Voron 2.4R2 electronic bay fans

[SamppaD]

Hi. My Voron has stock 2 pin (no pwm) Sunon electronic bay 24V fans that are way too loud. Exhaust fan is also 2pin no pwm fan. I was thinking to replace all stock fans for a Sunon 27db pwm 24V 2.04W fans MF60252VX-1000U-G99 and control them with Klipper expander.   What would be the easiest way to do this? I can take input 24V from HE2 but what about pwm signal?

[Crashdown]

I'm not aware of any commonly available Sunon 24V PWM fans. The PWM controlled fans they make are generally restricted to 12V because that is the standard for PC fans.

I believe they do have one special order or customised 60mm 24v PWM version but its not the MF series

There is some confusion around what a PWM fan is. If it has 4 wires it most likely follows the Intel PWM controlled fan standard and needs a specific 5V 25khz speed control signal. The fans have specific hardware built in that allows them to use the control signal. Some printer boards include specific headers that are designed to be used with PWM signal controlled fans. 

The Klipper expander is not one of the boards that inludes the hardware and circuitry for PWM signal control.

The other kind of PWM control is just using pulse width modulation on the negative line of a normal 2 wire fan. Its just turning the conection to ground on and off rapidly to produce the same effect as lowering voltage without the heat induced by using resistance to lower voltage. Thats how all normal DC fans are controlled on normal printer boards. So there isn't a specific PWM signal or PWM pin in that case. Its just the normal + and gpio -. The klipper expander board uses this type of fan control.

Sellers sometimes lable 2 pin DC fans as 'PWM' because they can be speed controlled with DC pulse width control of their power. Not because they have a PWM speed control input.

If you did want to use actual PWM fans the Tinyfan board is the easiest option  https://github.com/Gi7mo/TinyFan  It has the correct hardware and circuitry for true 4 pin PWM fan control.

Edited September 7 by Crashdown
detail and correction

[SamppaD]

Okei. Fans that i have are 3 pin fans.... red,black,yelow so its not pwm? Any good way to connect this 3 pin fans to expander?

I tested the fans and at 24 V good air flow and silent compared to the fans that i have on my voron . So in this case  connect red and black wires and leave yelow not connected?

Edited September 7 by SamppaD

[Crashdown]

OK so it could be a tachometer pin or a slightly different thing called an auto restart pin that just provides feedback on whether the fan rotor is locked.

Either way I don't think there is an easy way to use the extra pin with the klipper expander board. Some boards have extra pins assigned that can be used for fan tachometer and I don't think you can just use a seperate gpio pin on the klipper expander board as the tach pin.

You can try this without the monitoring macro 

https://ellis3dp.com/Print-Tuning-Guide/articles/useful_macros/hotend_fan_monitoring.html

But you might also need to add a diode to the tachometer wire.

More info here

https://support.dremc.com.au/support/solutions/articles/51000369297-dremc-fan-tachometer-information

https://www.nicksherlock.com/2022/01/driving-a-4-pin-computer-pwm-fan-on-the-btt-octopus-using-klipper/

Edited September 7 by Crashdown

[SamppaD]

Hi. This fan has a auto restart function based on a sheet so yelow lead is for that function?MF60252VX-1000U-G99 D06079260G-00.pdf

[zogzogzog]

Auto restart is internal to the fan - the yellow lead is a tach output.

Page 8 of the datasheet explains the math regarding how to interpret it - it's a pretty typical signal pattern that most circuits/software expecting a tach input from the fan will handle.

Edited September 7 by zogzogzog

[SamppaD]

Hi. Yes but there is no option  to use it with Klipper expander board and octopus 1.0. There is no dedicated pin to connect this lead.  Is there a way to use PI4 pins to connect tachometer lead?

 

Edited September 7 by SamppaD

[zogzogzog]

In our world, PWM is usually a software feature form the controlling board in terms of controlling power to the fan (typically switching ground as @Crashdown said).

That seems to work pretty well.

Sunon (and other manufacturers) make 4 wire fans with power, ground, tach output, and pwm input for speed control.  The PWM signal is not at the same level as power (12V or 24V for example) but is a logic level signal for easier interfacing to some control circuits (you don't need to switch a power circuit and can drive them from the control pin on many microcontrollers without having to actually switch a load).

I don't see any real advantage here for our application.

[zogzogzog]

Just tie the tachometer output to an unused input on your controller like a spare endstop or something else that can work as a GPIO input and add the configuration setting telling klipper it's a tach input for a specific fan - an example below:

[fan]
   [...]
   tachometer_pin: PC6 # Replace with your chosen GPIO pin
   tachometer_ppr: 1 # Pulse-per-revolution (adjust according to your fan's specifications)
   tachometer_poll_interval: 10 # Adjust the polling interval based on your system's requirements

[SamppaD]

Yes this will work. Thanks 

[JefferyS]

I don't know where I got this from but someone said taking off the Voron Fan covers made them quieter.

I took them off too and noticed quite a difference and the noise from the fans and not as noticeable.

You may try that before changing hardware though you do loose the guard if you have little ones poking fingers where they shouldn't but you could try a standard metal grill and see how it sounds.

 

[Mac_A_Million96]

Personally I found these too loud also, but I bought 4 noctua 12v fans and a Step-Down converter and run them at about 7-8v, the negative for the fans are still attached to the output of the controller board so I can still control them but only in an on-off setup, but they are vary quiet,

Just a note if anyone wants to do this, if you want to control the fans through a Step-Down converter, power the converter permanently and take the positive output to the fans, then connect the negative of the fans to the controller as the controller modulates the ground connection, connecting the converters input to the controllers output usually kills the converter

[SamppaD]

Yea, that one way to go if you want to use 12V fans. I have only 24V fans and a spare Klipper expander. 
So i was thinking of using expander to run 4 electronic bay fans (two for intake and 2 for exhaust side for electronic bay) and connect tachometer leads to octopus free endstop pin. New fans doesn't seems to be loud when i was testing them with bench power supply and airflow is really good.
I have to test when i have the time starting from removing fan guards and then try swapping fans for this low noise versions and see how it goes.
 I'm short on time at the moment but lets hope that i find some spare thinker time to test this.

Edited September 8 by SamppaD

[Mac_A_Million96]

Part of the issue I found with my fans is that trying to use PWM on non-PWM fans causes a high pitch whine and dosnt really control the speed vary well this was actually louder then running them at 100% for me, but this will vary significantly between different fans so the ones you use could work quite well,

but if they don’t you can always use a Step-Down converter on 24v fans and adjust the voltage to give you adequate airflow but at a reduces noise by running them at say 18v instead of the full 24v, the negative of the fans will still be controlled by the expander and the tach cable can still be wired into the octopus end stop pin so you still get the fan speed feedback