Popular transistors.

BC142 transistor.
Pinout. Datasheet.

Type Designator: BC142.
Package: TO-39, 1-collector, 2-base, 3-emitter.
Material of transistor: Si
Polarity: NPN
Total Devise power dissipation |PD|: 0.8 W(at ambient temperature + 25 )
Collector-base breakdown voltage |VCBO|: 80V
Collector-emitter breakdown voltage |VCEO|: 60V
Emitter-base breakdown voltage |VEBO|: 5V
Maximum collector current |Ic max|: 1A
Maximum junction temperature |Tj|: +200C
Transition frequency (ft) : 40MHz(min)
Collector Capacitance|Cc |:25pF
Collector-emitter saturation voltage|VCE|:150mV(IC=200mA,IB=20mA),
300mV(IC=500mA,IB= 50mA).
Base-emitter saturation voltage|VBE|:1,5V(IC=200mA,IB=20mA)
Forward current transfer ratio |hFE| : 100(IC=10mA,VCE=10V) .