DIY Mod Boosts USB Fan: Quieter & More Powerful Cooling

If you have an 8-inch USB brushless fan, you can directly modify the Type-C port, add infinite speed control, and increase the power. This type of fan is more durable and quieter than plastic ones.

However, when comparing 6-inch and 8-inch fans, the 6-inch fan has a power of only 2W and blows air over a small area. In this case, it would be better to modify a larger fan.

To keep up with the times, switch to blade-shaped fan blades. The more blades, the softer and quieter the airflow. It would be even better if the diameter is slightly larger. It has two-speed settings and uses a boost board, which makes speed control modification easier. The first speed is directly connected to the 5V motor, while the second speed is boosted to 8.1V and then goes to the motor.

The original USB cable is only 1.1 meters long, which is too short and prone to breakage over time. Moreover, this type of cable has relatively high resistance, close to 1 ohm. When running at 5V and 1A, it consumes 1W of power. It must be modified with a Type-C port.

The motor is directly connected to a QC power meter to measure the power. 5V is equivalent to the first speed, while 8.1V is equivalent to the second speed.

When the voltage reaches 10V, the motor's power peaks, and if the current exceeds 0.6A, protection kicks in, causing the motor to start and stop repeatedly. Based on this, the power can be adjusted. The power has increased by over 50% compared to the original.

The tested current matches the specifications in the 477H specification book. It can support a maximum of 22V. If the armature is rewound, the power can be increased to over 10 watts. It comes with over-current, over-temperature, and reverse connection protection, making it durable and reliable. The schematic diagram of the FP6291 boost module can be modified by adjusting R1 and R2 to output different voltages. It can be directly powered by a 3.7V lithium battery.

If you only have a 10k potentiometer, you can use it as the basis for configuring the other resistors. The adjustable voltage range is from 5.6V to 10.6V.

The shell has additional holes to directly solder the Type-C board onto the metal casing.

After modification, connect a diode in series with the first speed to further reduce the output.

Back view.

The minimum adjustable power is 1W, and the maximum power is 6.45W.

The FP6291 conversion efficiency is around 85% even with a current over 1A, which is decent.

During actual use, it can continuously run at maximum power for several hours without any issues. The airflow is substantial, conservatively larger than before by over 30%, and the wind is soft and dispersed. You don't need to drag a power cord around; just plug it into a power bank and it's ready to use, very convenient.