The BC817 40 from Hunan Jingxin Microelectronics is a Bipolar Junction Transistor with Collector Base Voltage 50 V, Continuous Collector Current 500 mA, DC Current Gain 250 to 600, Gain Bandwidth Product 100 MHz, Power Dissipation 0.3 W. Tags: Surface Mount, NPN Transistor. More details for BC817 40 can be seen below.