I have a circuit that you can see on upverter.
I've been using this for some time and have built a few of these, but I'm hooking one up now and it's not working. I troubleshot and narrowed it down to the fact that the MOSFET is simply not coming on with the 3.3V that is on the GPIO pin on my Raspberry Pi 2. If I give it 5V (manually) it activates fine. I switched the MOSFET out for another (same model) I have and it still fails the same way.
The datasheet says that it should have 2-4V for the GS voltage to turn it on, so I'm expecting 3.3V to work (and I've seen it work a few times). Any idea why it would be requiring 5V?
You can see in the upverter circuit diagram that my load is a little toy monkey that is essentially a DC motor with 2 AA batteries. I run wires to that circuit to effectively turn it on with my RP2.