I am building a circuit on a breadboard to see if I can get a 2N7000 NMOS to switch using a 3.3V V_gs signal. As far as I know, I've set up the circuit properly:
- This circuit causes the LED to light up regardless if V_gs is 3.3V or 0V. The transistor conducts no matter what.
- It works properly when I connect a 1MΩ resistor between Gate and Source. Now, when V_gs is 0V, the LED turns off and when V_gs is 3.3V, the LED turns on. I discovered this when I was probing Gate and Source with a multimeter, and I wondered if an 1MΩ resistor would achieve the same effect.
Can someone explain this phenomenon for me? Thank you very much.