Popular transistors.

MMBT3646 transistor.
Pinout. Datasheet.

Marking code: 23
Package: SOT-23, 1-collector, 2-emitter, 3-base.
Material of transistor: Si
Polarity: NPN
Total Devise power dissipation |PD|: 825 mW(at ambient temperature ≤ + 25 )
Collector-base breakdown voltage |VCBO|: 40V
Collector-emitter breakdown voltage |VCEO|: 15V
Emitter-base breakdown voltage |VEBO|: 5V
Maximum collector current |Ic max|: 0.3A
Maximum junction temperature |Tj|: +150 C
Transition frequency (ft) : 350MHz(min)
Collector Capacitance|Cc|:5pF(max.)
Collector-emitter saturation voltage|VCE|:0,3V(IC=30mA,IB=3mA)
Base-emitter saturation voltage|VBE|:0,95V(IC=30mA,IB=3mA)
Forward current transfer ratio |hFE| : 30-120,(IC=30mA,VCE=0,4V),
MMBT3646 Datasheet (PDF)