PWM Fan control

[gr4emeUK]

Is it possible to control PWM fans for extraction of air? I would like to have the fan run on a low speed during the day but if the enclosure becomes to hot then the fan speed increase to draw cooler air from the lower part of the enclosure. once the target temp has been met I would like the fan to go back to its original low setting

[diablomaster9045]

Yes you can use the PCA9685 dimmer to cycle the PWM fans. I use it to control Terrabloom fans for air injection and extraction from my vivarium.

[diablomaster9045]

I am still trying to figure out the dimmability of still on but low vs still on but high

[diablomaster9045]

figured it out and posted on your main thread.

[diablomaster9045]

Here is how I have my sensor setup.

How the PCA9685 dimmer is set up.

Here is how I have the area setup for the pwm controls for fans to drop humidity durring the day.

I hope this gives you the info you need to adjust it to your instance of using it to control temp.
here is also a more tempature related example from the website: https://theyosh.github.io/TerrariumPI/scenarios/

[diablomaster9045]

Also here are the fans I am using: https://terra-bloom.com/products/terrabloom-4-inline-duct-fan-quiet-energy-saving-ec-motor-with-fully-adjustable-speed-control-for-ventilation-exhaust-garden-and-hydroponics-airflow-boosting-160-cfm-18w

[gr4emeUK]

Interesting, I was looking at using one of the PWM outputs from the PI to control a noctua Fan, it looks like to would work based on the white paper Noctua has published about fan control
Noctua_PWM_specifications_white_paper.pdf

[diablomaster9045]

Just remember Noctua fans are not rated for high humidity. So if its for a arid tank, they will work well. but anything high humidity, it will probabily fail fairly quickly.

[gr4emeUK]

yeah mine is a dessert dweller so no humidity

[diablomaster9045]

yah the native ports on the Pi should be fine for a 5v fan.