I am trying to control three humidifiers using an Arduino Pro Micro. Everything works all fine when conecting just one of them, but when I connect all three at once, only one keeps working. They are connected as follows:
When CB of the Humidifiers (T1, T2 and T3) are connected to GND, they changes their state, turning on and off. Thereby I came up with using MOSFET transistros to connect them to GND when the Pro Micro board emits a HIGH for pin 9. However, it seems only W1 is getting that signal, since it is the only one which changes its state.
I've already checked that all is connected as it is supposed to, and I am running out of ideas. Do anybody have any idea?
[Humidifier used: 12V car humidifier]