Controlling 3 Fans with Wemos D1 Mini

[astrakid]

hi,
i have a wemos d1 mini in place for checking room temperature and getting values from my powermeter (serial server).
now i want to control 3 fans by pwm in that room.

what is the simpliest way to achieve that? do i need external mosfets?

regards,
andre

[TD-er]

Depends on what kind of motor you're using.
Usually the rpm of a DC motor is controlled by the voltage and the load.
This could be controlled via PWM, but I guess you may also need some capacitor to make sure it doesn't work as a brake.
Also don't forget to place a diode over the motor to protect the transistor and your power line.
Something like this (the 555 part can be seen as a PWM signal)


If the motor is an AC motor, you need to use a triac. But maybe better to use an existing controller and send the PWM signal isolated via an optocoupler?

[astrakid]

the fans are 4-pin fans, DC, 12V, so they can be controlled completely by pwm as far as i underrstood.
it would be enough if alle 3 are running in parallel (same RPM / PWM). is it possible to connect them all to the same wemos-output-pin to control all fans at once?
i hope to get a simpler circuit.

[jgrad]

I have experience with controlling "Single room ventilation unit KWL EC 45" (https://www.heliosventilatoren.de/en/ne ... -kwl-ec-45) by using ESP8266.
Ventilation unit have 3 pons: +12V, GND and PWM.

PWM input defines how unit operate: if duty cycle is below 50% then fan blow air IN, if dutycycle is above 50% then air goes OUT. How much above or below 50% duty cycle is faster fan operates. if duty cycle is 50% then fan stops.

How I control it via ESP (I actually control 3 units, every unit in separate room, for each unit I use different GPIO on ESP) below is handwritten schema - basically you need external switching transistor to pull PWM input to GND.

There are also PC computer CPU fans which speed is controlled by PWM - principle is similar.

ESP_control_KWL45.jpg

[astrakid]

hi,
i simply connected pwm-pin of the fan with an output of my wemos d1 mini and gnd of the fan with gnd of wemos d1 mini.
that works for a short time (5s, sometimes 10s, ...).

edit: will using the 2n2222 as in your picture stabilize it?

regards,
andre