This part is a kind of semiconductor called BC550.

Function of this product has LOW NOISE TRANSISTORS.

Manufacturers : Motorola

Image and pinout :

Some of the text within the PDF file :

MOTOROLA SEMICONDUCTOR TECHNICAL DATA Order this document by BC549B/D Low Noise Transistors NPN Silicon COLLECTOR 1 2 BASE 3 EMITTER MAXIMUM RATINGS Rating Symbol BC549 BC550 Unit Collector – Emitter Voltage Collector – Base Voltage Emitter – Base Voltage Collector Current Continuous Total Device Dissipation @ TA = 25°C Derate above 25°C VCEO VCBO VEBO IC PD 30 45 30 50 5.0 100 625 5.0 Vdc Vdc Vdc mAdc mW mW/°C Total Device Dissipation @ TC = 25°C Derate above 25°C PD 1.5 Watt 12 mW/°C Operating and Storage Junction Temperature Range TJ, Tstg – 55 to +150 °C THERMAL CHARACTERISTICS Characteristic Symbol Max Unit Thermal Resistance, Junction to Ambient RqJA 200 °C/W Thermal Resistance, Junction to Case RqJC 83.3 °C/W ELECTRICAL CHARACTERIST [ ... ]

BC550 PDF Datasheet Download