R1 is worth including. Its purpose is to ensure the mosfet is kept off when the system is powered up but the Arduino pin has not yet been configured as an output. It isn't needed if the pin feeds a BJT, but then you need a series resistor instead.
R1 is worth including. Its purpose is to ensure the mosfet is kept off when the system is powered up but the Arduino pin has not yet been configured as an output. It isn't needed if the pin feeds a BJT, but then you need a series resistor instead.