2N4921 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 40 V
• Collector-Base Voltage, max: 40 V
• Emitter-Base Voltage, max: 5 V
• Collector Current − Continuous, max: 4 A
• Collector Dissipation: 30 W
• DC Current Gain (h_fe): 30 to 150
• Transition Frequency, min: 3 MHz
• Operating and Storage Junction Temperature Range: -65 to +150 °C
• Package: TO-126

Here is an image showing the pin diagram of this transistor.The complementary PNP transistor to the 2N4921 is the 2N4918.You can replace the 2N4921 with the 2N4921G, 2N4922, 2N4922G, 2N4923, 2N4923G, MJE222, MJE225 or MJE242.