2N5551 High-Voltage, Low-Current NPN Bipolar Junction Transistor

A NPN bipolar junction transistor rated at 160V collector-emitter and 600 mA collector current, used for high voltage switching and amplification - its 160V rating suits nixie tube drivers, high voltage bias circuits and mains-adjacent low current work. As a NPN device it sinks current to ground when its base is driven high. Always fit a base resistor when driving it from a microcontroller pin - connecting a base directly to a logic output will damage both. A common starting value is 1K for switching applications. 160V and 600 mA rating suits moderate loads; TO-92 through-hole package fits breadboards; Very low cost and widely documented; Standard pinout for the 2N5551 family