Switching from 4 Pin to 2 Pin Fan won´t work

A Former User

You'd probably want to use a 35V or 50V rating, the picture does show 100uF- You may get some degree of control, but I wouldn't expect magic.

dc42

DO NOT connect a capacitor in parallel with the fan outputs to smooth the PWM! Doing so subjects the fan mosfet to peak currents likely to exceed its rating.

The safe way to smooth PWM is to use a flyback diode (which is already included in the Duet fan outputs, but not heater outputs) and inductor, optionally followed by a capacitor.

It's also possible to use a 10 ohm resistor followed by a capacitor, although that will reduce the maximum fan speed a little.

Frederik

@dc42 Ok, good to know.

What would the correct way ?
Connecting to a 2pin connector like out 7-9 ?

What do i have to change in my configt.g ?

Regards
Frederik

Veti

you could try different pwm frequencies

dc42

@Frederik said in Switching from 4 Pin to 2 Pin Fan won´t work:

@dc42 Ok, good to know.

What would the correct way ?
Connecting to a 2pin connector like out 7-9 ?

What do i have to change in my configt.g ?

Regards
Frederik

You can connect 2-pin fans to 4-pin connectors, between the VFAN pin and the FAN- pin. Connected in this way, they behave just like the 2-pin outputs.

Some 2-pin fans only work with PWM if you reduce the PWM frequency.

Frederik

@dc42 do you mean with the oins nr 2 and 4 when i am looking at the online wiring guide ?

Frederik

i mean for example: out 6: voutlc1 and the out6 ?

Frederik

@dc42 i have tried both out 9 and out 6. Now Function.
Hotend Fan on out8 working on or off. but the other fan wont start with the same values

; Fans
M950 F0 C"out8" Q500                                  ; create fan 0 on pin out8 and set its frequency
M106 P0 C"Hotend" S1 H1 T45                           ; set fan 0 name and value. Thermostatic control is turned on
M950 F1 C"out9" Q500                                 ; create fan 1 on pin !out4 and set its frequency
M106 P1 C"Bauteildüse" S1 H-1                         ; set fan 1 name and value. Thermostatic control is turned off

Veti

@Frederik said in Switching from 4 Pin to 2 Pin Fan won´t work:

Q500

try Q10

Veti

@Frederik

I bought some 2 pin sunon fans.
at 500 i had the same result as you.
at 25000 they are somewhat adjustable.

Frederik

@Veti what model are you using? Meanwhile I got it working. I connected them on the toolboard to out 2 and out1, used pwm 255 and connected to pwm out and 12v.
The control is for me good enough at the moment, I would guess that I'm getting ~10% steps.

What range did you get with 25000?

Thats the one I'm using:

Veti

@Frederik said in Switching from 4 Pin to 2 Pin Fan won´t work:

What range did you get with 25000?

i was able to go down to 10% with the fan still spinning.

Frederik

@Veti I tested with 25000 as value.

My Fans don't even start to spin.
Only at 100%, they start running

but at 99 it's standing still... why these big differences from similar Fans?

Veti

some fans do no like the pwm signal.

Phaedrux

You can try adding B1 to give it a blip of full power for 1 second to overcome any starting resistance.