Fan Controller Project

Using Arduino Project Guidance
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Hello,

I'm in the process of starting a fan controller project and trying to see if the plan in my head is feasible. Basically what I'm trying to do is wirelessly control a set of fans that can be used to push and pull air. I know that a lot of PC fans can easily be controlled as in/out depending on which lead is powered vs grounded. Before we get into that level of control, what I'm trying to figure out is if it's possible for something like an NodeMCU to be configured to receive wireless control signals from a device like a Raspberry Pi? My Arduino experience is limited to a simple set of code that once flashed to the device basically just runs in a loop, and I'm not too familiar with the signal control aspect. Am I on the right path on this project with the devices I'm looking to use? Or are Arduino's too limited and more suited for loop based projects? Basically this diagram shows the interface process of what I'm looking to achieve.

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The NodeMCU cannot power fans, it can control a driver that powers the fans. The type of driver depends on the type of motors in the fans.

You will need a power supply capable of supplying the voltage and current required by the fans.

Do I understand correctly that you want to be able to reverse the fans?

Can you post data sheets for the fans?

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Feasible, yes. I have fans, lights and heaters all over the house that are controlled over WiFi, and most often using the Wemos D1 Mini.

As groundFungus intimated, your description is such a high level that there's not much guidance that we can provide without a little more detail.

You said something like, "I want to get from point A to point B using wheels".

So, here's a start. Everything in my home is controlled using MQTT over WiFi. You can start your research here.

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Tihsho:
...fans that can be used to push and pull air. I know that a lot of PC fans can easily be controlled as in/out depending on which lead is powered vs grounded.

If you mean change direction of airflow, then NO.
No PC fan can do that. You must physically flip the fan.
Leo..

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First off, thanks for all the replies!

groundFungus:
The NodeMCU cannot power fans, it can control a driver that powers the fans. The type of driver depends on the type of motors in the fans.

You will need a power supply capable of supplying the voltage and current required by the fans.

Do I understand correctly that you want to be able to reverse the fans?

Can you post data sheets for the fans?

I figured as much, I thought there might be a need for a relay board that would have its power from a buck convertor. Let me update the diagram.
I was hoping that I could reverse the fans if possible. The point of this fan project is to regularly vent humid air from a closed environment (terrarium) based on a timed schedule. The enclosure will change humidity levels throughout the day due to misting, and to keep the glass clear I was looking to pull air out of the enclosure (there are passive vents that will allow in coming air) and on occasions I'd also like to push in air. The fans being used are going to be smaller PC style fans, but from what I read from another post this might not be doable. I thought the fans could be set on either a push/pull depending on the flow of current, but from what I'm reading that is not the case. It's been a while since I've tinkered with PC fans. In most cases I remember the orientation of the fan determined the flow in the case of a PC, but I thought that may have been limited to the connector as they only connect one way. The fans I'm going with are small and not high CFM, but I'm banking on them assisting with pulling out higher heat/humidity with convection.
As I'm going with some off brand Chinese fans, I only have a little information in regards to specs:

Dimensions: 40mm x 40mm x 10mm
Speed: 6000RPM
Bearing: Oil
Voltage: 12V DC
Working Current: 0.08A

SteveMann:
As groundFungus intimated, your description is such a high level that there's not much guidance that we can provide without a little more detail.

You said something like, "I want to get from point A to point B using wheels".

So, here's a start. Everything in my home is controlled using MQTT over WiFi. You can start your research here.

Sorry for the 30,000ft view on this. I was trying to look at the big picture to see if what I'm after is or is not capable with what I had in mind. In the analogy of "wheels" you posted, I'd like to clarify that I was trying to ask if the hardware (specifically the NodeMCU) would be able to accomplish this task as said wheel, or if what I had in mind was trying to use a rectangular wheel which would be a non starter.
I'm familiar, briefly, with MQTT as I used it in the past with another project when it came to NodeMCU's collecting data and kicking the file over to a remote database for trending. I'll have to look into it further for the control aspects of devices. Thanks!

Wawa:
If you mean change direction of airflow, then NO.
No PC fan can do that. You must physically flip the fan.
Leo..

I swore I remember that some PC fans were bi-directional. Again, this could be completely wrong, but I thought I tinkered with a set years ago that were able to be toggled as input or exhaust. I just tested on a 5V fan I had laying around and well, it looks like the standard may be single direction flow.

EDIT:

Here is the updated diagram per the inputs of what was mentioned. Does this help make things a little more clear?

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Most all computer fans, nowadays, are brushless motors that can't be reversed (as you found out).

I would recommend using MOSFETs to control the fans instead of relays. Relays need current through the coils, constantly, to be held on. MOSFETs only need a small current when turned on, voltage will hold them in conduction. Relays need transistors anyway so just use the transistor (MOSFET) and eliminate the relay. And you do not need the power supply for the relay coils.

For a brushless motor the diode and cap may not be necessary.

mosfet motor driver.jpg
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mosfet motor driver.jpg
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Dimensions: 40mm x 40mm x 10mm
Speed: 6000RPM
They could make the sound of a dentist drill.

Better spend a little more on 4-pin (Noctua) fans, so you also won't have to use that relay module and/or mosfets.

Could stack fans back2back, for air direction control.
Leo..

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@groundFungus - The only limitations for a MOSFET would be a 3 wire fan correct? So basically, all PWM fans will do? If so I'll change the spec of the fans. As of right now, the fans I have are 2 wire so they are either constant on or off, so that's the only reason I ended up putting a relay into the drawing.

@Wawa - I'll have to check to see what the sound is like. I'm sort of space limited as that's why I selected the 40x40mm fans. I get the smaller the fan the more high pitch the sound, so I'll have to take that into account later. The reason I went with the 2 pin for now is that I figured they were somewhat consumable items. In most controlled environments I can understand going with more quality fans, but as this will be pulling damp air out of an environment I figured that the life of these fans may be drastically degraded.

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Tihsho:
I can understand going with more quality fans, but as this will be pulling damp air out of an environment I figured that the life of these fans may be drastically degraded.

I think you got that one dead right! :grinning: The bearings in particular will be subject to corrosion,

Small fans will be much less efficient and noisy. Your original diagram suggests an array of fans, so you might just as well use one large fan instead of four small ones.

If you use three four pin fans, you do not need the FETs as the speed control pin is a logic level control - I think 5 V. Four three pin fans only include the tachometer connection you do not need but is no impediment.

I don't think the "back to back" is too practical, certainly not efficient - if that actually matters. The "opposite" fans will be spinning backwards as a result of the airflow - but will not be damaged as they are brushless. It occurs to me that of you have an inward and an outward fan side to side, you could have a lightweight plastic flap over the exit side of each that would lift up as the fan runs and probably not impair the flow too much.

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Let me clarify since size of the fans keep getting mentioned. I'm space limited, I'm trying to cram the largest fan I can in that will mount to a 3D printed funnel of sorts. The funnel will actually neck down the holes in the enclosure (which are already in the glass and are not exactly simple to re-drill or replace the pane. Originally, I was looking at 20x20mm fans but the CFM ratings were inconsequential compared to the volume of air I needed to move, so I stepped up to the 40x40mm.

Switching to 3-pin is an option. I'll have to see what I can find on the market that are 3-pin that I can constantly source as I plan on these fans needing replacements every few years.

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It was pointed out to me that three pin fans only include the tachometer connection and still require a FET to control them. Essentially, the tachometer is mainly used to warn of cooling failure.

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