Setup: Voltage divider using a potentiometer and a cds photoresistor controlling the base current to a MPS2222 NPN transistor. 12v supply. Common emitter. Load is a cold cathode light driver circuit.
Problem: When the photoresistor is put into darkness, the cathode tube lights up only half-way. I can adjust the pot to get the cathode tube to light up all the way but when the photoresistor is brought back into brightness, the cathode tube only turns off half-way.
I'm guessing the transistor is not fully saturated. Is there a way to increase the range of the photoresistor (without getting a new one) or some other way to turn this fully on when the lights go out?