Controlling server cabinet fans ?

[RedFrame]

I've got a few Sunon 3 wire fans that I use for cooling in the van, at the moment they just run on two wires at full chat all the time, I have a feeling that the speed might be able to be controlled via the third yellow wire but have no idea if this is correct, or, if it is, how to accomplish it. They're great during the day, shifting 180 odd cumecs an hour but at night the noise is a bit too much, it'd be great to be able to wind them down a bit to a gentle hum?

This link might be a red herring but it's all I could find and it's all Greek to me.... http://www.sunon.com/uFiles/file/03_products/07-Technology/005.pdf

Thanks in advance
Red, Chris and Bannock

 

[jollyrodger]

I don't think (I could be wrong) that the yellow wire would slow it down at all .
I used similar on a fridge vent cooler a while back and used one of these ,quite successful


All wiring instructions included but not rocket science .
Hope it helpful

 

[138go]

They are computer fans third wire Yellow just tells the processor how fast the fan is going. Only way you can slow them down is to reduce the voltage. It's simple enough to do with a resistor in the circuit.

Don't know exact model but assume 12v motor at 220mA. So motor is using 2.64W. So if you put a Resistor in the circuit before the motor that is 1W and 55 ohm resistance you will halve the supply to the motor. So motor will be running at 6V. The resistor will drop 6v over 55 ohms so 100mA = 1W resistor to be safe.

If you play around with the resistance lower than 55 ohms you will increase the speed of the motor.

Its only rough

10 ohm resistor at 1w drops voltage by 1v motor voltage 11v
20 ohm resistor at 1w drops voltage by 2v
30 ohm resistor at 1w drops voltage by 3v
40 ohm resistor at 1w drops voltage by 4v
50 ohm resistor at 1w drops voltage by 5v

Get a couple of resistors and try it. Have fun

 

[HandyAndy]

A lot easier to plug one of these in fella

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[Richard n Ann]

Simply wire them in pairs in SERIES, they will then get 6v each with no wastage via resistors.
You can wire a double pole, double throw switch to switch between series and parallel for high/low modes. Google it ?

Edit. Here you go ?

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[138go]

Its actually easier to use an Ardrino Uno micro computer board with heat sensor. Check the temp behind the fridge grill and if it’s above 35 degrees turn the fans on to half speed. Check again 5 minutes later and if the temp is still rising switch them on to full power. Then just keep checking every 5 minutes and switching the fans off / half / full speed depending on temp. Fully automatic and not usually on at night.

 

[RedFrame]

Thanks everyone for your responses, I'm using these to push air through the van rather than pull it through the back of the fridge so a housed dial type setup would be neater, the fans are running two off one supply and are marked as 12V 5.4W each (model # EEC0251B1-00-G99). Does anyone know how many fans the item suggested by jollyrodger could handle safely, would it be possible to run four or more off it?

Cheers
Bannock, Chris and Red.

 

[jollyrodger]

Thanks everyone for your responses, I'm using these to push air through the van rather than pull it through the back of the fridge so a housed dial type setup would be neater, the fans are running two off one supply and are marked as 12V 5.4W each (model # EEC0251B1-00-G99). Does anyone know how many fans the item suggested by jollyrodger could handle safely, would it be possible to run four or more off it?

Cheers
Bannock, Chris and Red.

I had 3 case fans similar to yours working as top vent fridge fans handled them perfectly switch on/off slow speed to full speed .
4 ? Can't say