DIY Simrig Driver Cooling

Little background:

For this project, some technical information is required to order the PCBA (ordering PCBA from example JLCPCB). There is lot's of video's online which help with that, this isn't the place to learn about that. This instructable only shows how i did design it myself and help anyone who also wants to design it. This design is not made to be remade over and over. I made 1, and especially for 3D printing, i was printing over and over till i got it working.

Project introduction:

I made an "simrig Aircon" which uses PC fans to keep the user cool during long stints or during hot summer days. This isn't a wind simulator, just an PCB to control 2 PC fans using a potentiometer. The VU-meter shows how much % is sent to the fans. System can be turned of completely using the switch. When i am completing multiple stints, i tent to use 3 to 4 bars on the display to keep me cool/fresh. So there is some headroom for hot summer days. I chose PC fans since those are easy to control, are quiet and dont need lots of space.

This page shows how i made it. These are the steps i took to complete my build:

1. Prototyping
2. Schematic design
3. PCB design
4. Testing PCBA
5. 3D printing

These steps should help you build your own. If there is any interest in buying sets from me, i think it is better (cost wise) to sell my production files. If there is any interest for that, i will set something up.

Yes, I think it is cheaper to use a simple fan in your room, but this makes it more custom and controllable from within the seat, that's why i made it. I did like the idea of the wind sim, but only because it cools and not from any immersion point of view. Thats why i made my own design simplifying this concept. I tried using those pipes to direct the flow of this system, but ended up using the free Noctua desk Fan 3D model since this seem to be more efficient, and requires less space.

Equipment i used:

1. 3D printer (i used a "Bambu Lab P1S")
2. Black PLA filament from Bambu Lab
3. Soldering iron / tin
4. Breadboard to verify the circuit

Parts (PCB):

1. Custom PCB
2. For the components of the PCB, see bom.xslx. This Bill of Material shows all used footprints, quantities, values and LCSC part MPN's, aswell as others supplier MPN's to complete the PCBA.
3. 12V DC jack power adapter. See what is available. Each fan draws 1,2W, so in total 2,4W. LEDs also draw some current. 12V 1A will be more then enough. I used 12V/3A since i had one at home already.

Fans:

1. 2x Noctua NF-A14 PWM (https://www.noctua.at/en/products/nf-a14-pwm/specifications)
2. 4pin PWM fan extension cable (to route the cables from PCB to fans. I measured the needed length using my cable management, this is different for each rig i suppose). It is important that the connectors fit on the Fans and PCB. Female to Male cable works.

When i started thinking about the prototype, i needed to know how PC fans have to be driven, which turned out to be relatively simple.

The fan has 4 pins:

1) GND

2) 12V

3) RPM speed (used as feedback to PC's, but i didnt use this pin)

4) 5V PWM signal (for controlling the speed)

Since the 12V and GND wil be provided by the 12V DC adapter, i only needed to make a circuit for making a PWM signal based on a user input.

I remembered that the NE555 (timer/pulse-generator chip) is very populair and i noticed people making PWM generators out of it. The input uses a potentiometer to control the PWM output. Exactly what i needed. I have built a prototype on a breadboard and it worked pretty good.

Once i noticed that this prototype worked, it was time to make the schematic and PCB.

I converted my prototype circuit to a schematic in KiCAD. I chose to use 0603 resistors/capacitors for the common uses. The more robust components are THT.

The circuits starts with J1 where the 12V comes in. To ensure the system can be turned of, a switch is used. The red LED indicates if the system is powered or not.

the L7805 makes 5V out of 12V. The reason i chose an LDO is because this is a low power project. Switched power supplies are more efficient in power loss for example, but this design has low power usage, so the LDO provides an small en easy 5V voltage.

The NE555 is so designed it will function like a PWM generator. If RV1 is rotated, the PWM on the OUT tag changes from 0 to 100%. This OUT tag provides the PWM for the fans and goes to the LED driver (LM3914).

This LM3914 expects an analogue voltage to drive the LEDs like a VU-meter. To make this analogue voltage, a low pass filter is made to filter the PWM signal into a analogue voltage between 0 and 5V. An 1k resistor and 330uF capacitor is used for this, which makes the SIG tag signal. This signal is slow to changes on the PWM input, but stable to keep the LEDs driving without jittering.

J2 and J3 are used to connect the fans to the board. The diodes placed act like flyback diodes. These diodes are placed to eliminate flyback when the system is turned of and the fans are generating voltage because they are still spinning like a flywheel.

When finished soldering, i tested the design and it worked out pretty well :)

PCB mounting to the simrig

Now the electronics are working, i started printing. The base of the PCB consist of 3 parts. The PCB-mount, a cover and a LED diffuser. This diffuser guides the light from the PCB to the outside of the casing. I also used translucent PETG filament from Bambu Lab, but this isn't neccesary, because the diffuser will guide the light enough. To mount the PCB-mount onto the rig, T-slots and a Mx are used. To mount the PCB to the PCB-mount, little M4 screws are used.

Noctua Desk Fan:

I did find a design for a desk fan from Noctua itsself, but ended up using the following remix so it has a GoPro styled mount: https://www.printables.com/model/189684-noctua-style-desk-fan-140mm

1. Feel free to use another fan if you want to, as long if it is 140mm it will work with the fans i use.

I starting printing 1 with my old printer (Prusa I3 MK3), and did not think of any warping, untill i saw my print was bending like crazy. Therefore, i recommend using a brim or better bed adheasion. Later when i recieved my new printer (Bambu Lab P1S), it printed fine. There are a lot of remixes of the model that can be found online. I ended up with one with a GoPro mount. This meant it can be adjusted before tighten the screws. I only needed to design a bracket to mount to the simrig.

GoPro sim bracket:

This is the bracket you mount against your rig where you want to place your fans. It can be mounted in different ways. Due to the GoPro styled connection, the fans can easily be adjusted during assembly. assembly uses M5 bolts. This step is W.I.P.