MJE340 NPN Bipolar Power Transistor (TO-126)

Where most power transistors in a general parts bin top out at 60-100V, the MJE340 is specifically built for the 300V range needed in switch-mode power supply primary-side switching, CRT monitor driver circuits, and other high-voltage applications that would destroy a standard-voltage power transistor almost immediately. Its moderate 500mA current rating reflects its role as a high-voltage switching part rather than a high-current one, making it the right tool for circuits where voltage headroom, not raw current, is the limiting factor.