I want to calculate the transistor base resistor. My transistor is 2N5088. The collector is connected to a motor's ground. The emitter is connected to the ground. The motor is connected to a 5V power supply and the base to a 3.3V power supply (but same ground).
Here is a scheme:
I tried to calculate in this way:
ICsat = 0.2A
IBsat = ICsat / 300 = 0.666mA (300 Hfe per 2N5088 datasheets)
BaseResistor = 3.3 / 6.66e-4 = 4950 Ohm.
So, I tried to use 5K ohm resistor, but nothing happens... Weaker resistors do work, but I don't know if what is the minimal resistor...
Why 5K ohm resistor isn't working at all? How to calculate the right resistor value?