2N5550 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 140 V
• Collector-Base Voltage, max: 160 V
• Emitter-Base Voltage, max: 6 V
• Collector Current − Continuous, max: 0.6 A
• Collector Dissipation: 0.625 W
• DC Current Gain (h_fe): 60 to 250
• Transition Frequency, min: 100 MHz
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: TO-92

The 2N5550 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 emitter, base, and collector leads.
Here is an image showing the pin diagram of this transistor.The complementary PNP transistor to the 2N5550 is the 2N5400.The KST5550 (SOT-23), MMBT5550 (SOT-23) and PMBT5550 (SOT-23) is the SMD version of the 2N5550 transistor. These transistors are of the same type, have similar parameters and are designed for surface mounting.You can replace the 2N5550 with the 2N5833, 2SC1009 or KSC1009.