middle of the PCB and then continue soldering all the components to reach sides. Finish by soldering fans connectors and potentiometers. All the components are soldered through holes except fans connectors.

The artwork I shared is made for 100*160mm PCBs to cut in half (to get 2 pieces of 50*160mm) once the PCB is made.

Step 4: Let's Build the Case

I use 3mm MDF to build the wooden case. There are:

- 2 pieces of 100*300mm

- 2pieces of 100*56mm for sides

- 1 or 2 pieces of 56*306mm, depending if you attached the case like me or if you want to completely close the box.

Trace some straight lines with the help of graduated square. Then cut all the pieces with a metal handsaw, it will be more acurate.

Step 5: Tracing Buttons Holes

Now print out the pattern of the button locations, cut each circle with a cutter (be patient, you have to be as precise as possible)

Use adhesive tape to attach the pattern on a 100 * 300 piece of wood. Place a dot in the center of each hole and mark the circles.

Proceed in the same way for the rear panel.

Holes (good scale).PDF
Download

Step 6: Drilling Holes

Use a small drill bit (about 1-2mm) and precisely drill a small hole into each center of circle you made before.

Then, widen them with a conical drill bit to the diameter of the buttons and switches you have.

For the rear panel, I used very good cutters to cut holes, it's very precise.

Step 7: More Style !

After that, you can give a style of carbon fiber to your box by applying an imitation sheet on pieces of wood. Then use a cutter to unclog the holes.

Step 8: Assembling !

Insert potentiometers and PCBs into the front panel, then solder wires to each buttons. Put and secure them with nuts. Then connect all the wires to screw terminal. Insert the left wooden side and use brackets and hot glue to attach it. Do the same for the right side.

Once you are done place the rear panel. Be careful with pins. Use brackets and hot glue again.

Step 9: Making Wires to Connect the Computers

You also have to create cables to link the box to the computer. (power, fans, USB ports...)

Fan: On one side clamp wires into femal pins and insert pins into the plastic connector. On the other side, solder male connector onto wires.

USB: Clamp wires into femal pins and insert pins into the plastic connector (as shown in pictures) Do it on each sides of the wire.

Power: Connect power jack to a MOLEX. The inside of the Jack to the yellow wire and the outside to a black wire.

Also connect wires of the key switch to the corresponding pins on your motherboard to power up the computer, do the same for the LEDs button, the reset pins and watercooling if you have. I can't give more details here, it depends of your motherboard. But feel free to ask me if you are not sure ! ;)