Hello, I have been trying to replicate your Arduino PID Temperature Controller using a MOSFET to control power applied to the heating element. I have built the circuit exactly as the schematic shows, but I keep getting stuck around part 3 of 4. Every time I experiment, the temperature of the heater keeps rising. I have also tried many different constants, and the heating element seems to always overheat, at the same speed. I have used an oscilloscope to test the PWM coming out of pin 3, and throughout both of the transistors, and it seems to be working fine. I have swapped them out just in case, but I am at a dead end. Do you have any suggestions to make it work?