The built PWM driver board. DC in on spade lugs; 2 pin header for PWM signal; wire leads to heater. IRFZ48 is the MOSFET we chose due to its 0.04 ohm Ron.


The heater PWM driver circuit is very simple. The 0-5V PWM signal from the controller passes to Q2 to isolate and buffer it. Q2 drives the base of Q3, which acts as a signal inverter and gives us enough voltage to drive Q1. Q1 is a low on resistance MOSFET that allows current to pass through the heater when the gate is pulled high by Q3.

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