MMST4124 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 25 V
• Collector-Base Voltage, max: 30 V
• Emitter-Base Voltage, max: 5 V
• Collector Current − Continuous, max: 0.2 A
• Collector Dissipation: 0.2 W
• DC Current Gain (h_fe): 120 to 480
• Transition Frequency, min: 300 MHz
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: SOT-323
• Electrically Similar to the Popular 2N4124 transistor

Here is an image showing the pin diagram of this transistor.The MMST4124 transistor is marked as "K1B".The complementary PNP transistor to the MMST4124 is the MMST4126.The 2N4124 is the TO-92 version of the MMST4124.You can replace the MMST4124 with the BC817W or BC818W.