Computer fan wiring question

I use cheap computer fans for cooling. They are MUCH cheaper and generally last for a few years. All you need is a cheap 12v DC power supply... Assuming you buy a 12v fan.
 
I used some cheap fans and two out of four failed after 4 months. Total run time was two months. The sleeve bearing was the failure.

I'll spend a little more from now on to get ball bearings. I saw ball bearing fans for around 10 bucks.
 
Thanks.

Not sure how a ball bearing setup compares to this setup. I understand ball bearings are reliable. I'm not sure from the description what type of bearing they are. Are you suggesting these bearing are prone to failure?

I guess my question stems more from this setup having a 4 pin connection and how is this compatible with a standard 12v adapter? What purpose may the other 2 wires serve, outside of the main power and ground?
 
The other two wires are a tacho (so the computer can check what speed the fan is running at) and a PWM input (to control that speed). Most computer fans will simply run at full speed if you ignore those two connections.

Tim
 
Basically all computer fans are 12V, and can run on 2 wires with just ground and power. 3 wire fans have a sensor that can report the RPM of the fan. 4 wire fans can be fed a PWM signal to control the speed on that extra wire.

You can also always drop the voltage (to some degree, most fans will not reliably start around 6-7V) to lower flow and noise as a result. Running a pair of fans at 9V may be less noisy and flow more than a single fan at 12V...

That fan is an oil bearing fan. It relies on a sealed oil chamber to act as the bearing. If it leaks the 'bearing' fails. If a ball bearing fan loses its seal it still works (with less friction!)... At the speeds and loads these things experience the bearing is not a significant factor for noise i would say. Rushing air will cover it up unless the bearing has truly failed.

Also, keep in mind that decibels are not linear. 30dB is 10 times louder than 20dB...
 
Last edited:
jayball said:
That first link has sleeve bearing fans, it does not take much tank humidity to make them seize. if you want something that will last you want a sealed bearing fan.
Click to expand...

I've had two of these in the back of my hood for several years now and they still work perfectly fine. They blow IN so they aren't moving humid air. They probably rust more sitting off then they do while running but even then they do just fine. And at ~$4 per fan shipped, I can afford to have spares should I ever need them. I've never seen the value of a $20 muffin fan. JMO.
 
Thanks for the links. I went with the cheap pack of 4. Going to have it pushing air in. I guess if they fail quick I can get a different fan
 
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