The top trace CH1 is the voltage across the load. The
variation in voltage seen is about 2 volts (x10 probe) which represent a current
change of (V/R) 2/12 = 166mA. Well it's nearly 150mA. I told you no
one's perfect!
The bottom trace CH2 is the switching transistor base voltage Remember this is a PNP transistor the transistor is on when the trace goes low. You may also notice the rise time on this trace is not good I was too idle to sort it out.
No you don't really want to see the test setup do you. Oh the
shame of it.