Electrical – NPN Transistor 2N2222 fixed bias MULTISIM

It looks like you need a current limiting resistor between your output pin and the transistor base (assuming you didn't omit it on purpose, for brevity). Without the resistor, when you set the output pin to HIGH, you are causing a short-circuit to ground. That may damage the pin, if it hasn't done so already.

I would guess that a 10K resistor would do it. That's what I use with my ATmegas and ATminis. But check your MCU datasheet for appropriate values.

It's quite a common mistake to think that the base-emitter junction already has some sort of current limiting property, but it doesn't. It has very low impedance. I usually think of it as a plain wire. That helps me avoid these kinds of mistakes. Same applies to collector-emitter junction.

By the way, your collector-emitter path has no current limiting resistor or load. Watch out! 

The beta of a transistor is a set of Ic and Ib combinations.This means that it varies(hfe=x-y).You can make use of the fact that you know what the resistance will be,using resistors.Now we'll think about the 3 transistors states :saturation,active mode and cut off.Take a beta of 10 and see if your transistor is saturated.Now if you change the value of the base resistor,you shouldn't notice any change in collector current(try connecting some motor to the collector).The beta you will get will be the forced beta.It's not yet what you need.Keep decreasing the base resistance until you notice a change in Ic.Now you will find the actual beta of the transistor(you'll be in the linear region-active mode).Collector current is now affected by Ib.Write this one down and keep decreasing base resistance until it shuts down and enters the cut-off state.The beta before your BJT turned off is the last.Write this one down,too.Now you have your answer(example:200-500).Note that for this,you should use beta= Ic/Ib.