I have a 40 W, 12 V resistance heater in the hotend. It also has a 100 kΩ thermistor built in. I am using an Arduino to read the temperature on the LCD. This is working fine.
I want to use this temperature using a MOSFET and the PWM signal that is generated by the ARDUINO. So I connected the PWM signal to the Gate of the MOSFET and connected the 12 V, 3 A supply to the drain of the MOSFET. And connected the Resistance heater of the 3D printer to the source and ground.
But the problem that I am facing is that the Current is flowing from drain and the source even without the gate signal to the MOSFET.
I am not able to control the current to the resistance heater.
Mosfet: IRFZ44N and the AC to DC adapter is 12 V, 3 A. PWM signal is max 2 V.