Question PWM Fan Controller Recommendations?

Aug 14, 2019
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Hello,

I am trying to build a wind tunnel for a school project to test the thermal efficiency of various heat sink designs.

I am using (4) 120x25mm PWM fans.

I am looking for a 12V output PWM controller with 4 channels and a minimum total output of 160W. It doesn't matter if it comes with a programmable software or just simple a potentiometer to adjust fan speed.

I also want to be able to adjust each fan speed if needed.

I am using a hot wire anemometer system for measuring air temperature and velocity using candlestick sensors within the wind tunnel.

I am relatively new at this and trying to learn as much as I can, so any help or insight will be great! Thanks!
 
You say you need 40W per channel at 12 VDC, which is a LOT of power for a standard computer case fan. Most of those run about 0.1 to 0.25 A, or max 3W per fan. So, exactly what fans are you planning to use?

Main reason for that question is that the fans for computer cases called "PWM fans" are NOT the same as the type often used in industry with PWM fan speed controller power supplies. For that reason, the PWM controller used for the common industrial fans is quite different from what it used with a computer PWM fan.

Now, IF you are using a computer-type "PWM fan", check that power spec. I know you CAN find such fans with very high air flow and power use ratings, but they are not common. But if you do have such, then there are two other problems to consider.
  1. Most computer case PWM fan controllers can deliver about 1 A current per output channel, or 12 W, not 40W. You'd need a special design for your specs.
  2. Almost all common third-party "fan controller" modules sold to be mounted in a computer case for vent fans have four-pin output ports for 4-pin PWM fans, BUT they do NOT actually use the PWM method of speed control! The design of the new "PWM fans" for computer cases includes a backwards compatibility feature. If one is plugged into an older mobo 3-pin header, it receives the Ground (Pin #1) and +VDC (Pin #2) connections, and the speed pulse signal (Pin #3) line. It gets NO PWM signal from the non-existent Pin #4 so it cannot use that signal to modify current flow from the power supply for speed changes. However, the power it does get from Pin #2 is NOT the constant 12 VDC that a 4-pin PWM header would provide. It is the varying Voltage of a 3-pin older header, and that CAN control the speed of the fan motor. So MANY fan controller makers use this feature, and their output ports ONLY supply the older varying-voltage 3-pin fan type of output signals. Thus you do NOT get the PWM type of speed control you expect even though you bought 4-pin fans. The controller effectively is a "universal" device that can control the speeds of any mix of 3- and 4-pin fans, and the maker does not have to design, manufacture and market different units for different users.
 

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