Hello everyone,
I recently built a PWM speed control for the motor you see in the picture. As a switch I used a 2n7000 NMOSFET, and I am puzzled by what happened when it was first implemented. The motor was running when there was no voltage applied to the gate. Somehow the voltage on the gate is greater than the threshold voltage when it is a floating pin. How is it that the transistor is conducting when there is nothing attached to the gate? I am assuming it has something to do with the 15V to the motor, but I am not sure.