BrewPi Chamber Fan Setup

[ModestoHagney]

I've been searching all over the forums and the internet trying to find out more about how the chamber fan works in a BrewPi.

What I am trying to figure out is what kind of fan you can use, 2, 3 or 4 pin.

Im thinking about using a 5v fan and powering it from the same power source as the pi. So I assume the 3 or 4 pin would work best with the +/- connected to the power supply and the 3rd(and 4th maybe?) connected to the arduino.

So basically can a 2 pin 5V fan be run directly from a pin on the arduino uno?
If not would a 3 or 4 pin unit be better?

 

[doomy86]

Normally PC fans require at least 7V even if the arduino can supply enough power i dont think its good driving the fan directly with it. I would just connect a relay like the cool/heat outputs.

Yes, you can use a 3pin fan, the 3rd pin(yellow wire) is only for fan speed mesurements.

4pin fans have pwm control so probably they would not work..

 

[ModestoHagney]

The reason I suggested 3 or 4 pin fans is I read that one is needed on the BrewPi site.

Our software supports driving a fan to circulate the air in the fridge. This will give you a more even fridge air temperature and faster response time. You can use an AC powered fan and switch it with an SSR or a computer fan. If you choose a computer fan, get one with 4 wires: one of the wires is the PWM input. You can connect the shield actuator output directly to the PWM input and GND.

Now that I read it again it looks like it is a 4 wire that's needed and I assume it needs a power source and the PWM wire connected to the arduino.

 

[gezzanet]

I've been running a brewpi for a while now. i didnt use the fan pins or the brewpi but instead i run an old pc case fan 12v off a walwart and leave it running 24/7. works great.

 

[doomy86]

The reason I suggested 3 or 4 pin fans is I read that one is needed on the BrewPi site.



Now that I read it again it looks like it is a 4 wire that's needed and I assume it needs a power source and the PWM wire connected to the arduino.

Thats interesting i did not know that.. so yes 12V power source directly to the Fan and PWM wire to arduino digital pin..

http://www.formfactors.org/developer/specs/4_Wire_PWM_Spec.pdf

The control signal is a square wave operating at 25 kHz, with the duty cycle determining the fan speed. Typically a fan can be driven between about 30% and 100% of the rated fan speed, using a signal with up to 100% duty cycle. The exact speed behavior (linear, off until a threshold value, or a minimum speed until a threshold) at low control levels is manufacturer dependent.

 

[ModestoHagney]

So judging by that if I wanted to run it from the arduino it would HAVE to be a 4 pin?

Good to know. I shall continue my search through the parts bin.