BC251B Bipolar Transistor

• Type: PNP
• Collector-Emitter Voltage, max: -45 V
• Collector-Base Voltage, max: -50 V
• Emitter-Base Voltage, max: -5 V
• Collector Current − Continuous, max: -0.1 A
• Collector Dissipation: 0.35 W
• DC Current Gain (h_fe): 180 to 460
• Transition Frequency, min: 320 MHz
• Noise Figure, max: 2 dB
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: TO-92

The BC251B 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 BC251B transistor can have a current gain of 180 to 460. The gain of the BC251 will be in the range from 120 to 800, for the BC251A it will be in the range from 120 to 220, for the BC251C it will be in the range from 380 to 800.The 2SA812 (SOT-23), BC857 (SOT-23), BC857W (SOT-323), BC860 (SOT-23), BC860W (SOT-323), KSA812 (SOT-23), KST5086 (SOT-23) and MMBT5086 (SOT-23) is the SMD version of the BC251B transistor. These transistors are of the same type, have similar parameters and are designed for surface mounting.You can replace the BC251B with the BC256, BC256B, BC307, BC307B, BC327, BC416, BC416B, BC446, BC446B, BC448, BC448B, BC556, BC557 or BC560.