MMBT4400 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 40 V
• Collector-Base Voltage, max: 60 V
• Emitter-Base Voltage, max: 6 V
• Collector Current − Continuous, max: 0.6 A
• Collector Dissipation: 0.35 W
• DC Current Gain (h_fe): 50 to 150
• Transition Frequency, min: 200 MHz
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: SOT-23

Here is an image showing the pin diagram of this transistor.The MMBT4400 transistor is marked as "83".You can replace the MMBT4400 with the FMMT451.