Making a basic fan controller?

[harveychestbreach]

I am trying to make a basic fan controller using a potentiometer to control the fan via PWM. I have been looking at videos but I can't figure it out. I saw someone using a BD139 Transistor and a 22K Resistor. I have the 22K resistor but I can't find a Bd139 transistor. I don't think that will work for the fan I am trying to control because its....   BLOWY-matron. Someone help I am a novice when it comes to this stuff.

[Electronics Wizardy]

Your gonna need more than a pot and a transistor to control a fan via pwm(and you really don't want to do voltage control linearly)

 

The lazy way is to use a micro that supports pwm. Pretty cheap and simple code to make this work.

[harveychestbreach]

Just now, Electronics Wizardy said:

Your gonna need more than a pot and a transistor to control a fan via pwm(and you really don't want to do voltage control linearly)

 

The lazy way is to use a micro that supports pwm. Pretty cheap and simple code to make this work.

Okay I should clarify I work at a computer shop so I have a crap ton of computer scrap. Can you think of anything that I could just yoink from a pcb to make one?

[Electronics Wizardy]

1 minute ago, harveychestbreach said:

Okay I should clarify I work at a computer shop so I have a crap ton of computer scrap. Can you think of anything that I could just yoink from a pcb to make one?

Id really just get a cheap fan controller like this guy on amazon https://www.amazon.com/icepc-Channels-Cooling-Controller-Interface/dp/B08CXYZLBK/ref=sr_1_9?crid=15VF4IZHD15KE&dchild=1&keywords=pwm+fan+controller&qid=1620870003&sprefix=pwm+fan+conto%2Celectronics%2C204&sr=8-9

 

But if you want to diy, those boards often araen't great to pull parts from, lots of surface mount stuff, and the fan controller chip probalby does much more here than just fans.

 

Lazy way to make the fan quiet is to just run it at 7v or 5v

[tkitch]

you can use a variable pot as a resistor, if you get one rated for the current.

 

But a variable rheostat is the easy way to do it.

[harveychestbreach]

3 minutes ago, Caroline said:

Why via PWM? easiest way is to use a 4/5 position switch, you can take 5 and 12V directly from the PSU and use inline resistors to make 7 and 9 volts and also turn it off.

Because it's not for a PC its for something else. I want to be able to control the fan RPM with a knob. I know it probably isn't necessary but I would like to make small adjustments.

[Electronics Wizardy]

Just now, harveychestbreach said:

Because it's not for a PC its for something else. I want to be able to control the fan RPM with a knob. I know it probably isn't necessary but I would like to make small adjustments.

Get a cheap fan controller? Thats really the best way to do it.

 

Doing it with a pot or a transistor is gonna get hot, esp with a high power fan.

 

If you want diy, id get a micro with analogue in and a pwm output. Probalby some chips that do only this too.