Agreed to that. But did you check the waveform i have attached? My question is why are those unwanted oscillations generated only when i use a MPSA42 transistor, while there are no oscillations when i use BC547 . Why is this so?For the stated application (motor driver) fT and interelectrode capacitance are not important characteristics --- Ic (maximum collector current), hfe or 'beta' (forward transadmitance [essentionaly current gain]) and maximum interelectrode 'voltages' will be the significant considerations...
Best regards
HP