How to control computer fans with Arduino UNO + vvvv (Firmata)

I already tried to use the circuit of 2nz (see image below). But in this case, all fans run super fast and I can’t control them with vvvv. Or did I connect something wrong here?

  • all yellow jumper wires go to the PWMs (3,5,10,11)
  • the green wire on the bottom to GND


Awesome! Now it works well! The solution is, that all PWM-Pins must be: 3,5,6 and 11. Now all Fans can be controlled smoothly. Instead of the Power-Plug in this picture, I used the Vin-Pin of the Arduino-Board.

The last thing is, that the circuit-noise is very loud. So I am gonna trying to use some resistors.

glad it works!

in your last picture you didnt connect your grounds properly:

  • your 12v voltage source has a positive and a negative wire. the negative one is referred to as ground. so you need to connect your green wire on the bottom to the negative wire of your voltage source.
  • and your green wires that go to the fans need to be connected to the positive wire of the voltage source.
  • also a cable from arduino ground pin to your negative voltage source!

Hey Markusch,
I’m glad you’ve managed to run the circuit. Double check your wiring according soriak post (special Attention for power supply and ground connection!).
You can limit your fan speed two ways to avoid noise:
-Adjust power supply voltage of your fans. Use regulated power supply 5-12V and adjust to the voltage that meet your requirements.
-Software limit from vvvv side. Just limit your control values. Narrow range from 0…255, to 0…128 for example (theoretically run half of your fan maximum speed).

BTW I remembered a strange behavior in my setup with maximum pwm value of 255. Led strip connected starts flickering. So i just limit my range to 0…254, which meet my needs, without diving deep in firmata communication.

How about using fences to keep the fans off stage... or perhaps some better bouncers? I know music and sports have good experience in this: