I need to drive a 12 volt motor with a signal from an arduino.
For this, I connect the ground of the arduino to the ground of the battery eliminator creating a common ground.
I then connect the collector of the transistor (NPN) to the positive end of the power source and the base to the output from the arduino. I finally connect the end emitter to the motor which is connect to the common ground
Not getting the desired results, I connect the base of the transistor to a pin with constant high signal from the arduino. I measure the voltage between the emitter and the common ground I find it to be about 3 volts.
What is happening? Why am I getting the potential difference between the base and the common ground instead of 12 V?