Hi,

I'm relatively new to circuit design and I'm trying to create a circuit to turn on/off a 6V DC motor using a microcontroller. To do this, I am using an N-channel MOSFET. The MOSFET appears to be working, because the drain to source resistance when the gate = 0V is ~10 MΩ, and when the gate = 3.3V it goes to ~0Ω. Despite this, when the gate is set to 0V, the motor runs (with ~330mA). When I apply 3.3V to the gate, the motor runs a bit faster (~380mA). I can't get the motor to ever stop running. How is the motor able to run despite the gate being 0V and the drain to source having such a huge resistance? Circuit diagram attached.

Note I'm using a 5V source for the 6V motor because that's all I have access to. The motor runs fine at 5V.

 

Hello,

Don't you have the source and drain exchanged?
If so, the body diode will conduct.

Bertus

 

Are you certain that you have drain and source connected the right way round?
[Edit] Snap!

 

Hello,

Don't you have the source and drain exchanged?
If so, the body diode will conduct.

Bertus

This was indeed the problem. I feel silly now hahaha. Thank you!