The BC517-D74Z is a Trans Darlington NPN 30V 1.2A 3-Pin TO-92 Ammo manufactured by ON Semiconductor. It is a high voltage and high current Darlinton switch. This part features a high gain of 1000, minimum saturation of 0.6V, low leakage current of 0.2mA, and a maximum power dissipation of 500mW. It is used in high frequency applications such as power supply applications, logical interfaces, and audio equipment. Additionally, it is designed to withstand reverse battery protection, high surge voltage, and operating temperature range of -40 to +85°C. The package size is an industry standard TO-92 package.