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4 fan controller for pc

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ll4m14

New Member
Hi frenz (I'ma n00b)
jus joined the site
I need a an controller for pc, it'll drive 4 fans
I need sum ideas
FAN - DC 12V 0.19 A
what power source should I use? a adapter is a simple option
 

Reloadron

Well-Known Member
Most Helpful Member
When it comes to PC Fan Speed Controllers it is generally easier to buy something like these than to build your own. PC fans are basically 12 volt fans and use the power (12 volts) from within the PC.

Ron
 

Birdman Adam

New Member
You must have a pretty nice system to use 4 fans :D

You said your a noob, so I'll just say this in case you don't know:

Any motherboard you buy today will be able to control at least 2 fans on its own, the CPU fan, and case fan. It will also vary at least the CPU fan depending on the temperature.

And another option: If you have modern fans that are PWM'ed to speed up/ slow them down, you can use this:

fan header splitter.jpg
Newegg.ca - Rosewill 12" PWM Splitter Model RCW-FPS-401

It takes the power of the PSU, and the PWM signal from the mobo to vary all of your fans.
 
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ll4m14

New Member
where's the fun in buying and using, I want to do that myself
besides my mobo doesnt has those extra fan plugin sockets, it has the solder points but no socket
plus, I want to make an isolated fan control system
tell me the values of potentiometers that I should use?
 

Reloadron

Well-Known Member
Most Helpful Member
Well OK then you have a few options for fan speed control. The simplest would involve using just a variable resistor (pot) to vary the voltage to the fan motor. Using that method we need to know a few things about the fan but nothing difficult.

Typically an 80 mm fan running at 12 volts draws about 170 mA (.170 Amp) give or take. Matter of fact the same holds about true for 120 mm and larger case fans. Therefore we can use that approximation or let's say the typical fan running on 12 volts won't draw a current exceeding 200 mA or .2 Amp. The current draw will also be proportional to the speed of the fan so as we reduce fan speed the current will reduce proportionally.

I don't think it is wise to run the fans on less than about 6 to 7 volts. They will actually run fine at those voltages but may not start spinning at the lower voltages. Therefore if while running you decrease the fan voltages below about 6 to 7 volts the next time you start the computer the fans may not start spinning. So we want to be able to run the fan on about 6 to 12 volts meaning the max voltage drop we want is about 6 volts.

Well if we want to drop 6 volts or so in the circuit and the current is 200 mA we can divide the current into the voltage (6.0 / .200 = 30) so we want a 30 Ohm resistor. So we could use a 30 Ohm variable resistor or a pot in the neighborhood of 25 to 30 Ohms give or take and the pot should be rated at 2 watts minimum.

If you have an unused 51/4 inch bay available the panel blank can be removed and the 4 pots mounted on the panel blank.

That would be a simple way to go about it. A more complex method would be PWM (Pulse Width Modulation) which gets more complex and would require more parts to drive 4 fans independently.

This web page shows an overview of fan speed control including a basic drawing of using a pot as I outlined here.

Questions?

Ron
 
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jareeb

New Member
You must have a pretty nice system to use 4 fans :D

You said your a noob, so I'll just say this in case you don't know:

Any motherboard you buy today will be able to control at least 2 fans on its own, the CPU fan, and case fan. It will also vary at least the CPU fan depending on the temperature.

And another option: If you have modern fans that are PWM'ed to speed up/ slow them down, you can use this:

View attachment 42378
Newegg.ca - Rosewill 12" PWM Splitter Model RCW-FPS-401

It takes the power of the PSU, and the PWM signal from the mobo to vary all of your fans.
most motherboards today have around 4-5 power slots for fans. cpu, ram,and 2 or 2 for the case
 

Boncuk

New Member
Hi IIem14,

I don't have all those problems with PC fans. There are three built in fans: Power supply, CPU fan and chassis fan. Those three are temperature controlled.

There are five more fans distributed well for HDD cooling and additional main board cooling. They all are not temperature controlled (for which reason? Ambient temperature is ~40deg/C, requiring maximum air flow anyway).

Using five HDDs and one DVC-writer the produced heat won't allow for low fan rpm anyway.

However the power supply has to be strong enough to handle the extra amps. My power supply delivers a total of 650W, well within power requirements.

Auxilliary fans normally are equipped with a cable and connectors allowing connection directly to the PSU with an extension allowing to connect a device.

If cables are an issue check for Y-cables, available for one input and three outputs. They are very cheap and reliable.

Boncuk
 
If you are looking at the possibility of making your own fan controller, then I would recommend using something like my fan controller. I have several versions of the controller and each does something different in terms of cooling.

Are you looking for a PWM controller or is a different type of controller acceptable?

Here is the schematic for one version of my fan controllers.
 

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Reloadron

Well-Known Member
Most Helpful Member
I need manual controller not temprature controlled
If you just want straight up manual control then just use simple pots to control the fan(s) speed(s). I provided some pot values to work with and suggested you place them in an open bay.

Ron
 
The only problem is that with a conventional pot, the current my not be high enough for the fan to operate, you need to add a transistor to increase the potential current.
 

Reloadron

Well-Known Member
Most Helpful Member
The only problem is that with a conventional pot, the current my not be high enough for the fan to operate, you need to add a transistor to increase the potential current.
I agree and that is why in a previous post I covered the following:

Typically an 80 mm fan running at 12 volts draws about 170 mA (.170 Amp) give or take. Matter of fact the same holds about true for 120 mm and larger case fans. Therefore we can use that approximation or let's say the typical fan running on 12 volts won't draw a current exceeding 200 mA or .2 Amp. The current draw will also be proportional to the speed of the fan so as we reduce fan speed the current will reduce proportionally.

I don't think it is wise to run the fans on less than about 6 to 7 volts. They will actually run fine at those voltages but may not start spinning at the lower voltages. Therefore if while running you decrease the fan voltages below about 6 to 7 volts the next time you start the computer the fans may not start spinning. So we want to be able to run the fan on about 6 to 12 volts meaning the max voltage drop we want is about 6 volts.

Well if we want to drop 6 volts or so in the circuit and the current is 200 mA we can divide the current into the voltage (6.0 / .200 = 30) so we want a 30 Ohm resistor. So we could use a 30 Ohm variable resistor or a pot in the neighborhood of 25 to 30 Ohms give or take and the pot should be rated at 2 watts minimum.
When the pot is adjusted for 0 Ω obviously there will be no current limiting. As the resistance of the pot is increased there will be a voltage drop across the pot and current limiting will ensue. The fan will subsequently slow down. Now there is a small problem with all this.

Experimenting with everyday generic 80mm and 120mm 12 VDC computer fans I was surprised that a 12 volt fan would run on as little as 3 volts. However, that same fan will not actually start spinning at 3 volts. They will start at about 6 to 7 volts without a problem. That is why I initially suggested using a variable resistor in the neighborhood of about 25 Ohms.

Yes, the fan could be driven with a transistor, however, in the interest of simplicity I figured a simple pot was a viable solution. If you peek inside most marketed fan speed controllers for computer fans you find pots in series with the fans.

Just My Take
Ron
 

MrAl

Well-Known Member
Most Helpful Member
Hi,


I bought a four fan controller for $12 USD, it uses transistors.

Some other ideas are simply:
1. Use a standard pot and transistor in voltage follower mode (very simple) to adjust voltage to the fan.
2. Use a standard pot and LM317 (also simple and cheap) to regulate/adjust voltage to the fan. You cant get max output with this though.


In either of these you can add a resistor to set the lower limit so the fan doesnt turn all the way off if you like.

Want to see the circuits?
 
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