2SD1803 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 50 V
• Collector-Base Voltage, max: 60 V
• Emitter-Base Voltage, max: 6 V
• Collector Current − Continuous, max: 5 A
• Collector Dissipation: 20 W
• DC Current Gain (h_fe): 70 to 400
• Transition Frequency, min: 180 MHz
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: TO-251

Here is an image showing the pin diagram of this transistor.The 2SD1803 transistor can have a current gain of 70 to 400. The gain of the 2SD1803-Q will be in the range from 70 to 120, for the 2SD1803-R it will be in the range from 100 to 200, for the 2SD1803-S it will be in the range from 140 to 280, for the 2SD1803-T it will be in the range from 200 to 400.Sometimes the "2S" prefix is not marked on the package - the 2SD1803 might only be marked "D1803".The complementary PNP transistor to the 2SD1803 is the 2SB1203.You can replace the 2SD1803 with the 2SD1804.