2SD666-D Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 80 V
• Collector-Base Voltage, max: 120 V
• Emitter-Base Voltage, max: 5 V
• Collector Current − Continuous, max: 0.05 A
• Collector Dissipation: 0.9 W
• DC Current Gain (h_fe): 160 to 320
• Transition Frequency, min: 140 MHz
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: TO-92MOD

Here is an image showing the pin diagram of this transistor.The 2SD666-D transistor can have a current gain of 160 to 320. The gain of the 2SD666 will be in the range from 60 to 320, for the 2SD666-B it will be in the range from 60 to 120, for the 2SD666-C it will be in the range from 100 to 200.Sometimes the "2S" prefix is not marked on the package - the 2SD666-D might only be marked "D666-D".The complementary PNP transistor to the 2SD666-D is the 2SB646-D.You can replace the 2SD666-D with the 2SC1509, 2SC2003, 2SC2230, 2SC2274K, 2SC2274K-F, 2SC2326, 2SC2326F, 2SC2326K, 2SC2326KF, 2SC2363, 2SC2363F, 2SC2383, 2SC2383-Y, 2SC2631, 2SC2632, 2SC2909, 2SC2910, 2SC3228, 2SC3228-Y, 2SC3245, 2SC3245A, 2SC3332, 2SC3708, 2SC3939, 2SD1211, 2SD438, 2SD438-F, 2SD667, 2SD667D, 2SD668, 2SD668-D, HSD1609S, HSD1609S-D, KSC1009C, KSC2383, KSC2383Y, KTC1006, KTC3228, KTC3228Y or NTE382.