gforce2010
Posts: 12
Joined: Fri Feb 08, 2019 7:09 pm

Fan Controller - Which way to do it?

Sat Jan 04, 2020 10:53 am

Hi.

I've been using arduino based boards for a while but now need to use a Pi for my next project so I have a question about fan control.

I am putting together a 3D printer control box and it needs cooling when in use so I was going to hook the fans up to the Pi so I had better control of them.

The fan's I am looking at come as standard(3 pin) or PWM(4 pin).

The fans and the PWM voltage are all 5V.

Looking around for examples I have found most use a 3 pin fan and use a transistor to PWM the voltage to the fan. One example I found for the 4 pin fan was still using a transistor to pulse 5v on the PWM input.

So seeing as the same hardware is required for both options is their any benefit of using a 4 pin fan over a 3 pin fan?

Thanks.

User avatar
Imperf3kt
Posts: 4665
Joined: Tue Jun 20, 2017 12:16 am
Location: Australia

Re: Fan Controller - Which way to do it?

Sun Jan 05, 2020 12:31 am

A 3 pin fan doesn't include a PWM input, it does however include a tachometer output (hook that up to your Pi directly and it might not work for long)
55:55:44:44:4C
52:4C:52:42:41

Rose tinted glasses are difficult to see through.

gforce2010
Posts: 12
Joined: Fri Feb 08, 2019 7:09 pm

Re: Fan Controller - Which way to do it?

Sun Jan 05, 2020 10:06 am

I know a 3 Pin fan doesn't have a PWM input but there are numerous examples online of people using a PWM signal from the Pi to pulse the VCC to control fan speed.

Basically I just want to know if using a fan with a separate PWM input has any benefit over just using the PWM signal from the Pi to pulse the VCC?

jbudd
Posts: 2043
Joined: Mon Dec 16, 2013 10:23 am

Re: Fan Controller - Which way to do it?

Sun Jan 05, 2020 11:56 am

According to Noctua https://noctua.at/en/nf-s12a-pwm their PWM enabled fan(s) have

"Noctua's novel, custom-designed NE-FD1 PWM IC that integrates Smooth Commutation Drive (SCD) technology. By providing smoother torque impulses, SCD suppresses PWM switching noises and thus makes the fan quieter at low speeds."

Edit - my Pi 4B fan, a Noctua NF-A4x10 5V is either fully on or off, and it's already very very quiet. But I suppose a bigger fan is bound to be louder.

Return to “General discussion”