This is NPN Transistor.
Part Number : A42
Function : 300V, NPN Transistor
Package : TO-92 Type

Description :

NPN Epitaxial Planar Silicon Transistor, High Voltage Transistor.

A42 transistor is an NPN BJT transistor designed for high voltage applications such as high voltage switching and high voltage amplifications.

Pinout

A42 pinout datasheet
Absolute maximum ratings ( Ta=25°C )

1. Collector to Base Voltage : Vcbo = 300 V
2. Collector to Emitter Voltage : Vceo = 300 V
3. Emitter to Base Voltage : Vebo = 6 V
4. Collector Current : Ic = 500 mA
5. Total Dissipation : Pc = 625 mW
6. Junction Temperature : Tj = 150°C
7. Storage Temperatue : Tsg = -55 ~ +150°C