BUL128 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 400 V
• Collector-Base Voltage, max: 700 V
• Emitter-Base Voltage, max: 9 V
• Collector Current − Continuous, max: 4 A
• Collector Dissipation: 70 W
• DC Current Gain (h_fe): 14 to 40
• Operating and Storage Junction Temperature Range: -65 to +150 °C
• Package: TO-220

Here is an image showing the pin diagram of this transistor.The BUL128 transistor can have a current gain of 14 to 40. The gain of the BUL128A will be in the range from 14 to 28, for the BUL128B it will be in the range from 25 to 40.You can replace the BUL128 with the 2N6740, 2SC3056, 2SC3056A, 2SC3057, 2SC3310, 2SC3795, 2SC3795A, 2SC4242, 2SC5241, BUL128FP, FJP13007, FJP13009, KSE13005, KSE13007, KSE13007F, KSE13009, MJE13005, MJE13005G, MJE13007, MJE13007A, MJE13007G, MJE13009, MJE13009G, MJE13070, MJE13071, MJE16002, MJE16004, MJE8502, MJE8503, STD13007, STD13007F, STD13007FC or STD13007P.