24V fan on GPIO?

deuce4884

I have enclosure fans on my printer that are 24V and would like to use them as a PWM but all 3 PWM fans are already being used. Is there a way to change a heater on the expansion pins to be able to use these fans or do I just need to get some 5V fans?

Phaedrux

Yes you can use a heater as a fan output.

In RRF3 you would just define the pin you want to use as a fan with M950 and away you go to control it with M106.

https://duet3d.dozuki.com/Wiki/RepRapFirmware_3_overview#Section_M950_Create_heater_fan_or_GPIO_servo_port

Veti

you can connect a fan to the heater output.
with version 3 firmware just configure the fan with the e1heat.

dc42

@deuce4884 said in 24V fan on GPIO?:

I have enclosure fans on my printer that are 24V and would like to use them as a PWM but all 3 PWM fans are already being used. Is there a way to change a heater on the expansion pins to be able to use these fans or do I just need to get some 5V fans?

To use a heater output on the Duet 2 expansion connector to control a fan, you must use an external mosfet because the signals on the expansion connector are 3.3V only.

deuce4884

@dc42 Thanks for the info. Would there be any particular MOSFET you'd recommend? I've looked at some on Amazon

https://www.amazon.com/HiLetgo-IRF520-MOSFET-Arduino-Raspberry/dp/B01I1J14MO/ref=sxin_9_ac_d_rm?ac_md=2-2-bW9zZmV0IG1vZHVsZQ%3D%3D-ac_d_rm&cv_ct_cx=mosfet&dchild=1&keywords=mosfet&pd_rd_i=B01I1J14MO&pd_rd_r=27f5f5bb-e48c-4822-aa3b-a4d5a42d8e91&pd_rd_w=Kzu5j&pd_rd_wg=CCzxg&pf_rd_p=7cfffee0-ee78-4003-a5f6-8c51c133c0aa&pf_rd_r=7NKTHM162GY2ECW9VXVT&psc=1&qid=1610781897&sr=1-3-12d4272d-8adb-4121-8624-135149aa9081

Is this something like you are saying needs to be used? Sorry for all the questions. Little new to something like this. Thanks

dc42

That one is not ideal because the IRF520 mosfet can have a gate threshold voltage as high as 4V, so it should not be used with 3.3V signals, despite the fact that many product listings for it claim that it can be used with 3.3V. A module using the IRLB3036PbF would be better.

deuce4884

@dc42 I can't find a module like the IRF520 using the IRLB3036PbF. Can I just replace the mosfet or would I have to change the 102 resistors as well?

A Former User

@deuce4884 said in 24V fan on GPIO?:

Can I just replace the mosfet or would I have to change the 102 resistors as well?

odds are replacing the mosfet will be fine, the resistor(s) is there just to limit the gate current (due to the gate capacitance) and to limit the LED current so they probably should stay the same values regardless of mosfet.

having said that I think another user is using a module that looks identical so while the listing says irf520 that might not be what you get; or it could be a a "irf520".

edit: maybe look at this, https://www.amazon.com/DGZZI-Transistor-Trigger-Regulator-Electronic/dp/B07PT4MMCK/ it seems to sport an AOD4184A

deuce4884

@bearer I ended up using these and so far so good. I appreciate the help. Thanks.