Frequency for 24v fan?
-
I've been tweaking and having a really hard time figuring that out.
How do you set the proper frequency for a 2 wire fan?
I have one on my Ender 3 Pro (Duet 3) that has Q25000. Still cannot get full range of RPM on it. If I select 10% fan, it doesn't even turn. When it was at Q500, anything below 80% fan would not even turn.
On my Tronxy, I have it set at Q500, seems to work ok but i feel like it should output more (50x15mm fan, 6500rpm 24v).
On my Railcore, I have it set at Q500 as well, it is a Delta 51x15mm fan 24V.
Any pointers?
Railcore II 300ZL with lots of upgrades (Duet 3 6HC)
Heavily modified Ender 3 Pro (Duet 3 6HC)
Heavily modified Tronxy X5SA-500 Pro with Chimera+ and dual bondtech (Duet 3 6HC)
CR-10S Pro V2 (Duet 3 Mini 5+)
and a bunch of SLA printers.. -
Trial and error. Some fans just don't play well with it.
-
@Thalios said in Frequency for 24v fan?:
If I select 10% fan, it doesn't even turn.
thats probaly more normal than not, as pointed out 2 wire fans aren't made for speed control with pwm.
also, do you need 10%?
-
When printing PETG I like having a slight breeze on the print. (10%)
Question. If I send 100% fan output, will it send 100% output no matter what the frequency is or i need to tweak it to see?
Railcore II 300ZL with lots of upgrades (Duet 3 6HC)
Heavily modified Ender 3 Pro (Duet 3 6HC)
Heavily modified Tronxy X5SA-500 Pro with Chimera+ and dual bondtech (Duet 3 6HC)
CR-10S Pro V2 (Duet 3 Mini 5+)
and a bunch of SLA printers.. -
If you need that granular control a 4-wire fan is the way to go, but I suspect some will have limits in that regards as well.
yes, 100% should be a steady Vfan output independent of the frequency
-
@Thalios said in Frequency for 24v fan?:
If I send 100% fan output, will it send 100% output no matter what the frequency
Yes, but I've found with some fans that a higher frequency will limit the available low end range, so even when sending 30% it would behave as if it were sent 60%. So lowering the freq gave a much wider usable range (up to a point where very low % wouldn't even spin)
-
@bearer said in Frequency for 24v fan?:
If you need that granular control a 4-wire fan is the way to go, but I suspect some will have limits in that regards as well.
My understanding is that the Intel 4-wire fan spec (which is the closest thing there is to a standard for this) allows PWM below 20% to be 'undefined behaviour'. Some fans stop at some point below 20%, some run at a minimum speed for any PWM below 20% (including 0%). Normally the data sheet specifies.
Most (but not all) Noctuas stop at 0%, but are undefined between 0% and 20%. https://noctua.at/pub/media/wysiwyg/Noctua_PWM_specifications_white_paper.pdf
San Ace say they can provide fans that do either, but the last San Ace fans I bought run even if there is 0% on the PWM line. https://www.sanyodenki.com/archive/document/product/cooling/DC_technical_material_en.pdf
-
at least they'll be engineered to be consistent.
a 2 wire brushless fan can't run the the electronics to commutate the fan when you turn off the power for the majority of the time on average (yes, they have electronic driver inside whose job it is to run at a steady speed)
-
@Thalios, I had a similar scenario / question - some information here: https://forum.duet3d.com/topic/18246/determining-best-fan-pwm-frequency
