Air Purifiers - Arduino: Speed Control a 4pin Fan

I decided to make my own Air Purifiers.

The project is a basic idea, what can be done with hand tools and as cheap as possible. This is a single-fan filter, in the stores the prices of these devices are very high. I looked at several projects until I make my idea. I decided to buy a filter, not to make a filter (maybe I will make a filter in the next version). I'm using a P1 HEPA system filter. For the fan I use - Arctic 120mm PWM. I decided to do a control with NodeMCU - Arduino. My idea was to make an hourly schedule, when to blow strong and weak. I also added a temperature sensor, as there were free pins on the board. I am also waiting for a Dust Sensor PPD42NJ to see if there is a result of everything I did. The biggest problem is the management of the PWM FAN. It took me a long time to make it work and and also a long time to make it work hard.

Materials used:
Prices are approximate and by memory.

• Arctic 120mm P12 PWM - ACFAN00119A - 5 €
• Alfawise P1 Filter Element for P1 HEPA Desktop Air Purifier - Gray Goose - 11.57€ https://www.gearbest.com/air-purifier/pp_00950328...
• 3.3V 5V 12V Multi Output Voltage - 0.50€ https://www.gearbest.com/air-purifier/pp_00950328...
• NodeMCU V3 Lua - 3€ https://www.gearbest.com/air-purifier/pp_00950328...
• DHT22/DHT11 Digital Temperature and Humidity - 2€
• Rresistor pack - 0.0001€ок
• 12V 2A Power Adapter, for Router (dead router ) - free
• Wood Glue - 2.5€
• Wooden profile - 2/0.5 - 1m X 9prce -6€
• Wooden profile - 4/1- 2m X1prce - 2€

I made a wooden box of wooden profiles. It seemed to me easy and beautiful.

In the end, it was not very accurate. I did it on the kitchen counter. I am not very good with the saw.

I also put paddles on it to take the vibrations and not scratch the furniture.

This is the Arduin code

https://github.com/jasenpashov/Arduino-read-out-an...

new code

What I understood based on my practices and on of many attempts

• The NodeMCU and the fan must have a common GND.
• I can not achieve the maximum fan speed.
• The system operates unstable without a 560R resistor. I am not sure whether it is OK with other values.

TEST CODE:

int fanPulse = D3;

int fanControl = D2;

unsigned long pulseDuration;

int p = 0;

void setup() {

Serial.begin(9600);

pinMode(fanPulse, INPUT);

digitalWrite(fanPulse,HIGH);

pinMode(fanControl, OUTPUT); }

void readPulse() {

pulseDuration = pulseIn(fanPulse, LOW);

double frequency = 1000000/pulseDuration;

Serial.print("pulse duration:");

Serial.println(pulseDuration);

Serial.print("time for full rev. (microsec.):");

Serial.println(pulseDuration*2);

Serial.print("freq. (Hz):");

Serial.println(frequency/2);

Serial.print("RPM:");

Serial.println(frequency/2*60);

}

void loop() { analogWrite(fanControl,1200);

delay(5000);

readPulse();

analogWrite(fanControl,200);

delay(5000);

readPulse();

}

Sources:

https://handyman.dulare.com/client-server-communic...

https://codebender.cc/sketch:177208#PWM_Fan.ino

http://forum.arduino.cc/index.php?topic=18742.15

http://www.beefrankly.org/blog/2011/12/21/read-out...

https://www.picmicrolab.com/arduino-pwm-fan-contro...

http://www.theorycircuit.com/reading-dc-fan-rpm-ar...

https://www.avrfreaks.net/forum/control-pwm-pc-12v...

https://www.instructables.com/id/OPEN-SOURCE-AIR-PURIFIER/