Raspberry Pi circuit for N channel Mosfet switch

I just received my order of N channel Mosfets

FQP30N06L Datasheet here

Unfortunately my novice skills don’t yet extend to interpreting the data sheet and I’m trying to check if my Raspberry Pi GPIO 3.3 volt signal will be sufficient to open the gate fully.

I’m also struggling to find a good tutorial on the wiring of this circuit. In particular I’m confused about the connection of the GROUND.

Several of thecircuit diagrams I’ve seen show the negative connection from the battery connected not only to the device being powered but also to the GROUND pin of the microcontroller.

I’m a novice and concerned that connecting the -12 volt output of my power source, will be damaging to my RPi.
Any suggestions appreciated

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Hey Nigel,
Just to be clear, you will need to connect all the Grounds of your circuit (Pi & 12V Supply) together. Additionally the RPi GPIO should fully open the gate on this MOSFET.

This won’t supply -12VDC to the GPIO Pins on your Pi, so you don’t need to worry about that. There’s plenty of in-depth guidance available here.

Thanks Aidan,

I got it working but I was holding my breath when I connected the “negative” output from my 12v supply to the Pi. I’ve struggled to find a simple tutorial on the subject but now I am starting to think that the negative is simply the ground for the battery.

I do wonder what would be the scenario if, for instance I wanted to operate two different voltage devices from my GPIOs… say a 24 volt device and a 12 volt one?

I’ll follow the link you kindly supplied and seek the answer there.



For reliable operation, everything needs a common ground. For example: