Popular transistors.

TIP41 transistor.
Pinout. Datasheet.

Type Designator: TIP41.
Package: TO-220, 1-base, 2-collector, 3-emitter.
Material of transistor: Si
Polarity: NPN
Total Devise power dissipation |PD|: 65W
Collector-base breakdown voltage |VCBO|:40V(TIP41),60V(TIP41A), 80V(TIP41B),100V(TIP41C)
Collector-emitter breakdown voltage |VCEO|:40V(TIP41), 60V(TIP41A), 80V(TIP41B),100V(TIP41C)
Emitter-base breakdown voltage |VEBO|: 5V
Maximum collector current |Ic max|: 6A
Maximum junction temperature |Tj|: +150 C
Transition frequency (ft) : 3MHz
Collector-emitter saturation voltage|VCE|:1.5V(IC=6A,IB=600mA)
Base-emitter saturation voltage|VBE|:2V(IC=6A,IB=4V)
Forward current transfer ratio |hFE| : 15-75(IC=0,3 A,VCE=4V)