I need to control 12v Fan with 3v3 uC. I need to stop and start it using uC gpio pins. I tried to use this schematic first: But when I set uC gpio (14 in my case) to 0, fan starts to make a weird noice. I measured voltage on the fan and found about 6v on it. I replaced fet with the 2N7000 - the same result. So, I replaced fet with the npn then (removing r4) - the same. I thought it might be the problem with other pins, so I removed pins 3 and 4 in order to disconnect them - the same. Please help. I searched the internet and this site as well and found a lot of answers that it should work either with n-ch or npn transistor. What am I doing wrong? I didn't try to use 2 npns yet since a lot of sources says it shall work as it is.
I use tps62172 to power uC from the same 12v power supply as fan, so the ground plane is common.