2N5551 is an NPN amplifier Transistor with an amplification factor (hfe) of 80 when the collector current is 10mA. It also has decent switching characteristics (Transition frequency is 100MHz) hence can amplify low-level signals.
Package Type: TO-92
Transistor Type: NPN
Max Collector Current(IC): 6A or 600mA
Max Collector-Emitter Voltage (VCE): 160V
Max Collector-Base Voltage (VCB): 180V
Max Emitter-Base Voltage (VBE): 6V
Max Collector Dissipation (Pc): 625 mW
Max Transition Frequency (fT): 100 MHz
Minimum & Maximum DC Current Gain (hFE): 80 – 250
Max Storage & Operating temperature Should be: -55 to +150 Centigrade