This part is a kind of semiconductor called BA159.

Function of this product has FAST SWITCHING PLASITC RECTIFIER.

Manufacturers : GOOD-ARK Electronics

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BA157 THRU BA159 FAST SWITCHING PLASITC RECTIFIER Reverse Voltage - 400 to 1000 Volts Forward Current - 1.0 Ampere Features Plastic package has Underwriters Laboratory Flammability Classification 94V-0 High surge current capabability Void-free plastic package Fast switching for high efficiency High temperature soldering guaranteed: 350 /10 seconds, 0.375” (9.5mm) lead length, 5 lbs. (2.3Kg) tension Mechanical Data Case: DO-41 molded plastic body Terminals: Plated axial leads, solderable per MIL-STD-750, method 2026 Polarity: Color band denotes cathode end Mounting Position: Any Weight: 0.012 ounce, 0.33 gram DIM ENSIONS DIM A B C D inches Min. 0.165 0.079 0.028 1.000 Max. 0.205 0.106 0.034 Min. 4.2 2.0 0.71 25.40 mm Max. 5.2 2.7 0.86 Note Maximum Ratings and Electrical Characteristics [ ... ]

BA159 PDF Datasheet Download