2SD1841 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 100 V
• Collector-Base Voltage, max: 110 V
• Emitter-Base Voltage, max: 6 V
• Collector Current − Continuous, max: 25 A
• Collector Dissipation: 120 W
• DC Current Gain (h_fe): 50 to 140
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: TO-3P

Here is an image showing the pin diagram of this transistor.The 2SD1841 transistor can have a current gain of 50 to 140. The gain of the 2SD1841-P will be in the range from 50 to 100, for the 2SD1841-Q it will be in the range from 70 to 140.Sometimes the "2S" prefix is not marked on the package - the 2SD1841 might only be marked "D1841".The complementary PNP transistor to the 2SD1841 is the 2SB1231.You can replace the 2SD1841 with the 2SD1842, BD249C or TIP35CA.