Fan Speed Control

ajriding wrote:
ok. good points.
I dont think my fan is worn in any way. The noise is a ringing, not a mechanical issue. The controller I showed , as I mentioned, is similar, and I am not able to find anywhere the exact controller online anywhere to be able to look at its specifications... It might operate in the human ear range and be audible.

The FF has coils that act like a heating element to burn off power. However you want to exactly define what a heating element is or not does not matter bc in the end it still is doing the same thing, heating up a wire at the expense of power. I thought I used words to give clues that this is not important nor something that matters or needs further discussion. What I keep try to say politely is that I dont really care if you call it this or that. Nothing changed now that you defined it. It is hard to write on a forum post something that can both be understood and polite, I tried. Now lets stop with the heater analysis....

Your chasing a lot of rabbits down the rabbit hole.

Yes, a resistor will waste some energy as heat, but it isn't as much as you think.

Your fan motor will draw max current (max wattage) when full voltage and load are present.

Insert a resistor and the motor now sees less voltage and that in turn slows the fan blades lessening the load the fan sees which reduces the current drawn through the fan motor and resistor.

We are talking on the order of a couple of Watts worth of power being shed as wasted heat.

PWM controllers while they can reduce SOME of the wasted energy over a resistor can in fact use more energy than one realizes. PWM controllers do get hot, that heat is wasted energy from the controller's output transistors.

Typically the most energy you are going to save may be on the order of 1W or less on small low power applications such as a small fan motor..

Not to mention, you have now added a bunch of complicated circuitry with the potential to break down easier and to create a lot of RF noise in the process..