NOTE: Yes, I know I should have a flywheel diode in there somewhere. This does NOT turn it on (again, measured with a multimeter and not the actual motor), even though I thought it should. The problem comes when I attach a steady 5V from the Arduino to the gate. I measure 0V on my multimeter when I do that. Third question: why doesn’t this setup work? When the Arduino is unattached, there’s no voltage across the gate, so the motor should not be powered. Second question: Why is that? My guess is that it’s a means of discharging the gate, but I don’t know if that’s right or if that’s a good thing for the MOSFET, anyway. I see everywhere I look that there’s supposed to be a resistor between source and gate. If I had to take a guess, it’s that building up charge while the MOSFET is off with the voltages reversed would somehow hurt the semiconductor inside, but that’s just a guess without any physical knowledge of its inner workings behind it. I’m not sure why it’s there, and I don’t think it affects anything. There is a diode there inside of the MOSFET I have according to the spec sheet. This circuit is somehow wrong, and I don’t know why. The problem is that MOSFET’s clearly don’t work the way I thought they do, because my setup isn’t working like I expected it to. Hypothetically (and idealistically), all I need is for the MOSFET to behave like a switch. A MOSFET is just a device that I found other people using in this way online. That way, I would basically have a 120V PWM signal instead of the 5V PWM signal, and I could change the duty cycle to control the motor’s speed. The MOSFET switch would then be connected to a 120V power supply, which runs a motor (really high voltage rating for a motor, I know, but it’s correct). I have an Arduino to put out a PWM signal, and the hope is that I can use a MOSFET to behave as a switch that turns on and off with the PWM signal. I recently got a MOSFET, and the intention was to use it as a “signal amplifier” of sorts. I’m a physics student, so something as electronically involved as this is a little outside of my wheelhouse, at least in this stage of my education.
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