The 0B2 (sometimes labelled OB2) is a miniature, inert gas-filled, cold-cathode vacuum tube designed for use as a voltage regulator or reference. It typically maintains a regulated voltage of about 108 volts across a current range from 5 to 30 mA

This tube operates similarly to a Zener diode but provides much greater stability and lower thermal drift—making it especially suitable for precision power supply circuits, audio amplifiers, and radio equipment

As a Sovtek-branded tube, the 0B2 reflects Russian electronics manufacturing heritage. Sovtek is a brand of vacuum tubes owned by New Sensor Corporation, produced in Saratov, Russia, and widely used in guitar amplifiers and professional audio gear