2SD821 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 600 V
• Collector-Base Voltage, max: 1500 V
• Emitter-Base Voltage, max: 5 V
• Collector Current − Continuous, max: 6 A
• Collector Dissipation: 50 W
• DC Current Gain (h_fe): 8
• Transition Frequency, min: 3 MHz
• Operating and Storage Junction Temperature Range: -65 to +150 °C
• Package: TO-3

Here is an image showing the pin diagram of this transistor.Sometimes the "2S" prefix is not marked on the package - the 2SD821 might only be marked "D821".You can replace the 2SD821 with the 2SD822, 2SD871, BUX48B, BUX48C, MJ12005, MJ8504 or MJ8505.