Reduce Fan Speed With Resistor

If the motor draws constant current then the resistor will drop a constant voltage and the motor will run at a fixed lower speed.

Reduce fan speed with resistor.

However the motor will draw more current when starting up and as the load increases causing higher voltage drop and reducing speed even more. Use the 3 pin cable to connect the power supply to your cooling fan it will reduce the speed of the fan and cut the noise output dramatically. Use the 3 pin cable to connect the power supply to your cooling fan it will reduce the speed of the fan and cut the noise output dramatically. 3 pin male to female.

Among all circuits i have make this is the simplest one. So to achieve a voltage drop of 5v we would need a resistor with value of 42 ohms and capable of dissipating 0 6w of power. Designed with a resistor on the cable. This highlights one potential pitfall of this method you can t safely use 1 4w resistors for this unless you make up the target resistance using several smaller resistors of equal value in series.

In our psc example we would likely have had to slow the fan speed by 7 15 to give us the ability to get much closer to our target of 350 cfm ton. Emmawatsun sep 20 2018 6 48 am in response to rayjai you should put a big size resistor on the 5 volt side. 3 pin male to female resistance. I have a 5v usb fan and i want to reduce the speed.

This voltage drop will be subtracted from the overall voltage on the fan and therefore the voltage across the fan will be reduced. Ecm motors typically offer all the same speed adjustments as psc s with the added ability to reduce speed in smaller increments from the low medium low medium high and high settings. It uses a resistor to generate voltage drop and thus reduce the speed of a dc motor like the pc fan. Quite practical and useful.

The resistor will cause a voltage drop across its leads.