MOSFET switch getting hot

Other Hardware General Electronics
1

I'm using an N-channel MOSFET to complete the circuit and make a motor spin (no PPM, just connecting the battery + to the motor +, and the battery - to the motor -). It's a small dc motor from a toy car. However, the FET starts getting extremely warm as soon as I connect wires to the source and drain and my meter shows continuity between the source and drain.

I have a 10K pulldown resistor so I don't know how the source and drain can be connected. All my common wires are connected, and I've tried to replicate a number of Arduino DC motor examples with no luck. I got things to work perfectly a week ago, now that I've rebuilt my circuit I can't get it to work at all. The only other thing to not is that my meter shows continuity between the + and - leads coming off the motor.

Here is my circuit:

Any suggestions apprecaited!

2

It would have been better to continue this in your other threads about this subject.
Then you won't have to inform the readers again what motor, what Arduino, etc. your're using.

One question though.
Which mosfet.
Logic level or not.
Leo..

3

Thanks Leo. I linked to the original post below. It's a logic level FET.

I followed multiple arduino examples that people suggested and got everything to work perfectly a week ago. I simplified it to a single MOSFET and it's always on and I'm banging my head against the wall.

Origianl Post

4

Figured it out. I tried a new FET and it works like a charm! (four hours later):wink:

Now I have to figure out how to test the FET wasn't working to see what went wrong. I swear sometimes the simple things are the hardest.

5

There is an unlabelled resistor in that diagram - is it 10k or something much bigger than 220?

Most MOSFETs have no protection on their gates so should be handled with anti-static precautions.

6

Mark, it's a 10K pulldown resistor to keep the gate low unless the arduino tells it to go high.