The 2N4393 is a JFET (Junction Gate Field Effect Transistor) manufactured by Vishay. It is an N-channel enhancement type field effect transistor, meaning it is a 3 terminal device with a gate and two source/drain terminals. It is commonly used for voltage or current regulation, audio amplifiers, switching and other similar applications. The 2N4393 has a Drain-Source Voltage (VDS) max rating of 40V, a Gate-Source Voltage (VGS) max rating of 20V, and an Id max rating of 0.5A. It is typically available in either a TO-92 or a SOT-23 package.