I am brand new to transistor circuits, mainly interested in DC motor control. I want to use a 2N3904 transistor as a switch to turn on a 12v computer fan. I am using a PIC16F690 to send a 5V digital signal to the transistor gate. I am using a converted desktop PC power supply for the +12V (verified with multimeter). My problem is that when I turn on power supply the fan turns on without the high digital signal at the gate. In fact pressing my switch to activate the digital signal does nothing. I have the positive lead from the power supply connected to the positive wire of the fan motor. The ground of the fan motor is connected to the collector. The ground of the power supply is connected to the emitter. The digital signal is connected from the microcontroller port to the gate through a 560 ohm resistor.
Why is my circuit open when the power is on and no gate current is applied (removed resistor from gate to be sure)?
Why is my circuit open when the power is on and no gate current is applied (removed resistor from gate to be sure)?