Reducing motor speed

Thread Starter


Joined Dec 31, 2019
Hi everyone, I need a little advice here. I have a small inductive blower out of a Microwave and need a real slow speed. Problem is that even on low the speed is too fast. It’s presently operated by a 4 position switch. I tried a rheostat, that only matched the original low speed setting. Is there a way to lower the speed lower than the present low. This is a very low amperage motor controlled with a capacitor. Any help is appreciated


Joined Jan 21, 2019
Not an easy question. most motors have a limit to how slow they can operate... without knowing how fast your fan is going and all the details of the fan and controls it’s hard to say. Is it AC or DC? ... anyhow lots of questions. most of us will need more information unless you want guesses which can lead to permanent damage.


Joined Nov 13, 2015
A simple induction motor really wants to run synchronous to the line frequency. But being less than 100% efficient, it slips and runs a bit slower. You can slow it down by reducing the voltage (and therefore the motor torque) and/or increasing the load. Unfortunatly, there comes a point where the 'slippage' is so great that the motor simply gives up and stops.


Joined Feb 20, 2016
Forget the induction motor. Just get a 12V DC fan, like from a from a PC power supply. Then you can PWM it to control the speed.