DIY Sim Wind Simulator – 120mm Fan Hardware Kit

120mm hardware kit for mounting and enjoying immersion and comfort. Left and right channel.  

What to print

2x 120mm T-Junction: Credited to CodeVent on Thingiverse

2x 120mm-to-76mm Reducers: Note: The screw holes on these are not lined up perfectly; you may need to drill them out slightly if you are using fatter mounting screws.

2x Monitor Ball Joint Mounts: Allows for directional adjustment.

2x Fan Rig Mounts: Designed to clamp onto bars measuring 29.5mm x 16mm.

2x Honeycomb Exhaust Ports: For airflow straightening and it looks cool. 

How to use this contraption

Because there are lots of ways to drive this I will suggest the easiest method you can use. 

You'll need some parts:

4x 120mm fans of your choice

1x Arduino nano. 

1x PCA9685 16 Channel 12 bit PWM Servo Motor Driver I2C

1x 12V 5A Power Supply Adapter Converter Transformer 60W AC 100-240V. 

3 Inch Air Ducting, 8 Feet Flexible Aluminum Dryer Vent Hose

The screws are your choice. Find your best junk drawer. Some threads are fastened into holes directly. Theres not a whole lot of pressure going on with the mounts or ducts.  But you can use inserts if you want. 

SIMHUB

You can configure this anyway you like, idle only, race wind simulation, curves, etc, the packet will send the calculated value to the arduino. 

I like using a high idle speed. Gotta keep those giblets cool on and off the tarmac. 

Simhub Packet: 

'w<' + format([ShakeItWindPlugin.OutputLeft], '0') + ',' + format([ShakeItWindPlugin.OutputRight], '0') + ‘>\n’

SimHub Custom Serial Device Configuration:

Note:  You must enable Custom Serial Devices in the settings menu. It is a plugin. 

Arduino Information:

Wiring diagram

Dependencies

You will need to install the Adafruit PWM Servo Driver Library via the Arduino Library Manager (or lib_deps in PlatformIO).

Standalone Wind Simulator Script

#include <Arduino.h>
#include <Wire.h>
#include <Adafruit_PWMServoDriver.h>

// --- Configuration ---
#define I2C_ADDRESS 0x40      // Default address for PCA9685
#define SERIAL_BAUD 115200    // Match this in SimHub
#define TIMEOUT_MS 2000       // Turn off fans if no data received for 2 seconds

// --- Globals ---
Adafruit_PWMServoDriver pwm = Adafruit_PWMServoDriver(I2C_ADDRESS);
unsigned long lastUpdate = 0;
char buffer[64];
int bufIdx = 0;

// --- Helper Function to Set Fan Speed ---
void setWind(int left, int right) {
 // Map 0-100 input from SimHub to 12-bit PWM (0-4095)
 int pwmLeft = map(constrain(left, 0, 100), 0, 100, 0, 4095);
 int pwmRight = map(constrain(right, 0, 100), 0, 100, 0, 4095);

 // --- Channel 0: Left Fan ---
 if (pwmLeft == 0) {
     // Special value 4096 in 'off' parameter turns it fully off
     pwm.setPWM(0, 0, 4096); 
 } else if (pwmLeft >= 4095) {
     // Special value 4096 in 'on' parameter turns it fully on
     pwm.setPWM(0, 4096, 0); 
 } else {
     // Standard PWM duty cycle
     pwm.setPWM(0, 0, pwmLeft);
 }

 // --- Channel 1: Right Fan ---
 if (pwmRight == 0) {
     pwm.setPWM(1, 0, 4096); 
 } else if (pwmRight >= 4095) {
     pwm.setPWM(1, 4096, 0); 
 } else {
     pwm.setPWM(1, 0, pwmRight);
 }
}

void setup() {
 Serial.begin(SERIAL_BAUD);
 
 // Initialize PCA9685
 pwm.begin();
 pwm.setOscillatorFrequency(27000000); // Standard for many breakout boards
 pwm.setPWMFreq(1600);                 // Max frequency, good for DC fans
 
 // Initialize fans to OFF
 setWind(0, 0);
 
 // Wait for Serial
 while (!Serial) { delay(10); }
}

void loop() {
 // --- Safety Timeout ---
 // If SimHub crashes or disconnects, turn off the fans
 if (millis() - lastUpdate > TIMEOUT_MS) {
   setWind(0, 0);
 }

 // --- Serial Parsing ---
 while (Serial.available() > 0) {
   char c = (char)Serial.read();
   
   // Check for end of line (newline or carriage return)
   if (c == '\n' || c == '\r') {
     if (bufIdx > 0) {
       buffer[bufIdx] = '\0'; // Null-terminate the string
       
       // Expected format: "w<LEFT,RIGHT>" (e.g., "w<100,50>")
       if (strncmp(buffer, "w<", 2) == 0) {
          char* endPtr = strchr(buffer, '>');
          if (endPtr) {
            *endPtr = '\0'; // Terminate at '>'
            
            char* params = buffer + 2; // Skip "w<"
            char* comma = strchr(params, ',');
            
            if (comma) {
              *comma = '\0'; // Split at comma
              int leftVal = atoi(params);
              int rightVal = atoi(comma + 1);
              
              setWind(leftVal, rightVal);
              lastUpdate = millis();
            }
          }
       }
       // Handle SimHub "END" command to stop fans immediately
       else if (strncmp(buffer, "END", 3) == 0) {
          setWind(0, 0);
       }
     }
     // Reset buffer for next message
     bufIdx = 0;
   } 
   else if (bufIdx < (int)sizeof(buffer) - 1) {
     // Add character to buffer if there is space
     buffer[bufIdx++] = c;
   }
 }
}
 

🚀If you happen to like the project pretty please boost🚀