Controlling a 240v ventilation fan with potentiometer through arduino??

I have a brew room to brew beer in. In this room, I have a pretty decent ventilation system in place. It is a large 125mm Systemair fan.

Now, the fan has seven wire slots. L, N, Ground, Tacho output (for counting speed), 10V gnd, Signal in, 10V out.

I also have a potentiometer box with the following connections: 10V in, Signal out, GND. I've wired it according to instructions and it works perfectly. The potentiometer dims the fan speed.

Now, I want to take it up a notch. I want to take the potentiometer away and control the speed through an arduino...

At first I was thinking, could I use a Mosfet module to dim the signal? I would wite the GNDs together and to the fan GND. Then I would wire 10V out on the fan together with In on the Mosfet and the out signal back to the fan. Would this work, or will it over complicate things?

Any other ideas?

I also have a potentiometer box with the following connections: 10V in, Signal out, GND. I've wired it according to instructions and it works perfectly. The potentiometer dims the fan speed.

If I have understood correctly the fan controller uses a 0 to 10V input to control the fan speed. You need to check this and and confirm it is true.

If that's the case then you need a 0 to 10V variable output, which you can achieve by using analogueWrite(), which will give you a PWM signals, filter thism with an RC filter to give a varying voltage between 0 and 5V, then double it with an op-amp to give 0 to 10V

Robert's your father's brother.

PerryBebbington:
If I have understood correctly the fan controller uses a 0 to 10V input to control the fan speed. You need to check this and and confirm it is true.

If that's the case then you need a 0 to 10V variable output, which you can achieve by using analogueWrite(), which will give you a PWM signals, filter thism with an RC filter to give a varying voltage between 0 and 5V, then double it with an op-amp to give 0 to 10V

Robert's your father's brother.

I would test and send PWM directly to the gate. Use a rather low PWM frequency. The 490 Hz. N channel logic MOSFET....
I've PWMed 48 volt cooling fans even though the seller said "No" to speed control. He changed his mind when he saw the result.

Railroader:
I would test and send PWM directly to the gate. Use a rather low PWM frequency. The 490 Hz. N channel logic MOSFET....
I've PWMed 48 volt cooling fans even though the seller said "No" to speed control. He changed his mind when he saw the result.

You may well be correct, I was being cautious.

Nobody gets fired for being cautious.

My rebellic approach to those fans came from this: Hold the cables in Your hand and make contact during a very short time. The fan makes "a jump", rotates a little and stops. Let the short pulses be "a little bit longer".... Pulsing 10 volts to that fan has a good chance of working I think.

Nobody gets fired for being cautious.

I agree. When I first came here folk were repeatedly told that I2C doesn't work over more than about 0.5m. I have since pointed out many times that I have it working over about 30m. I accept it might not have been designed for such distances, but it can be made to work. I've not found out what the limit it.

Sure. If You don’t go for the very high frequencies, have a well selected load (pullup) and not any sparking evil devices near the cable, so why not?
At my first job after exam they ran RS232 for a lot longer distance than 10 meters. 9600 baud and well selected cables, no problem.

PerryBebbington:
If I have understood correctly the fan controller uses a 0 to 10V input to control the fan speed. You need to check this and and confirm it is true.

If that's the case then you need a 0 to 10V variable output, which you can achieve by using analogueWrite(), which will give you a PWM signals, filter thism with an RC filter to give a varying voltage between 0 and 5V, then double it with an op-amp to give 0 to 10V

Robert's your father's brother.

That seems correct. The fan is installed at my work place, so I have yet to test it with a multimeter. But the connections are that way. It even says (0 - 10V / pwm) in the wiring schematic. If I were to be so crazy as to connect an arduino to it. Would I then connect GND from fan to Arduino GND too?

Yes. The MOSFET connects the fan to "a GND" and the Arduino control signal to the MOSFET gate also needs GND so those 2 GNDs must be connected to each other.

Railroader:
Yes. The MOSFET connects the fan to "a GND" and the Arduino control signal to the MOSFET gate also needs GND so those 2 GNDs must be connected to each other.

I was thinking of using a module like this one: https://www.kjell.com/no/produkter/elektro-og-verktoy/arduino/moduler/luxorparts-mosfet-modul-for-arduino-p90631
Then I figure it would do the same function as the physical potentiometer does, right? It would scale the signal from 0(off) to 10v(fully on) and everything in between?
So I would put 10V out (the supplied 10V signal) into the Vin part. GND from pump both to GND and V- and a wire from V+ to Signal In on the pump?

That module will not “scale” anything to an analog voltage. It’s a pure MOSFET transistor working as told in the replies. You could do this using 180 Ohm between controller and the gate of the fet and a 10 kOhm resistor from gate to GND.

Simple
Just put a servo on the pot

#9 is even more simple.

ryuujin87:
That seems correct. The fan is installed at my work place, so I have yet to test it with a multimeter. But the connections are that way. It even says (0 - 10V / pwm) in the wiring schematic. If I were to be so crazy as to connect an arduino to it. Would I then connect GND from fan to Arduino GND too?

Check the datasheet what voltage the PWM has to be. It could be that it works at 5V PWM, that'd be great. In that case Arduino output to fan input and Arduino gnd to fan 10V Gnd.

If it expects a 10V PWM signal, you need a level shifter. Still very easy. That can be built from a single transistor - do note that those circuits tend to invert the signal so an analogWrite(255) is 0% and analogWrite(0) is 100% duty on the output, a trivial change in your code.

The MOSFET module as you posted will be able to do this. It's just a bit overkill for this application.

Railroader:
I've PWMed 48 volt cooling fans even though the seller said "No" to speed control. He changed his mind when he saw the result.

The OP appears to be using a fan powered by AC mains. Will need a different approach :slight_smile: Phase cutting may work, depending on the internal workings.

PerryBebbington:
I agree. When I first came here folk were repeatedly told that I2C doesn't work over more than about 0.5m. I have since pointed out many times that I have it working over about 30m. I accept it might not have been designed for such distances, but it can be made to work. I've not found out what the limit it.

I'm not really surprised, knowing how I2C works. As long as the stray capacitance of your wires is low enough, you get the signals to rise fast enough with respect to the clock speed (fall time will be less of an issue), and can keep noise sufficiently low, it should work at just about any length.

The OP appears to be using a fan powered by AC mains. Will need a different approach :slight_smile: Phase cutting may work, depending on the internal workings.

The impression I got it that it's mains powered with a controller that takes a 0 to 10V control input or PWM, the controller converting this input into an appropriate drive for the fan.

Here are the datasheets for both the fan and the potentiometer. It seems to me it needs 10V, but again - it says max 12V. It does not say anything about 4-20mA or something regular to me…

I have the KC125 EC

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