The MPSA42BK from Diotec Semiconductor is a Bipolar Junction Transistor with Emitter Base Voltage 6 V, Base Emitter Saturation Voltage 900 mV, Emitter Cut off Current 100 nA, Collector Base Voltage 300 V, Collector Cut off Current 100 nA. Tags: Through Hole, NPN Transistor. More details for MPSA42BK can be seen below.