[SOLVED] How to make a low/high switch for an Intel CPU fan?

[s355]

I have an old Intel E29477-002 fan lying around and I want to turn it into a desk fan. Any ideas how to make a Low/Off/High speed switch for it with a SPDT switch? The fan should spin on 50% speed on low and full speed on high.

 

[Eximo]

Stupid ways, yes. How are you powering it?

 

[geofelt]

If you are looking for three states, a switch with two output states may not do it for you.
I might doubt the cooling capacity of a 92mm fan. 120mm would be better.
But, assuming you have some sort of method of mounting the fan to aim at your face, you could connect it to a motherboard fan header via a long cable.
To control the speed of the fan, get a rheostat type fan controller like a zalman fanmate:
https://www.amazon.com/Zalman-Fan-Speed-Controller-FANMATE-2/dp/B000292DO0

 

[Eximo]

If you had 12V, and a SPDT switch, you could wire up a big resistor to slow the fan down, and straight through for full power. Unplugging it would be your third state.

A potentiometer would make more sense, then you wouldn't need a switch at all. Unless you wanted to get rid of the waste of heating the potentiometer all day when you turn it up to stop the fan going.

 

[TerryLaze]

Since there is a bunch of electronics involved to do this I would go with something that is already made to do this, like this one.
It uses standard USB plugs for input and output so it's going to be easy to connect power and the fan to it.
Of course you should spend some more time in research, since I just looked one up as an example real quick.
https://www.ebay.com/itm/1Pc-5V-to-...ch-Fan-Speed-Regulator-Module-JB/254338051938

 

[s355]

If you had 12V, and a SPDT switch, you could wire up a big resistor to slow the fan down, and straight through for full power. Unplugging it would be your third state.

A potentiometer would make more sense, then you wouldn't need a switch at all. Unless you wanted to get rid of the waste of heating the potentiometer all day when you turn it up to stop the fan going.

My SPDT switch has three positions: On1, Off, and On2. I tried that, but the fan whined on the LOW setting. I am powering it with a 9v battery.

 

[madmatt30]

My SPDT switch has three positions: On1, Off, and On2. I tried that, but the fan whined on the LOW setting. I am powering it with a 9v battery.

Its a 12v fan.
If you're powering it with a 9v battery then on low you're only hitting it with 4. 5v at the most - that's not enough, the motor is struggling to turn the fan hence the whine.

Use a 12v battery instead.

 

[s355]

Its a 12v fan.
If you're powering it with a 9v battery then on low you're only hitting it with 4. 5v at the most - that's not enough, the motor is struggling to turn the fan hence the whine.

Use a 12v battery instead.

It whines, but still spins at half speed on the low setting. The voltage is 5v on low.

 

[punkncat]

I was also going to mention a rheo.

I am sure you realize that you can buy cheesy cheap desk fans for less than the trouble to make this work.

 

[s355]

I was also going to mention a rheo.

I am sure you realize that you can buy cheesy cheap desk fans for less than the trouble to make this work.

Should I use voltage control or PWM? If PWM's better, how do we do a PWM low/high switch?

 

[Eximo]

Pulse Width Modulation works by rapidly switching a fixed DC source to reduce power output. You can't do this manually with a switch. It is done with a transistor (MOSFET usually) and is a lot more complicated then it sounds.

You have a single pull triple throw if there are three discrete positions. Same would apply, closed circuit, resistor that lets half power through, and open circuit. Would need to be like a 2W resistor for safety. Or a resistor divider to spread the load a little. Something like a 200 Ohm and 400 Ohm maybe, fan V+ would get connected between the two resistor in series. With the larger being closer to the 9V+.

9V battery, yeah, not really enough for a 12V fan. When the battery is full it will be like 10V+. Not really sure what half speed would be there, fan might spin at 5V, but not something I have tried with a stock Intel fan. I have a lot of 12V fan that will just spin at 5V though, even from stopped. Might be a scenario where you start it on high and then move it to 'half' speed. (How AC fans work, actually.)

 

[s355]

Pulse Width Modulation works by rapidly switching a fixed DC source to reduce power output. You can't do this manually with a switch. It is done with a transistor (MOSFET usually) and is a lot more complicated then it sounds.

You have a single pull triple throw if there are three discrete positions. Same would apply, closed circuit, resistor that lets half power through, and open circuit. Would need to be like a 2W resistor for safety. Or a resistor divider to spread the load a little. Something like a 200 Ohm and 400 Ohm maybe, fan V+ would get connected between the two resistor in series. With the larger being closer to the 9V+.

9V battery, yeah, not really enough for a 12V fan. When the battery is full it will be like 10V+. Not really sure what half speed would be there, fan might spin at 5V, but not something I have tried with a stock Intel fan. I have a lot of 12V fan that will just spin at 5V though, even from stopped. Might be a scenario where you start it on high and then move it to 'half' speed. (How AC fans work, actually.)

If I voltage control the fan, it whines on the LOW setting, but it does spin up.