24v dc fans

[artie]

One of my ongoing part time projects is ventilating this old house.

I have an almost adequate system at present, but recently acquired two 24v centrifugal fans.

They have four wires 1 pos 1 neg 1 input for speed control and 1 output for a tachometer if desired.

May be I've got it wrong?

So asking here for advice re wiring/controlling them.

Ideally with speed control, maybe even a humidity switch.

 

[artie]

No one??

 

[Sideways]

Hiya. Not enough info to go on without knowing the fan make and model

If it's like a PC fan then this gives as good an overview as any.
https://www.electroschematics.com/4-wire-pc-fan/
You'll want to buy a ready made controller.

 

[ajs]

You really need a device data sheet or at least make & model, there are way too many variables otherwise.

 

[artie]

Would this help?

 

[gmgmgm]

Many fans will work at a lower voltage, at a lower speed, and thus much more quietly. In the old days it was reasonably common to run 12v computer fans at 7v (7v was an easy voltage to get in a computer); you should be able to run these fans at 12v nearly silently. Perhaps that is helpful?

 

[ajs]

Would this help?
View attachment 173588

It's an off-brand copy of a Papst fan, full datasheet here: https://www.mouser.co.uk/datasheet/2/120/ebm_papst_R1G190AB2702-1880174.pdf

Speed control is easy enough, it can be controlled via a variable voltage in the range 0-10V on the yellow wire - that's a high impedance signal rather than power so a simple pot would allow you to set the speed. Alternatively pulse width modulation, the datasheet has an example drive circuit from logic levels. That gives a series of pulses at a rate of 1-10kHz, the proportion of the time the input is at "high2 voltage sets the speed. That tends to be a more appropriate method for computer control. You'll need to arrange either signal from the controller according to what you have in mind.

 

[artie]

Many fans will work at a lower voltage, at a lower speed, and thus much more quietly. In the old days it was reasonably common to run 12v computer fans at 7v (7v was an easy voltage to get in a computer); you should be able to run these fans at 12v nearly silently. Perhaps that is helpful?

Thanks, but these fans won't run even at 24v without a third input.

 

[artie]

It's an off-brand copy of a Papst fan, full datasheet here: https://www.mouser.co.uk/datasheet/2/120/ebm_papst_R1G190AB2702-1880174.pdf

Speed control is easy enough, it can be controlled via a variable voltage in the range 0-10V on the yellow wire - that's a high impedance signal rather than power so a simple pot would allow you to set the speed. Alternatively pulse width modulation, the datasheet has an example drive circuit from logic levels. That gives a series of pulses at a rate of 1-10kHz, the proportion of the time the input is at "high2 voltage sets the speed. That tends to be a more appropriate method for computer control. You'll need to arrange either signal from the controller according to what you have in mind.

Thanks, that's the info I need.

I was reticent to apply a DC voltage as I wasn't sure if it had to be PWM.

So just to confirm before I do something stupid, if I apply a DC voltage less than 10v to the yellow wire the fan will go and if I insert a 10k pot I can adjust?