BC550 Bipolar Transistor

• Type - NPN
• Collector-Emitter Voltage: 45 V
• Collector-Base Voltage: 50 V
• Emitter-Base Voltage: 5 V
• Collector Current: 0.1 A
• Collector Dissipation - 0.5 W
• DC Current Gain (h_fe) - 110 to 800
• Transition Frequency - 150 MHz
• Noise Figure - 1.2 dB
• Operating and Storage Junction Temperature Range -65 to +150 °C
• Package - TO-92

The BC550 is manufactured in a plastic TO-92 case. When looking at the flat side with the leads pointed downward, the three leads emerging from the transistor are, from left to right, the collector, base, and emitter leads.
Here is an image showing the pin diagram of this transistor.The BC550 transistor might have a current gain anywhere between 110 and 800. The gain of the BC550A will be in the range from 110 to 220, BC550B ranges from 200 to 450, BC550C ranges from 420 to 800, BC550CG ranges from 420 to 800.The complementary PNP transistor to the BC550 is the BC560.The SMD versions of the BC550 are available as the BC847 (SOT-23), BC847W (SOT-323), BC850 (SOT-23) and BC850W (SOT-323).You can replace the BC550 with the BC546 or BC547