Powering Stir Plate Fans

[zak77777]

I'm looking for a bit more info on how to power/control the fans for the nutrient stir-plates. It looks like the youtube video of the grow room uses a relay but i'm not positive. If so I don't know how that would work...Does it draw power from the power supply or from mains voltage? I'm also seeing some pwm fans and wondering...is it possible to control those the same way I do with the driver for my peristaltic pumps with the l92n motor driver?

I'm really excited about this. I just got my peristaltic pumps working with a service call through HASS and connected it with a Nextion touch screen this weekend. I'm hoping to get this up and running before my PH probe arrives on Monday and get to testing! If anyone has knowledge/ideas I definitely need and appreciate it.
Thanks!

[rdrake]

Does it draw power from the power supply or from mains voltage?

COM (relay) - +12V (PSU)
NO (relay) - +12V (fan)
GND (fan) - GND (PSU)

I'm also seeing some pwm fans and wondering...is it possible to control those the same way I do with the driver for my peristaltic pumps with the l92n motor driver?

You could use 2, 3, or 4-pin fans with a motor driver.

+12V (fan) - output (motor driver)
GND (fan) - GND (PSU)
PWM (fan) - (unconnected)

Here's how I connected the fans with a DRV8847S:

Alternatively you can use PWM and skip the motor driver. I haven't tested this but some details are here.

+12V (fan) - +12V (PSU)
GND (fan) - GND (PSU)
PWM (fan) - PWM (Pi/Arduino)

I found running at 100% speed caused the stir bars to fly off. Since I only had 3-pin fans, I went the motor driver route. It's a bit noisy but it works.

[zak77777]

Thank you for the info and resources! very helpful!